From 8f02bf0b94b8fd5c8a6ada9fa86acd76fc2d5915 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Mon, 13 May 2024 10:21:13 +0100
Subject: [PATCH 01/38] Separate IsGVGraph and IsGVDigraph

---
 gap/dot.gd    |  51 ++++++++------
 gap/dot.gi    | 190 +++++++++++++++++++++++++-------------------------
 gap/splash.gi |   4 +-
 3 files changed, 125 insertions(+), 120 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 3921015..86c50b3 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -35,12 +35,15 @@
 #! objects. These are graphs, digraphs, nodes and edges respectively.
 #! All are direct subcategories of IsGVObject excluding IsGVDigraph which is a
 #! subcategory of is GVGraph.
+
+# TODO replace GV -> graphviz
 DeclareCategory("IsGVObject", IsObject);
-DeclareCategory("IsGVGraph", IsGVObject);
+DeclareCategory("IsGVGraphOrDigraph", IsGVObject);
 # TODO change to IsGVObject below, since digraphs aren't a special kind of
 # graph, unless I'm (JDM) mistaken?
-DeclareCategory("IsGVDigraph", IsGVGraph);
-DeclareCategory("IsGVContext", IsGVGraph);
+DeclareCategory("IsGVGraph", IsGVGraphOrDigraph);
+DeclareCategory("IsGVDigraph", IsGVGraphOrDigraph);
+DeclareCategory("IsGVContext", IsGVGraphOrDigraph);
 DeclareCategory("IsGVNode", IsGVObject);
 DeclareCategory("IsGVEdge", IsGVObject);
 #! @EndGroup
@@ -87,14 +90,14 @@ DeclareOperation("GraphvizAttrs", [IsGVObject]);
 #! @Returns the nodes of the provided graphviz graph.
 #! @Description Gets the nodes of the provided graphviz graph.
 #! Node names can only be [a-zA-Z0-9_£] TODO check exact docs.
-DeclareOperation("GraphvizNodes", [IsGVGraph]);
-DeclareOperation("GraphvizNode", [IsGVGraph, IsObject]);
+DeclareOperation("GraphvizNodes", [IsGVGraphOrDigraph]);
+DeclareOperation("GraphvizNode", [IsGVGraphOrDigraph, IsObject]);
 
 #! @Arguments graph
 #! @Returns the subgraphs of the provided graphviz graph.
 #! @Description gets the subgraphs of a provided graphviz graph.
-DeclareOperation("GraphvizSubgraphs", [IsGVGraph]);
-DeclareOperation("GraphvizGetSubgraph", [IsGVGraph, IsObject]);
+DeclareOperation("GraphvizSubgraphs", [IsGVGraphOrDigraph]);
+DeclareOperation("GraphvizGetSubgraph", [IsGVGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, name
 #! @Returns a graph with the provided name.
@@ -103,13 +106,13 @@ DeclareOperation("GraphvizGetSubgraph", [IsGVGraph, IsObject]);
 #! with the provided name.
 #! It returns the graph if it exists.
 #! If no such graph exists then it will return fail.
-DeclareOperation("GraphvizFindGraph", [IsGVGraph, IsObject]);
+DeclareOperation("GraphvizFindGraph", [IsGVGraphOrDigraph, IsObject]);
 
 #! @Arguments graph
 #! @Returns the edges of the provided graphviz graph.
 #! @Description Gets the edges of the provided graphviz graph.
-DeclareOperation("GraphvizEdges", [IsGVGraph]);
-DeclareOperation("GraphvizEdges", [IsGVGraph, IsObject, IsObject]);
+DeclareOperation("GraphvizEdges", [IsGVGraphOrDigraph]);
+DeclareOperation("GraphvizEdges", [IsGVGraphOrDigraph, IsObject, IsObject]);
 
 #! @Subsection For only edges.
 
@@ -131,13 +134,13 @@ DeclareOperation("GraphvizTail", [IsGVEdge]);
 #! @Arguments graph, name
 #! @Returns the modified graph.
 #! @Description Sets the name of a graphviz graph or digraph.
-DeclareOperation("GraphvizSetName", [IsGVGraph, IsObject]);
+DeclareOperation("GraphvizSetName", [IsGVGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Adds a node to the graph.
 #! If a node with the same name is already present the operation fails.
-DeclareOperation("GraphvizAddNode", [IsGVGraph, IsObject]);
+DeclareOperation("GraphvizAddNode", [IsGVGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, edge
 #! @Returns the modified graph.
@@ -145,35 +148,35 @@ DeclareOperation("GraphvizAddNode", [IsGVGraph, IsObject]);
 #! If no nodes with the same name are in the graph then the edge's nodes will be
 #! added to the graph. If different nodes with the same name are in the graph
 #! then the operation fails.
-DeclareOperation("GraphvizAddEdge", [IsGVGraph, IsObject, IsObject]);
+DeclareOperation("GraphvizAddEdge", [IsGVGraphOrDigraph, IsObject, IsObject]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new subgraph.
 #! @Description Adds a subgraph to a graph.
-DeclareOperation("GraphvizAddSubgraph", [IsGVGraph, IsObject]);
-DeclareOperation("GraphvizAddSubgraph", [IsGVGraph]);
+DeclareOperation("GraphvizAddSubgraph", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizAddSubgraph", [IsGVGraphOrDigraph]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new context.
 #! @Description Adds a context to a graph.
-DeclareOperation("GraphvizAddContext", [IsGVGraph, IsObject]);
-DeclareOperation("GraphvizAddContext", [IsGVGraph]);
+DeclareOperation("GraphvizAddContext", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizAddContext", [IsGVGraphOrDigraph]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Removes the node from the graph.
-DeclareOperation("GraphvizRemoveNode", [IsGVGraph, IsObject]);
+DeclareOperation("GraphvizRemoveNode", [IsGVGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, predicate
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges using the provided predicate.
-DeclareOperation("GraphvizFilterEdges", [IsGVGraph, IsFunction]);
+DeclareOperation("GraphvizFilterEdges", [IsGVGraphOrDigraph, IsFunction]);
 
 #! @Arguments graph, head_name, tail_name
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges, removing edges between nodes with
 #! the specified names.
-DeclareOperation("GraphvizFilterEnds", [IsGVGraph, IsObject, IsObject]);
+DeclareOperation("GraphvizFilterEnds", [IsGVGraphOrDigraph, IsObject, IsObject]);
 
 #! @Subsection For modifying object attributes.
 
@@ -214,7 +217,9 @@ DeclareOperation("GraphvizRemoveAttr", [IsGVObject, IsObject]);
 #! @Section Outputting
 #! @Arguments graph
 #! @Returns the dot representation of the graphviz object.
-DeclareOperation("AsString", [IsGVGraph]);
+DeclareOperation("AsString", [IsGVGraphOrDigraph]);
+
+# TODO PrintObj
 
 #! @Arguments obj
 #! @Returns the graphviz representation of the object.
@@ -223,6 +228,6 @@ DeclareOperation("AsString", [IsGVGraph]);
 #!  Should output the graphviz package representation of the object.
 DeclareOperation("Graphviz", [IsObject]);
 
-DeclareOperation("GraphvizSetNodeColors", [IsGVGraph, IsList]);
-DeclareOperation("GraphvizSetNodeLabels", [IsGVGraph, IsList]);
+DeclareOperation("GraphvizSetNodeColors", [IsGVGraphOrDigraph, IsList]);
+DeclareOperation("GraphvizSetNodeLabels", [IsGVGraphOrDigraph, IsList]);
 DeclareGlobalFunction("ErrorFormatted");
diff --git a/gap/dot.gi b/gap/dot.gi
index 2dfa745..82f3bcd 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -50,21 +50,21 @@ function(arg...)
       [msg]);
 end);
 
-DeclareOperation("GV_GetCounter", [IsGVGraph]);
-DeclareOperation("GV_IncCounter", [IsGVGraph]);
-DeclareCategory("IsGV_Map", IsObject);
-DeclareAttribute("Size", IsGV_Map);
-
-DeclareOperation("GV_StringifyGraphHead", [IsGVGraph]);
-DeclareOperation("GV_StringifyDigraphHead", [IsGVGraph]);
-DeclareOperation("GV_StringifySubgraphHead", [IsGVGraph]);
-DeclareOperation("GV_StringifyContextHead", [IsGVGraph]);
+DeclareOperation("GV_GetCounter", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_IncCounter", [IsGVGraphOrDigraph]);
+DeclareCategory("GV_IsMap", IsObject);
+DeclareAttribute("Size", GV_IsMap);
+
+DeclareOperation("GV_StringifyGraphHead", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifyDigraphHead", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifySubgraphHead", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifyContextHead", [IsGVGraphOrDigraph]);
 DeclareOperation("GV_StringifyNode", [IsGVNode]);
-DeclareOperation("GV_StringifyGraphAttrs", [IsGVGraph]);
-DeclareOperation("GV_StringifyNodeEdgeAttrs", [IsGV_Map]);
-DeclareOperation("GV_StringifyGraph", [IsGVGraph, IsBool]);
+DeclareOperation("GV_StringifyGraphAttrs", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifyNodeEdgeAttrs", [GV_IsMap]);
+DeclareOperation("GV_StringifyGraph", [IsGVGraphOrDigraph, IsBool]);
 
-DeclareOperation("GV_FindNode", [IsGVGraph, IsObject]);
+DeclareOperation("GV_FindNode", [IsGVGraphOrDigraph, IsObject]);
 
 ## COPY OF GAP PLURALIZE TO ALLOW OLD VERSIONS OF GAP TO USE THE PACKAGE
 DeclareOperation("GV_Pluralize", [IsInt, IsString]);
@@ -307,7 +307,7 @@ BindGlobal("GV_ObjectFamily",
                      IsGVObject));
 
 BindGlobal("GV_MapType", NewType(GV_ObjectFamily,
-                                 IsGV_Map and
+                                 GV_IsMap and
                                  IsComponentObjectRep and
                                  IsAttributeStoringRep));
 
@@ -344,18 +344,18 @@ InstallMethod(\=, "for IsGVNode and IsGVNode",
 # Constructors etc
 ###############################################################################
 
-DeclareOperation("GV_Node", [IsGVGraph, IsString]);
-DeclareOperation("GV_Edge", [IsGVGraph, IsGVNode, IsGVNode]);
-DeclareOperation("GV_Graph", [IsGVGraph, IsString]);
+DeclareOperation("GV_Node", [IsGVGraphOrDigraph, IsString]);
+DeclareOperation("GV_Edge", [IsGVGraphOrDigraph, IsGVNode, IsGVNode]);
+DeclareOperation("GV_Graph", [IsGVGraphOrDigraph, IsString]);
 DeclareOperation("GV_Digraph", [IsGVDigraph, IsString]);
-DeclareOperation("GV_Context", [IsGVGraph, IsString]);
+DeclareOperation("GV_Context", [IsGVGraphOrDigraph, IsString]);
 DeclareOperation("GV_Map", []);
 
 InstallMethod(GV_Map, "for no args",
 [], {} -> Objectify(GV_MapType, rec(Data := rec())));
 
 InstallMethod(GV_Node, "for a string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(graph, name)
   local out;
   if Length(name) = 0 then
@@ -371,7 +371,7 @@ function(graph, name)
 end);
 
 InstallMethod(GV_Edge, "for two graphviz nodes",
-[IsGVGraph, IsGVNode, IsGVNode],
+[IsGVGraphOrDigraph, IsGVNode, IsGVNode],
 function(graph, head, tail)
   local out;
   out := Objectify(GV_EdgeType,
@@ -403,7 +403,7 @@ end);
 
 InstallMethod(GV_Graph,
 "for a graphviz graph and a string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(parent, name)
   local out;
 
@@ -417,7 +417,7 @@ end);
 
 InstallMethod(GV_Context,
 "for a string and a positive integer",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(parent, name)
   local out;
 
@@ -489,7 +489,7 @@ InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
 
 InstallOtherMethod(\[\],
 "for a graphviz map and an object",
-[IsGV_Map, IsObject],
+[GV_IsMap, IsObject],
 function(m, o)
   if IsBound(m[o]) then
     return m!.Data.(o);
@@ -499,33 +499,33 @@ end);
 
 InstallOtherMethod(\[\]\:\=,
 "for a graphviz map and two objects",
-[IsGV_Map, IsObject, IsObject],
+[GV_IsMap, IsObject, IsObject],
 function(m, key, val)
   m!.Data.(key) := val;
 end);
 
 InstallOtherMethod(Unbind\[\],
 "for a graphviz map and an object",
-[IsGV_Map, IsObject],
+[GV_IsMap, IsObject],
 function(m, key)
   Unbind(m!.Data.(key));
 end);
 
 InstallOtherMethod(IsBound\[\],
 "for a graphviz map and an object",
-[IsGV_Map, IsObject],
+[GV_IsMap, IsObject],
 {m, key} -> IsBound(m!.Data.(key)));
 
-DeclareOperation("GV_MapNames", [IsGV_Map]);
+DeclareOperation("GV_MapNames", [GV_IsMap]);
 
 InstallMethod(GV_MapNames, "for a graphviz map",
-[IsGV_Map], m -> RecNames(m!.Data));
+[GV_IsMap], m -> RecNames(m!.Data));
 
-InstallMethod(ViewString, "for a graphviz map", [IsGV_Map],
+InstallMethod(ViewString, "for a graphviz map", [GV_IsMap],
 m -> String(m!.Data));
 
 InstallMethod(Size, "for a graphviz map",
-[IsGV_Map], m -> Length(GV_MapNames(m)));
+[GV_IsMap], m -> Length(GV_MapNames(m)));
 
 ############################################################
 # Stringify
@@ -544,7 +544,7 @@ function(e)
                          GraphvizName(tail));
 end);
 
-InstallMethod(ViewString, "for a graphviz graph", [IsGVGraph],
+InstallMethod(ViewString, "for a graphviz graph", [IsGVGraphOrDigraph],
 function(g)
   local result, edges, nodes, kind;
 
@@ -585,20 +585,20 @@ x -> x!.Attrs);
 # TODO remove, the returned value is mutable, looks like a record but isn't
 # one. Mutability is a problem, since if we do GraphvizNodes(gv)[1] := 2; then
 # the object is corrupt.
-InstallMethod(GraphvizNodes, "for a graphviz graph", [IsGVGraph],
+InstallMethod(GraphvizNodes, "for a graphviz graph", [IsGVGraphOrDigraph],
 x -> x!.Nodes);
 
 InstallMethod(GraphvizNode, "for a graphviz graph and object",
-[IsGVGraph, IsObject], {gv, obj} -> gv!.Nodes[String(obj)]);
+[IsGVGraphOrDigraph, IsObject], {gv, obj} -> gv!.Nodes[String(obj)]);
 
 # TODO remove for the same reason as GraphvizNodes, unless we can make the list
 # immutable or return a copy.
 InstallMethod(GraphvizEdges, "for a graphviz graph",
-[IsGVGraph], x -> x!.Edges);
+[IsGVGraphOrDigraph], x -> x!.Edges);
 
 InstallMethod(GraphvizEdges,
 "for a graphviz graph, object, and object",
-[IsGVGraph, IsObject, IsObject],
+[IsGVGraphOrDigraph, IsObject, IsObject],
 function(gv, head, tail)
     head := GraphvizNode(gv, head);
     tail := GraphvizNode(gv, tail);
@@ -607,7 +607,7 @@ function(gv, head, tail)
     GraphvizTail(x) = tail);
 end);
 
-InstallMethod(GraphvizSubgraphs, "for a graphviz graph", [IsGVGraph],
+InstallMethod(GraphvizSubgraphs, "for a graphviz graph", [IsGVGraphOrDigraph],
 x -> x!.Subgraphs);
 
 InstallMethod(GraphvizTail, "for a graphviz edge", [IsGVEdge], x -> x!.Tail);
@@ -616,22 +616,22 @@ InstallMethod(GraphvizHead, "for a graphviz edge", [IsGVEdge], x -> x!.Head);
 
 InstallMethod(GraphvizGetSubgraph,
 "for a graphviz graph and string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 {x, name} -> GraphvizSubgraphs(x)[name]);
 
 InstallMethod(GraphvizGetSubgraph,
 "for a graphviz graph and an object",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 {x, o} -> GraphvizSubgraphs(x)[ViewString(o)]);
 
 InstallMethod(GV_IncCounter,
 "for a graphviz graph",
-[IsGVGraph],
+[IsGVGraphOrDigraph],
 function(x)
   x!.Counter := x!.Counter + 1;
 end);
 
-InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGVGraph],
+InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGVGraphOrDigraph],
 x -> x!.Counter);
 
 # Converting strings
@@ -703,32 +703,32 @@ end);
 
 InstallOtherMethod(\[\],
 "for a graphviz graph and string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 {graph, node} -> GraphvizNodes(graph)[node]);
 
 InstallOtherMethod(\[\],
 "for a graphviz graph and string",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 {g, o} -> g[ViewString(o)]);
 
-DeclareOperation("GV_HasNode", [IsGVGraph, IsObject]);
+DeclareOperation("GV_HasNode", [IsGVGraphOrDigraph, IsObject]);
 
 InstallMethod(GV_HasNode,
 "for a graphviz graph",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 {g, name} -> name in GV_MapNames(GraphvizNodes(g)));
 
-DeclareOperation("GV_GetParent", [IsGVGraph]);
+DeclareOperation("GV_GetParent", [IsGVGraphOrDigraph]);
 
 InstallMethod(GV_GetParent,
 "for a graphviz graph",
-[IsGVGraph], graph -> graph!.Parent);
+[IsGVGraphOrDigraph], graph -> graph!.Parent);
 
-DeclareOperation("GV_GraphTreeSearch", [IsGVGraph, IsFunction]);
+DeclareOperation("GV_GraphTreeSearch", [IsGVGraphOrDigraph, IsFunction]);
 
 InstallMethod(GV_GraphTreeSearch,
 "for a graphviz graph and a predicate",
-[IsGVGraph, IsFunction],
+[IsGVGraphOrDigraph, IsFunction],
 function(graph, pred)
   local seen, to_visit, g, key, subgraph, parent;
   seen     := [graph];
@@ -753,7 +753,7 @@ function(graph, pred)
 
     # add parent if not visited
     parent := GV_GetParent(g);
-    if not IsGVGraph(parent) then
+    if not IsGVGraphOrDigraph(parent) then
       continue;
     fi;
     if not ForAny(seen, s -> IsIdenticalObj(s, parent)) then
@@ -765,16 +765,16 @@ function(graph, pred)
   return fail;
 end);
 
-DeclareOperation("GV_FindGraphWithNode", [IsGVGraph, IsString]);
+DeclareOperation("GV_FindGraphWithNode", [IsGVGraphOrDigraph, IsString]);
 InstallMethod(GV_FindGraphWithNode,
 "for a graphviz graph and a node",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 {g, n} -> GV_GraphTreeSearch(g, v -> v[n] <> fail));
 
-DeclareOperation("GV_GetRoot", [IsGVGraph]);
+DeclareOperation("GV_GetRoot", [IsGVGraphOrDigraph]);
 InstallMethod(GV_GetRoot,
 "for a graphviz graph",
-[IsGVGraph],
+[IsGVGraphOrDigraph],
 function(graph)
   while GV_GetParent(graph) <> fail do
     graph := GV_GetParent(graph);
@@ -784,17 +784,17 @@ end);
 
 InstallMethod(GraphvizFindGraph,
 "for a graphviz graph and a string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 {g, s} -> GV_GraphTreeSearch(g, v -> GraphvizName(v) = s));
 
 InstallMethod(GraphvizFindGraph,
 "for a graphviz graph and a string",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 {g, o} -> GraphvizFindGraph(g, ViewString(o)));
 
 InstallMethod(GV_FindNode,
 "for a graphviz graph and a string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(g, n)
   local graph;
   graph := GV_FindGraphWithNode(g, n);
@@ -809,14 +809,14 @@ end);
 ############################################################
 
 InstallMethod(GraphvizSetName, "for a graphviz object and string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(x, name)
   x!.Name := name;
   return x;
 end);
 
 InstallMethod(GraphvizSetName, "for a graphviz object and string",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 {g, o} -> GraphvizSetName(g, ViewString(o)));
 
 InstallMethod(GraphvizSetAttrs, "for a graphviz object and record",
@@ -846,7 +846,7 @@ function(x, name, value)
 end);
 
 InstallMethod(GraphvizSetAttr, "for a graphviz graph, object and object",
-[IsGVGraph, IsObject, IsObject],
+[IsGVGraphOrDigraph, IsObject, IsObject],
 function(x, name, value)
   local attrs, string, msg;
 
@@ -874,7 +874,7 @@ function(x, name, value)
 end);
 
 InstallMethod(GraphvizSetAttr, "for a graphviz object, object and object",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 function(x, value)
   local attrs;
   attrs := GraphvizAttrs(x);
@@ -893,10 +893,10 @@ InstallMethod(GraphvizSetColor,
 [IsGVObject, IsObject],
 {x, color} -> GraphvizSetAttr(x, "color", color));
 
-DeclareOperation("GV_AddNode", [IsGVGraph, IsGVNode]);
+DeclareOperation("GV_AddNode", [IsGVGraphOrDigraph, IsGVNode]);
 InstallMethod(GV_AddNode,
 "for a graphviz graph and node",
-[IsGVGraph, IsGVNode],
+[IsGVGraphOrDigraph, IsGVNode],
 function(x, node)
   local found, error, name, nodes;
   name  := GraphvizName(node);
@@ -914,7 +914,7 @@ function(x, node)
 end);
 
 InstallMethod(GraphvizAddNode, "for a graphviz graph and string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(x, name)
   local node;
   node := GV_Node(x, name);
@@ -924,7 +924,7 @@ end);
 
 # TODO required?
 InstallMethod(GraphvizAddNode, "for a graphviz graph and string",
-[IsGVGraph, IsGVNode],
+[IsGVGraphOrDigraph, IsGVNode],
 function(_, __)  # gaplint: disable=analyse-lvars
   local error;
   error := "Cannot add node objects directly to graphs. ";
@@ -934,13 +934,13 @@ end);
 
 InstallMethod(GraphvizAddNode,
 "for a graphviz graph and string",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 {x, name} -> GraphvizAddNode(x, ViewString(name)));
 
-DeclareOperation("GV_AddEdge", [IsGVGraph, IsGVEdge]);
+DeclareOperation("GV_AddEdge", [IsGVGraphOrDigraph, IsGVEdge]);
 InstallMethod(GV_AddEdge,
 "for a graphviz graph and edge",
-[IsGVGraph, IsGVEdge],
+[IsGVGraphOrDigraph, IsGVEdge],
 function(x, edge)
   local head, head_name, tail_name, tail, hg, error, tg;
 
@@ -980,7 +980,7 @@ end);
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz graph and two graphviz nodes",
-[IsGVGraph, IsGVNode, IsGVNode],
+[IsGVGraphOrDigraph, IsGVNode, IsGVNode],
 function(x, head, tail)
   local edge, head_name, tail_name;
 
@@ -1002,7 +1002,7 @@ end);
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz graph and two strings",
-[IsGVGraph, IsString, IsString],
+[IsGVGraphOrDigraph, IsString, IsString],
 function(x, head, tail)
   local head_node, tail_node;
 
@@ -1021,7 +1021,7 @@ end);
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz graph and two objects",
-[IsGVGraph, IsObject, IsObject],
+[IsGVGraphOrDigraph, IsObject, IsObject],
 function(x, o1, o2)
   if not IsString(o1) then
     o1 := ViewString(o1);
@@ -1034,7 +1034,7 @@ end);
 
 InstallMethod(GraphvizAddSubgraph,
 "for a graphviz graph and string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(graph, name)
   local error, subgraphs, subgraph;
 
@@ -1046,7 +1046,7 @@ function(graph, name)
 
   if IsGVDigraph(graph) then
     subgraph := GV_Digraph(graph, name);
-  elif IsGVGraph(graph) then
+  elif IsGVGraph(graph) or IsGVContext(graph) then
     subgraph := GV_Graph(graph, name);
   else
     ErrorNoReturn("Filter must be a filter for a graph category.");
@@ -1058,12 +1058,12 @@ end);
 
 InstallMethod(GraphvizAddSubgraph,
 "for a graphviz graph and an object",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 {g, o} -> GraphvizAddSubgraph(g, ViewString(o)));
 
 InstallMethod(GraphvizAddSubgraph,
 "for a grpahviz graph",
-[IsGVGraph],
+[IsGVGraphOrDigraph],
 function(graph)
   return GraphvizAddSubgraph(graph, StringFormatted("no_name_{}",
                                                String(GV_GetCounter(graph))));
@@ -1071,7 +1071,7 @@ end);
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz graph and a string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(graph, name)
   local ctx, error, subgraphs;
 
@@ -1088,23 +1088,23 @@ end);
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz graph",
-[IsGVGraph],
+[IsGVGraphOrDigraph],
 g -> GraphvizAddContext(g, StringFormatted("no_name_{}",
                                       String(GV_GetCounter(g)))));
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz graph and an object",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 {g, o} -> GraphvizAddContext(g, ViewString(o)));
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz graph and node",
-[IsGVGraph, IsGVNode],
+[IsGVGraphOrDigraph, IsGVNode],
 {g, node} -> GraphvizRemoveNode(g, GraphvizName(node)));
 
 # TODO GraphvizRemoveEdges(gv, n1, n2)
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz graph and a string",
-[IsGVGraph, IsString],
+[IsGVGraphOrDigraph, IsString],
 function(g, name)
   local nodes;
   # TODO error if there's no such node
@@ -1124,11 +1124,11 @@ function(g, name)
 end);
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz graph and a string",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 {g, o} -> GraphvizRemoveNode(g, ViewString(o)));
 
 InstallMethod(GraphvizFilterEdges, "for a graphviz graph and edge filter",
-[IsGVGraph, IsFunction],
+[IsGVGraphOrDigraph, IsFunction],
 function(g, filter)
   local edge, idx, edges;
 
@@ -1146,7 +1146,7 @@ function(g, filter)
 end);
 
 InstallMethod(GraphvizFilterEnds, "for a graphviz graph and two strings",
-[IsGVGraph, IsString, IsString],
+[IsGVGraphOrDigraph, IsString, IsString],
 function(g, hn, tn)
   GraphvizFilterEdges(g,
     function(e)
@@ -1165,7 +1165,7 @@ function(g, hn, tn)
 end);
 
 InstallMethod(GraphvizFilterEnds, "for a graphviz graph and two strings",
-[IsGVGraph, IsObject, IsObject],
+[IsGVGraphOrDigraph, IsObject, IsObject],
 function(g, o1, o2)
   if not IsString(o1) then
     o1 := ViewString(o1);
@@ -1187,7 +1187,7 @@ function(obj, attr)
 end);
 
 InstallMethod(GraphvizRemoveAttr, "for a graphviz graph and an object",
-[IsGVGraph, IsObject],
+[IsGVGraphOrDigraph, IsObject],
 function(obj, attr)
   local attrs;
   attrs      := GraphvizAttrs(obj);
@@ -1200,7 +1200,7 @@ end);
 # ##############################################################################
 
 # @ Return DOT graph head line.
-InstallMethod(GV_StringifyGraphHead, "for a string", [IsGVGraph],
+InstallMethod(GV_StringifyGraphHead, "for a string", [IsGVGraphOrDigraph],
 graph -> StringFormatted("graph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT digraph head line.
@@ -1208,7 +1208,7 @@ InstallMethod(GV_StringifyDigraphHead, "for a string", [IsGVDigraph],
 graph -> StringFormatted("digraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
-InstallMethod(GV_StringifySubgraphHead, "for a string", [IsGVGraph],
+InstallMethod(GV_StringifySubgraphHead, "for a string", [IsGVGraphOrDigraph],
 graph -> StringFormatted("subgraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
@@ -1267,7 +1267,7 @@ end);
 
 InstallMethod(GV_StringifyGraphAttrs,
 "for a graphviz graph",
-[IsGVGraph],
+[IsGVGraphOrDigraph],
 function(graph)
   local result, attrs, kv;
   attrs  := GraphvizAttrs(graph);
@@ -1286,7 +1286,7 @@ end);
 
 InstallMethod(GV_StringifyNodeEdgeAttrs,
 "for a GV_Map",
-[IsGV_Map],
+[GV_IsMap],
 function(attrs)
   local result, keys, key, val, n, i, tmp;
 
@@ -1351,10 +1351,10 @@ InstallMethod(GV_GetIdx,
 [IsGVObject],
 x -> x!.Idx);
 
-DeclareOperation("GV_ConstructHistory", [IsGVGraph]);
+DeclareOperation("GV_ConstructHistory", [IsGVGraphOrDigraph]);
 InstallMethod(GV_ConstructHistory,
 "for a graphviz graph",
-[IsGVGraph],
+[IsGVGraphOrDigraph],
 function(graph)
   local nodes, edges, subs, node_hist, edge_hist, subs_hist, hist;
 
@@ -1375,7 +1375,7 @@ end);
 
 InstallMethod(GV_StringifyGraph,
 "for a graphviz graph and a string",
-[IsGVGraph, IsBool],
+[IsGVGraphOrDigraph, IsBool],
 function(graph, is_subgraph)
   local result, obj;
   result := "";
@@ -1406,7 +1406,7 @@ function(graph, is_subgraph)
 
   # Add child graphviz objects
   for obj in GV_ConstructHistory(graph) do
-    if IsGVGraph(obj) then
+    if IsGVGraphOrDigraph(obj) then
       Append(result, GV_StringifyGraph(obj, true));
     elif IsGVNode(obj) then
       Append(result, GV_StringifyNode(obj));
@@ -1434,7 +1434,7 @@ function(graph, is_subgraph)
 end);
 
 InstallMethod(AsString, "for a graphviz graph",
-[IsGVGraph],
+[IsGVGraphOrDigraph],
 graph -> GV_StringifyGraph(graph, false));
 
 BindGlobal("GV_IsValidRGBColor",
@@ -1487,7 +1487,7 @@ end);
 
 InstallMethod(GraphvizSetNodeLabels,
 "for a graphviz graph and list of colors",
-[IsGVGraph, IsList],
+[IsGVGraphOrDigraph, IsList],
 function(gv, labels)
   local nodes, i;
   # TODO error if labels and nodes aren't same size
@@ -1501,7 +1501,7 @@ end);
 
 InstallMethod(GraphvizSetNodeColors,
 "for a graphviz graph and list of colors",
-[IsGVGraph, IsList],
+[IsGVGraphOrDigraph, IsList],
 function(gv, colors)
   local nodes, i;
 
diff --git a/gap/splash.gi b/gap/splash.gi
index 4effacb..17cb9be 100644
--- a/gap/splash.gi
+++ b/gap/splash.gi
@@ -12,10 +12,10 @@ if not IsBound(Splash) then
 
     if IsEmpty(arg) then
       ErrorNoReturn("the must be at least 1 argument, found none");
-    elif not IsString(arg[1]) and not IsGVGraph(arg[1]) then
+    elif not IsString(arg[1]) and not IsGVGraphOrDigraph(arg[1]) then
       ErrorFormatted("the 1st argument must be a string or ",
                      "graphviz graph, found {}", TNAM_OBJ(arg[1]));
-    elif IsGVGraph(arg[1]) then
+    elif IsGVGraphOrDigraph(arg[1]) then
       arg[1] := AsString(arg[1]);
     fi;
     str := arg[1];

From 73573811c4c563bca387e02e58cd172da5e18328 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Mon, 13 May 2024 10:24:20 +0100
Subject: [PATCH 02/38] Separate file for ErrorFormatted

---
 gap/dot.gd   |  1 -
 gap/dot.gi   | 37 -------------------------------------
 gap/error.gd | 11 +++++++++++
 gap/error.gi | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 init.g       |  1 +
 read.g       |  3 ++-
 6 files changed, 61 insertions(+), 39 deletions(-)
 create mode 100644 gap/error.gd
 create mode 100644 gap/error.gi

diff --git a/gap/dot.gd b/gap/dot.gd
index 86c50b3..5d36e3b 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -230,4 +230,3 @@ DeclareOperation("Graphviz", [IsObject]);
 
 DeclareOperation("GraphvizSetNodeColors", [IsGVGraphOrDigraph, IsList]);
 DeclareOperation("GraphvizSetNodeLabels", [IsGVGraphOrDigraph, IsList]);
-DeclareGlobalFunction("ErrorFormatted");
diff --git a/gap/dot.gi b/gap/dot.gi
index 82f3bcd..259ad57 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -12,43 +12,6 @@
 # Private functionality
 #############################################################################
 
-BindGlobal("NumberOfSubstrings",
-function(string, substring)
-  local pos, count;
-
-  pos := 0;
-  count := 0;
-  while pos <= Length(string) and pos <> fail do
-    pos := PositionSublist(string, substring, pos);
-    if pos <> fail then
-      count := count + 1;
-    fi;
-  od;
-  return count;
-end);
-
-InstallGlobalFunction(ErrorFormatted,
-function(arg...)
-  local pos, fmt, n, msg;
-
-  pos := PositionProperty(arg, x -> not IsString(x));
-  if pos = fail then
-    pos := Length(arg) + 1;
-  fi;
-  fmt := Concatenation(arg{[1 .. pos - 1]});
-  n := NumberOfSubstrings(fmt, "{}");
-  arg := Concatenation([Concatenation(arg{[1 .. Length(arg) - n]})],
-                       arg{[Length(arg) - n + 1 .. Length(arg)]});
-  msg := CallFuncList(StringFormatted, arg);
-  # RemoveCharacters(msg, "\\\n");
-  ErrorInner(
-      rec(context := ParentLVars(GetCurrentLVars()),
-          mayReturnVoid := false,
-          mayReturnObj := false,
-          lateMessage := "type 'quit;' to quit to outer loop",
-          printThisStatement := false),
-      [msg]);
-end);
 
 DeclareOperation("GV_GetCounter", [IsGVGraphOrDigraph]);
 DeclareOperation("GV_IncCounter", [IsGVGraphOrDigraph]);
diff --git a/gap/error.gd b/gap/error.gd
new file mode 100644
index 0000000..56fea6d
--- /dev/null
+++ b/gap/error.gd
@@ -0,0 +1,11 @@
+#############################################################################
+##
+##  error.gd
+##  Copyright (C) 2024                                      James Mitchell
+##
+##  Licensing information can be found in the README file of this package.
+##
+#############################################################################
+##
+
+DeclareGlobalFunction("ErrorFormatted");
diff --git a/gap/error.gi b/gap/error.gi
new file mode 100644
index 0000000..605e83c
--- /dev/null
+++ b/gap/error.gi
@@ -0,0 +1,47 @@
+#############################################################################
+##
+##  error.gi
+##  Copyright (C) 2024                                      James Mitchell
+##
+##  Licensing information can be found in the README file of this package.
+##
+#############################################################################
+##
+
+BindGlobal("NumberOfSubstrings",
+function(string, substring)
+  local pos, count;
+
+  pos := 0;
+  count := 0;
+  while pos <= Length(string) and pos <> fail do
+    pos := PositionSublist(string, substring, pos);
+    if pos <> fail then
+      count := count + 1;
+    fi;
+  od;
+  return count;
+end);
+
+InstallGlobalFunction(ErrorFormatted,
+function(arg...)
+  local pos, fmt, n, msg;
+
+  pos := PositionProperty(arg, x -> not IsString(x));
+  if pos = fail then
+    pos := Length(arg) + 1;
+  fi;
+  fmt := Concatenation(arg{[1 .. pos - 1]});
+  n := NumberOfSubstrings(fmt, "{}");
+  arg := Concatenation([Concatenation(arg{[1 .. Length(arg) - n]})],
+                       arg{[Length(arg) - n + 1 .. Length(arg)]});
+  msg := CallFuncList(StringFormatted, arg);
+  # RemoveCharacters(msg, "\\\n");
+  ErrorInner(
+      rec(context := ParentLVars(GetCurrentLVars()),
+          mayReturnVoid := false,
+          mayReturnObj := false,
+          lateMessage := "type 'quit;' to quit to outer loop",
+          printThisStatement := false),
+      [msg]);
+end);
diff --git a/init.g b/init.g
index 2d54325..7d8d023 100644
--- a/init.g
+++ b/init.g
@@ -8,4 +8,5 @@
 #############################################################################
 ##
 
+ReadPackage("graphviz", "gap/error.gd");
 ReadPackage("graphviz", "gap/dot.gd");
diff --git a/read.g b/read.g
index 4dbac1a..794be60 100644
--- a/read.g
+++ b/read.g
@@ -7,6 +7,7 @@
 ##
 #############################################################################
 ##
+
 ReadPackage("graphviz", "gap/dot.gi");
+ReadPackage("graphviz", "gap/error.gi");
 ReadPackage("graphviz", "gap/splash.gi");
-ReadPackage("graphviz", "gap/defaults.gi");

From bb6572d4f065818daf06ed81aacc590843fb8a23 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Mon, 13 May 2024 10:26:49 +0100
Subject: [PATCH 03/38] Remove redundant funcs

---
 gap/dot.gd    | 18 ------------------
 gap/dot.gi    | 10 ----------
 tst/edge.tst  |  6 +++---
 tst/graph.tst |  4 ++--
 tst/node.tst  |  4 ++--
 5 files changed, 7 insertions(+), 35 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 5d36e3b..e82e0b6 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -191,24 +191,6 @@ DeclareOperation("GraphvizSetAttrs", [IsGVObject, IsRecord]);
 DeclareOperation("GraphvizSetAttr", [IsGVObject, IsObject, IsObject]);
 DeclareOperation("GraphvizSetAttr", [IsGVObject, IsObject]);
 
-#! @Arguments obj, label
-#! @Returns the modified object.
-#! @Description
-#!    Updates the label of the object.
-#!    If a label already exists and a new value is provided, the old value will
-#!    be overwritten.
-# TODO remove
-DeclareOperation("GraphvizSetLabel", [IsGVObject, IsObject]);
-
-#! @Arguments obj, color
-#! @Returns the modified object.
-#! @Description
-#!    Updates the color of the object.
-#!    If a color already exists and a new value is provided, the old value will
-#!    be overwritten.
-# TODO remove
-DeclareOperation("GraphvizSetColor", [IsGVObject, IsObject]);
-
 #! @Arguments obj, attr
 #! @Returns the modified object.
 #! @Description Removes an attribute from the object provided.
diff --git a/gap/dot.gi b/gap/dot.gi
index 259ad57..13f6d3c 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -846,16 +846,6 @@ function(x, value)
   return x;
 end);
 
-InstallMethod(GraphvizSetLabel,
-"for a graphviz object and an object",
-[IsGVObject, IsObject],
-{x, label} -> GraphvizSetAttr(x, "label", label));
-
-InstallMethod(GraphvizSetColor,
-"for a graphviz object and an object",
-[IsGVObject, IsObject],
-{x, color} -> GraphvizSetAttr(x, "color", color));
-
 DeclareOperation("GV_AddNode", [IsGVGraphOrDigraph, IsGVNode]);
 InstallMethod(GV_AddNode,
 "for a graphviz graph and node",
diff --git a/tst/edge.tst b/tst/edge.tst
index 5f5f8d4..c0117db 100644
--- a/tst/edge.tst
+++ b/tst/edge.tst
@@ -143,16 +143,16 @@ gap> n["color"];
 # Test set label (edge)
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddEdge(g, "n", "m");;
-gap> GraphvizSetLabel(n, "test");;
+gap> GraphvizSetAttr(n, "label", "test");;
 gap> GraphvizAttrs(n);
 rec( label := "test" )
 
 # Test set color (edge)
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddEdge(g, "n", "m");;
-gap> GraphvizSetColor(n, "red");;
+gap> GraphvizSetAttr(n, "color", "red");;
 gap> GraphvizAttrs(n);
 rec( color := "red" )
 
 #
-gap> STOP_TEST("graphviz package: edge.tst", 0);
+gap> STOP_TEST("graphviz package: edge.tst");
diff --git a/tst/graph.tst b/tst/graph.tst
index a0aea1d..175d1d1 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -231,13 +231,13 @@ gap> GraphvizSetName(g, ["a"]);
 
 # Test set label (graph)
 gap> g := GraphvizGraph();;
-gap> GraphvizSetLabel(g, "test");;
+gap> GraphvizSetAttr(g, "label", "test");;
 gap> GraphvizAttrs(g);
 [ "label=test" ]
 
 # Test set color (graph)
 gap> g := GraphvizGraph();;
-gap> GraphvizSetColor(g, "red");;
+gap> GraphvizSetAttr(g, "color", "red");;
 gap> GraphvizAttrs(g);
 [ "color=red" ]
 
diff --git a/tst/node.tst b/tst/node.tst
index 6388f06..92dc589 100644
--- a/tst/node.tst
+++ b/tst/node.tst
@@ -94,14 +94,14 @@ gap> n["color"];
 # Test set label (node)
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "n");;
-gap> GraphvizSetLabel(n, "test");;
+gap> GraphvizSetAttr(n, "label", "test");;
 gap> GraphvizAttrs(n);
 rec( label := "test" )
 
 # Test set color (node)
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "n");;
-gap> GraphvizSetColor(n, "red");;
+gap> GraphvizSetAttr(n, "color", "red");;
 gap> GraphvizAttrs(n);
 rec( color := "red" )
 

From fbd0390894f1d9664c4a86199aa274086c78c055 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Mon, 13 May 2024 10:51:09 +0100
Subject: [PATCH 04/38] Reorganise files

---
 gap/dot.gd    |   2 +
 gap/dot.gi    | 934 ++------------------------------------------------
 gap/gv.gd     | 216 ++++++++++++
 gap/gv.gi     | 679 ++++++++++++++++++++++++++++++++++++
 gap/splash.gd |   0
 init.g        |   1 +
 read.g        |   1 +
 7 files changed, 926 insertions(+), 907 deletions(-)
 create mode 100644 gap/gv.gd
 create mode 100644 gap/gv.gi
 create mode 100644 gap/splash.gd

diff --git a/gap/dot.gd b/gap/dot.gd
index e82e0b6..57891d0 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -212,3 +212,5 @@ DeclareOperation("Graphviz", [IsObject]);
 
 DeclareOperation("GraphvizSetNodeColors", [IsGVGraphOrDigraph, IsList]);
 DeclareOperation("GraphvizSetNodeLabels", [IsGVGraphOrDigraph, IsList]);
+
+DeclareGlobalFunction("ErrorIfNotValidColor");
diff --git a/gap/dot.gi b/gap/dot.gi
index 13f6d3c..510f54a 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -9,401 +9,10 @@
 ##
 
 #############################################################################
-# Private functionality
+# Constructors
 #############################################################################
 
-
-DeclareOperation("GV_GetCounter", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_IncCounter", [IsGVGraphOrDigraph]);
-DeclareCategory("GV_IsMap", IsObject);
-DeclareAttribute("Size", GV_IsMap);
-
-DeclareOperation("GV_StringifyGraphHead", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifyDigraphHead", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifySubgraphHead", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifyContextHead", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifyNode", [IsGVNode]);
-DeclareOperation("GV_StringifyGraphAttrs", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifyNodeEdgeAttrs", [GV_IsMap]);
-DeclareOperation("GV_StringifyGraph", [IsGVGraphOrDigraph, IsBool]);
-
-DeclareOperation("GV_FindNode", [IsGVGraphOrDigraph, IsObject]);
-
-## COPY OF GAP PLURALIZE TO ALLOW OLD VERSIONS OF GAP TO USE THE PACKAGE
-DeclareOperation("GV_Pluralize", [IsInt, IsString]);
-
-BindGlobal("GV_KNOWN_ATTRS", [
-  "_background", "area", "arrowhead", "arrowsize", "arrowtail", "bb",
-  "beautify", "bgcolor", "center", "charset", "class", "cluster", "clusterrank",
-  "color", "colorscheme", "comment", "compound", "concentrate", "constraint",
-  "Damping", "decorate", "defaultdist", "dim", "dimen", "dir",
-  "diredgeconstraints", "distortion", "dpi", "edgehref", "edgetarget",
-  "edgetooltip", "edgeURL", "epsilon", "esep", "fillcolor", "fixedsize",
-  "fontcolor", "fontname", "fontnames", "fontpath", "fontsize", "forcelabels",
-  "gradientangle", "group", "head_lp", "headclip", "headhref", "headlabel",
-  "headport", "headtarget", "headtooltip", "headURL", "height", "href", "id",
-  "image", "imagepath", "imagepos", "imagescale", "inputscale", "K", "label",
-  "label_scheme", "labelangle", "labeldistance", "labelfloat", "labelfontcolor",
-  "labelfontname", "labelfontsize", "labelhref", "labeljust", "labelloc",
-  "labeltarget", "labeltooltip", "labelURL", "landscape", "layer",
-  "layerlistsep", "layers", "layerselect", "layersep", "layout", "len",
-  "levels", "levelsgap", "lhead", "lheight", "linelength", "lp", "ltail",
-  "lwidth", "margin", "maxiter", "mclimit", "mindist", "minlen", "mode",
-  "model", "newrank", "nodesep", "nojustify", "normalize", "notranslate",
-  "nslimit", "nslimit1", "oneblock", "ordering", "orientation", "outputorder",
-  "overlap", "overlap_scaling", "overlap_shrink", "pack", "packmode", "pad",
-  "page", "pagedir", "pencolor", "penwidth", "peripheries", "pin", "pos",
-  "quadtree", "quantum", "rank", "rankdir", "ranksep", "ratio", "rects",
-  "regular", "remincross", "repulsiveforce", "resolution", "root", "rotate",
-  "rotation", "samehead", "sametail", "samplepoints", "scale", "searchsize",
-  "sep", "shape", "shapefile", "showboxes", "sides", "size", "skew",
-  "smoothing", "sortv", "splines", "start", "style", "stylesheet", "tail_lp",
-  "tailclip", "tailhref", "taillabel", "tailport", "tailtarget", "tailtooltip",
-  "tailURL", "target", "TBbalance", "tooltip", "truecolor", "URL", "vertices",
-  "viewport", "voro_margin", "weight", "width", "xdotversion", "xlabel", "xlp",
-  "z"
-]);
-
-BindGlobal("GV_ValidColorNames",
-  ["aliceblue", "antiquewhite", "antiquewhite1", "antiquewhite2",
-  "antiquewhite3", "antiquewhite4", "aquamarine", "aquamarine1", "aquamarine2",
-  "aquamarine3", "aquamarine4", "azure", "azure1", "azure2", "azure3",
-  "azure4", "beige", "bisque", "bisque1", "bisque2", "bisque3", "bisque4",
-  "black", "blanchedalmond", "blue", "blue1", "blue2", "blue3", "blue4",
-  "blueviolet", "brown", "brown1", "brown2", "brown3", "brown4", "burlywood",
-  "burlywood1", "burlywood2", "burlywood3", "burlywood4", "cadetblue",
-  "cadetblue1", "cadetblue2", "cadetblue3", "cadetblue4", "chartreuse",
-  "chartreuse1", "chartreuse2", "chartreuse3", "chartreuse4", "chocolate",
-  "chocolate1", "chocolate2", "chocolate3", "chocolate4", "coral", "coral1",
-  "coral2", "coral3", "coral4", "cornflowerblue", "cornsilk", "cornsilk1",
-  "cornsilk2", "cornsilk3", "cornsilk4", "crimson", "cyan", "cyan1", "cyan2",
-  "cyan3", "cyan4", "darkgoldenrod", "darkgoldenrod1", "darkgoldenrod2",
-  "darkgoldenrod3", "darkgoldenrod4", "darkgreen", "darkkhaki",
-  "darkolivegreen", "darkolivegreen1", "darkolivegreen2", "darkolivegreen3",
-  "darkolivegreen4", "darkorange", "darkorange1", "darkorange2", "darkorange3",
-  "darkorange4", "darkorchid", "darkorchid1", "darkorchid2", "darkorchid3",
-  "darkorchid4", "darksalmon", "darkseagreen", "darkseagreen1",
-  "darkseagreen2", "darkseagreen3", "darkseagreen4", "darkslateblue",
-  "darkslategray", "darkslategray1", "darkslategray2", "darkslategray3",
-  "darkslategray4", "darkslategrey", "darkturquoise", "darkviolet", "deeppink",
-  "deeppink1", "deeppink2", "deeppink3", "deeppink4", "deepskyblue",
-  "deepskyblue1", "deepskyblue2", "deepskyblue3", "deepskyblue4", "dimgray",
-  "dimgrey", "dodgerblue", "dodgerblue1", "dodgerblue2", "dodgerblue3",
-  "dodgerblue4", "firebrick", "firebrick1", "firebrick2", "firebrick3",
-  "firebrick4", "floralwhite", "forestgreen", "gainsboro", "ghostwhite",
-  "gold", "gold1", "gold2", "gold3", "gold4", "goldenrod", "goldenrod1",
-  "goldenrod2", "goldenrod3", "goldenrod4", "gray", "gray0", "gray1", "gray10",
-  "gray100", "gray11", "gray12", "gray13", "gray14", "gray15", "gray16",
-  "gray17", "gray18", "gray19", "gray2", "gray20", "gray21", "gray22",
-  "gray23", "gray24", "gray25", "gray26", "gray27", "gray28", "gray29",
-  "gray3", "gray30", "gray31", "gray32", "gray33", "gray34", "gray35",
-  "gray36", "gray37", "gray38", "gray39", "gray4", "gray40", "gray41",
-  "gray42", "gray43", "gray44", "gray45", "gray46", "gray47", "gray48",
-  "gray49", "gray5", "gray50", "gray51", "gray52", "gray53", "gray54",
-  "gray55", "gray56", "gray57", "gray58", "gray59", "gray6", "gray60",
-  "gray61", "gray62", "gray63", "gray64", "gray65", "gray66", "gray67",
-  "gray68", "gray69", "gray7", "gray70", "gray71", "gray72", "gray73",
-  "gray74", "gray75", "gray76", "gray77", "gray78", "gray79", "gray8",
-  "gray80", "gray81", "gray82", "gray83", "gray84", "gray85", "gray86",
-  "gray87", "gray88", "gray89", "gray9", "gray90", "gray91", "gray92",
-  "gray93", "gray94", "gray95", "gray96", "gray97", "gray98", "gray99",
-  "green", "green1", "green2", "green3", "green4", "greenyellow", "grey",
-  "grey0", "grey1", "grey10", "grey100", "grey11", "grey12", "grey13",
-  "grey14", "grey15", "grey16", "grey17", "grey18", "grey19", "grey2",
-  "grey20", "grey21", "grey22", "grey23", "grey24", "grey25", "grey26",
-  "grey27", "grey28", "grey29", "grey3", "grey30", "grey31", "grey32",
-  "grey33", "grey34", "grey35", "grey36", "grey37", "grey38", "grey39",
-  "grey4", "grey40", "grey41", "grey42", "grey43", "grey44", "grey45",
-  "grey46", "grey47", "grey48", "grey49", "grey5", "grey50", "grey51",
-  "grey52", "grey53", "grey54", "grey55", "grey56", "grey57", "grey58",
-  "grey59", "grey6", "grey60", "grey61", "grey62", "grey63", "grey64",
-  "grey65", "grey66", "grey67", "grey68", "grey69", "grey7", "grey70",
-  "grey71", "grey72", "grey73", "grey74", "grey75", "grey76", "grey77",
-  "grey78", "grey79", "grey8", "grey80", "grey81", "grey82", "grey83",
-  "grey84", "grey85", "grey86", "grey87", "grey88", "grey89", "grey9",
-  "grey90", "grey91", "grey92", "grey93", "grey94", "grey95", "grey96",
-  "grey97", "grey98", "grey99", "honeydew", "honeydew1", "honeydew2",
-  "honeydew3", "honeydew4", "hotpink", "hotpink1", "hotpink2", "hotpink3",
-  "hotpink4", "indianred", "indianred1", "indianred2", "indianred3",
-  "indianred4", "indigo", "invis", "ivory", "ivory1", "ivory2", "ivory3",
-  "ivory4", "khaki", "khaki1", "khaki2", "khaki3", "khaki4", "lavender",
-  "lavenderblush", "lavenderblush1", "lavenderblush2", "lavenderblush3",
-  "lavenderblush4", "lawngreen", "lemonchiffon", "lemonchiffon1",
-  "lemonchiffon2", "lemonchiffon3", "lemonchiffon4", "lightblue", "lightblue1",
-  "lightblue2", "lightblue3", "lightblue4", "lightcoral", "lightcyan",
-  "lightcyan1", "lightcyan2", "lightcyan3", "lightcyan4", "lightgoldenrod",
-  "lightgoldenrod1", "lightgoldenrod2", "lightgoldenrod3", "lightgoldenrod4",
-  "lightgoldenrodyellow", "lightgray", "lightgrey", "lightpink", "lightpink1",
-  "lightpink2", "lightpink3", "lightpink4", "lightsalmon", "lightsalmon1",
-  "lightsalmon2", "lightsalmon3", "lightsalmon4", "lightseagreen",
-  "lightskyblue", "lightskyblue1", "lightskyblue2", "lightskyblue3",
-  "lightskyblue4", "lightslateblue", "lightslategray", "lightslategrey",
-  "lightsteelblue", "lightsteelblue1", "lightsteelblue2", "lightsteelblue3",
-  "lightsteelblue4", "lightyellow", "lightyellow1", "lightyellow2",
-  "lightyellow3", "lightyellow4", "limegreen", "linen", "magenta", "magenta1",
-  "magenta2", "magenta3", "magenta4", "maroon", "maroon1", "maroon2",
-  "maroon3", "maroon4", "mediumaquamarine", "mediumblue", "mediumorchid",
-  "mediumorchid1", "mediumorchid2", "mediumorchid3", "mediumorchid4",
-  "mediumpurple", "mediumpurple1", "mediumpurple2", "mediumpurple3",
-  "mediumpurple4", "mediumseagreen", "mediumslateblue", "mediumspringgreen",
-  "mediumturquoise", "mediumvioletred", "midnightblue", "mintcream",
-  "mistyrose", "mistyrose1", "mistyrose2", "mistyrose3", "mistyrose4",
-  "moccasin", "navajowhite", "navajowhite1", "navajowhite2", "navajowhite3",
-  "navajowhite4", "navy", "navyblue", "none", "oldlace", "olivedrab",
-  "olivedrab1", "olivedrab2", "olivedrab3", "olivedrab4", "orange", "orange1",
-  "orange2", "orange3", "orange4", "orangered", "orangered1", "orangered2",
-  "orangered3", "orangered4", "orchid", "orchid1", "orchid2", "orchid3",
-  "orchid4", "palegoldenrod", "palegreen", "palegreen1", "palegreen2",
-  "palegreen3", "palegreen4", "paleturquoise", "paleturquoise1",
-  "paleturquoise2", "paleturquoise3", "paleturquoise4", "palevioletred",
-  "palevioletred1", "palevioletred2", "palevioletred3", "palevioletred4",
-  "papayawhip", "peachpuff", "peachpuff1", "peachpuff2", "peachpuff3",
-  "peachpuff4", "peru", "pink", "pink1", "pink2", "pink3", "pink4", "plum",
-  "plum1", "plum2", "plum3", "plum4", "powderblue", "purple", "purple1",
-  "purple2", "purple3", "purple4", "red", "red1", "red2", "red3", "red4",
-  "rosybrown", "rosybrown1", "rosybrown2", "rosybrown3", "rosybrown4",
-  "royalblue", "royalblue1", "royalblue2", "royalblue3", "royalblue4",
-  "saddlebrown", "salmon", "salmon1", "salmon2", "salmon3", "salmon4",
-  "sandybrown", "seagreen", "seagreen1", "seagreen2", "seagreen3", "seagreen4",
-  "seashell", "seashell1", "seashell2", "seashell3", "seashell4", "sienna",
-  "sienna1", "sienna2", "sienna3", "sienna4", "skyblue", "skyblue1",
-  "skyblue2", "skyblue3", "skyblue4", "slateblue", "slateblue1", "slateblue2",
-  "slateblue3", "slateblue4", "slategray", "slategray1", "slategray2",
-  "slategray3", "slategray4", "slategrey", "snow", "snow1", "snow2", "snow3",
-  "snow4", "springgreen", "springgreen1", "springgreen2", "springgreen3",
-  "springgreen4", "steelblue", "steelblue1", "steelblue2", "steelblue3",
-  "steelblue4", "tan", "tan1", "tan2", "tan3", "tan4", "thistle", "thistle1",
-  "thistle2", "thistle3", "thistle4", "tomato", "tomato1", "tomato2",
-  "tomato3", "tomato4", "transparent", "turquoise", "turquoise1", "turquoise2",
-  "turquoise3", "turquoise4", "violet", "violetred", "violetred1",
-  "violetred2", "violetred3", "violetred4", "wheat", "wheat1", "wheat2",
-  "wheat3", "wheat4", "white", "whitesmoke", "yellow", "yellow1", "yellow2",
-  "yellow3", "yellow4", "yellowgreen"]);
-
-# code from the GAP standard library
-InstallMethod(GV_Pluralize,
-"for an integer and a string",
-[IsInt, IsString],
-function(args...)
-  local nargs, i, count, include_num, str, len, out;
-
-  nargs := Length(args);
-  if nargs >= 1 and IsInt(args[1]) and args[1] >= 0 then
-    i           := 2;
-    count       := args[1];
-    include_num := true;
-  else
-    i           := 1;
-    include_num := false;  # if not given, assume pluralization is wanted.
-  fi;
-
-  if not (nargs in [i, i + 1] and
-          IsString(args[i]) and
-          (nargs = i or IsString(args[i + 1]))) then
-    ErrorNoReturn("Usage: GV_Pluralize([<count>, ]<string>[, <plural>])");
-  fi;
-
-  str := args[i];
-  len := Length(str);
-
-  if len = 0 then
-    ErrorNoReturn("the argument <str> must be a non-empty string");
-  elif include_num and count = 1 then  # no pluralization needed
-    return Concatenation("\>1\< ", str);
-  elif nargs = i + 1 then  # pluralization given
-    out := args[i + 1];
-  elif len <= 2 then
-    out := Concatenation(str, "s");
-
-    # Guess and return the plural form of <str>.
-    # Inspired by the "Ruby on Rails" inflection rules.
-
-    # Uncountable nouns
-  elif str in ["equipment", "information"] then
-    out := str;
-
-    # Irregular plurals
-  elif str = "axis" then
-    out := "axes";
-  elif str = "child" then
-    out := "children";
-  elif str = "person" then
-    out := "people";
-
-    # Peculiar endings
-  elif EndsWith(str, "ix") or EndsWith(str, "ex") then
-    out := Concatenation(str{[1 .. len - 2]}, "ices");
-  elif EndsWith(str, "x") then
-    out := Concatenation(str, "es");
-  elif EndsWith(str, "tum") or EndsWith(str, "ium") then
-    out := Concatenation(str{[1 .. len - 2]}, "a");
-  elif EndsWith(str, "sis") then
-    out := Concatenation(str{[1 .. len - 3]}, "ses");
-  elif EndsWith(str, "fe") and not EndsWith(str, "ffe") then
-    out := Concatenation(str{[1 .. len - 2]}, "ves");
-  elif EndsWith(str, "lf") or EndsWith(str, "rf") or EndsWith(str, "loaf") then
-    out := Concatenation(str{[1 .. len - 1]}, "ves");
-  elif EndsWith(str, "y") and not str[len - 1] in "aeiouy" then
-    out := Concatenation(str{[1 .. len - 1]}, "ies");
-  elif str{[len - 1, len]} in ["ch", "ss", "sh"] then
-    out := Concatenation(str, "es");
-  elif EndsWith(str, "s") then
-    out := str;
-
-    # Default to appending 's'
-  else
-    out := Concatenation(str, "s");
-  fi;
-
-  if include_num then
-    return Concatenation("\>", String(args[1]), "\< ", out);
-  fi;
-  return out;
-end);
-
-###############################################################################
-# Family + type
-###############################################################################
-
-BindGlobal("GV_ObjectFamily",
-           NewFamily("GV_ObjectFamily",
-                     IsGVObject));
-
-BindGlobal("GV_MapType", NewType(GV_ObjectFamily,
-                                 GV_IsMap and
-                                 IsComponentObjectRep and
-                                 IsAttributeStoringRep));
-
-BindGlobal("GV_DigraphType", NewType(GV_ObjectFamily,
-                                    IsGVDigraph and
-                                    IsComponentObjectRep and
-                                    IsAttributeStoringRep));
-
-BindGlobal("GV_GraphType", NewType(GV_ObjectFamily,
-                                    IsGVGraph and
-                                    IsComponentObjectRep and
-                                    IsAttributeStoringRep));
-
-BindGlobal("GV_NodeType", NewType(GV_ObjectFamily,
-                                    IsGVNode and
-                                    IsComponentObjectRep and
-                                    IsAttributeStoringRep));
-
-BindGlobal("GV_EdgeType", NewType(GV_ObjectFamily,
-                                    IsGVEdge and
-                                    IsComponentObjectRep and
-                                    IsAttributeStoringRep));
-
-BindGlobal("GV_ContextType", NewType(GV_ObjectFamily,
-                                    IsGVContext and
-                                    IsComponentObjectRep and
-                                    IsAttributeStoringRep));
-
-InstallMethod(\=, "for IsGVNode and IsGVNode",
-[IsGVNode, IsGVNode],
-{n1, n2} -> GraphvizName(n1) = GraphvizName(n2));
-
-###############################################################################
-# Constructors etc
-###############################################################################
-
-DeclareOperation("GV_Node", [IsGVGraphOrDigraph, IsString]);
-DeclareOperation("GV_Edge", [IsGVGraphOrDigraph, IsGVNode, IsGVNode]);
-DeclareOperation("GV_Graph", [IsGVGraphOrDigraph, IsString]);
-DeclareOperation("GV_Digraph", [IsGVDigraph, IsString]);
-DeclareOperation("GV_Context", [IsGVGraphOrDigraph, IsString]);
-DeclareOperation("GV_Map", []);
-
-InstallMethod(GV_Map, "for no args",
-[], {} -> Objectify(GV_MapType, rec(Data := rec())));
-
-InstallMethod(GV_Node, "for a string",
-[IsGVGraphOrDigraph, IsString],
-function(graph, name)
-  local out;
-  if Length(name) = 0 then
-    ErrorNoReturn("the 2nd argument (string/node name) cannot be empty");
-  fi;
-  out := Objectify(GV_NodeType,
-                  rec(
-                    Name  := name,
-                    Attrs := GV_Map(),
-                    Idx   := GV_GetCounter(graph)));
-  GV_IncCounter(graph);
-  return out;
-end);
-
-InstallMethod(GV_Edge, "for two graphviz nodes",
-[IsGVGraphOrDigraph, IsGVNode, IsGVNode],
-function(graph, head, tail)
-  local out;
-  out := Objectify(GV_EdgeType,
-                rec(
-                  Name  := "",
-                  Head  := head,
-                  Tail  := tail,
-                  Attrs := GV_Map(),
-                  Idx   := GV_GetCounter(graph)));
-  GV_IncCounter(graph);
-  return out;
-end);
-
-# Graph constructors
-
-InstallMethod(GV_Digraph,
-"for a graphviz digraph and a string",
-[IsGVDigraph, IsString],
-function(parent, name)
-  local out;
-
-  out         := GraphvizDigraph(name);
-  out!.Parent := parent;
-  out!.Idx    := GV_GetCounter(parent);
-
-  GV_IncCounter(parent);
-  return out;
-end);
-
-InstallMethod(GV_Graph,
-"for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsString],
-function(parent, name)
-  local out;
-
-  out         := GraphvizGraph(name);
-  out!.Parent := parent;
-  out!.Idx    := GV_GetCounter(parent);
-
-  GV_IncCounter(parent);
-  return out;
-end);
-
-InstallMethod(GV_Context,
-"for a string and a positive integer",
-[IsGVGraphOrDigraph, IsString],
-function(parent, name)
-  local out;
-
-  out := Objectify(GV_ContextType,
-                      rec(
-                        Name      := name,
-                        Subgraphs := GV_Map(),
-                        Nodes     := GV_Map(),
-                        Edges     := [],
-                        Attrs     := [],
-                        Parent    := parent,
-                        Idx       := GV_GetCounter(parent),
-                        Counter   := 1));
-
-  GV_IncCounter(parent);
-  return out;
-end);
-
-# public constructors
-
-InstallMethod(GraphvizGraph,
-"for a string",
-[IsString],
+InstallMethod(GraphvizGraph, "for a string", [IsString],
 function(name)
   return Objectify(GV_GraphType,
                       rec(
@@ -417,14 +26,12 @@ function(name)
                         Counter   := 1));
 end);
 
-InstallMethod(GraphvizGraph,
-"for an object",
-[IsObject],
+InstallMethod(GraphvizGraph, "for no args", [], {} -> GraphvizGraph(""));
+
+InstallMethod(GraphvizGraph, "for an object", [IsObject],
 o -> GraphvizGraph(ViewString(o)));
 
-InstallMethod(GraphvizDigraph,
-"for a string",
-[IsString],
+InstallMethod(GraphvizDigraph, "for a string", [IsString],
 function(name)
   return Objectify(GV_DigraphType,
                       rec(
@@ -438,57 +45,10 @@ function(name)
                         Counter   := 1));
 end);
 
-InstallMethod(GraphvizDigraph,
-"for an object",
-[IsObject],
-o -> GraphvizDigraph(ViewString(o)));
-
-InstallMethod(GraphvizGraph, "for no args", [], {} -> GraphvizGraph(""));
 InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
 
-# ###########################################################
-# Graphviz Map Functions
-# ###########################################################
-
-InstallOtherMethod(\[\],
-"for a graphviz map and an object",
-[GV_IsMap, IsObject],
-function(m, o)
-  if IsBound(m[o]) then
-    return m!.Data.(o);
-  fi;
-  return fail;
-end);
-
-InstallOtherMethod(\[\]\:\=,
-"for a graphviz map and two objects",
-[GV_IsMap, IsObject, IsObject],
-function(m, key, val)
-  m!.Data.(key) := val;
-end);
-
-InstallOtherMethod(Unbind\[\],
-"for a graphviz map and an object",
-[GV_IsMap, IsObject],
-function(m, key)
-  Unbind(m!.Data.(key));
-end);
-
-InstallOtherMethod(IsBound\[\],
-"for a graphviz map and an object",
-[GV_IsMap, IsObject],
-{m, key} -> IsBound(m!.Data.(key)));
-
-DeclareOperation("GV_MapNames", [GV_IsMap]);
-
-InstallMethod(GV_MapNames, "for a graphviz map",
-[GV_IsMap], m -> RecNames(m!.Data));
-
-InstallMethod(ViewString, "for a graphviz map", [GV_IsMap],
-m -> String(m!.Data));
-
-InstallMethod(Size, "for a graphviz map",
-[GV_IsMap], m -> Length(GV_MapNames(m)));
+InstallMethod(GraphvizDigraph, "for an object", [IsObject],
+o -> GraphvizDigraph(ViewString(o)));
 
 ############################################################
 # Stringify
@@ -545,17 +105,12 @@ InstallMethod(GraphvizName, "for a graphviz object", [IsGVObject], x -> x!.Name)
 InstallMethod(GraphvizAttrs, "for a graphviz object", [IsGVObject],
 x -> x!.Attrs);
 
-# TODO remove, the returned value is mutable, looks like a record but isn't
-# one. Mutability is a problem, since if we do GraphvizNodes(gv)[1] := 2; then
-# the object is corrupt.
 InstallMethod(GraphvizNodes, "for a graphviz graph", [IsGVGraphOrDigraph],
 x -> x!.Nodes);
 
 InstallMethod(GraphvizNode, "for a graphviz graph and object",
 [IsGVGraphOrDigraph, IsObject], {gv, obj} -> gv!.Nodes[String(obj)]);
 
-# TODO remove for the same reason as GraphvizNodes, unless we can make the list
-# immutable or return a copy.
 InstallMethod(GraphvizEdges, "for a graphviz graph",
 [IsGVGraphOrDigraph], x -> x!.Edges);
 
@@ -587,29 +142,6 @@ InstallMethod(GraphvizGetSubgraph,
 [IsGVGraphOrDigraph, IsObject],
 {x, o} -> GraphvizSubgraphs(x)[ViewString(o)]);
 
-InstallMethod(GV_IncCounter,
-"for a graphviz graph",
-[IsGVGraphOrDigraph],
-function(x)
-  x!.Counter := x!.Counter + 1;
-end);
-
-InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGVGraphOrDigraph],
-x -> x!.Counter);
-
-# Converting strings
-
-DeclareOperation("GV_EnsureString", [IsObject]);
-# TODO required? Replace with AsString
-InstallMethod(GV_EnsureString,
-"for an object",
-[IsObject], ViewString);
-
-InstallMethod(GV_EnsureString,
-"for a string",
-[IsString],
-x -> x);
-
 # Accessing node attributes
 
 InstallOtherMethod(\[\],
@@ -674,77 +206,6 @@ InstallOtherMethod(\[\],
 [IsGVGraphOrDigraph, IsObject],
 {g, o} -> g[ViewString(o)]);
 
-DeclareOperation("GV_HasNode", [IsGVGraphOrDigraph, IsObject]);
-
-InstallMethod(GV_HasNode,
-"for a graphviz graph",
-[IsGVGraphOrDigraph, IsString],
-{g, name} -> name in GV_MapNames(GraphvizNodes(g)));
-
-DeclareOperation("GV_GetParent", [IsGVGraphOrDigraph]);
-
-InstallMethod(GV_GetParent,
-"for a graphviz graph",
-[IsGVGraphOrDigraph], graph -> graph!.Parent);
-
-DeclareOperation("GV_GraphTreeSearch", [IsGVGraphOrDigraph, IsFunction]);
-
-InstallMethod(GV_GraphTreeSearch,
-"for a graphviz graph and a predicate",
-[IsGVGraphOrDigraph, IsFunction],
-function(graph, pred)
-  local seen, to_visit, g, key, subgraph, parent;
-  seen     := [graph];
-  to_visit := [graph];
-
-  while Length(to_visit) > 0 do
-    g := Remove(to_visit, Length(to_visit));
-
-    # Check this graph
-    if pred(g) then
-      return g;
-    fi;
-
-    # add subgraphs to list of to visit if not visited
-    for key in GV_MapNames(GraphvizSubgraphs(g)) do
-      subgraph := GraphvizSubgraphs(g)[key];
-      if not ForAny(seen, s -> IsIdenticalObj(s, subgraph)) then
-        Add(seen, subgraph);
-        Add(to_visit, subgraph);
-      fi;
-    od;
-
-    # add parent if not visited
-    parent := GV_GetParent(g);
-    if not IsGVGraphOrDigraph(parent) then
-      continue;
-    fi;
-    if not ForAny(seen, s -> IsIdenticalObj(s, parent)) then
-      Add(seen, parent);
-      Add(to_visit, parent);
-    fi;
-  od;
-
-  return fail;
-end);
-
-DeclareOperation("GV_FindGraphWithNode", [IsGVGraphOrDigraph, IsString]);
-InstallMethod(GV_FindGraphWithNode,
-"for a graphviz graph and a node",
-[IsGVGraphOrDigraph, IsString],
-{g, n} -> GV_GraphTreeSearch(g, v -> v[n] <> fail));
-
-DeclareOperation("GV_GetRoot", [IsGVGraphOrDigraph]);
-InstallMethod(GV_GetRoot,
-"for a graphviz graph",
-[IsGVGraphOrDigraph],
-function(graph)
-  while GV_GetParent(graph) <> fail do
-    graph := GV_GetParent(graph);
-  od;
-  return graph;
-end);
-
 InstallMethod(GraphvizFindGraph,
 "for a graphviz graph and a string",
 [IsGVGraphOrDigraph, IsString],
@@ -755,18 +216,6 @@ InstallMethod(GraphvizFindGraph,
 [IsGVGraphOrDigraph, IsObject],
 {g, o} -> GraphvizFindGraph(g, ViewString(o)));
 
-InstallMethod(GV_FindNode,
-"for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsString],
-function(g, n)
-  local graph;
-  graph := GV_FindGraphWithNode(g, n);
-  if graph = fail then
-    return graph;
-  fi;
-  return graph[n];
-end);
-
 ############################################################
 # Setters
 ############################################################
@@ -846,26 +295,6 @@ function(x, value)
   return x;
 end);
 
-DeclareOperation("GV_AddNode", [IsGVGraphOrDigraph, IsGVNode]);
-InstallMethod(GV_AddNode,
-"for a graphviz graph and node",
-[IsGVGraphOrDigraph, IsGVNode],
-function(x, node)
-  local found, error, name, nodes;
-  name  := GraphvizName(node);
-  nodes := GraphvizNodes(x);
-
-  # dont add if already node with the same name
-  found := GV_FindGraphWithNode(x, name);
-  if found <> fail then
-    error := "Already node with name {} in graph {}.";
-    ErrorNoReturn(StringFormatted(error, name, GraphvizName(found)));
-  fi;
-
-  nodes[name] := node;
-  return x;
-end);
-
 InstallMethod(GraphvizAddNode, "for a graphviz graph and string",
 [IsGVGraphOrDigraph, IsString],
 function(x, name)
@@ -890,47 +319,6 @@ InstallMethod(GraphvizAddNode,
 [IsGVGraphOrDigraph, IsObject],
 {x, name} -> GraphvizAddNode(x, ViewString(name)));
 
-DeclareOperation("GV_AddEdge", [IsGVGraphOrDigraph, IsGVEdge]);
-InstallMethod(GV_AddEdge,
-"for a graphviz graph and edge",
-[IsGVGraphOrDigraph, IsGVEdge],
-function(x, edge)
-  local head, head_name, tail_name, tail, hg, error, tg;
-
-  head      := GraphvizHead(edge);
-  tail      := GraphvizTail(edge);
-  head_name := GraphvizName(head);
-  tail_name := GraphvizName(tail);
-  hg        := GV_FindGraphWithNode(x, head_name);
-  tg        := GV_FindGraphWithNode(x, tail_name);
-
-  # if not already existing, add the nodes to the graph
-  if hg = fail then
-    GV_AddNode(x, head);
-  fi;
-  if tg = fail then
-    GV_AddNode(x, tail);
-  fi;
-
-  # make sure the nodes exist / are the same as existing ones
-  if hg <> fail and not IsIdenticalObj(head, hg[head_name]) then
-    # TODO improve
-    ErrorFormatted("Different node in graph {} with name {}",
-                   GraphvizName(hg),
-                   head_name);
-  fi;
-  if tg <> fail and not IsIdenticalObj(tail, tg[tail_name]) then
-    # TODO improve
-    error := "Different node in graph {} with name {}.";
-    ErrorNoReturn(StringFormatted(error,
-                                         GraphvizName(tg),
-                                         tail_name));
-  fi;
-
-  Add(x!.Edges, edge);
-  return x;
-end);
-
 InstallMethod(GraphvizAddEdge,
 "for a graphviz graph and two graphviz nodes",
 [IsGVGraphOrDigraph, IsGVNode, IsGVNode],
@@ -1148,295 +536,12 @@ function(obj, attr)
   return obj;
 end);
 
-# ##############################################################################
-# Stringifying
-# ##############################################################################
-
-# @ Return DOT graph head line.
-InstallMethod(GV_StringifyGraphHead, "for a string", [IsGVGraphOrDigraph],
-graph -> StringFormatted("graph {} {{\n", GraphvizName(graph)));
-
-# @ Return DOT digraph head line.
-InstallMethod(GV_StringifyDigraphHead, "for a string", [IsGVDigraph],
-graph -> StringFormatted("digraph {} {{\n", GraphvizName(graph)));
-
-# @ Return DOT subgraph head line.
-InstallMethod(GV_StringifySubgraphHead, "for a string", [IsGVGraphOrDigraph],
-graph -> StringFormatted("subgraph {} {{\n", GraphvizName(graph)));
-
-# @ Return DOT subgraph head line.
-InstallMethod(GV_StringifyContextHead, "for a string", [IsGVContext],
-graph -> StringFormatted("// {} context \n", GraphvizName(graph)));
-
-BindGlobal("GV_StringifyNodeName",
-function(node)
-  local name, old;
-
-  Assert(0, IsGVNode(node));
-  name  := GraphvizName(node);
-  if (ForAny("- .+", x -> x in name)
-      or (IsDigitChar(First(name)) and IsAlphaChar(Last(name))))
-      and not StartsWith(name, "\"") then
-    old  := name;
-    name := StringFormatted("\"{}\"", name);
-    Info(InfoWarning,
-         1,
-         "invalid node name ",
-         old,
-         " using ",
-         name,
-         " instead");
-  fi;
-  return name;
-end);
-
-# @ Return DOT node statement line.
-InstallMethod(GV_StringifyNode, "for string and record",
-[IsGVNode],
-function(node)
-  local name, attrs;
-  name  := GV_StringifyNodeName(node);
-  attrs := GraphvizAttrs(node);
-  return StringFormatted("\t{}{}\n", name, GV_StringifyNodeEdgeAttrs(attrs));
-end);
-
-# @ Return DOT graph edge statement line.
-BindGlobal("GV_StringifyEdge",
-function(edge, edge_str)
-  local head, tail, attrs;
-  Assert(0, IsGVEdge(edge));
-  Assert(0, IsString(edge_str));
-  head  := GV_StringifyNodeName(GraphvizHead(edge));
-  tail  := GV_StringifyNodeName(GraphvizTail(edge));
-  attrs := GraphvizAttrs(edge);
-
-  # handle : syntax
-  return StringFormatted("\t{} {} {}{}\n",
-                         head,
-                         edge_str,
-                         tail,
-                         GV_StringifyNodeEdgeAttrs(attrs));
-end);
-
-InstallMethod(GV_StringifyGraphAttrs,
-"for a graphviz graph",
-[IsGVGraphOrDigraph],
-function(graph)
-  local result, attrs, kv;
-  attrs  := GraphvizAttrs(graph);
-  result := "";
-
-  if Length(attrs) <> 0 then
-    Append(result, "\t");
-    for kv in attrs do
-      Append(result,
-             StringFormatted("{} ", kv));
-    od;
-    Append(result, "\n");
-  fi;
-  return result;
-end);
-
-InstallMethod(GV_StringifyNodeEdgeAttrs,
-"for a GV_Map",
-[GV_IsMap],
-function(attrs)
-  local result, keys, key, val, n, i, tmp;
-
-  result := "";
-  n      := Length(GV_MapNames(attrs));
-  keys   := SSortedList(GV_MapNames(attrs));
-
-  if n <> 0 then
-    Append(result, " [");
-    for i in [1 .. n - 1] do
-        key := keys[i];
-        val := attrs[key];
-
-        tmp := Chomp(val);
-        if "label" = key and StartsWith(tmp, "<<") and EndsWith(tmp, ">>") then
-          val := StringFormatted("{}", val);
-        else
-          if ' ' in key then
-            key := StringFormatted("\"{}\"", key);
-          fi;
-          if ' ' in val or '>' in val or '^' in val or '#' in val then
-              # TODO avoid code duplication here, and below
-            val := StringFormatted("\"{}\"", val);
-          fi;
-        fi;
-
-        Append(result,
-               StringFormatted("{}={}, ",
-                               key,
-                               val));
-    od;
-
-    # handle last element
-    key := keys[n];
-    val := attrs[key];
-
-    tmp := Chomp(val);
-    if "label" = key and StartsWith(tmp, "<<") and EndsWith(tmp, ">>") then
-      val := StringFormatted("{}", val);
-    else
-        if ' ' in key then
-          key := StringFormatted("\"{}\"", key);
-        fi;
-        if ' ' in val or '>' in val or '^' in val or '#' in val then
-          # TODO what are the allowed things in the value?
-          val := StringFormatted("\"{}\"", val);
-        fi;
-    fi;
-
-    Append(result,
-           StringFormatted("{}={}]",
-                           key,
-                           val));
-  fi;
-
-  return result;
-end);
-
-DeclareOperation("GV_GetIdx", [IsGVObject]);
-InstallMethod(GV_GetIdx,
-"for a graphviz object",
-[IsGVObject],
-x -> x!.Idx);
-
-DeclareOperation("GV_ConstructHistory", [IsGVGraphOrDigraph]);
-InstallMethod(GV_ConstructHistory,
-"for a graphviz graph",
-[IsGVGraphOrDigraph],
-function(graph)
-  local nodes, edges, subs, node_hist, edge_hist, subs_hist, hist;
-
-  nodes := GraphvizNodes(graph);
-  edges := GraphvizEdges(graph);
-  subs  := GraphvizSubgraphs(graph);
-
-  node_hist := List(GV_MapNames(nodes), n -> [GV_GetIdx(nodes[n]), nodes[n]]);
-  subs_hist := List(GV_MapNames(subs), s -> [GV_GetIdx(subs[s]), subs[s]]);
-  edge_hist := List(edges, e -> [GV_GetIdx(e), e]);
-
-  hist := Concatenation(node_hist, edge_hist, subs_hist);
-  SortBy(hist, v -> v[1]);
-
-  Apply(hist, x -> x[2]);
-  return hist;
-end);
-
-InstallMethod(GV_StringifyGraph,
-"for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsBool],
-function(graph, is_subgraph)
-  local result, obj;
-  result := "";
-
-  # get the correct head to use
-  if is_subgraph then
-    if IsGVContext(graph) then
-      Append(result, GV_StringifyContextHead(graph));
-    elif IsGVGraph(graph) or IsGVDigraph(graph) then
-      Append(result, GV_StringifySubgraphHead(graph));
-    else
-      ErrorNoReturn("Invalid subgraph type.");
-    fi;
-  elif IsGVDigraph(graph) then
-    Append(result, "//dot\n");
-    Append(result, GV_StringifyDigraphHead(graph));
-  elif IsGVGraph(graph) then
-    Append(result, "//dot\n");
-    Append(result, GV_StringifyGraphHead(graph));
-  elif IsGVContext(graph) then
-    Append(result, "//dot\n");
-    Append(result, GV_StringifyContextHead(graph));
-  else
-    ErrorNoReturn("Invalid graph type.");
-  fi;
-
-  Append(result, GV_StringifyGraphAttrs(graph));
-
-  # Add child graphviz objects
-  for obj in GV_ConstructHistory(graph) do
-    if IsGVGraphOrDigraph(obj) then
-      Append(result, GV_StringifyGraph(obj, true));
-    elif IsGVNode(obj) then
-      Append(result, GV_StringifyNode(obj));
-    elif IsGVEdge(obj) then
-      if IsGVDigraph(GV_GetRoot(graph)) then
-        Append(result, GV_StringifyEdge(obj, "->"));
-      else
-        Append(result, GV_StringifyEdge(obj, "--"));
-      fi;
-    else
-      ErrorNoReturn("Invalid graphviz object type.");
-    fi;
-  od;
-
-  if IsGVContext(graph) then
-    # reset attributes following the context
-    if GV_GetParent(graph) <> fail then
-      Append(result, GV_StringifyGraphAttrs(GV_GetParent(graph)));
-    fi;
-    Append(result, "\n");
-  else
-    Append(result, "}\n");
-  fi;
-  return result;
-end);
+########################################################################
+# Stringify
+########################################################################
 
 InstallMethod(AsString, "for a graphviz graph",
-[IsGVGraphOrDigraph],
-graph -> GV_StringifyGraph(graph, false));
-
-BindGlobal("GV_IsValidRGBColor",
-function(str)
-  local valid, i;
-
-  valid := "0123456789ABCDEFabcdef";
-
-  if Length(str) <> 7 or str[1] <> '#' then
-    return false;
-  fi;
-
-  for i in [2 .. 7] do
-    if not str[i] in valid then
-      return false;
-    fi;
-  od;
-  return true;
-end);
-
-BindGlobal("GV_IsValidColor",
-c -> IsString(c) and (GV_IsValidRGBColor(c) or c in GV_ValidColorNames));
-
-BindGlobal("GV_ErrorIfNotValidColor",
-function(c)
-  if not GV_IsValidColor(c) then
-    if IsString(c) then
-      c := StringFormatted("\"{}\"", c);
-    fi;
-    ErrorFormatted("invalid color {} ({}), ",
-        "valid colors are RGB values or names from ",
-        "the GraphViz 2.44.1 X11 Color Scheme",
-        " http://graphviz.org/doc/info/colors.html",
-        c,
-        TNAM_OBJ(c));
-  fi;
-end);
-
-BindGlobal("GV_ErrorIfNotNodeColoring",
-function(gv, colors)
-  local N;
-  N := Size(GraphvizNodes(gv));
-  if Length(colors) <> N then
-    ErrorFormatted(
-        "the number of node colors must be the same as the number",
-        " of nodes, expected {} but found {}", N, Length(colors));
-  fi;
-  Perform(colors, GV_ErrorIfNotValidColor);
-end);
+[IsGVGraphOrDigraph], graph -> GV_StringifyGraph(graph, false));
 
 InstallMethod(GraphvizSetNodeLabels,
 "for a graphviz graph and list of colors",
@@ -1468,3 +573,18 @@ function(gv, colors)
   od;
   return gv;
 end);
+
+InstallGlobalFunction(ErrorIfNotValidColor,
+function(c)
+  if not GV_IsValidColor(c) then
+    if IsString(c) then
+      c := StringFormatted("\"{}\"", c);
+    fi;
+    ErrorFormatted("invalid color {} ({}), ",
+        "valid colors are RGB values or names from ",
+        "the GraphViz 2.44.1 X11 Color Scheme",
+        " http://graphviz.org/doc/info/colors.html",
+        c,
+        TNAM_OBJ(c));
+  fi;
+end);
diff --git a/gap/gv.gd b/gap/gv.gd
new file mode 100644
index 0000000..ec6461b
--- /dev/null
+++ b/gap/gv.gd
@@ -0,0 +1,216 @@
+#############################################################################
+##
+##  gv.gd
+##  Copyright (C) 2024                                      James Mitchell
+##
+##  Licensing information can be found in the README file of this package.
+##
+#############################################################################
+##
+
+## This file contains declarations of the internal/private functions for the
+## graphviz package.
+
+DeclareOperation("GV_GetCounter", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_IncCounter", [IsGVGraphOrDigraph]);
+DeclareCategory("GV_IsMap", IsObject);
+DeclareAttribute("Size", GV_IsMap);
+
+DeclareOperation("GV_StringifyGraphHead", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifyDigraphHead", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifySubgraphHead", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifyContextHead", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifyNode", [IsGVNode]);
+DeclareOperation("GV_StringifyGraphAttrs", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifyNodeEdgeAttrs", [GV_IsMap]);
+DeclareOperation("GV_StringifyGraph", [IsGVGraphOrDigraph, IsBool]);
+
+DeclareOperation("GV_FindNode", [IsGVGraphOrDigraph, IsObject]);
+
+DeclareOperation("GV_Pluralize", [IsInt, IsString]);
+
+DeclareOperation("GV_Node", [IsGVGraphOrDigraph, IsString]);
+DeclareOperation("GV_Edge", [IsGVGraphOrDigraph, IsGVNode, IsGVNode]);
+DeclareOperation("GV_Graph", [IsGVGraphOrDigraph, IsString]);
+DeclareOperation("GV_Digraph", [IsGVDigraph, IsString]);
+DeclareOperation("GV_Context", [IsGVGraphOrDigraph, IsString]);
+DeclareOperation("GV_Map", []);
+DeclareOperation("GV_MapNames", [GV_IsMap]);
+
+# TODO required? Replace with AsString or just String?
+DeclareOperation("GV_EnsureString", [IsObject]);
+
+DeclareOperation("GV_HasNode", [IsGVGraphOrDigraph, IsObject]);
+
+DeclareOperation("GV_GetParent", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_GraphTreeSearch", [IsGVGraphOrDigraph, IsFunction]);
+DeclareOperation("GV_FindGraphWithNode", [IsGVGraphOrDigraph, IsString]);
+DeclareOperation("GV_GetRoot", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_AddNode", [IsGVGraphOrDigraph, IsGVNode]);
+DeclareOperation("GV_AddEdge", [IsGVGraphOrDigraph, IsGVEdge]);
+DeclareOperation("GV_GetIdx", [IsGVObject]);
+DeclareOperation("GV_ConstructHistory", [IsGVGraphOrDigraph]);
+
+DeclareGlobalFunction("GV_IsValidColor");
+DeclareGlobalFunction("GV_ErrorIfNotNodeColoring");
+
+BindGlobal("GV_ObjectFamily",
+           NewFamily("GV_ObjectFamily", IsGVObject));
+
+BindGlobal("GV_DigraphType", NewType(GV_ObjectFamily,
+                                    IsGVDigraph and
+                                    IsComponentObjectRep and
+                                    IsAttributeStoringRep));
+
+BindGlobal("GV_GraphType", NewType(GV_ObjectFamily,
+                                    IsGVGraph and
+                                    IsComponentObjectRep and
+                                    IsAttributeStoringRep));
+
+BindGlobal("GV_KNOWN_ATTRS", [
+  "_background", "area", "arrowhead", "arrowsize", "arrowtail", "bb",
+  "beautify", "bgcolor", "center", "charset", "class", "cluster", "clusterrank",
+  "color", "colorscheme", "comment", "compound", "concentrate", "constraint",
+  "Damping", "decorate", "defaultdist", "dim", "dimen", "dir",
+  "diredgeconstraints", "distortion", "dpi", "edgehref", "edgetarget",
+  "edgetooltip", "edgeURL", "epsilon", "esep", "fillcolor", "fixedsize",
+  "fontcolor", "fontname", "fontnames", "fontpath", "fontsize", "forcelabels",
+  "gradientangle", "group", "head_lp", "headclip", "headhref", "headlabel",
+  "headport", "headtarget", "headtooltip", "headURL", "height", "href", "id",
+  "image", "imagepath", "imagepos", "imagescale", "inputscale", "K", "label",
+  "label_scheme", "labelangle", "labeldistance", "labelfloat", "labelfontcolor",
+  "labelfontname", "labelfontsize", "labelhref", "labeljust", "labelloc",
+  "labeltarget", "labeltooltip", "labelURL", "landscape", "layer",
+  "layerlistsep", "layers", "layerselect", "layersep", "layout", "len",
+  "levels", "levelsgap", "lhead", "lheight", "linelength", "lp", "ltail",
+  "lwidth", "margin", "maxiter", "mclimit", "mindist", "minlen", "mode",
+  "model", "newrank", "nodesep", "nojustify", "normalize", "notranslate",
+  "nslimit", "nslimit1", "oneblock", "ordering", "orientation", "outputorder",
+  "overlap", "overlap_scaling", "overlap_shrink", "pack", "packmode", "pad",
+  "page", "pagedir", "pencolor", "penwidth", "peripheries", "pin", "pos",
+  "quadtree", "quantum", "rank", "rankdir", "ranksep", "ratio", "rects",
+  "regular", "remincross", "repulsiveforce", "resolution", "root", "rotate",
+  "rotation", "samehead", "sametail", "samplepoints", "scale", "searchsize",
+  "sep", "shape", "shapefile", "showboxes", "sides", "size", "skew",
+  "smoothing", "sortv", "splines", "start", "style", "stylesheet", "tail_lp",
+  "tailclip", "tailhref", "taillabel", "tailport", "tailtarget", "tailtooltip",
+  "tailURL", "target", "TBbalance", "tooltip", "truecolor", "URL", "vertices",
+  "viewport", "voro_margin", "weight", "width", "xdotversion", "xlabel", "xlp",
+  "z"
+]);
+
+BindGlobal("GV_ValidColorNames",
+  ["aliceblue", "antiquewhite", "antiquewhite1", "antiquewhite2",
+  "antiquewhite3", "antiquewhite4", "aquamarine", "aquamarine1", "aquamarine2",
+  "aquamarine3", "aquamarine4", "azure", "azure1", "azure2", "azure3",
+  "azure4", "beige", "bisque", "bisque1", "bisque2", "bisque3", "bisque4",
+  "black", "blanchedalmond", "blue", "blue1", "blue2", "blue3", "blue4",
+  "blueviolet", "brown", "brown1", "brown2", "brown3", "brown4", "burlywood",
+  "burlywood1", "burlywood2", "burlywood3", "burlywood4", "cadetblue",
+  "cadetblue1", "cadetblue2", "cadetblue3", "cadetblue4", "chartreuse",
+  "chartreuse1", "chartreuse2", "chartreuse3", "chartreuse4", "chocolate",
+  "chocolate1", "chocolate2", "chocolate3", "chocolate4", "coral", "coral1",
+  "coral2", "coral3", "coral4", "cornflowerblue", "cornsilk", "cornsilk1",
+  "cornsilk2", "cornsilk3", "cornsilk4", "crimson", "cyan", "cyan1", "cyan2",
+  "cyan3", "cyan4", "darkgoldenrod", "darkgoldenrod1", "darkgoldenrod2",
+  "darkgoldenrod3", "darkgoldenrod4", "darkgreen", "darkkhaki",
+  "darkolivegreen", "darkolivegreen1", "darkolivegreen2", "darkolivegreen3",
+  "darkolivegreen4", "darkorange", "darkorange1", "darkorange2", "darkorange3",
+  "darkorange4", "darkorchid", "darkorchid1", "darkorchid2", "darkorchid3",
+  "darkorchid4", "darksalmon", "darkseagreen", "darkseagreen1",
+  "darkseagreen2", "darkseagreen3", "darkseagreen4", "darkslateblue",
+  "darkslategray", "darkslategray1", "darkslategray2", "darkslategray3",
+  "darkslategray4", "darkslategrey", "darkturquoise", "darkviolet", "deeppink",
+  "deeppink1", "deeppink2", "deeppink3", "deeppink4", "deepskyblue",
+  "deepskyblue1", "deepskyblue2", "deepskyblue3", "deepskyblue4", "dimgray",
+  "dimgrey", "dodgerblue", "dodgerblue1", "dodgerblue2", "dodgerblue3",
+  "dodgerblue4", "firebrick", "firebrick1", "firebrick2", "firebrick3",
+  "firebrick4", "floralwhite", "forestgreen", "gainsboro", "ghostwhite",
+  "gold", "gold1", "gold2", "gold3", "gold4", "goldenrod", "goldenrod1",
+  "goldenrod2", "goldenrod3", "goldenrod4", "gray", "gray0", "gray1", "gray10",
+  "gray100", "gray11", "gray12", "gray13", "gray14", "gray15", "gray16",
+  "gray17", "gray18", "gray19", "gray2", "gray20", "gray21", "gray22",
+  "gray23", "gray24", "gray25", "gray26", "gray27", "gray28", "gray29",
+  "gray3", "gray30", "gray31", "gray32", "gray33", "gray34", "gray35",
+  "gray36", "gray37", "gray38", "gray39", "gray4", "gray40", "gray41",
+  "gray42", "gray43", "gray44", "gray45", "gray46", "gray47", "gray48",
+  "gray49", "gray5", "gray50", "gray51", "gray52", "gray53", "gray54",
+  "gray55", "gray56", "gray57", "gray58", "gray59", "gray6", "gray60",
+  "gray61", "gray62", "gray63", "gray64", "gray65", "gray66", "gray67",
+  "gray68", "gray69", "gray7", "gray70", "gray71", "gray72", "gray73",
+  "gray74", "gray75", "gray76", "gray77", "gray78", "gray79", "gray8",
+  "gray80", "gray81", "gray82", "gray83", "gray84", "gray85", "gray86",
+  "gray87", "gray88", "gray89", "gray9", "gray90", "gray91", "gray92",
+  "gray93", "gray94", "gray95", "gray96", "gray97", "gray98", "gray99",
+  "green", "green1", "green2", "green3", "green4", "greenyellow", "grey",
+  "grey0", "grey1", "grey10", "grey100", "grey11", "grey12", "grey13",
+  "grey14", "grey15", "grey16", "grey17", "grey18", "grey19", "grey2",
+  "grey20", "grey21", "grey22", "grey23", "grey24", "grey25", "grey26",
+  "grey27", "grey28", "grey29", "grey3", "grey30", "grey31", "grey32",
+  "grey33", "grey34", "grey35", "grey36", "grey37", "grey38", "grey39",
+  "grey4", "grey40", "grey41", "grey42", "grey43", "grey44", "grey45",
+  "grey46", "grey47", "grey48", "grey49", "grey5", "grey50", "grey51",
+  "grey52", "grey53", "grey54", "grey55", "grey56", "grey57", "grey58",
+  "grey59", "grey6", "grey60", "grey61", "grey62", "grey63", "grey64",
+  "grey65", "grey66", "grey67", "grey68", "grey69", "grey7", "grey70",
+  "grey71", "grey72", "grey73", "grey74", "grey75", "grey76", "grey77",
+  "grey78", "grey79", "grey8", "grey80", "grey81", "grey82", "grey83",
+  "grey84", "grey85", "grey86", "grey87", "grey88", "grey89", "grey9",
+  "grey90", "grey91", "grey92", "grey93", "grey94", "grey95", "grey96",
+  "grey97", "grey98", "grey99", "honeydew", "honeydew1", "honeydew2",
+  "honeydew3", "honeydew4", "hotpink", "hotpink1", "hotpink2", "hotpink3",
+  "hotpink4", "indianred", "indianred1", "indianred2", "indianred3",
+  "indianred4", "indigo", "invis", "ivory", "ivory1", "ivory2", "ivory3",
+  "ivory4", "khaki", "khaki1", "khaki2", "khaki3", "khaki4", "lavender",
+  "lavenderblush", "lavenderblush1", "lavenderblush2", "lavenderblush3",
+  "lavenderblush4", "lawngreen", "lemonchiffon", "lemonchiffon1",
+  "lemonchiffon2", "lemonchiffon3", "lemonchiffon4", "lightblue", "lightblue1",
+  "lightblue2", "lightblue3", "lightblue4", "lightcoral", "lightcyan",
+  "lightcyan1", "lightcyan2", "lightcyan3", "lightcyan4", "lightgoldenrod",
+  "lightgoldenrod1", "lightgoldenrod2", "lightgoldenrod3", "lightgoldenrod4",
+  "lightgoldenrodyellow", "lightgray", "lightgrey", "lightpink", "lightpink1",
+  "lightpink2", "lightpink3", "lightpink4", "lightsalmon", "lightsalmon1",
+  "lightsalmon2", "lightsalmon3", "lightsalmon4", "lightseagreen",
+  "lightskyblue", "lightskyblue1", "lightskyblue2", "lightskyblue3",
+  "lightskyblue4", "lightslateblue", "lightslategray", "lightslategrey",
+  "lightsteelblue", "lightsteelblue1", "lightsteelblue2", "lightsteelblue3",
+  "lightsteelblue4", "lightyellow", "lightyellow1", "lightyellow2",
+  "lightyellow3", "lightyellow4", "limegreen", "linen", "magenta", "magenta1",
+  "magenta2", "magenta3", "magenta4", "maroon", "maroon1", "maroon2",
+  "maroon3", "maroon4", "mediumaquamarine", "mediumblue", "mediumorchid",
+  "mediumorchid1", "mediumorchid2", "mediumorchid3", "mediumorchid4",
+  "mediumpurple", "mediumpurple1", "mediumpurple2", "mediumpurple3",
+  "mediumpurple4", "mediumseagreen", "mediumslateblue", "mediumspringgreen",
+  "mediumturquoise", "mediumvioletred", "midnightblue", "mintcream",
+  "mistyrose", "mistyrose1", "mistyrose2", "mistyrose3", "mistyrose4",
+  "moccasin", "navajowhite", "navajowhite1", "navajowhite2", "navajowhite3",
+  "navajowhite4", "navy", "navyblue", "none", "oldlace", "olivedrab",
+  "olivedrab1", "olivedrab2", "olivedrab3", "olivedrab4", "orange", "orange1",
+  "orange2", "orange3", "orange4", "orangered", "orangered1", "orangered2",
+  "orangered3", "orangered4", "orchid", "orchid1", "orchid2", "orchid3",
+  "orchid4", "palegoldenrod", "palegreen", "palegreen1", "palegreen2",
+  "palegreen3", "palegreen4", "paleturquoise", "paleturquoise1",
+  "paleturquoise2", "paleturquoise3", "paleturquoise4", "palevioletred",
+  "palevioletred1", "palevioletred2", "palevioletred3", "palevioletred4",
+  "papayawhip", "peachpuff", "peachpuff1", "peachpuff2", "peachpuff3",
+  "peachpuff4", "peru", "pink", "pink1", "pink2", "pink3", "pink4", "plum",
+  "plum1", "plum2", "plum3", "plum4", "powderblue", "purple", "purple1",
+  "purple2", "purple3", "purple4", "red", "red1", "red2", "red3", "red4",
+  "rosybrown", "rosybrown1", "rosybrown2", "rosybrown3", "rosybrown4",
+  "royalblue", "royalblue1", "royalblue2", "royalblue3", "royalblue4",
+  "saddlebrown", "salmon", "salmon1", "salmon2", "salmon3", "salmon4",
+  "sandybrown", "seagreen", "seagreen1", "seagreen2", "seagreen3", "seagreen4",
+  "seashell", "seashell1", "seashell2", "seashell3", "seashell4", "sienna",
+  "sienna1", "sienna2", "sienna3", "sienna4", "skyblue", "skyblue1",
+  "skyblue2", "skyblue3", "skyblue4", "slateblue", "slateblue1", "slateblue2",
+  "slateblue3", "slateblue4", "slategray", "slategray1", "slategray2",
+  "slategray3", "slategray4", "slategrey", "snow", "snow1", "snow2", "snow3",
+  "snow4", "springgreen", "springgreen1", "springgreen2", "springgreen3",
+  "springgreen4", "steelblue", "steelblue1", "steelblue2", "steelblue3",
+  "steelblue4", "tan", "tan1", "tan2", "tan3", "tan4", "thistle", "thistle1",
+  "thistle2", "thistle3", "thistle4", "tomato", "tomato1", "tomato2",
+  "tomato3", "tomato4", "transparent", "turquoise", "turquoise1", "turquoise2",
+  "turquoise3", "turquoise4", "violet", "violetred", "violetred1",
+  "violetred2", "violetred3", "violetred4", "wheat", "wheat1", "wheat2",
+  "wheat3", "wheat4", "white", "whitesmoke", "yellow", "yellow1", "yellow2",
+  "yellow3", "yellow4", "yellowgreen"]);
diff --git a/gap/gv.gi b/gap/gv.gi
new file mode 100644
index 0000000..185aa4b
--- /dev/null
+++ b/gap/gv.gi
@@ -0,0 +1,679 @@
+#############################################################################
+##
+##  gv.gi
+##  Copyright (C) 2024                                      James Mitchell
+##
+##  Licensing information can be found in the README file of this package.
+##
+#############################################################################
+##
+
+# code from the GAP standard library
+InstallMethod(GV_Pluralize,
+"for an integer and a string",
+[IsInt, IsString],
+function(args...)
+  local nargs, i, count, include_num, str, len, out;
+
+  nargs := Length(args);
+  if nargs >= 1 and IsInt(args[1]) and args[1] >= 0 then
+    i           := 2;
+    count       := args[1];
+    include_num := true;
+  else
+    i           := 1;
+    include_num := false;  # if not given, assume pluralization is wanted.
+  fi;
+
+  if not (nargs in [i, i + 1] and
+          IsString(args[i]) and
+          (nargs = i or IsString(args[i + 1]))) then
+    ErrorNoReturn("Usage: GV_Pluralize([<count>, ]<string>[, <plural>])");
+  fi;
+
+  str := args[i];
+  len := Length(str);
+
+  if len = 0 then
+    ErrorNoReturn("the argument <str> must be a non-empty string");
+  elif include_num and count = 1 then  # no pluralization needed
+    return Concatenation("\>1\< ", str);
+  elif nargs = i + 1 then  # pluralization given
+    out := args[i + 1];
+  elif len <= 2 then
+    out := Concatenation(str, "s");
+
+    # Guess and return the plural form of <str>.
+    # Inspired by the "Ruby on Rails" inflection rules.
+
+    # Uncountable nouns
+  elif str in ["equipment", "information"] then
+    out := str;
+
+    # Irregular plurals
+  elif str = "axis" then
+    out := "axes";
+  elif str = "child" then
+    out := "children";
+  elif str = "person" then
+    out := "people";
+
+    # Peculiar endings
+  elif EndsWith(str, "ix") or EndsWith(str, "ex") then
+    out := Concatenation(str{[1 .. len - 2]}, "ices");
+  elif EndsWith(str, "x") then
+    out := Concatenation(str, "es");
+  elif EndsWith(str, "tum") or EndsWith(str, "ium") then
+    out := Concatenation(str{[1 .. len - 2]}, "a");
+  elif EndsWith(str, "sis") then
+    out := Concatenation(str{[1 .. len - 3]}, "ses");
+  elif EndsWith(str, "fe") and not EndsWith(str, "ffe") then
+    out := Concatenation(str{[1 .. len - 2]}, "ves");
+  elif EndsWith(str, "lf") or EndsWith(str, "rf") or EndsWith(str, "loaf") then
+    out := Concatenation(str{[1 .. len - 1]}, "ves");
+  elif EndsWith(str, "y") and not str[len - 1] in "aeiouy" then
+    out := Concatenation(str{[1 .. len - 1]}, "ies");
+  elif str{[len - 1, len]} in ["ch", "ss", "sh"] then
+    out := Concatenation(str, "es");
+  elif EndsWith(str, "s") then
+    out := str;
+
+    # Default to appending 's'
+  else
+    out := Concatenation(str, "s");
+  fi;
+
+  if include_num then
+    return Concatenation("\>", String(args[1]), "\< ", out);
+  fi;
+  return out;
+end);
+
+###############################################################################
+# Family + type
+###############################################################################
+
+BindGlobal("GV_MapType", NewType(GV_ObjectFamily,
+                                 GV_IsMap and
+                                 IsComponentObjectRep and
+                                 IsAttributeStoringRep));
+
+BindGlobal("GV_NodeType", NewType(GV_ObjectFamily,
+                                    IsGVNode and
+                                    IsComponentObjectRep and
+                                    IsAttributeStoringRep));
+
+BindGlobal("GV_EdgeType", NewType(GV_ObjectFamily,
+                                    IsGVEdge and
+                                    IsComponentObjectRep and
+                                    IsAttributeStoringRep));
+
+BindGlobal("GV_ContextType", NewType(GV_ObjectFamily,
+                                    IsGVContext and
+                                    IsComponentObjectRep and
+                                    IsAttributeStoringRep));
+
+InstallMethod(\=, "for IsGVNode and IsGVNode",
+[IsGVNode, IsGVNode],
+{n1, n2} -> GraphvizName(n1) = GraphvizName(n2));
+
+###############################################################################
+# Constructors etc
+###############################################################################
+
+
+InstallMethod(GV_Map, "for no args",
+[], {} -> Objectify(GV_MapType, rec(Data := rec())));
+
+InstallMethod(GV_Node, "for a string",
+[IsGVGraphOrDigraph, IsString],
+function(graph, name)
+  local out;
+  if Length(name) = 0 then
+    ErrorNoReturn("the 2nd argument (string/node name) cannot be empty");
+  fi;
+  out := Objectify(GV_NodeType,
+                  rec(
+                    Name  := name,
+                    Attrs := GV_Map(),
+                    Idx   := GV_GetCounter(graph)));
+  GV_IncCounter(graph);
+  return out;
+end);
+
+InstallMethod(GV_Edge, "for two graphviz nodes",
+[IsGVGraphOrDigraph, IsGVNode, IsGVNode],
+function(graph, head, tail)
+  local out;
+  out := Objectify(GV_EdgeType,
+                rec(
+                  Name  := "",
+                  Head  := head,
+                  Tail  := tail,
+                  Attrs := GV_Map(),
+                  Idx   := GV_GetCounter(graph)));
+  GV_IncCounter(graph);
+  return out;
+end);
+
+# Graph constructors
+
+InstallMethod(GV_Digraph,
+"for a graphviz digraph and a string",
+[IsGVDigraph, IsString],
+function(parent, name)
+  local out;
+
+  out         := GraphvizDigraph(name);
+  out!.Parent := parent;
+  out!.Idx    := GV_GetCounter(parent);
+
+  GV_IncCounter(parent);
+  return out;
+end);
+
+InstallMethod(GV_Graph,
+"for a graphviz graph and a string",
+[IsGVGraphOrDigraph, IsString],
+function(parent, name)
+  local out;
+
+  out         := GraphvizGraph(name);
+  out!.Parent := parent;
+  out!.Idx    := GV_GetCounter(parent);
+
+  GV_IncCounter(parent);
+  return out;
+end);
+
+InstallMethod(GV_Context,
+"for a string and a positive integer",
+[IsGVGraphOrDigraph, IsString],
+function(parent, name)
+  local out;
+
+  out := Objectify(GV_ContextType,
+                      rec(
+                        Name      := name,
+                        Subgraphs := GV_Map(),
+                        Nodes     := GV_Map(),
+                        Edges     := [],
+                        Attrs     := [],
+                        Parent    := parent,
+                        Idx       := GV_GetCounter(parent),
+                        Counter   := 1));
+
+  GV_IncCounter(parent);
+  return out;
+end);
+
+############################################################
+# Graphviz Map Functions
+############################################################
+
+InstallOtherMethod(\[\],
+"for a graphviz map and an object",
+[GV_IsMap, IsObject],
+function(m, o)
+  if IsBound(m[o]) then
+    return m!.Data.(o);
+  fi;
+  return fail;
+end);
+
+InstallOtherMethod(\[\]\:\=,
+"for a graphviz map and two objects",
+[GV_IsMap, IsObject, IsObject],
+function(m, key, val)
+  m!.Data.(key) := val;
+end);
+
+InstallOtherMethod(Unbind\[\],
+"for a graphviz map and an object",
+[GV_IsMap, IsObject],
+function(m, key)
+  Unbind(m!.Data.(key));
+end);
+
+InstallOtherMethod(IsBound\[\],
+"for a graphviz map and an object",
+[GV_IsMap, IsObject],
+{m, key} -> IsBound(m!.Data.(key)));
+
+
+InstallMethod(GV_MapNames, "for a graphviz map",
+[GV_IsMap], m -> RecNames(m!.Data));
+
+InstallMethod(ViewString, "for a graphviz map", [GV_IsMap],
+m -> String(m!.Data));
+
+InstallMethod(Size, "for a graphviz map",
+[GV_IsMap], m -> Length(GV_MapNames(m)));
+
+# ??
+
+InstallMethod(GV_IncCounter,
+"for a graphviz graph",
+[IsGVGraphOrDigraph],
+function(x)
+  x!.Counter := x!.Counter + 1;
+end);
+
+InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGVGraphOrDigraph],
+x -> x!.Counter);
+
+# Converting strings
+
+InstallMethod(GV_EnsureString,
+"for an object",
+[IsObject], ViewString);
+
+InstallMethod(GV_EnsureString,
+"for a string",
+[IsString],
+x -> x);
+
+# Nodes
+
+InstallMethod(GV_HasNode,
+"for a graphviz graph",
+[IsGVGraphOrDigraph, IsString],
+{g, name} -> name in GV_MapNames(GraphvizNodes(g)));
+
+InstallMethod(GV_GetParent,
+"for a graphviz graph",
+[IsGVGraphOrDigraph], graph -> graph!.Parent);
+
+InstallMethod(GV_GraphTreeSearch,
+"for a graphviz graph and a predicate",
+[IsGVGraphOrDigraph, IsFunction],
+function(graph, pred)
+  local seen, to_visit, g, key, subgraph, parent;
+  seen     := [graph];
+  to_visit := [graph];
+
+  while Length(to_visit) > 0 do
+    g := Remove(to_visit, Length(to_visit));
+
+    # Check this graph
+    if pred(g) then
+      return g;
+    fi;
+
+    # add subgraphs to list of to visit if not visited
+    for key in GV_MapNames(GraphvizSubgraphs(g)) do
+      subgraph := GraphvizSubgraphs(g)[key];
+      if not ForAny(seen, s -> IsIdenticalObj(s, subgraph)) then
+        Add(seen, subgraph);
+        Add(to_visit, subgraph);
+      fi;
+    od;
+
+    # add parent if not visited
+    parent := GV_GetParent(g);
+    if not IsGVGraphOrDigraph(parent) then
+      continue;
+    fi;
+    if not ForAny(seen, s -> IsIdenticalObj(s, parent)) then
+      Add(seen, parent);
+      Add(to_visit, parent);
+    fi;
+  od;
+
+  return fail;
+end);
+
+InstallMethod(GV_FindGraphWithNode,
+"for a graphviz graph and a node",
+[IsGVGraphOrDigraph, IsString],
+{g, n} -> GV_GraphTreeSearch(g, v -> v[n] <> fail));
+
+InstallMethod(GV_GetRoot,
+"for a graphviz graph",
+[IsGVGraphOrDigraph],
+function(graph)
+  while GV_GetParent(graph) <> fail do
+    graph := GV_GetParent(graph);
+  od;
+  return graph;
+end);
+
+InstallMethod(GV_FindNode,
+"for a graphviz graph and a string",
+[IsGVGraphOrDigraph, IsString],
+function(g, n)
+  local graph;
+  graph := GV_FindGraphWithNode(g, n);
+  if graph = fail then
+    return graph;
+  fi;
+  return graph[n];
+end);
+
+InstallMethod(GV_AddNode,
+"for a graphviz graph and node",
+[IsGVGraphOrDigraph, IsGVNode],
+function(x, node)
+  local found, error, name, nodes;
+  name  := GraphvizName(node);
+  nodes := GraphvizNodes(x);
+
+  # dont add if already node with the same name
+  found := GV_FindGraphWithNode(x, name);
+  if found <> fail then
+    error := "Already node with name {} in graph {}.";
+    ErrorNoReturn(StringFormatted(error, name, GraphvizName(found)));
+  fi;
+
+  nodes[name] := node;
+  return x;
+end);
+
+InstallMethod(GV_AddEdge,
+"for a graphviz graph and edge",
+[IsGVGraphOrDigraph, IsGVEdge],
+function(x, edge)
+  local head, head_name, tail_name, tail, hg, error, tg;
+
+  head      := GraphvizHead(edge);
+  tail      := GraphvizTail(edge);
+  head_name := GraphvizName(head);
+  tail_name := GraphvizName(tail);
+  hg        := GV_FindGraphWithNode(x, head_name);
+  tg        := GV_FindGraphWithNode(x, tail_name);
+
+  # if not already existing, add the nodes to the graph
+  if hg = fail then
+    GV_AddNode(x, head);
+  fi;
+  if tg = fail then
+    GV_AddNode(x, tail);
+  fi;
+
+  # make sure the nodes exist / are the same as existing ones
+  if hg <> fail and not IsIdenticalObj(head, hg[head_name]) then
+    # TODO improve
+    ErrorFormatted("Different node in graph {} with name {}",
+                   GraphvizName(hg),
+                   head_name);
+  fi;
+  if tg <> fail and not IsIdenticalObj(tail, tg[tail_name]) then
+    # TODO improve
+    error := "Different node in graph {} with name {}.";
+    ErrorNoReturn(StringFormatted(error,
+                                         GraphvizName(tg),
+                                         tail_name));
+  fi;
+
+  Add(x!.Edges, edge);
+  return x;
+end);
+
+###############################################################################
+# Stringifying
+###############################################################################
+
+# @ Return DOT graph head line.
+InstallMethod(GV_StringifyGraphHead, "for a string", [IsGVGraphOrDigraph],
+graph -> StringFormatted("graph {} {{\n", GraphvizName(graph)));
+
+# @ Return DOT digraph head line.
+InstallMethod(GV_StringifyDigraphHead, "for a string", [IsGVDigraph],
+graph -> StringFormatted("digraph {} {{\n", GraphvizName(graph)));
+
+# @ Return DOT subgraph head line.
+InstallMethod(GV_StringifySubgraphHead, "for a string", [IsGVGraphOrDigraph],
+graph -> StringFormatted("subgraph {} {{\n", GraphvizName(graph)));
+
+# @ Return DOT subgraph head line.
+InstallMethod(GV_StringifyContextHead, "for a string", [IsGVContext],
+graph -> StringFormatted("// {} context \n", GraphvizName(graph)));
+
+BindGlobal("GV_StringifyNodeName",
+function(node)
+  local name, old;
+
+  Assert(0, IsGVNode(node));
+  name  := GraphvizName(node);
+  if (ForAny("- .+", x -> x in name)
+      or (IsDigitChar(First(name)) and IsAlphaChar(Last(name))))
+      and not StartsWith(name, "\"") then
+    old  := name;
+    name := StringFormatted("\"{}\"", name);
+    Info(InfoWarning,
+         1,
+         "invalid node name ",
+         old,
+         " using ",
+         name,
+         " instead");
+  fi;
+  return name;
+end);
+
+# @ Return DOT node statement line.
+InstallMethod(GV_StringifyNode, "for string and record",
+[IsGVNode],
+function(node)
+  local name, attrs;
+  name  := GV_StringifyNodeName(node);
+  attrs := GraphvizAttrs(node);
+  return StringFormatted("\t{}{}\n", name, GV_StringifyNodeEdgeAttrs(attrs));
+end);
+
+# @ Return DOT graph edge statement line.
+BindGlobal("GV_StringifyEdge",
+function(edge, edge_str)
+  local head, tail, attrs;
+  Assert(0, IsGVEdge(edge));
+  Assert(0, IsString(edge_str));
+  head  := GV_StringifyNodeName(GraphvizHead(edge));
+  tail  := GV_StringifyNodeName(GraphvizTail(edge));
+  attrs := GraphvizAttrs(edge);
+
+  # handle : syntax
+  return StringFormatted("\t{} {} {}{}\n",
+                         head,
+                         edge_str,
+                         tail,
+                         GV_StringifyNodeEdgeAttrs(attrs));
+end);
+
+InstallMethod(GV_StringifyGraphAttrs,
+"for a graphviz graph",
+[IsGVGraphOrDigraph],
+function(graph)
+  local result, attrs, kv;
+  attrs  := GraphvizAttrs(graph);
+  result := "";
+
+  if Length(attrs) <> 0 then
+    Append(result, "\t");
+    for kv in attrs do
+      Append(result,
+             StringFormatted("{} ", kv));
+    od;
+    Append(result, "\n");
+  fi;
+  return result;
+end);
+
+InstallMethod(GV_StringifyNodeEdgeAttrs,
+"for a GV_Map",
+[GV_IsMap],
+function(attrs)
+  local result, keys, key, val, n, i, tmp;
+
+  result := "";
+  n      := Length(GV_MapNames(attrs));
+  keys   := SSortedList(GV_MapNames(attrs));
+
+  if n <> 0 then
+    Append(result, " [");
+    for i in [1 .. n - 1] do
+        key := keys[i];
+        val := attrs[key];
+
+        tmp := Chomp(val);
+        if "label" = key and StartsWith(tmp, "<<") and EndsWith(tmp, ">>") then
+          val := StringFormatted("{}", val);
+        else
+          if ' ' in key then
+            key := StringFormatted("\"{}\"", key);
+          fi;
+          if ' ' in val or '>' in val or '^' in val or '#' in val then
+              # TODO avoid code duplication here, and below
+            val := StringFormatted("\"{}\"", val);
+          fi;
+        fi;
+
+        Append(result,
+               StringFormatted("{}={}, ",
+                               key,
+                               val));
+    od;
+
+    # handle last element
+    key := keys[n];
+    val := attrs[key];
+
+    tmp := Chomp(val);
+    if "label" = key and StartsWith(tmp, "<<") and EndsWith(tmp, ">>") then
+      val := StringFormatted("{}", val);
+    else
+        if ' ' in key then
+          key := StringFormatted("\"{}\"", key);
+        fi;
+        if ' ' in val or '>' in val or '^' in val or '#' in val then
+          # TODO what are the allowed things in the value?
+          val := StringFormatted("\"{}\"", val);
+        fi;
+    fi;
+
+    Append(result,
+           StringFormatted("{}={}]",
+                           key,
+                           val));
+  fi;
+
+  return result;
+end);
+
+InstallMethod(GV_GetIdx,
+"for a graphviz object",
+[IsGVObject],
+x -> x!.Idx);
+
+InstallMethod(GV_ConstructHistory,
+"for a graphviz graph",
+[IsGVGraphOrDigraph],
+function(graph)
+  local nodes, edges, subs, node_hist, edge_hist, subs_hist, hist;
+
+  nodes := GraphvizNodes(graph);
+  edges := GraphvizEdges(graph);
+  subs  := GraphvizSubgraphs(graph);
+
+  node_hist := List(GV_MapNames(nodes), n -> [GV_GetIdx(nodes[n]), nodes[n]]);
+  subs_hist := List(GV_MapNames(subs), s -> [GV_GetIdx(subs[s]), subs[s]]);
+  edge_hist := List(edges, e -> [GV_GetIdx(e), e]);
+
+  hist := Concatenation(node_hist, edge_hist, subs_hist);
+  SortBy(hist, v -> v[1]);
+
+  Apply(hist, x -> x[2]);
+  return hist;
+end);
+
+InstallMethod(GV_StringifyGraph,
+"for a graphviz graph and a string",
+[IsGVGraphOrDigraph, IsBool],
+function(graph, is_subgraph)
+  local result, obj;
+  result := "";
+
+  # get the correct head to use
+  if is_subgraph then
+    if IsGVContext(graph) then
+      Append(result, GV_StringifyContextHead(graph));
+    elif IsGVGraph(graph) or IsGVDigraph(graph) then
+      Append(result, GV_StringifySubgraphHead(graph));
+    else
+      ErrorNoReturn("Invalid subgraph type.");
+    fi;
+  elif IsGVDigraph(graph) then
+    Append(result, "//dot\n");
+    Append(result, GV_StringifyDigraphHead(graph));
+  elif IsGVGraph(graph) then
+    Append(result, "//dot\n");
+    Append(result, GV_StringifyGraphHead(graph));
+  elif IsGVContext(graph) then
+    Append(result, "//dot\n");
+    Append(result, GV_StringifyContextHead(graph));
+  else
+    ErrorNoReturn("Invalid graph type.");
+  fi;
+
+  Append(result, GV_StringifyGraphAttrs(graph));
+
+  # Add child graphviz objects
+  for obj in GV_ConstructHistory(graph) do
+    if IsGVGraphOrDigraph(obj) then
+      Append(result, GV_StringifyGraph(obj, true));
+    elif IsGVNode(obj) then
+      Append(result, GV_StringifyNode(obj));
+    elif IsGVEdge(obj) then
+      if IsGVDigraph(GV_GetRoot(graph)) then
+        Append(result, GV_StringifyEdge(obj, "->"));
+      else
+        Append(result, GV_StringifyEdge(obj, "--"));
+      fi;
+    else
+      ErrorNoReturn("Invalid graphviz object type.");
+    fi;
+  od;
+
+  if IsGVContext(graph) then
+    # reset attributes following the context
+    if GV_GetParent(graph) <> fail then
+      Append(result, GV_StringifyGraphAttrs(GV_GetParent(graph)));
+    fi;
+    Append(result, "\n");
+  else
+    Append(result, "}\n");
+  fi;
+  return result;
+end);
+
+BindGlobal("GV_IsValidRGBColor",
+function(str)
+  local valid, i;
+
+  valid := "0123456789ABCDEFabcdef";
+
+  if Length(str) <> 7 or str[1] <> '#' then
+    return false;
+  fi;
+
+  for i in [2 .. 7] do
+    if not str[i] in valid then
+      return false;
+    fi;
+  od;
+  return true;
+end);
+
+InstallGlobalFunction(GV_IsValidColor,
+c -> IsString(c) and (GV_IsValidRGBColor(c) or c in GV_ValidColorNames));
+
+InstallGlobalFunction(GV_ErrorIfNotNodeColoring,
+function(gv, colors)
+  local N;
+  N := Size(GraphvizNodes(gv));
+  if Length(colors) <> N then
+    ErrorFormatted(
+        "the number of node colors must be the same as the number",
+        " of nodes, expected {} but found {}", N, Length(colors));
+  fi;
+  Perform(colors, ErrorIfNotValidColor);
+end);
diff --git a/gap/splash.gd b/gap/splash.gd
new file mode 100644
index 0000000..e69de29
diff --git a/init.g b/init.g
index 7d8d023..b6ccf00 100644
--- a/init.g
+++ b/init.g
@@ -10,3 +10,4 @@
 
 ReadPackage("graphviz", "gap/error.gd");
 ReadPackage("graphviz", "gap/dot.gd");
+ReadPackage("graphviz", "gap/gv.gd");
diff --git a/read.g b/read.g
index 794be60..a13f5fb 100644
--- a/read.g
+++ b/read.g
@@ -10,4 +10,5 @@
 
 ReadPackage("graphviz", "gap/dot.gi");
 ReadPackage("graphviz", "gap/error.gi");
+ReadPackage("graphviz", "gap/gv.gi");
 ReadPackage("graphviz", "gap/splash.gi");

From 39d0b0c821fea48cdd26c7d912f444fa340a151f Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Mon, 13 May 2024 10:53:41 +0100
Subject: [PATCH 05/38] etc: add code-coverage-test-gap.py

---
 etc/code-coverage-test-gap.py | 107 ++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100755 etc/code-coverage-test-gap.py

diff --git a/etc/code-coverage-test-gap.py b/etc/code-coverage-test-gap.py
new file mode 100755
index 0000000..e50ea5a
--- /dev/null
+++ b/etc/code-coverage-test-gap.py
@@ -0,0 +1,107 @@
+#!/usr/bin/env python3
+"""
+This is a simple script to run code coverage for some test files.
+"""
+# pylint: disable=invalid-name
+
+import argparse
+import os
+import re
+import subprocess
+import sys
+import tempfile
+
+from os.path import exists, isdir, isfile
+from os import getcwd
+
+_ERR_PREFIX = "\033[31mcode-coverage-test-gap.py: error: "
+_INFO_PREFIX = "\033[0m\033[1m"
+
+_PARSER = argparse.ArgumentParser(
+    prog="code-coverage-test-gap.py", usage="%(prog)s [options]"
+)
+_PARSER.add_argument(
+    "tstfiles",
+    nargs="+",
+    type=str,
+    help="the test files you want to check code coverage for"
+    + "(must be at least one)",
+)
+_PARSER.add_argument(
+    "--gap-root",
+    nargs="?",
+    type=str,
+    help="the gap root directory (default: ~/gap)",
+    default="~/gap/",
+)
+_PARSER.add_argument(
+    "--open",
+    nargs="?",
+    type=str,
+    help=("open the html page for this file (default: None)"),
+    default=None,
+)
+
+_ARGS = _PARSER.parse_args()
+if not _ARGS.gap_root[-1] == "/":
+    _ARGS.gap_root += "/"
+
+if exists("gap") and isdir("gap"):
+    _PROFILE_DIR = "/gap/"
+elif exists("lib") and isdir("lib"):
+    _PROFILE_DIR = "/lib/"
+else:
+    sys.exit(f"{_ERR_PREFIX}no directory gap or lib to profile!\033[0m")
+
+_ARGS.gap_root = os.path.expanduser(_ARGS.gap_root)
+if not (exists(_ARGS.gap_root) and isdir(_ARGS.gap_root)):
+    sys.exit(f"{_ERR_PREFIX}can't find GAP root directory!\033[0m")
+
+for f in _ARGS.tstfiles:
+    if not (exists(f) and isfile(f)):
+        sys.exit(f"{_ERR_PREFIX}{f} does not exist!\033[0m")
+
+_DIR = tempfile.mkdtemp()
+print(f"{_INFO_PREFIX}Using temporary directory: {_DIR}\033[0m")
+
+_COMMANDS = 'echo "'
+_COMMANDS += "".join(rf"Test(\"{f}\");;\n" for f in _ARGS.tstfiles)
+_COMMANDS += rf"""UncoverageLineByLine();;
+LoadPackage(\"profiling\", false);;
+filesdir := \"{getcwd()}{_PROFILE_DIR}\";;\n"""
+
+_COMMANDS += rf"outdir := \"{_DIR}\";;\n"
+_COMMANDS += rf"x := ReadLineByLineProfile(\"{_DIR}/profile.gz\");;\n"
+_COMMANDS += 'OutputAnnotatedCodeCoverageFiles(x, filesdir, outdir);"'
+
+_RUN_GAP = f"{_ARGS.gap_root}/gap -A -m 1g -T --cover {_DIR}/profile.gz"
+
+with subprocess.Popen(_COMMANDS, stdout=subprocess.PIPE, shell=True) as pro1:
+    try:
+        with subprocess.Popen(_RUN_GAP, stdin=pro1.stdout, shell=True) as pro2:
+            pro2.wait()
+    except KeyboardInterrupt:
+        pro1.terminate()
+        pro1.wait()
+        sys.exit("\033[31mKilled!\033[0m")
+    except (subprocess.CalledProcessError, IOError, OSError):
+        sys.exit(_ERR_PREFIX + "Something went wrong calling GAP!\033[0m")
+
+
+def rewrite_fname(fname: str) -> str:
+    return fname.replace("/", "_")
+
+
+suffix = ""
+if _ARGS.open:
+    filename = f"{_DIR}/{rewrite_fname(getcwd())}/{rewrite_fname(_ARGS.open)}.html"
+    p = re.compile(r"<tr class='missed'><td><a name=\"line(\d+)\">")
+    with open(filename, "r", encoding="utf-8") as f:
+        m = p.search(f.read())
+        if m:
+            suffix += "#line" + m.group(1)
+else:
+    filename = _DIR + "/index.html"
+print(f"{_INFO_PREFIX}\nSUCCESS!\033[0m")
+print(f"{_INFO_PREFIX} See {filename}")
+sys.exit(0)

From 3e436747c6ee08ac32b97e2cf77ba99e5c996b93 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Mon, 13 May 2024 11:27:16 +0100
Subject: [PATCH 06/38] Improve error messages

---
 gap/dot.gi    | 19 ++++++++++---------
 tst/graph.tst | 22 ----------------------
 2 files changed, 10 insertions(+), 31 deletions(-)

diff --git a/gap/dot.gi b/gap/dot.gi
index 510f54a..cbba2c2 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -28,9 +28,6 @@ end);
 
 InstallMethod(GraphvizGraph, "for no args", [], {} -> GraphvizGraph(""));
 
-InstallMethod(GraphvizGraph, "for an object", [IsObject],
-o -> GraphvizGraph(ViewString(o)));
-
 InstallMethod(GraphvizDigraph, "for a string", [IsString],
 function(name)
   return Objectify(GV_DigraphType,
@@ -47,9 +44,6 @@ end);
 
 InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
 
-InstallMethod(GraphvizDigraph, "for an object", [IsObject],
-o -> GraphvizDigraph(ViewString(o)));
-
 ############################################################
 # Stringify
 ############################################################
@@ -119,10 +113,17 @@ InstallMethod(GraphvizEdges,
 [IsGVGraphOrDigraph, IsObject, IsObject],
 function(gv, head, tail)
     head := GraphvizNode(gv, head);
+    if head = fail then
+      ErrorNoReturn("the 2nd argument (head of an edge) is not a node ",
+                    "of the 1st argument (a graphviz graph or digraph)");
+    fi;
     tail := GraphvizNode(gv, tail);
-    # TODO if head = fail then...
-    return Filtered(GraphvizEdges(gv), x -> GraphvizHead(x) = head and
-    GraphvizTail(x) = tail);
+    if tail = fail then
+      ErrorNoReturn("the 2nd argument (head of an edge) is not a node ",
+                    "of the 1st argument (a graphviz graph or digraph)");
+    fi;
+    return Filtered(GraphvizEdges(gv),
+                    x -> GraphvizHead(x) = head and GraphvizTail(x) = tail);
 end);
 
 InstallMethod(GraphvizSubgraphs, "for a graphviz graph", [IsGVGraphOrDigraph],
diff --git a/tst/graph.tst b/tst/graph.tst
index 175d1d1..dcdd261 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -208,28 +208,6 @@ gap> g[1];
 <graphviz node 1>
 gap> g[["a"]];
 <graphviz node [ "a" ]>
-
-# Test making a graph with a non-string name
-gap> g := GraphvizGraph(11);
-<graphviz graph 11 with 0 nodes and 0 edges>
-
-# Test setting a graph name to a non-string value
-gap> g := GraphvizGraph(11);
-<graphviz graph 11 with 0 nodes and 0 edges>
-gap> GraphvizSetName(g, ["a"]);
-<graphviz graph [ "a" ] with 0 nodes and 0 edges>
-
-# Test making a digraph with a non-string name
-gap> g := GraphvizDigraph(11);
-<graphviz digraph 11 with 0 nodes and 0 edges>
-
-# Test setting a digraph name to a non-string value
-gap> g := GraphvizDigraph(11);
-<graphviz digraph 11 with 0 nodes and 0 edges>
-gap> GraphvizSetName(g, ["a"]);
-<graphviz digraph [ "a" ] with 0 nodes and 0 edges>
-
-# Test set label (graph)
 gap> g := GraphvizGraph();;
 gap> GraphvizSetAttr(g, "label", "test");;
 gap> GraphvizAttrs(g);

From 2b85ffd1e421227dfafb1eb6b90921f323dba420 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Mon, 13 May 2024 11:29:22 +0100
Subject: [PATCH 07/38] Replace GV with Graphviz in some places

---
 gap/dot.gd    |  85 +++++++++++++++++------------------
 gap/dot.gi    | 120 +++++++++++++++++++++++++-------------------------
 gap/gv.gd     |  54 +++++++++++------------
 gap/gv.gi     |  84 +++++++++++++++++------------------
 gap/splash.gi |   4 +-
 5 files changed, 172 insertions(+), 175 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 57891d0..8856d38 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -30,22 +30,19 @@
 #! @Section Graphviz Categories
 
 #! @BeginGroup Filters
-#! @Description Every object in graphviz belongs to the IsGVObject category.
-#! The categories following it are for further specificity on the type of
-#! objects. These are graphs, digraphs, nodes and edges respectively.
-#! All are direct subcategories of IsGVObject excluding IsGVDigraph which is a
-#! subcategory of is GVGraph.
-
-# TODO replace GV -> graphviz
-DeclareCategory("IsGVObject", IsObject);
-DeclareCategory("IsGVGraphOrDigraph", IsGVObject);
-# TODO change to IsGVObject below, since digraphs aren't a special kind of
-# graph, unless I'm (JDM) mistaken?
-DeclareCategory("IsGVGraph", IsGVGraphOrDigraph);
-DeclareCategory("IsGVDigraph", IsGVGraphOrDigraph);
-DeclareCategory("IsGVContext", IsGVGraphOrDigraph);
-DeclareCategory("IsGVNode", IsGVObject);
-DeclareCategory("IsGVEdge", IsGVObject);
+#! @Description Every object in graphviz belongs to the IsGraphvizObject
+#! category. The categories following it are for further specificity on the
+#! type of objects. These are graphs, digraphs, nodes and edges respectively.
+#! All are direct subcategories of IsGraphvizObject excluding IsGraphvizDigraph
+#! which is a subcategory of is IsGraphvizGraph.
+
+DeclareCategory("IsGraphvizObject", IsObject);
+DeclareCategory("IsGraphvizGraphOrDigraph", IsGraphvizObject);
+DeclareCategory("IsGraphvizGraph", IsGraphvizGraphOrDigraph);
+DeclareCategory("IsGraphvizDigraph", IsGraphvizGraphOrDigraph);
+DeclareCategory("IsGraphvizContext", IsGraphvizGraphOrDigraph);
+DeclareCategory("IsGraphvizNode", IsGraphvizObject);
+DeclareCategory("IsGraphvizEdge", IsGraphvizObject);
 #! @EndGroup
 
 #! @Section Constructors
@@ -77,12 +74,12 @@ DeclareOperation("GraphvizDigraph", []);
 #! @Arguments obj
 #! @Returns the name of the provided graphviz object
 #! @Description Gets the name of the provided graphviz object.
-DeclareOperation("GraphvizName", [IsGVObject]);
+DeclareOperation("GraphvizName", [IsGraphvizObject]);
 
 #! @Arguments obj
 #! @Returns the attributes of the provided graphviz object
 #! @Description Gets the attributes of the provided graphviz object.
-DeclareOperation("GraphvizAttrs", [IsGVObject]);
+DeclareOperation("GraphvizAttrs", [IsGraphvizObject]);
 
 #! @Subsection For only graphs and digraphs.
 
@@ -90,14 +87,14 @@ DeclareOperation("GraphvizAttrs", [IsGVObject]);
 #! @Returns the nodes of the provided graphviz graph.
 #! @Description Gets the nodes of the provided graphviz graph.
 #! Node names can only be [a-zA-Z0-9_£] TODO check exact docs.
-DeclareOperation("GraphvizNodes", [IsGVGraphOrDigraph]);
-DeclareOperation("GraphvizNode", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizNodes", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GraphvizNode", [IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph
 #! @Returns the subgraphs of the provided graphviz graph.
 #! @Description gets the subgraphs of a provided graphviz graph.
-DeclareOperation("GraphvizSubgraphs", [IsGVGraphOrDigraph]);
-DeclareOperation("GraphvizGetSubgraph", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizSubgraphs", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GraphvizGetSubgraph", [IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, name
 #! @Returns a graph with the provided name.
@@ -106,25 +103,25 @@ DeclareOperation("GraphvizGetSubgraph", [IsGVGraphOrDigraph, IsObject]);
 #! with the provided name.
 #! It returns the graph if it exists.
 #! If no such graph exists then it will return fail.
-DeclareOperation("GraphvizFindGraph", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizFindGraph", [IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph
 #! @Returns the edges of the provided graphviz graph.
 #! @Description Gets the edges of the provided graphviz graph.
-DeclareOperation("GraphvizEdges", [IsGVGraphOrDigraph]);
-DeclareOperation("GraphvizEdges", [IsGVGraphOrDigraph, IsObject, IsObject]);
+DeclareOperation("GraphvizEdges", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GraphvizEdges", [IsGraphvizGraphOrDigraph, IsObject, IsObject]);
 
 #! @Subsection For only edges.
 
 #! @Arguments edge
 #! @Returns the head of the provided graphviz edge.
 #! @Description Gets the head of the provided graphviz graph.
-DeclareOperation("GraphvizHead", [IsGVEdge]);
+DeclareOperation("GraphvizHead", [IsGraphvizEdge]);
 
 #! @Arguments edge
 #! @Returns the head of the provided graphviz tail.
 #! @Description Gets the tail of the provided graphviz graph.
-DeclareOperation("GraphvizTail", [IsGVEdge]);
+DeclareOperation("GraphvizTail", [IsGraphvizEdge]);
 
 #! @Section Set Operations
 #! This section covers operations for modifying graphviz objects.
@@ -134,13 +131,13 @@ DeclareOperation("GraphvizTail", [IsGVEdge]);
 #! @Arguments graph, name
 #! @Returns the modified graph.
 #! @Description Sets the name of a graphviz graph or digraph.
-DeclareOperation("GraphvizSetName", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizSetName", [IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Adds a node to the graph.
 #! If a node with the same name is already present the operation fails.
-DeclareOperation("GraphvizAddNode", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizAddNode", [IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, edge
 #! @Returns the modified graph.
@@ -148,35 +145,35 @@ DeclareOperation("GraphvizAddNode", [IsGVGraphOrDigraph, IsObject]);
 #! If no nodes with the same name are in the graph then the edge's nodes will be
 #! added to the graph. If different nodes with the same name are in the graph
 #! then the operation fails.
-DeclareOperation("GraphvizAddEdge", [IsGVGraphOrDigraph, IsObject, IsObject]);
+DeclareOperation("GraphvizAddEdge", [IsGraphvizGraphOrDigraph, IsObject, IsObject]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new subgraph.
 #! @Description Adds a subgraph to a graph.
-DeclareOperation("GraphvizAddSubgraph", [IsGVGraphOrDigraph, IsObject]);
-DeclareOperation("GraphvizAddSubgraph", [IsGVGraphOrDigraph]);
+DeclareOperation("GraphvizAddSubgraph", [IsGraphvizGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizAddSubgraph", [IsGraphvizGraphOrDigraph]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new context.
 #! @Description Adds a context to a graph.
-DeclareOperation("GraphvizAddContext", [IsGVGraphOrDigraph, IsObject]);
-DeclareOperation("GraphvizAddContext", [IsGVGraphOrDigraph]);
+DeclareOperation("GraphvizAddContext", [IsGraphvizGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizAddContext", [IsGraphvizGraphOrDigraph]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Removes the node from the graph.
-DeclareOperation("GraphvizRemoveNode", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizRemoveNode", [IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, predicate
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges using the provided predicate.
-DeclareOperation("GraphvizFilterEdges", [IsGVGraphOrDigraph, IsFunction]);
+DeclareOperation("GraphvizFilterEdges", [IsGraphvizGraphOrDigraph, IsFunction]);
 
 #! @Arguments graph, head_name, tail_name
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges, removing edges between nodes with
 #! the specified names.
-DeclareOperation("GraphvizFilterEnds", [IsGVGraphOrDigraph, IsObject, IsObject]);
+DeclareOperation("GraphvizFilterEnds", [IsGraphvizGraphOrDigraph, IsObject, IsObject]);
 
 #! @Subsection For modifying object attributes.
 
@@ -187,19 +184,19 @@ DeclareOperation("GraphvizFilterEnds", [IsGVGraphOrDigraph, IsObject, IsObject])
 #!    All current attributes remain.
 #!    If an attribute already exists and a new value is provided, the old value
 #!    will be overwritten.
-DeclareOperation("GraphvizSetAttrs", [IsGVObject, IsRecord]);
-DeclareOperation("GraphvizSetAttr", [IsGVObject, IsObject, IsObject]);
-DeclareOperation("GraphvizSetAttr", [IsGVObject, IsObject]);
+DeclareOperation("GraphvizSetAttrs", [IsGraphvizObject, IsRecord]);
+DeclareOperation("GraphvizSetAttr", [IsGraphvizObject, IsObject, IsObject]);
+DeclareOperation("GraphvizSetAttr", [IsGraphvizObject, IsObject]);
 
 #! @Arguments obj, attr
 #! @Returns the modified object.
 #! @Description Removes an attribute from the object provided.
-DeclareOperation("GraphvizRemoveAttr", [IsGVObject, IsObject]);
+DeclareOperation("GraphvizRemoveAttr", [IsGraphvizObject, IsObject]);
 
 #! @Section Outputting
 #! @Arguments graph
 #! @Returns the dot representation of the graphviz object.
-DeclareOperation("AsString", [IsGVGraphOrDigraph]);
+DeclareOperation("AsString", [IsGraphvizGraphOrDigraph]);
 
 # TODO PrintObj
 
@@ -210,7 +207,7 @@ DeclareOperation("AsString", [IsGVGraphOrDigraph]);
 #!  Should output the graphviz package representation of the object.
 DeclareOperation("Graphviz", [IsObject]);
 
-DeclareOperation("GraphvizSetNodeColors", [IsGVGraphOrDigraph, IsList]);
-DeclareOperation("GraphvizSetNodeLabels", [IsGVGraphOrDigraph, IsList]);
+DeclareOperation("GraphvizSetNodeColors", [IsGraphvizGraphOrDigraph, IsList]);
+DeclareOperation("GraphvizSetNodeLabels", [IsGraphvizGraphOrDigraph, IsList]);
 
 DeclareGlobalFunction("ErrorIfNotValidColor");
diff --git a/gap/dot.gi b/gap/dot.gi
index cbba2c2..5549b4d 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -48,10 +48,10 @@ InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
 # Stringify
 ############################################################
 
-InstallMethod(ViewString, "for a graphviz node", [IsGVNode],
+InstallMethod(ViewString, "for a graphviz node", [IsGraphvizNode],
 n -> StringFormatted("<graphviz node {}>", GraphvizName(n)));
 
-InstallMethod(ViewString, "for a graphviz edge", [IsGVEdge],
+InstallMethod(ViewString, "for a graphviz edge", [IsGraphvizEdge],
 function(e)
   local head, tail;
   head := GraphvizHead(e);
@@ -61,7 +61,7 @@ function(e)
                          GraphvizName(tail));
 end);
 
-InstallMethod(ViewString, "for a graphviz graph", [IsGVGraphOrDigraph],
+InstallMethod(ViewString, "for a graphviz graph", [IsGraphvizGraphOrDigraph],
 function(g)
   local result, edges, nodes, kind;
 
@@ -70,9 +70,9 @@ function(g)
   nodes  :=
             Length(GV_MapNames(GraphvizNodes(g)));
 
-  if IsGVDigraph(g) then
+  if IsGraphvizDigraph(g) then
     kind := "digraph";
-  elif IsGVContext(g) then
+  elif IsGraphvizContext(g) then
     kind := "context";
   else
     kind := "graph";
@@ -94,23 +94,23 @@ end);
 # Getters
 ############################################################
 
-InstallMethod(GraphvizName, "for a graphviz object", [IsGVObject], x -> x!.Name);
+InstallMethod(GraphvizName, "for a graphviz object", [IsGraphvizObject], x -> x!.Name);
 
-InstallMethod(GraphvizAttrs, "for a graphviz object", [IsGVObject],
+InstallMethod(GraphvizAttrs, "for a graphviz object", [IsGraphvizObject],
 x -> x!.Attrs);
 
-InstallMethod(GraphvizNodes, "for a graphviz graph", [IsGVGraphOrDigraph],
+InstallMethod(GraphvizNodes, "for a graphviz graph", [IsGraphvizGraphOrDigraph],
 x -> x!.Nodes);
 
 InstallMethod(GraphvizNode, "for a graphviz graph and object",
-[IsGVGraphOrDigraph, IsObject], {gv, obj} -> gv!.Nodes[String(obj)]);
+[IsGraphvizGraphOrDigraph, IsObject], {gv, obj} -> gv!.Nodes[String(obj)]);
 
 InstallMethod(GraphvizEdges, "for a graphviz graph",
-[IsGVGraphOrDigraph], x -> x!.Edges);
+[IsGraphvizGraphOrDigraph], x -> x!.Edges);
 
 InstallMethod(GraphvizEdges,
 "for a graphviz graph, object, and object",
-[IsGVGraphOrDigraph, IsObject, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(gv, head, tail)
     head := GraphvizNode(gv, head);
     if head = fail then
@@ -126,47 +126,47 @@ function(gv, head, tail)
                     x -> GraphvizHead(x) = head and GraphvizTail(x) = tail);
 end);
 
-InstallMethod(GraphvizSubgraphs, "for a graphviz graph", [IsGVGraphOrDigraph],
+InstallMethod(GraphvizSubgraphs, "for a graphviz graph", [IsGraphvizGraphOrDigraph],
 x -> x!.Subgraphs);
 
-InstallMethod(GraphvizTail, "for a graphviz edge", [IsGVEdge], x -> x!.Tail);
+InstallMethod(GraphvizTail, "for a graphviz edge", [IsGraphvizEdge], x -> x!.Tail);
 
-InstallMethod(GraphvizHead, "for a graphviz edge", [IsGVEdge], x -> x!.Head);
+InstallMethod(GraphvizHead, "for a graphviz edge", [IsGraphvizEdge], x -> x!.Head);
 
 InstallMethod(GraphvizGetSubgraph,
 "for a graphviz graph and string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 {x, name} -> GraphvizSubgraphs(x)[name]);
 
 InstallMethod(GraphvizGetSubgraph,
 "for a graphviz graph and an object",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 {x, o} -> GraphvizSubgraphs(x)[ViewString(o)]);
 
 # Accessing node attributes
 
 InstallOtherMethod(\[\],
 "for a graphviz node and a string",
-[IsGVNode, IsString],
+[IsGraphvizNode, IsString],
 {node, key} -> GraphvizAttrs(node)[key]);
 
 InstallOtherMethod(\[\],
 "for a graphviz node and an object",
-[IsGVNode, IsObject],
+[IsGraphvizNode, IsObject],
 {node, key} -> node[GV_EnsureString(key)]);
 
 # Setting node attributes
 
 InstallOtherMethod(\[\]\:\=,
 "for a graphviz node and two strings",
-[IsGVNode, IsString, IsString],
+[IsGraphvizNode, IsString, IsString],
 function(node, key, val)
   GraphvizAttrs(node)[key] := val;
 end);
 
 InstallOtherMethod(\[\]\:\=,
 "for a graphviz node and two strings",
-[IsGVNode, IsObject, IsObject],
+[IsGraphvizNode, IsObject, IsObject],
 function(node, key, val)
   node[GV_EnsureString(key)] := GV_EnsureString(val);
 end);
@@ -175,46 +175,46 @@ end);
 
 InstallOtherMethod(\[\],
 "for a graphviz node and a string",
-[IsGVEdge, IsString],
+[IsGraphvizEdge, IsString],
 {edge, key} -> GraphvizAttrs(edge)[key]);
 
 InstallOtherMethod(\[\],
 "for a graphviz node and an object",
-[IsGVEdge, IsObject],
+[IsGraphvizEdge, IsObject],
 {edge, key} -> edge[GV_EnsureString(key)]);
 
 InstallOtherMethod(\[\]\:\=,
 "for a graphviz node and a string",
-[IsGVEdge, IsString, IsString],
+[IsGraphvizEdge, IsString, IsString],
 function(edge, key, val)
   GraphvizAttrs(edge)[key] := val;
 end);
 
 InstallOtherMethod(\[\]\:\=,
 "for a graphviz node and an object",
-[IsGVEdge, IsObject, IsObject],
+[IsGraphvizEdge, IsObject, IsObject],
 function(edge, key, val)
   edge[GV_EnsureString(key)] := GV_EnsureString(val);
 end);
 
 InstallOtherMethod(\[\],
 "for a graphviz graph and string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 {graph, node} -> GraphvizNodes(graph)[node]);
 
 InstallOtherMethod(\[\],
 "for a graphviz graph and string",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> g[ViewString(o)]);
 
 InstallMethod(GraphvizFindGraph,
 "for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 {g, s} -> GV_GraphTreeSearch(g, v -> GraphvizName(v) = s));
 
 InstallMethod(GraphvizFindGraph,
 "for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> GraphvizFindGraph(g, ViewString(o)));
 
 ############################################################
@@ -222,18 +222,18 @@ InstallMethod(GraphvizFindGraph,
 ############################################################
 
 InstallMethod(GraphvizSetName, "for a graphviz object and string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(x, name)
   x!.Name := name;
   return x;
 end);
 
 InstallMethod(GraphvizSetName, "for a graphviz object and string",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> GraphvizSetName(g, ViewString(o)));
 
 InstallMethod(GraphvizSetAttrs, "for a graphviz object and record",
-[IsGVObject, IsRecord],
+[IsGraphvizObject, IsRecord],
 function(x, attrs)
   local name;
   for name in RecNames(attrs) do
@@ -243,7 +243,7 @@ function(x, attrs)
 end);
 
 InstallMethod(GraphvizSetAttr, "for a graphviz object, object and object",
-[IsGVObject, IsObject, IsObject],
+[IsGraphvizObject, IsObject, IsObject],
 function(x, name, value)
   local msg;
 
@@ -259,7 +259,7 @@ function(x, name, value)
 end);
 
 InstallMethod(GraphvizSetAttr, "for a graphviz graph, object and object",
-[IsGVGraphOrDigraph, IsObject, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(x, name, value)
   local attrs, string, msg;
 
@@ -287,7 +287,7 @@ function(x, name, value)
 end);
 
 InstallMethod(GraphvizSetAttr, "for a graphviz object, object and object",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 function(x, value)
   local attrs;
   attrs := GraphvizAttrs(x);
@@ -297,7 +297,7 @@ function(x, value)
 end);
 
 InstallMethod(GraphvizAddNode, "for a graphviz graph and string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(x, name)
   local node;
   node := GV_Node(x, name);
@@ -307,7 +307,7 @@ end);
 
 # TODO required?
 InstallMethod(GraphvizAddNode, "for a graphviz graph and string",
-[IsGVGraphOrDigraph, IsGVNode],
+[IsGraphvizGraphOrDigraph, IsGraphvizNode],
 function(_, __)  # gaplint: disable=analyse-lvars
   local error;
   error := "Cannot add node objects directly to graphs. ";
@@ -317,12 +317,12 @@ end);
 
 InstallMethod(GraphvizAddNode,
 "for a graphviz graph and string",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 {x, name} -> GraphvizAddNode(x, ViewString(name)));
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz graph and two graphviz nodes",
-[IsGVGraphOrDigraph, IsGVNode, IsGVNode],
+[IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode],
 function(x, head, tail)
   local edge, head_name, tail_name;
 
@@ -344,7 +344,7 @@ end);
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz graph and two strings",
-[IsGVGraphOrDigraph, IsString, IsString],
+[IsGraphvizGraphOrDigraph, IsString, IsString],
 function(x, head, tail)
   local head_node, tail_node;
 
@@ -363,7 +363,7 @@ end);
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz graph and two objects",
-[IsGVGraphOrDigraph, IsObject, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(x, o1, o2)
   if not IsString(o1) then
     o1 := ViewString(o1);
@@ -376,7 +376,7 @@ end);
 
 InstallMethod(GraphvizAddSubgraph,
 "for a graphviz graph and string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(graph, name)
   local error, subgraphs, subgraph;
 
@@ -386,9 +386,9 @@ function(graph, name)
     ErrorNoReturn(StringFormatted(error, name));
   fi;
 
-  if IsGVDigraph(graph) then
+  if IsGraphvizDigraph(graph) then
     subgraph := GV_Digraph(graph, name);
-  elif IsGVGraph(graph) or IsGVContext(graph) then
+  elif IsGraphvizGraph(graph) or IsGraphvizContext(graph) then
     subgraph := GV_Graph(graph, name);
   else
     ErrorNoReturn("Filter must be a filter for a graph category.");
@@ -400,12 +400,12 @@ end);
 
 InstallMethod(GraphvizAddSubgraph,
 "for a graphviz graph and an object",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> GraphvizAddSubgraph(g, ViewString(o)));
 
 InstallMethod(GraphvizAddSubgraph,
 "for a grpahviz graph",
-[IsGVGraphOrDigraph],
+[IsGraphvizGraphOrDigraph],
 function(graph)
   return GraphvizAddSubgraph(graph, StringFormatted("no_name_{}",
                                                String(GV_GetCounter(graph))));
@@ -413,7 +413,7 @@ end);
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(graph, name)
   local ctx, error, subgraphs;
 
@@ -430,23 +430,23 @@ end);
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz graph",
-[IsGVGraphOrDigraph],
+[IsGraphvizGraphOrDigraph],
 g -> GraphvizAddContext(g, StringFormatted("no_name_{}",
                                       String(GV_GetCounter(g)))));
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz graph and an object",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> GraphvizAddContext(g, ViewString(o)));
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz graph and node",
-[IsGVGraphOrDigraph, IsGVNode],
+[IsGraphvizGraphOrDigraph, IsGraphvizNode],
 {g, node} -> GraphvizRemoveNode(g, GraphvizName(node)));
 
 # TODO GraphvizRemoveEdges(gv, n1, n2)
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(g, name)
   local nodes;
   # TODO error if there's no such node
@@ -466,11 +466,11 @@ function(g, name)
 end);
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> GraphvizRemoveNode(g, ViewString(o)));
 
 InstallMethod(GraphvizFilterEdges, "for a graphviz graph and edge filter",
-[IsGVGraphOrDigraph, IsFunction],
+[IsGraphvizGraphOrDigraph, IsFunction],
 function(g, filter)
   local edge, idx, edges;
 
@@ -488,14 +488,14 @@ function(g, filter)
 end);
 
 InstallMethod(GraphvizFilterEnds, "for a graphviz graph and two strings",
-[IsGVGraphOrDigraph, IsString, IsString],
+[IsGraphvizGraphOrDigraph, IsString, IsString],
 function(g, hn, tn)
   GraphvizFilterEdges(g,
     function(e)
       local head, tail, tmp;
       head := GraphvizHead(e);
       tail := GraphvizTail(e);
-      if IsGVDigraph(g) then
+      if IsGraphvizDigraph(g) then
         return tn <> GraphvizName(tail) or hn <> GraphvizName(head);
       else
         tmp := tn <> GraphvizName(tail) or hn <> GraphvizName(head);
@@ -507,7 +507,7 @@ function(g, hn, tn)
 end);
 
 InstallMethod(GraphvizFilterEnds, "for a graphviz graph and two strings",
-[IsGVGraphOrDigraph, IsObject, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(g, o1, o2)
   if not IsString(o1) then
     o1 := ViewString(o1);
@@ -520,7 +520,7 @@ function(g, o1, o2)
 end);
 
 InstallMethod(GraphvizRemoveAttr, "for a graphviz object and an object",
-[IsGVObject, IsObject],
+[IsGraphvizObject, IsObject],
 function(obj, attr)
   local attrs;
   attrs := GraphvizAttrs(obj);
@@ -529,7 +529,7 @@ function(obj, attr)
 end);
 
 InstallMethod(GraphvizRemoveAttr, "for a graphviz graph and an object",
-[IsGVGraphOrDigraph, IsObject],
+[IsGraphvizGraphOrDigraph, IsObject],
 function(obj, attr)
   local attrs;
   attrs      := GraphvizAttrs(obj);
@@ -542,11 +542,11 @@ end);
 ########################################################################
 
 InstallMethod(AsString, "for a graphviz graph",
-[IsGVGraphOrDigraph], graph -> GV_StringifyGraph(graph, false));
+[IsGraphvizGraphOrDigraph], graph -> GV_StringifyGraph(graph, false));
 
 InstallMethod(GraphvizSetNodeLabels,
 "for a graphviz graph and list of colors",
-[IsGVGraphOrDigraph, IsList],
+[IsGraphvizGraphOrDigraph, IsList],
 function(gv, labels)
   local nodes, i;
   # TODO error if labels and nodes aren't same size
@@ -560,7 +560,7 @@ end);
 
 InstallMethod(GraphvizSetNodeColors,
 "for a graphviz graph and list of colors",
-[IsGVGraphOrDigraph, IsList],
+[IsGraphvizGraphOrDigraph, IsList],
 function(gv, colors)
   local nodes, i;
 
diff --git a/gap/gv.gd b/gap/gv.gd
index ec6461b..9af7225 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -11,59 +11,59 @@
 ## This file contains declarations of the internal/private functions for the
 ## graphviz package.
 
-DeclareOperation("GV_GetCounter", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_IncCounter", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_GetCounter", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_IncCounter", [IsGraphvizGraphOrDigraph]);
 DeclareCategory("GV_IsMap", IsObject);
 DeclareAttribute("Size", GV_IsMap);
 
-DeclareOperation("GV_StringifyGraphHead", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifyDigraphHead", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifySubgraphHead", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifyContextHead", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_StringifyNode", [IsGVNode]);
-DeclareOperation("GV_StringifyGraphAttrs", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_StringifyGraphHead", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_StringifyDigraphHead", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_StringifySubgraphHead", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_StringifyContextHead", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_StringifyNode", [IsGraphvizNode]);
+DeclareOperation("GV_StringifyGraphAttrs", [IsGraphvizGraphOrDigraph]);
 DeclareOperation("GV_StringifyNodeEdgeAttrs", [GV_IsMap]);
-DeclareOperation("GV_StringifyGraph", [IsGVGraphOrDigraph, IsBool]);
+DeclareOperation("GV_StringifyGraph", [IsGraphvizGraphOrDigraph, IsBool]);
 
-DeclareOperation("GV_FindNode", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GV_FindNode", [IsGraphvizGraphOrDigraph, IsObject]);
 
 DeclareOperation("GV_Pluralize", [IsInt, IsString]);
 
-DeclareOperation("GV_Node", [IsGVGraphOrDigraph, IsString]);
-DeclareOperation("GV_Edge", [IsGVGraphOrDigraph, IsGVNode, IsGVNode]);
-DeclareOperation("GV_Graph", [IsGVGraphOrDigraph, IsString]);
-DeclareOperation("GV_Digraph", [IsGVDigraph, IsString]);
-DeclareOperation("GV_Context", [IsGVGraphOrDigraph, IsString]);
+DeclareOperation("GV_Node", [IsGraphvizGraphOrDigraph, IsString]);
+DeclareOperation("GV_Edge", [IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode]);
+DeclareOperation("GV_Graph", [IsGraphvizGraphOrDigraph, IsString]);
+DeclareOperation("GV_Digraph", [IsGraphvizDigraph, IsString]);
+DeclareOperation("GV_Context", [IsGraphvizGraphOrDigraph, IsString]);
 DeclareOperation("GV_Map", []);
 DeclareOperation("GV_MapNames", [GV_IsMap]);
 
 # TODO required? Replace with AsString or just String?
 DeclareOperation("GV_EnsureString", [IsObject]);
 
-DeclareOperation("GV_HasNode", [IsGVGraphOrDigraph, IsObject]);
+DeclareOperation("GV_HasNode", [IsGraphvizGraphOrDigraph, IsObject]);
 
-DeclareOperation("GV_GetParent", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_GraphTreeSearch", [IsGVGraphOrDigraph, IsFunction]);
-DeclareOperation("GV_FindGraphWithNode", [IsGVGraphOrDigraph, IsString]);
-DeclareOperation("GV_GetRoot", [IsGVGraphOrDigraph]);
-DeclareOperation("GV_AddNode", [IsGVGraphOrDigraph, IsGVNode]);
-DeclareOperation("GV_AddEdge", [IsGVGraphOrDigraph, IsGVEdge]);
-DeclareOperation("GV_GetIdx", [IsGVObject]);
-DeclareOperation("GV_ConstructHistory", [IsGVGraphOrDigraph]);
+DeclareOperation("GV_GetParent", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_GraphTreeSearch", [IsGraphvizGraphOrDigraph, IsFunction]);
+DeclareOperation("GV_FindGraphWithNode", [IsGraphvizGraphOrDigraph, IsString]);
+DeclareOperation("GV_GetRoot", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_AddNode", [IsGraphvizGraphOrDigraph, IsGraphvizNode]);
+DeclareOperation("GV_AddEdge", [IsGraphvizGraphOrDigraph, IsGraphvizEdge]);
+DeclareOperation("GV_GetIdx", [IsGraphvizObject]);
+DeclareOperation("GV_ConstructHistory", [IsGraphvizGraphOrDigraph]);
 
 DeclareGlobalFunction("GV_IsValidColor");
 DeclareGlobalFunction("GV_ErrorIfNotNodeColoring");
 
 BindGlobal("GV_ObjectFamily",
-           NewFamily("GV_ObjectFamily", IsGVObject));
+           NewFamily("GV_ObjectFamily", IsGraphvizObject));
 
 BindGlobal("GV_DigraphType", NewType(GV_ObjectFamily,
-                                    IsGVDigraph and
+                                    IsGraphvizDigraph and
                                     IsComponentObjectRep and
                                     IsAttributeStoringRep));
 
 BindGlobal("GV_GraphType", NewType(GV_ObjectFamily,
-                                    IsGVGraph and
+                                    IsGraphvizGraph and
                                     IsComponentObjectRep and
                                     IsAttributeStoringRep));
 
diff --git a/gap/gv.gi b/gap/gv.gi
index 185aa4b..b109058 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -99,22 +99,22 @@ BindGlobal("GV_MapType", NewType(GV_ObjectFamily,
                                  IsAttributeStoringRep));
 
 BindGlobal("GV_NodeType", NewType(GV_ObjectFamily,
-                                    IsGVNode and
+                                    IsGraphvizNode and
                                     IsComponentObjectRep and
                                     IsAttributeStoringRep));
 
 BindGlobal("GV_EdgeType", NewType(GV_ObjectFamily,
-                                    IsGVEdge and
+                                    IsGraphvizEdge and
                                     IsComponentObjectRep and
                                     IsAttributeStoringRep));
 
 BindGlobal("GV_ContextType", NewType(GV_ObjectFamily,
-                                    IsGVContext and
+                                    IsGraphvizContext and
                                     IsComponentObjectRep and
                                     IsAttributeStoringRep));
 
-InstallMethod(\=, "for IsGVNode and IsGVNode",
-[IsGVNode, IsGVNode],
+InstallMethod(\=, "for IsGraphvizNode and IsGraphvizNode",
+[IsGraphvizNode, IsGraphvizNode],
 {n1, n2} -> GraphvizName(n1) = GraphvizName(n2));
 
 ###############################################################################
@@ -126,7 +126,7 @@ InstallMethod(GV_Map, "for no args",
 [], {} -> Objectify(GV_MapType, rec(Data := rec())));
 
 InstallMethod(GV_Node, "for a string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(graph, name)
   local out;
   if Length(name) = 0 then
@@ -142,7 +142,7 @@ function(graph, name)
 end);
 
 InstallMethod(GV_Edge, "for two graphviz nodes",
-[IsGVGraphOrDigraph, IsGVNode, IsGVNode],
+[IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode],
 function(graph, head, tail)
   local out;
   out := Objectify(GV_EdgeType,
@@ -160,7 +160,7 @@ end);
 
 InstallMethod(GV_Digraph,
 "for a graphviz digraph and a string",
-[IsGVDigraph, IsString],
+[IsGraphvizDigraph, IsString],
 function(parent, name)
   local out;
 
@@ -174,7 +174,7 @@ end);
 
 InstallMethod(GV_Graph,
 "for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(parent, name)
   local out;
 
@@ -188,7 +188,7 @@ end);
 
 InstallMethod(GV_Context,
 "for a string and a positive integer",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(parent, name)
   local out;
 
@@ -254,12 +254,12 @@ InstallMethod(Size, "for a graphviz map",
 
 InstallMethod(GV_IncCounter,
 "for a graphviz graph",
-[IsGVGraphOrDigraph],
+[IsGraphvizGraphOrDigraph],
 function(x)
   x!.Counter := x!.Counter + 1;
 end);
 
-InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGVGraphOrDigraph],
+InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGraphvizGraphOrDigraph],
 x -> x!.Counter);
 
 # Converting strings
@@ -277,16 +277,16 @@ x -> x);
 
 InstallMethod(GV_HasNode,
 "for a graphviz graph",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 {g, name} -> name in GV_MapNames(GraphvizNodes(g)));
 
 InstallMethod(GV_GetParent,
 "for a graphviz graph",
-[IsGVGraphOrDigraph], graph -> graph!.Parent);
+[IsGraphvizGraphOrDigraph], graph -> graph!.Parent);
 
 InstallMethod(GV_GraphTreeSearch,
 "for a graphviz graph and a predicate",
-[IsGVGraphOrDigraph, IsFunction],
+[IsGraphvizGraphOrDigraph, IsFunction],
 function(graph, pred)
   local seen, to_visit, g, key, subgraph, parent;
   seen     := [graph];
@@ -311,7 +311,7 @@ function(graph, pred)
 
     # add parent if not visited
     parent := GV_GetParent(g);
-    if not IsGVGraphOrDigraph(parent) then
+    if not IsGraphvizGraphOrDigraph(parent) then
       continue;
     fi;
     if not ForAny(seen, s -> IsIdenticalObj(s, parent)) then
@@ -325,12 +325,12 @@ end);
 
 InstallMethod(GV_FindGraphWithNode,
 "for a graphviz graph and a node",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 {g, n} -> GV_GraphTreeSearch(g, v -> v[n] <> fail));
 
 InstallMethod(GV_GetRoot,
 "for a graphviz graph",
-[IsGVGraphOrDigraph],
+[IsGraphvizGraphOrDigraph],
 function(graph)
   while GV_GetParent(graph) <> fail do
     graph := GV_GetParent(graph);
@@ -340,7 +340,7 @@ end);
 
 InstallMethod(GV_FindNode,
 "for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsString],
+[IsGraphvizGraphOrDigraph, IsString],
 function(g, n)
   local graph;
   graph := GV_FindGraphWithNode(g, n);
@@ -352,7 +352,7 @@ end);
 
 InstallMethod(GV_AddNode,
 "for a graphviz graph and node",
-[IsGVGraphOrDigraph, IsGVNode],
+[IsGraphvizGraphOrDigraph, IsGraphvizNode],
 function(x, node)
   local found, error, name, nodes;
   name  := GraphvizName(node);
@@ -371,7 +371,7 @@ end);
 
 InstallMethod(GV_AddEdge,
 "for a graphviz graph and edge",
-[IsGVGraphOrDigraph, IsGVEdge],
+[IsGraphvizGraphOrDigraph, IsGraphvizEdge],
 function(x, edge)
   local head, head_name, tail_name, tail, hg, error, tg;
 
@@ -414,26 +414,26 @@ end);
 ###############################################################################
 
 # @ Return DOT graph head line.
-InstallMethod(GV_StringifyGraphHead, "for a string", [IsGVGraphOrDigraph],
+InstallMethod(GV_StringifyGraphHead, "for a string", [IsGraphvizGraphOrDigraph],
 graph -> StringFormatted("graph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT digraph head line.
-InstallMethod(GV_StringifyDigraphHead, "for a string", [IsGVDigraph],
+InstallMethod(GV_StringifyDigraphHead, "for a string", [IsGraphvizDigraph],
 graph -> StringFormatted("digraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
-InstallMethod(GV_StringifySubgraphHead, "for a string", [IsGVGraphOrDigraph],
+InstallMethod(GV_StringifySubgraphHead, "for a string", [IsGraphvizGraphOrDigraph],
 graph -> StringFormatted("subgraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
-InstallMethod(GV_StringifyContextHead, "for a string", [IsGVContext],
+InstallMethod(GV_StringifyContextHead, "for a string", [IsGraphvizContext],
 graph -> StringFormatted("// {} context \n", GraphvizName(graph)));
 
 BindGlobal("GV_StringifyNodeName",
 function(node)
   local name, old;
 
-  Assert(0, IsGVNode(node));
+  Assert(0, IsGraphvizNode(node));
   name  := GraphvizName(node);
   if (ForAny("- .+", x -> x in name)
       or (IsDigitChar(First(name)) and IsAlphaChar(Last(name))))
@@ -453,7 +453,7 @@ end);
 
 # @ Return DOT node statement line.
 InstallMethod(GV_StringifyNode, "for string and record",
-[IsGVNode],
+[IsGraphvizNode],
 function(node)
   local name, attrs;
   name  := GV_StringifyNodeName(node);
@@ -465,7 +465,7 @@ end);
 BindGlobal("GV_StringifyEdge",
 function(edge, edge_str)
   local head, tail, attrs;
-  Assert(0, IsGVEdge(edge));
+  Assert(0, IsGraphvizEdge(edge));
   Assert(0, IsString(edge_str));
   head  := GV_StringifyNodeName(GraphvizHead(edge));
   tail  := GV_StringifyNodeName(GraphvizTail(edge));
@@ -481,7 +481,7 @@ end);
 
 InstallMethod(GV_StringifyGraphAttrs,
 "for a graphviz graph",
-[IsGVGraphOrDigraph],
+[IsGraphvizGraphOrDigraph],
 function(graph)
   local result, attrs, kv;
   attrs  := GraphvizAttrs(graph);
@@ -561,12 +561,12 @@ end);
 
 InstallMethod(GV_GetIdx,
 "for a graphviz object",
-[IsGVObject],
+[IsGraphvizObject],
 x -> x!.Idx);
 
 InstallMethod(GV_ConstructHistory,
 "for a graphviz graph",
-[IsGVGraphOrDigraph],
+[IsGraphvizGraphOrDigraph],
 function(graph)
   local nodes, edges, subs, node_hist, edge_hist, subs_hist, hist;
 
@@ -587,27 +587,27 @@ end);
 
 InstallMethod(GV_StringifyGraph,
 "for a graphviz graph and a string",
-[IsGVGraphOrDigraph, IsBool],
+[IsGraphvizGraphOrDigraph, IsBool],
 function(graph, is_subgraph)
   local result, obj;
   result := "";
 
   # get the correct head to use
   if is_subgraph then
-    if IsGVContext(graph) then
+    if IsGraphvizContext(graph) then
       Append(result, GV_StringifyContextHead(graph));
-    elif IsGVGraph(graph) or IsGVDigraph(graph) then
+    elif IsGraphvizGraph(graph) or IsGraphvizDigraph(graph) then
       Append(result, GV_StringifySubgraphHead(graph));
     else
       ErrorNoReturn("Invalid subgraph type.");
     fi;
-  elif IsGVDigraph(graph) then
+  elif IsGraphvizDigraph(graph) then
     Append(result, "//dot\n");
     Append(result, GV_StringifyDigraphHead(graph));
-  elif IsGVGraph(graph) then
+  elif IsGraphvizGraph(graph) then
     Append(result, "//dot\n");
     Append(result, GV_StringifyGraphHead(graph));
-  elif IsGVContext(graph) then
+  elif IsGraphvizContext(graph) then
     Append(result, "//dot\n");
     Append(result, GV_StringifyContextHead(graph));
   else
@@ -618,12 +618,12 @@ function(graph, is_subgraph)
 
   # Add child graphviz objects
   for obj in GV_ConstructHistory(graph) do
-    if IsGVGraphOrDigraph(obj) then
+    if IsGraphvizGraphOrDigraph(obj) then
       Append(result, GV_StringifyGraph(obj, true));
-    elif IsGVNode(obj) then
+    elif IsGraphvizNode(obj) then
       Append(result, GV_StringifyNode(obj));
-    elif IsGVEdge(obj) then
-      if IsGVDigraph(GV_GetRoot(graph)) then
+    elif IsGraphvizEdge(obj) then
+      if IsGraphvizDigraph(GV_GetRoot(graph)) then
         Append(result, GV_StringifyEdge(obj, "->"));
       else
         Append(result, GV_StringifyEdge(obj, "--"));
@@ -633,7 +633,7 @@ function(graph, is_subgraph)
     fi;
   od;
 
-  if IsGVContext(graph) then
+  if IsGraphvizContext(graph) then
     # reset attributes following the context
     if GV_GetParent(graph) <> fail then
       Append(result, GV_StringifyGraphAttrs(GV_GetParent(graph)));
diff --git a/gap/splash.gi b/gap/splash.gi
index 17cb9be..b959344 100644
--- a/gap/splash.gi
+++ b/gap/splash.gi
@@ -12,10 +12,10 @@ if not IsBound(Splash) then
 
     if IsEmpty(arg) then
       ErrorNoReturn("the must be at least 1 argument, found none");
-    elif not IsString(arg[1]) and not IsGVGraphOrDigraph(arg[1]) then
+    elif not IsString(arg[1]) and not IsGraphvizGraphOrDigraph(arg[1]) then
       ErrorFormatted("the 1st argument must be a string or ",
                      "graphviz graph, found {}", TNAM_OBJ(arg[1]));
-    elif IsGVGraphOrDigraph(arg[1]) then
+    elif IsGraphvizGraphOrDigraph(arg[1]) then
       arg[1] := AsString(arg[1]);
     fi;
     str := arg[1];

From 99c6639f1f4b9407d4d807d64ac58f1b365409b3 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Mon, 13 May 2024 12:02:18 +0100
Subject: [PATCH 08/38] Fix description strings

---
 gap/dot.gd   |  13 ++++
 gap/dot.gi   | 206 ++++++++++++++++++++++++++++-----------------------
 gap/gv.gi    |  11 +--
 tst/node.tst |   3 +-
 4 files changed, 132 insertions(+), 101 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 8856d38..e082948 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -211,3 +211,16 @@ DeclareOperation("GraphvizSetNodeColors", [IsGraphvizGraphOrDigraph, IsList]);
 DeclareOperation("GraphvizSetNodeLabels", [IsGraphvizGraphOrDigraph, IsList]);
 
 DeclareGlobalFunction("ErrorIfNotValidColor");
+
+# TODO doc
+DeclareOperation("\[\]", [IsGraphvizNode, IsObject]);
+# TODO doc
+DeclareOperation("\[\]\:\=", [IsGraphvizNode, IsObject, IsObject]);
+
+# TODO doc
+DeclareOperation("\[\]", [IsGraphvizEdge, IsObject]);
+# TODO doc
+DeclareOperation("\[\]\:\=", [IsGraphvizEdge, IsObject, IsObject]);
+
+# TODO doc
+DeclareOperation("\[\]", [IsGraphvizGraphOrDigraph, IsObject]);
diff --git a/gap/dot.gi b/gap/dot.gi
index 5549b4d..961a991 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -8,9 +8,9 @@
 #############################################################################
 ##
 
-#############################################################################
+########################################################################
 # Constructors
-#############################################################################
+########################################################################
 
 InstallMethod(GraphvizGraph, "for a string", [IsString],
 function(name)
@@ -44,9 +44,9 @@ end);
 
 InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
 
-############################################################
-# Stringify
-############################################################
+########################################################################
+# ViewString
+########################################################################
 
 InstallMethod(ViewString, "for a graphviz node", [IsGraphvizNode],
 n -> StringFormatted("<graphviz node {}>", GraphvizName(n)));
@@ -61,7 +61,7 @@ function(e)
                          GraphvizName(tail));
 end);
 
-InstallMethod(ViewString, "for a graphviz graph", [IsGraphvizGraphOrDigraph],
+InstallMethod(ViewString, "for a graphviz (di)graph", [IsGraphvizGraphOrDigraph],
 function(g)
   local result, edges, nodes, kind;
 
@@ -94,22 +94,23 @@ end);
 # Getters
 ############################################################
 
-InstallMethod(GraphvizName, "for a graphviz object", [IsGraphvizObject], x -> x!.Name);
+InstallMethod(GraphvizName, "for a graphviz object", [IsGraphvizObject],
+x -> x!.Name);
 
 InstallMethod(GraphvizAttrs, "for a graphviz object", [IsGraphvizObject],
 x -> x!.Attrs);
 
-InstallMethod(GraphvizNodes, "for a graphviz graph", [IsGraphvizGraphOrDigraph],
+InstallMethod(GraphvizNodes, "for a graphviz (di)graph", [IsGraphvizGraphOrDigraph],
 x -> x!.Nodes);
 
-InstallMethod(GraphvizNode, "for a graphviz graph and object",
+InstallMethod(GraphvizNode, "for a graphviz (di)graph and object",
 [IsGraphvizGraphOrDigraph, IsObject], {gv, obj} -> gv!.Nodes[String(obj)]);
 
-InstallMethod(GraphvizEdges, "for a graphviz graph",
+InstallMethod(GraphvizEdges, "for a graphviz (di)graph",
 [IsGraphvizGraphOrDigraph], x -> x!.Edges);
 
 InstallMethod(GraphvizEdges,
-"for a graphviz graph, object, and object",
+"for a graphviz (di)graph, object, and object",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(gv, head, tail)
     head := GraphvizNode(gv, head);
@@ -126,111 +127,122 @@ function(gv, head, tail)
                     x -> GraphvizHead(x) = head and GraphvizTail(x) = tail);
 end);
 
-InstallMethod(GraphvizSubgraphs, "for a graphviz graph", [IsGraphvizGraphOrDigraph],
-x -> x!.Subgraphs);
+InstallMethod(GraphvizSubgraphs, "for a graphviz (di)graph",
+[IsGraphvizGraphOrDigraph], x -> x!.Subgraphs);
 
-InstallMethod(GraphvizTail, "for a graphviz edge", [IsGraphvizEdge], x -> x!.Tail);
+InstallMethod(GraphvizTail, "for a graphviz edge", [IsGraphvizEdge],
+x -> x!.Tail);
 
-InstallMethod(GraphvizHead, "for a graphviz edge", [IsGraphvizEdge], x -> x!.Head);
+InstallMethod(GraphvizHead, "for a graphviz edge", [IsGraphvizEdge],
+x -> x!.Head);
 
 InstallMethod(GraphvizGetSubgraph,
-"for a graphviz graph and string",
+"for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
 {x, name} -> GraphvizSubgraphs(x)[name]);
 
 InstallMethod(GraphvizGetSubgraph,
-"for a graphviz graph and an object",
+"for a graphviz (di)graph and an object",
 [IsGraphvizGraphOrDigraph, IsObject],
-{x, o} -> GraphvizSubgraphs(x)[ViewString(o)]);
+{x, o} -> GraphvizSubgraphs(x)[String(o)]);
 
 # Accessing node attributes
 
-InstallOtherMethod(\[\],
+InstallMethod(\[\],
 "for a graphviz node and a string",
 [IsGraphvizNode, IsString],
 {node, key} -> GraphvizAttrs(node)[key]);
 
-InstallOtherMethod(\[\],
+InstallMethod(\[\],
 "for a graphviz node and an object",
 [IsGraphvizNode, IsObject],
-{node, key} -> node[GV_EnsureString(key)]);
+{node, key} -> node[String(key)]);
 
 # Setting node attributes
 
-InstallOtherMethod(\[\]\:\=,
+InstallMethod(\[\]\:\=,
 "for a graphviz node and two strings",
 [IsGraphvizNode, IsString, IsString],
 function(node, key, val)
   GraphvizAttrs(node)[key] := val;
 end);
 
-InstallOtherMethod(\[\]\:\=,
+InstallMethod(\[\]\:\=,
 "for a graphviz node and two strings",
 [IsGraphvizNode, IsObject, IsObject],
 function(node, key, val)
-  node[GV_EnsureString(key)] := GV_EnsureString(val);
+  node[String(key)] := String(val);
 end);
 
 # Accessing edge attributes
 
-InstallOtherMethod(\[\],
-"for a graphviz node and a string",
+InstallMethod(\[\],
+"for a graphviz edge and a string",
 [IsGraphvizEdge, IsString],
 {edge, key} -> GraphvizAttrs(edge)[key]);
 
-InstallOtherMethod(\[\],
-"for a graphviz node and an object",
+InstallMethod(\[\],
+"for a graphviz edge and an object",
 [IsGraphvizEdge, IsObject],
-{edge, key} -> edge[GV_EnsureString(key)]);
+{edge, key} -> edge[String(key)]);
 
-InstallOtherMethod(\[\]\:\=,
-"for a graphviz node and a string",
+InstallMethod(\[\]\:\=,
+"for a graphviz edge and a string",
 [IsGraphvizEdge, IsString, IsString],
 function(edge, key, val)
   GraphvizAttrs(edge)[key] := val;
 end);
 
-InstallOtherMethod(\[\]\:\=,
-"for a graphviz node and an object",
+InstallMethod(\[\]\:\=,
+"for a graphviz edge and an object",
 [IsGraphvizEdge, IsObject, IsObject],
 function(edge, key, val)
   edge[GV_EnsureString(key)] := GV_EnsureString(val);
 end);
 
-InstallOtherMethod(\[\],
-"for a graphviz graph and string",
+# Accessor for graphs and digraphs
+
+# TODO remove either this or GraphvizNode(gv, name);
+InstallMethod(\[\],
+"for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
 {graph, node} -> GraphvizNodes(graph)[node]);
 
-InstallOtherMethod(\[\],
-"for a graphviz graph and string",
+InstallMethod(\[\],
+"for a graphviz (di)graph and object",
 [IsGraphvizGraphOrDigraph, IsObject],
-{g, o} -> g[ViewString(o)]);
+{g, o} -> g[String(o)]);
+
+# TODO is this named appropriately? Should it be FindSubgraph?
 
 InstallMethod(GraphvizFindGraph,
-"for a graphviz graph and a string",
+"for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsString],
 {g, s} -> GV_GraphTreeSearch(g, v -> GraphvizName(v) = s));
 
 InstallMethod(GraphvizFindGraph,
-"for a graphviz graph and a string",
+"for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsObject],
-{g, o} -> GraphvizFindGraph(g, ViewString(o)));
+{g, o} -> GraphvizFindGraph(g, String(o)));
 
 ############################################################
-# Setters
+# GraphvizSetName
 ############################################################
 
-InstallMethod(GraphvizSetName, "for a graphviz object and string",
+InstallMethod(GraphvizSetName, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(x, name)
   x!.Name := name;
   return x;
 end);
 
-InstallMethod(GraphvizSetName, "for a graphviz object and string",
+InstallMethod(GraphvizSetName, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsObject],
-{g, o} -> GraphvizSetName(g, ViewString(o)));
+{g, o} -> GraphvizSetName(g, String(o)));
+
+############################################################
+# GraphvizSetAttr(s)
+############################################################
 
 InstallMethod(GraphvizSetAttrs, "for a graphviz object and record",
 [IsGraphvizObject, IsRecord],
@@ -242,23 +254,22 @@ function(x, attrs)
   return x;
 end);
 
-InstallMethod(GraphvizSetAttr, "for a graphviz object, object and object",
+# TODO combine this and the next method
+InstallMethod(GraphvizSetAttr, "for a graphviz object, object, and object",
 [IsGraphvizObject, IsObject, IsObject],
 function(x, name, value)
-  local msg;
 
   if not name in GV_KNOWN_ATTRS then
-    msg := Concatenation(
-           StringFormatted("unknown attribute \"{}\", the", name),
-           " graphviz object may no longer be valid, it can",
-           " be removed using GraphvizRemoveAttr");
-    Info(InfoWarning, 1, msg);
+    Info(InfoWarning, 1,
+         StringFormatted("unknown attribute \"{}\", the", name),
+         " graphviz object may no longer be valid, it can",
+         " be removed using GraphvizRemoveAttr");
   fi;
   GraphvizAttrs(x)[String(name)] := String(value);
   return x;
 end);
 
-InstallMethod(GraphvizSetAttr, "for a graphviz graph, object and object",
+InstallMethod(GraphvizSetAttr, "for a graphviz (di)graph, object and object",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(x, name, value)
   local attrs, string, msg;
@@ -278,6 +289,7 @@ function(x, name, value)
     name := StringFormatted("\"{}\"", name);
   fi;
   if ' ' in value then
+    # Replace with call to GV_QuoteName or whatever TODO
     value := StringFormatted("\"{}\"", value);
   fi;
 
@@ -286,7 +298,7 @@ function(x, name, value)
   return x;
 end);
 
-InstallMethod(GraphvizSetAttr, "for a graphviz object, object and object",
+InstallMethod(GraphvizSetAttr, "for a graphviz (di)graph and object",
 [IsGraphvizGraphOrDigraph, IsObject],
 function(x, value)
   local attrs;
@@ -296,7 +308,11 @@ function(x, value)
   return x;
 end);
 
-InstallMethod(GraphvizAddNode, "for a graphviz graph and string",
+############################################################
+# GraphvizAddNode
+############################################################
+
+InstallMethod(GraphvizAddNode, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(x, name)
   local node;
@@ -305,23 +321,25 @@ function(x, name)
   return node;
 end);
 
-# TODO required?
-InstallMethod(GraphvizAddNode, "for a graphviz graph and string",
+InstallMethod(GraphvizAddNode, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsGraphvizNode],
-function(_, __)  # gaplint: disable=analyse-lvars
-  local error;
-  error := "Cannot add node objects directly to graphs. ";
-  error := Concatenation(error, "Please use the node's name.");
-  ErrorNoReturn(error);
+function(gv, name)  # gaplint: disable=analyse-lvars
+  ErrorNoReturn("it is not currently possible to add Graphviz node ",
+                "objects directly to Graphviz graphs or digraphs, use ",
+                "the node's name instead");
 end);
 
 InstallMethod(GraphvizAddNode,
-"for a graphviz graph and string",
+"for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsObject],
-{x, name} -> GraphvizAddNode(x, ViewString(name)));
+{x, name} -> GraphvizAddNode(x, String(name)));
+
+############################################################
+# GraphvizAddEdge
+############################################################
 
 InstallMethod(GraphvizAddEdge,
-"for a graphviz graph and two graphviz nodes",
+"for a graphviz (di)graph and two graphviz nodes",
 [IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode],
 function(x, head, tail)
   local edge, head_name, tail_name;
@@ -343,7 +361,7 @@ function(x, head, tail)
 end);
 
 InstallMethod(GraphvizAddEdge,
-"for a graphviz graph and two strings",
+"for a graphviz (di)graph and two strings",
 [IsGraphvizGraphOrDigraph, IsString, IsString],
 function(x, head, tail)
   local head_node, tail_node;
@@ -362,20 +380,24 @@ function(x, head, tail)
 end);
 
 InstallMethod(GraphvizAddEdge,
-"for a graphviz graph and two objects",
+"for a graphviz (di)graph and two objects",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(x, o1, o2)
   if not IsString(o1) then
-    o1 := ViewString(o1);
+    o1 := String(o1);
   fi;
   if not IsString(o2) then
-    o2 := ViewString(o2);
+    o2 := String(o2);
   fi;
   return GraphvizAddEdge(x, o1, o2);
 end);
 
+############################################################
+# GraphvizAddSubgraph
+############################################################
+
 InstallMethod(GraphvizAddSubgraph,
-"for a graphviz graph and string",
+"for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(graph, name)
   local error, subgraphs, subgraph;
@@ -399,20 +421,18 @@ function(graph, name)
 end);
 
 InstallMethod(GraphvizAddSubgraph,
-"for a graphviz graph and an object",
+"for a graphviz (di)graph and an object",
 [IsGraphvizGraphOrDigraph, IsObject],
-{g, o} -> GraphvizAddSubgraph(g, ViewString(o)));
+{g, o} -> GraphvizAddSubgraph(g, String(o)));
 
-InstallMethod(GraphvizAddSubgraph,
-"for a grpahviz graph",
+InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph",
 [IsGraphvizGraphOrDigraph],
-function(graph)
-  return GraphvizAddSubgraph(graph, StringFormatted("no_name_{}",
-                                               String(GV_GetCounter(graph))));
-end);
+graph -> GraphvizAddSubgraph(graph,
+                             StringFormatted("no_name_{}",
+                                             GV_GetCounter(graph))));
 
 InstallMethod(GraphvizAddContext,
-"for a graphviz graph and a string",
+"for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(graph, name)
   local ctx, error, subgraphs;
@@ -429,23 +449,23 @@ function(graph, name)
 end);
 
 InstallMethod(GraphvizAddContext,
-"for a graphviz graph",
+"for a graphviz (di)graph",
 [IsGraphvizGraphOrDigraph],
 g -> GraphvizAddContext(g, StringFormatted("no_name_{}",
                                       String(GV_GetCounter(g)))));
 
 InstallMethod(GraphvizAddContext,
-"for a graphviz graph and an object",
+"for a graphviz (di)graph and an object",
 [IsGraphvizGraphOrDigraph, IsObject],
-{g, o} -> GraphvizAddContext(g, ViewString(o)));
+{g, o} -> GraphvizAddContext(g, String(o)));
 
-InstallMethod(GraphvizRemoveNode, "for a graphviz graph and node",
+InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and node",
 [IsGraphvizGraphOrDigraph, IsGraphvizNode],
 {g, node} -> GraphvizRemoveNode(g, GraphvizName(node)));
 
 # TODO GraphvizRemoveEdges(gv, n1, n2)
 
-InstallMethod(GraphvizRemoveNode, "for a graphviz graph and a string",
+InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(g, name)
   local nodes;
@@ -465,11 +485,11 @@ function(g, name)
   return g;
 end);
 
-InstallMethod(GraphvizRemoveNode, "for a graphviz graph and a string",
+InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsObject],
-{g, o} -> GraphvizRemoveNode(g, ViewString(o)));
+{g, o} -> GraphvizRemoveNode(g, String(o)));
 
-InstallMethod(GraphvizFilterEdges, "for a graphviz graph and edge filter",
+InstallMethod(GraphvizFilterEdges, "for a graphviz (di)graph and edge filter",
 [IsGraphvizGraphOrDigraph, IsFunction],
 function(g, filter)
   local edge, idx, edges;
@@ -487,7 +507,9 @@ function(g, filter)
   return g;
 end);
 
-InstallMethod(GraphvizFilterEnds, "for a graphviz graph and two strings",
+# TODO remove?
+
+InstallMethod(GraphvizFilterEnds, "for a graphviz (di)graph and two strings",
 [IsGraphvizGraphOrDigraph, IsString, IsString],
 function(g, hn, tn)
   GraphvizFilterEdges(g,
@@ -506,14 +528,14 @@ function(g, hn, tn)
   return g;
 end);
 
-InstallMethod(GraphvizFilterEnds, "for a graphviz graph and two strings",
+InstallMethod(GraphvizFilterEnds, "for a graphviz (di)graph and two objects",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(g, o1, o2)
   if not IsString(o1) then
-    o1 := ViewString(o1);
+    o1 := String(o1);
   fi;
   if not IsString(o2) then
-    o2 := ViewString(o2);
+    o2 := String(o2);
   fi;
 
   GraphvizFilterEnds(g, o1, o2);
@@ -528,7 +550,7 @@ function(obj, attr)
   return obj;
 end);
 
-InstallMethod(GraphvizRemoveAttr, "for a graphviz graph and an object",
+InstallMethod(GraphvizRemoveAttr, "for a graphviz (di)graph and an object",
 [IsGraphvizGraphOrDigraph, IsObject],
 function(obj, attr)
   local attrs;
diff --git a/gap/gv.gi b/gap/gv.gi
index b109058..0c2d9c8 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -264,14 +264,9 @@ x -> x!.Counter);
 
 # Converting strings
 
-InstallMethod(GV_EnsureString,
-"for an object",
-[IsObject], ViewString);
-
-InstallMethod(GV_EnsureString,
-"for a string",
-[IsString],
-x -> x);
+InstallMethod(GV_EnsureString, "for an object", [IsObject], String);
+
+InstallMethod(GV_EnsureString, "for a string", [IsString], IdFunc);
 
 # Nodes
 
diff --git a/tst/node.tst b/tst/node.tst
index 92dc589..9a8a506 100644
--- a/tst/node.tst
+++ b/tst/node.tst
@@ -110,7 +110,8 @@ gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "n");;
 gap> s := GraphvizGraph();;
 gap> GraphvizAddNode(s, n);
-Error, Cannot add node objects directly to graphs. Please use the node's name.
+Error, it is not currently possible to add Graphviz node objects directly to G\
+raphviz graphs or digraphs, use the node's name instead
 
 #
 gap> STOP_TEST("graphviz package: node.tst", 0);

From e6a7d22ed7888cbe855b9b17f3bdbe042a34b952 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 09:09:40 +0100
Subject: [PATCH 09/38] More cleanups

---
 gap/dot.gd       |  10 +--
 gap/dot.gi       | 163 +++++++++++++++++++++--------------------------
 gap/gv.gd        |   3 +-
 gap/gv.gi        |   5 +-
 tst/subgraph.tst |   3 +-
 5 files changed, 83 insertions(+), 101 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index e082948..cc38809 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -88,7 +88,6 @@ DeclareOperation("GraphvizAttrs", [IsGraphvizObject]);
 #! @Description Gets the nodes of the provided graphviz graph.
 #! Node names can only be [a-zA-Z0-9_£] TODO check exact docs.
 DeclareOperation("GraphvizNodes", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GraphvizNode", [IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph
 #! @Returns the subgraphs of the provided graphviz graph.
@@ -109,7 +108,8 @@ DeclareOperation("GraphvizFindGraph", [IsGraphvizGraphOrDigraph, IsObject]);
 #! @Returns the edges of the provided graphviz graph.
 #! @Description Gets the edges of the provided graphviz graph.
 DeclareOperation("GraphvizEdges", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GraphvizEdges", [IsGraphvizGraphOrDigraph, IsObject, IsObject]);
+DeclareOperation("GraphvizEdges",
+[IsGraphvizGraphOrDigraph, IsObject, IsObject]);
 
 #! @Subsection For only edges.
 
@@ -145,7 +145,8 @@ DeclareOperation("GraphvizAddNode", [IsGraphvizGraphOrDigraph, IsObject]);
 #! If no nodes with the same name are in the graph then the edge's nodes will be
 #! added to the graph. If different nodes with the same name are in the graph
 #! then the operation fails.
-DeclareOperation("GraphvizAddEdge", [IsGraphvizGraphOrDigraph, IsObject, IsObject]);
+DeclareOperation("GraphvizAddEdge",
+[IsGraphvizGraphOrDigraph, IsObject, IsObject]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new subgraph.
@@ -173,7 +174,8 @@ DeclareOperation("GraphvizFilterEdges", [IsGraphvizGraphOrDigraph, IsFunction]);
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges, removing edges between nodes with
 #! the specified names.
-DeclareOperation("GraphvizFilterEnds", [IsGraphvizGraphOrDigraph, IsObject, IsObject]);
+DeclareOperation("GraphvizFilterEnds",
+[IsGraphvizGraphOrDigraph, IsObject, IsObject]);
 
 #! @Subsection For modifying object attributes.
 
diff --git a/gap/dot.gi b/gap/dot.gi
index 961a991..f83b620 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -8,9 +8,9 @@
 #############################################################################
 ##
 
-########################################################################
+#############################################################################
 # Constructors
-########################################################################
+#############################################################################
 
 InstallMethod(GraphvizGraph, "for a string", [IsString],
 function(name)
@@ -44,9 +44,9 @@ end);
 
 InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
 
-########################################################################
+#############################################################################
 # ViewString
-########################################################################
+#############################################################################
 
 InstallMethod(ViewString, "for a graphviz node", [IsGraphvizNode],
 n -> StringFormatted("<graphviz node {}>", GraphvizName(n)));
@@ -90,9 +90,9 @@ function(g)
   return result;
 end);
 
-############################################################
+#############################################################################
 # Getters
-############################################################
+#############################################################################
 
 InstallMethod(GraphvizName, "for a graphviz object", [IsGraphvizObject],
 x -> x!.Name);
@@ -100,11 +100,8 @@ x -> x!.Name);
 InstallMethod(GraphvizAttrs, "for a graphviz object", [IsGraphvizObject],
 x -> x!.Attrs);
 
-InstallMethod(GraphvizNodes, "for a graphviz (di)graph", [IsGraphvizGraphOrDigraph],
-x -> x!.Nodes);
-
-InstallMethod(GraphvizNode, "for a graphviz (di)graph and object",
-[IsGraphvizGraphOrDigraph, IsObject], {gv, obj} -> gv!.Nodes[String(obj)]);
+InstallMethod(GraphvizNodes, "for a graphviz (di)graph",
+[IsGraphvizGraphOrDigraph], x -> x!.Nodes);
 
 InstallMethod(GraphvizEdges, "for a graphviz (di)graph",
 [IsGraphvizGraphOrDigraph], x -> x!.Edges);
@@ -113,12 +110,12 @@ InstallMethod(GraphvizEdges,
 "for a graphviz (di)graph, object, and object",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(gv, head, tail)
-    head := GraphvizNode(gv, head);
+    head := GraphvizNodes(gv)[head];
     if head = fail then
       ErrorNoReturn("the 2nd argument (head of an edge) is not a node ",
                     "of the 1st argument (a graphviz graph or digraph)");
     fi;
-    tail := GraphvizNode(gv, tail);
+    tail := GraphvizNodes(gv)[tail];
     if tail = fail then
       ErrorNoReturn("the 2nd argument (head of an edge) is not a node ",
                     "of the 1st argument (a graphviz graph or digraph)");
@@ -136,39 +133,35 @@ x -> x!.Tail);
 InstallMethod(GraphvizHead, "for a graphviz edge", [IsGraphvizEdge],
 x -> x!.Head);
 
-InstallMethod(GraphvizGetSubgraph,
-"for a graphviz (di)graph and string",
+# TODO remove the next two?
+
+InstallMethod(GraphvizGetSubgraph, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
 {x, name} -> GraphvizSubgraphs(x)[name]);
 
-InstallMethod(GraphvizGetSubgraph,
-"for a graphviz (di)graph and an object",
+InstallMethod(GraphvizGetSubgraph, "for a graphviz (di)graph and an object",
 [IsGraphvizGraphOrDigraph, IsObject],
 {x, o} -> GraphvizSubgraphs(x)[String(o)]);
 
 # Accessing node attributes
 
-InstallMethod(\[\],
-"for a graphviz node and a string",
+InstallMethod(\[\], "for a graphviz node and a string",
 [IsGraphvizNode, IsString],
 {node, key} -> GraphvizAttrs(node)[key]);
 
-InstallMethod(\[\],
-"for a graphviz node and an object",
+InstallMethod(\[\], "for a graphviz node and an object",
 [IsGraphvizNode, IsObject],
 {node, key} -> node[String(key)]);
 
 # Setting node attributes
 
-InstallMethod(\[\]\:\=,
-"for a graphviz node and two strings",
+InstallMethod(\[\]\:\=, "for a graphviz node and two strings",
 [IsGraphvizNode, IsString, IsString],
 function(node, key, val)
   GraphvizAttrs(node)[key] := val;
 end);
 
-InstallMethod(\[\]\:\=,
-"for a graphviz node and two strings",
+InstallMethod(\[\]\:\=, "for a graphviz node and two strings",
 [IsGraphvizNode, IsObject, IsObject],
 function(node, key, val)
   node[String(key)] := String(val);
@@ -176,25 +169,21 @@ end);
 
 # Accessing edge attributes
 
-InstallMethod(\[\],
-"for a graphviz edge and a string",
+InstallMethod(\[\], "for a graphviz edge and a string",
 [IsGraphvizEdge, IsString],
 {edge, key} -> GraphvizAttrs(edge)[key]);
 
-InstallMethod(\[\],
-"for a graphviz edge and an object",
+InstallMethod(\[\], "for a graphviz edge and an object",
 [IsGraphvizEdge, IsObject],
 {edge, key} -> edge[String(key)]);
 
-InstallMethod(\[\]\:\=,
-"for a graphviz edge and a string",
+InstallMethod(\[\]\:\=, "for a graphviz edge and a string",
 [IsGraphvizEdge, IsString, IsString],
 function(edge, key, val)
   GraphvizAttrs(edge)[key] := val;
 end);
 
-InstallMethod(\[\]\:\=,
-"for a graphviz edge and an object",
+InstallMethod(\[\]\:\=, "for a graphviz edge and an object",
 [IsGraphvizEdge, IsObject, IsObject],
 function(edge, key, val)
   edge[GV_EnsureString(key)] := GV_EnsureString(val);
@@ -203,13 +192,11 @@ end);
 # Accessor for graphs and digraphs
 
 # TODO remove either this or GraphvizNode(gv, name);
-InstallMethod(\[\],
-"for a graphviz (di)graph and string",
+InstallMethod(\[\], "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
 {graph, node} -> GraphvizNodes(graph)[node]);
 
-InstallMethod(\[\],
-"for a graphviz (di)graph and object",
+InstallMethod(\[\], "for a graphviz (di)graph and object",
 [IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> g[String(o)]);
 
@@ -225,9 +212,9 @@ InstallMethod(GraphvizFindGraph,
 [IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> GraphvizFindGraph(g, String(o)));
 
-############################################################
+#############################################################################
 # GraphvizSetName
-############################################################
+#############################################################################
 
 InstallMethod(GraphvizSetName, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
@@ -240,9 +227,9 @@ InstallMethod(GraphvizSetName, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> GraphvizSetName(g, String(o)));
 
-############################################################
+#############################################################################
 # GraphvizSetAttr(s)
-############################################################
+#############################################################################
 
 InstallMethod(GraphvizSetAttrs, "for a graphviz object and record",
 [IsGraphvizObject, IsRecord],
@@ -308,9 +295,9 @@ function(x, value)
   return x;
 end);
 
-############################################################
+#############################################################################
 # GraphvizAddNode
-############################################################
+#############################################################################
 
 InstallMethod(GraphvizAddNode, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
@@ -334,9 +321,9 @@ InstallMethod(GraphvizAddNode,
 [IsGraphvizGraphOrDigraph, IsObject],
 {x, name} -> GraphvizAddNode(x, String(name)));
 
-############################################################
+#############################################################################
 # GraphvizAddEdge
-############################################################
+#############################################################################
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz (di)graph and two graphviz nodes",
@@ -382,46 +369,42 @@ end);
 InstallMethod(GraphvizAddEdge,
 "for a graphviz (di)graph and two objects",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
-function(x, o1, o2)
-  if not IsString(o1) then
-    o1 := String(o1);
-  fi;
-  if not IsString(o2) then
-    o2 := String(o2);
-  fi;
-  return GraphvizAddEdge(x, o1, o2);
-end);
+{gv, o1, o2} -> GraphvizAddEdge(gv, String(o1), String(o2)));
 
-############################################################
+#############################################################################
 # GraphvizAddSubgraph
-############################################################
+#############################################################################
 
-InstallMethod(GraphvizAddSubgraph,
-"for a graphviz (di)graph and string",
+InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
-function(graph, name)
-  local error, subgraphs, subgraph;
+function(gv, name)
+  local subgraphs, subgraph;
 
-  subgraphs := GraphvizSubgraphs(graph);
+  subgraphs := GraphvizSubgraphs(gv);
   if IsBound(subgraphs[name]) then
-    error := "The graph already contains a subgraph with name {}.";
-    ErrorNoReturn(StringFormatted(error, name));
+    ErrorFormatted("the 1st argument (a graphviz (di)graph) already has ",
+                   " a subgraph with name \"{}\"", name);
   fi;
 
-  if IsGraphvizDigraph(graph) then
-    subgraph := GV_Digraph(graph, name);
-  elif IsGraphvizGraph(graph) or IsGraphvizContext(graph) then
-    subgraph := GV_Graph(graph, name);
-  else
-    ErrorNoReturn("Filter must be a filter for a graph category.");
+  # TODO why are the graph and context cases conflated here?
+  # Shouldn't this be something like
+  # if IsGraphvizContext(gv) then
+  # root := GraphvizRoot(gv);
+  # else
+  # root := gv;
+  # fi;
+  # Then use root instead of gv below?
+  if IsGraphvizDigraph(gv) then
+    subgraph := GV_Digraph(gv, name);
+  elif IsGraphvizGraph(gv) or IsGraphvizContext(gv) then
+    subgraph := GV_Graph(gv, name);
   fi;
 
   subgraphs[name] := subgraph;
   return subgraph;
 end);
 
-InstallMethod(GraphvizAddSubgraph,
-"for a graphviz (di)graph and an object",
+InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph and an object",
 [IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> GraphvizAddSubgraph(g, String(o)));
 
@@ -435,12 +418,15 @@ InstallMethod(GraphvizAddContext,
 "for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(graph, name)
-  local ctx, error, subgraphs;
+  local subgraphs, ctx;
 
   subgraphs := GraphvizSubgraphs(graph);
+  # TODO is GraphvizSubgraphs appropriately named? It seems to contain both
+  # contexts and subgraphs, rather than just subgraphs as the name suggests
   if IsBound(subgraphs[name]) then
-    error := "The graph already contains a subgraph with name {}.";
-    ErrorNoReturn(StringFormatted(error, name));
+    # TODO why are we talking about subgraphs in the error?
+    ErrorFormatted("the 1st argument (a graphviz (di)graph) already has ",
+                   " a subgraph with name \"{}\"", name);
   fi;
 
   ctx             := GV_Context(graph, name);
@@ -451,8 +437,7 @@ end);
 InstallMethod(GraphvizAddContext,
 "for a graphviz (di)graph",
 [IsGraphvizGraphOrDigraph],
-g -> GraphvizAddContext(g, StringFormatted("no_name_{}",
-                                      String(GV_GetCounter(g)))));
+g -> GraphvizAddContext(g, StringFormatted("no_name_{}", GV_GetCounter(g))));
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz (di)graph and an object",
@@ -469,7 +454,7 @@ InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(g, name)
   local nodes;
-  # TODO error if there's no such node
+  # TODO error if there's no such node?
   nodes := GraphvizNodes(g);
   Unbind(nodes[name]);
 
@@ -528,18 +513,11 @@ function(g, hn, tn)
   return g;
 end);
 
+# TODO remove?
+
 InstallMethod(GraphvizFilterEnds, "for a graphviz (di)graph and two objects",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
-function(g, o1, o2)
-  if not IsString(o1) then
-    o1 := String(o1);
-  fi;
-  if not IsString(o2) then
-    o2 := String(o2);
-  fi;
-
-  GraphvizFilterEnds(g, o1, o2);
-end);
+{gv, o1, o2} -> GraphvizFilterEnds(gv, String(o1), String(o2)));
 
 InstallMethod(GraphvizRemoveAttr, "for a graphviz object and an object",
 [IsGraphvizObject, IsObject],
@@ -559,15 +537,16 @@ function(obj, attr)
   return obj;
 end);
 
-########################################################################
+#############################################################################
 # Stringify
-########################################################################
+#############################################################################
 
-InstallMethod(AsString, "for a graphviz graph",
+# TODO AsString -> String
+InstallMethod(AsString, "for a graphviz (di)graph",
 [IsGraphvizGraphOrDigraph], graph -> GV_StringifyGraph(graph, false));
 
 InstallMethod(GraphvizSetNodeLabels,
-"for a graphviz graph and list of colors",
+"for a graphviz (di)graph and list of colors",
 [IsGraphvizGraphOrDigraph, IsList],
 function(gv, labels)
   local nodes, i;
@@ -581,7 +560,7 @@ function(gv, labels)
 end);
 
 InstallMethod(GraphvizSetNodeColors,
-"for a graphviz graph and list of colors",
+"for a graphviz (di)graph and list of colors",
 [IsGraphvizGraphOrDigraph, IsList],
 function(gv, colors)
   local nodes, i;
diff --git a/gap/gv.gd b/gap/gv.gd
index 9af7225..3658ce0 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -30,7 +30,8 @@ DeclareOperation("GV_FindNode", [IsGraphvizGraphOrDigraph, IsObject]);
 DeclareOperation("GV_Pluralize", [IsInt, IsString]);
 
 DeclareOperation("GV_Node", [IsGraphvizGraphOrDigraph, IsString]);
-DeclareOperation("GV_Edge", [IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode]);
+DeclareOperation("GV_Edge",
+[IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode]);
 DeclareOperation("GV_Graph", [IsGraphvizGraphOrDigraph, IsString]);
 DeclareOperation("GV_Digraph", [IsGraphvizDigraph, IsString]);
 DeclareOperation("GV_Context", [IsGraphvizGraphOrDigraph, IsString]);
diff --git a/gap/gv.gi b/gap/gv.gi
index 0c2d9c8..4395d86 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -121,7 +121,6 @@ InstallMethod(\=, "for IsGraphvizNode and IsGraphvizNode",
 # Constructors etc
 ###############################################################################
 
-
 InstallMethod(GV_Map, "for no args",
 [], {} -> Objectify(GV_MapType, rec(Data := rec())));
 
@@ -240,7 +239,6 @@ InstallOtherMethod(IsBound\[\],
 [GV_IsMap, IsObject],
 {m, key} -> IsBound(m!.Data.(key)));
 
-
 InstallMethod(GV_MapNames, "for a graphviz map",
 [GV_IsMap], m -> RecNames(m!.Data));
 
@@ -417,7 +415,8 @@ InstallMethod(GV_StringifyDigraphHead, "for a string", [IsGraphvizDigraph],
 graph -> StringFormatted("digraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
-InstallMethod(GV_StringifySubgraphHead, "for a string", [IsGraphvizGraphOrDigraph],
+InstallMethod(GV_StringifySubgraphHead, "for a string",
+[IsGraphvizGraphOrDigraph],
 graph -> StringFormatted("subgraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 94d0bc3..fe7141f 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -253,7 +253,8 @@ edge [label=testing123] node[color=blue] edge[color=blue] \n\n}\n"
 gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(g, "a");
-Error, The graph already contains a subgraph with name a.
+Error, the 1st argument (a graphviz (di)graph) already has  a subgraph with na\
+me "a"
 
 # Test getting subgraphs by name
 gap> g := GraphvizDigraph();;

From 4dbf0cd8c31f3fb55ca0542d6df750c2936ea773 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 09:31:44 +0100
Subject: [PATCH 10/38] Remove GraphvizGetSubgraph and rename GraphvizFindGraph
 -> GraphvizFindSubgraphRecursive

---
 gap/dot.gd       |  6 +++---
 gap/dot.gi       | 19 +++----------------
 gap/gv.gi        |  7 ++++++-
 tst/subgraph.tst | 30 +++++++++++++++---------------
 4 files changed, 27 insertions(+), 35 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index cc38809..d7412b6 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -93,7 +93,6 @@ DeclareOperation("GraphvizNodes", [IsGraphvizGraphOrDigraph]);
 #! @Returns the subgraphs of the provided graphviz graph.
 #! @Description gets the subgraphs of a provided graphviz graph.
 DeclareOperation("GraphvizSubgraphs", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GraphvizGetSubgraph", [IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph, name
 #! @Returns a graph with the provided name.
@@ -101,8 +100,9 @@ DeclareOperation("GraphvizGetSubgraph", [IsGraphvizGraphOrDigraph, IsObject]);
 #! Searches through the tree of subgraphs connected to this subgraph for a graph
 #! with the provided name.
 #! It returns the graph if it exists.
-#! If no such graph exists then it will return fail.
-DeclareOperation("GraphvizFindGraph", [IsGraphvizGraphOrDigraph, IsObject]);
+#! If no such graph exists then it will return <K>fail<K>.
+DeclareOperation("GraphvizFindSubgraphRecursive",
+[IsGraphvizGraphOrDigraph, IsObject]);
 
 #! @Arguments graph
 #! @Returns the edges of the provided graphviz graph.
diff --git a/gap/dot.gi b/gap/dot.gi
index f83b620..228f2fe 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -133,16 +133,6 @@ x -> x!.Tail);
 InstallMethod(GraphvizHead, "for a graphviz edge", [IsGraphvizEdge],
 x -> x!.Head);
 
-# TODO remove the next two?
-
-InstallMethod(GraphvizGetSubgraph, "for a graphviz (di)graph and string",
-[IsGraphvizGraphOrDigraph, IsString],
-{x, name} -> GraphvizSubgraphs(x)[name]);
-
-InstallMethod(GraphvizGetSubgraph, "for a graphviz (di)graph and an object",
-[IsGraphvizGraphOrDigraph, IsObject],
-{x, o} -> GraphvizSubgraphs(x)[String(o)]);
-
 # Accessing node attributes
 
 InstallMethod(\[\], "for a graphviz node and a string",
@@ -191,7 +181,6 @@ end);
 
 # Accessor for graphs and digraphs
 
-# TODO remove either this or GraphvizNode(gv, name);
 InstallMethod(\[\], "for a graphviz (di)graph and string",
 [IsGraphvizGraphOrDigraph, IsString],
 {graph, node} -> GraphvizNodes(graph)[node]);
@@ -200,17 +189,15 @@ InstallMethod(\[\], "for a graphviz (di)graph and object",
 [IsGraphvizGraphOrDigraph, IsObject],
 {g, o} -> g[String(o)]);
 
-# TODO is this named appropriately? Should it be FindSubgraph?
-
-InstallMethod(GraphvizFindGraph,
+InstallMethod(GraphvizFindSubgraphRecursive,
 "for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsString],
 {g, s} -> GV_GraphTreeSearch(g, v -> GraphvizName(v) = s));
 
-InstallMethod(GraphvizFindGraph,
+InstallMethod(GraphvizFindSubgraphRecursive,
 "for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsObject],
-{g, o} -> GraphvizFindGraph(g, String(o)));
+{g, o} -> GraphvizFindSubgraphRecursive(g, String(o)));
 
 #############################################################################
 # GraphvizSetName
diff --git a/gap/gv.gi b/gap/gv.gi
index 4395d86..d06a488 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -212,7 +212,7 @@ end);
 
 InstallOtherMethod(\[\],
 "for a graphviz map and an object",
-[GV_IsMap, IsObject],
+[GV_IsMap, IsString],
 function(m, o)
   if IsBound(m[o]) then
     return m!.Data.(o);
@@ -220,6 +220,11 @@ function(m, o)
   return fail;
 end);
 
+InstallOtherMethod(\[\],
+"for a graphviz map and an object",
+[GV_IsMap, IsObject],
+{m, o} -> m[String(o)]);
+
 InstallOtherMethod(\[\]\:\=,
 "for a graphviz map and two objects",
 [GV_IsMap, IsObject, IsObject],
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index fe7141f..55cf739 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -260,31 +260,31 @@ me "a"
 gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(g, "b");;
-gap> GraphvizGetSubgraph(g, "a");
+gap> GraphvizSubgraphs(g)["a"];
 <graphviz digraph a with 0 nodes and 0 edges>
-gap> GraphvizGetSubgraph(g, "b");
+gap> GraphvizSubgraphs(g)["b"];
 <graphviz digraph b with 0 nodes and 0 edges>
-gap> GraphvizGetSubgraph(g, "d");
+gap> GraphvizSubgraphs(g)["d"];
 fail
 
 # Test getting context (subgraph) by name
 gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddContext(g, "c");;
-gap> GraphvizGetSubgraph(g, "a");
+gap> GraphvizSubgraphs(g)["a"];
 <graphviz digraph a with 0 nodes and 0 edges>
-gap> GraphvizGetSubgraph(g, "c");
+gap> GraphvizSubgraphs(g)["c"];
 <graphviz context c with 0 nodes and 0 edges>
 
 # Test adding a nested subgraph
 gap> g := GraphvizGraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(s1, "c");;
-gap> GraphvizGetSubgraph(g, "a");
+gap> GraphvizSubgraphs(g)["a"];
 <graphviz graph a with 0 nodes and 0 edges>
-gap> GraphvizGetSubgraph(g, "c");
+gap> GraphvizSubgraphs(g)["c"];
 fail
-gap> GraphvizGetSubgraph(s1, "c");
+gap> GraphvizSubgraphs(s1)["c"];
 <graphviz graph c with 0 nodes and 0 edges>
 
 # Test displaying a nested subgraph
@@ -307,13 +307,13 @@ gap> GraphvizAddContext(g, 11);
 # Test getting subgraphs with non-string names
 gap> g := GraphvizGraph();;
 gap> GraphvizAddContext(g, ["a"]);;
-gap> GraphvizGetSubgraph(g, ["a"]);
+gap> GraphvizSubgraphs(g)[["a"]];
 <graphviz context [ "a" ] with 0 nodes and 0 edges>
 
 # Test finding subgraph (parent)
 gap> g := GraphvizGraph("a");;
 gap> s := GraphvizAddSubgraph(g, "b");;
-gap> o := GraphvizFindGraph(s, "a");
+gap> o := GraphvizFindSubgraphRecursive(s, "a");
 <graphviz graph a with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, g);
 true
@@ -321,7 +321,7 @@ true
 # Test finding subgraph (child)
 gap> g := GraphvizGraph("a");;
 gap> s := GraphvizAddSubgraph(g, "b");;
-gap> o := GraphvizFindGraph(g, "b");
+gap> o := GraphvizFindSubgraphRecursive(g, "b");
 <graphviz graph b with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, s);
 true
@@ -330,14 +330,14 @@ true
 gap> g  := GraphvizGraph("a");;
 gap> s  := GraphvizAddSubgraph(g, "b");;
 gap> s2 := GraphvizAddSubgraph(g, "c");;
-gap> o  := GraphvizFindGraph(s, "c");
+gap> o  := GraphvizFindSubgraphRecursive(s, "c");
 <graphviz graph c with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, s2);
 true
 
 # Test finding subgraph (self)
 gap> g := GraphvizGraph("a");;
-gap> o := GraphvizFindGraph(g, "a");
+gap> o := GraphvizFindSubgraphRecursive(g, "a");
 <graphviz graph a with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, g);
 true
@@ -350,7 +350,7 @@ gap> a3 := GraphvizAddSubgraph(a2, "a3");;
 gap> b1 := GraphvizAddSubgraph(g, "b1");;
 gap> b2 := GraphvizAddSubgraph(b1, "b2");;
 gap> b3 := GraphvizAddSubgraph(b2, "b3");;
-gap> o  := GraphvizFindGraph(a3, "b3");
+gap> o  := GraphvizFindSubgraphRecursive(a3, "b3");
 <graphviz graph b3 with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, b3);
 true
@@ -376,7 +376,7 @@ gap> AsString(g);
 # Test finding subgraph (non-string name)
 gap> g := GraphvizGraph("r");;
 gap> s := GraphvizAddSubgraph(g, 1);;
-gap> o := GraphvizFindGraph(g, 1);
+gap> o := GraphvizFindSubgraphRecursive(g, 1);
 <graphviz graph 1 with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, s);
 true

From 2eb081b16bcf1d78c988232c8131fc7eafae654c Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 09:44:19 +0100
Subject: [PATCH 11/38] More cleanups

---
 TODO.md     |  4 ++--
 gap/dot.gi  | 14 +++++++++-----
 tst/dot.tst |  3 +++
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/TODO.md b/TODO.md
index 8ba8f71..5165e96 100644
--- a/TODO.md
+++ b/TODO.md
@@ -8,11 +8,11 @@
  - make it so when duplicates are added to global graph attrs the old values are automatically replaced
  - Improve behaviour around ':' syntax - mimic python package
 
-## TODO (ONCE THIS IS EMPTY THEN DONE!)
- - Ask about `Pluralize` - think james said to remove for old versions of gap
+## TODO
  - Update docs
  - Add more unit tests
  - Thoroughly test the ':' syntax more (might have broke when the quotes were changed)
+ - PrintObj method is missing for nodes (and probably edges)
 
 ## Other
  - relates to deadnaut github issue https://www.mankier.com/1/nauty-dretodot
diff --git a/gap/dot.gi b/gap/dot.gi
index 228f2fe..c13c537 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -259,9 +259,6 @@ function(x, name, value)
   attrs := GraphvizAttrs(x);
   name := String(name);
   value := String(value);
-  if ' ' in name then
-    name := StringFormatted("\"{}\"", name);
-  fi;
   if ' ' in value then
     # Replace with call to GV_QuoteName or whatever TODO
     value := StringFormatted("\"{}\"", value);
@@ -410,6 +407,7 @@ function(graph, name)
   subgraphs := GraphvizSubgraphs(graph);
   # TODO is GraphvizSubgraphs appropriately named? It seems to contain both
   # contexts and subgraphs, rather than just subgraphs as the name suggests
+  # See https://github.com/digraphs/graphviz/issues/19
   if IsBound(subgraphs[name]) then
     # TODO why are we talking about subgraphs in the error?
     ErrorFormatted("the 1st argument (a graphviz (di)graph) already has ",
@@ -441,9 +439,15 @@ InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(g, name)
   local nodes;
-  # TODO error if there's no such node?
   nodes := GraphvizNodes(g);
-  Unbind(nodes[name]);
+  if nodes[name] <> fail then
+    Unbind(nodes[name]);
+  else
+    # Don't just silently do nothing
+    ErrorFormatted("the 2nd argument (node name string) \"{}\"",
+                   " is not a node of the 1st argument (a graphviz (di)graph)",
+                   name);
+  fi;
 
   # remove incident edges
   GraphvizFilterEdges(g,
diff --git a/tst/dot.tst b/tst/dot.tst
index 4f0c708..366dc37 100644
--- a/tst/dot.tst
+++ b/tst/dot.tst
@@ -37,6 +37,9 @@ gap> n := GraphvizAddNode(g, "test");;
 gap> GraphvizSetAttrs(n, rec(color := "red", label := "lab"));;
 gap> AsString(g);
 "//dot\ngraph  {\n\ttest [color=red, label=lab]\n}\n"
+gap> GraphvizRemoveNode(g, "banana");
+Error, the 2nd argument (node name string) "banana" is not a node of the 1st a\
+rgument (a graphviz (di)graph)
 
 # Test stringify with edge (digraphs)
 gap> g := GraphvizDigraph();;

From 61e63b44066481d1f74fe4d3682101e89ab181e9 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 09:55:43 +0100
Subject: [PATCH 12/38] Rename GraphvizFilterEnds -> GraphvizRemoveEdges

---
 gap/dot.gd       |  2 +-
 gap/dot.gi       | 19 +++++++++----------
 tst/edge.tst     | 26 +++++++++++++-------------
 tst/subgraph.tst |  2 +-
 4 files changed, 24 insertions(+), 25 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index d7412b6..e862db5 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -174,7 +174,7 @@ DeclareOperation("GraphvizFilterEdges", [IsGraphvizGraphOrDigraph, IsFunction]);
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges, removing edges between nodes with
 #! the specified names.
-DeclareOperation("GraphvizFilterEnds",
+DeclareOperation("GraphvizRemoveEdges",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject]);
 
 #! @Subsection For modifying object attributes.
diff --git a/gap/dot.gi b/gap/dot.gi
index c13c537..daaa43d 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -433,8 +433,6 @@ InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and node",
 [IsGraphvizGraphOrDigraph, IsGraphvizNode],
 {g, node} -> GraphvizRemoveNode(g, GraphvizName(node)));
 
-# TODO GraphvizRemoveEdges(gv, n1, n2)
-
 InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
 [IsGraphvizGraphOrDigraph, IsString],
 function(g, name)
@@ -483,9 +481,7 @@ function(g, filter)
   return g;
 end);
 
-# TODO remove?
-
-InstallMethod(GraphvizFilterEnds, "for a graphviz (di)graph and two strings",
+InstallMethod(GraphvizRemoveEdges, "for a graphviz (di)graph and two strings",
 [IsGraphvizGraphOrDigraph, IsString, IsString],
 function(g, hn, tn)
   GraphvizFilterEdges(g,
@@ -504,17 +500,16 @@ function(g, hn, tn)
   return g;
 end);
 
-# TODO remove?
-
-InstallMethod(GraphvizFilterEnds, "for a graphviz (di)graph and two objects",
+InstallMethod(GraphvizRemoveEdges, "for a graphviz (di)graph and two objects",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
-{gv, o1, o2} -> GraphvizFilterEnds(gv, String(o1), String(o2)));
+{gv, o1, o2} -> GraphvizRemoveEdges(gv, String(o1), String(o2)));
 
 InstallMethod(GraphvizRemoveAttr, "for a graphviz object and an object",
 [IsGraphvizObject, IsObject],
 function(obj, attr)
   local attrs;
   attrs := GraphvizAttrs(obj);
+  # TODO error if no such attr?
   Unbind(attrs[String(attr)]);
   return obj;
 end);
@@ -541,7 +536,11 @@ InstallMethod(GraphvizSetNodeLabels,
 [IsGraphvizGraphOrDigraph, IsList],
 function(gv, labels)
   local nodes, i;
-  # TODO error if labels and nodes aren't same size
+  if Size(GraphvizNodes(gv)) <> Size(labels) then
+    ErrorFormatted("the 2nd argument (list of node labels) ",
+                   "has incorrect length, expected {}, but ",
+                   "found {}", Size(GraphvizNodes(gv)), Size(labels));
+  fi;
   # TODO GV_ErrorIfNotValidLabel
   nodes := GraphvizNodes(gv);
   for i in [1 .. Size(nodes)] do
diff --git a/tst/edge.tst b/tst/edge.tst
index c0117db..ebd5bc3 100644
--- a/tst/edge.tst
+++ b/tst/edge.tst
@@ -36,19 +36,19 @@ gap> c := GraphvizAddNode(g, "c");;
 gap> d := GraphvizAddNode(g, "d");;
 gap> ab := GraphvizAddEdge(g, a, b);;
 gap> cd := GraphvizAddEdge(g, c, d);;
-gap> GraphvizFilterEnds(g, "a", "c");
+gap> GraphvizRemoveEdges(g, "a", "c");
 <graphviz digraph with 4 nodes and 2 edges>
-gap> GraphvizFilterEnds(g, "b", "d");
+gap> GraphvizRemoveEdges(g, "b", "d");
 <graphviz digraph with 4 nodes and 2 edges>
-gap> GraphvizFilterEnds(g, "a", "b");
+gap> GraphvizRemoveEdges(g, "a", "b");
 <graphviz digraph with 4 nodes and 1 edge>
 gap> GraphvizEdges(g);
 [ <graphviz edge (c, d)> ]
-gap> GraphvizFilterEnds(g, "c", "d");
+gap> GraphvizRemoveEdges(g, "c", "d");
 <graphviz digraph with 4 nodes and 0 edges>
 gap> GraphvizEdges(g);
 [  ]
-gap> GraphvizFilterEnds(g, "c", "d");
+gap> GraphvizRemoveEdges(g, "c", "d");
 <graphviz digraph with 4 nodes and 0 edges>
 
 # Test filtering edges by names (graph)
@@ -59,19 +59,19 @@ gap> c := GraphvizAddNode(g, "c");;
 gap> d := GraphvizAddNode(g, "d");;
 gap> ab := GraphvizAddEdge(g, a, b);;
 gap> cd := GraphvizAddEdge(g, c, d);;
-gap> GraphvizFilterEnds(g, "a", "c");
+gap> GraphvizRemoveEdges(g, "a", "c");
 <graphviz graph with 4 nodes and 2 edges>
-gap> GraphvizFilterEnds(g, "b", "d");
+gap> GraphvizRemoveEdges(g, "b", "d");
 <graphviz graph with 4 nodes and 2 edges>
-gap> GraphvizFilterEnds(g, "b", "a");
+gap> GraphvizRemoveEdges(g, "b", "a");
 <graphviz graph with 4 nodes and 1 edge>
 gap> GraphvizEdges(g);
 [ <graphviz edge (c, d)> ]
-gap> GraphvizFilterEnds(g, "d", "c");
+gap> GraphvizRemoveEdges(g, "d", "c");
 <graphviz graph with 4 nodes and 0 edges>
 gap> GraphvizEdges(g);
 [  ]
-gap> GraphvizFilterEnds(g, "c", "d");
+gap> GraphvizRemoveEdges(g, "c", "d");
 <graphviz graph with 4 nodes and 0 edges>
 
 # Test adding edge between nodes which are not in the graph, but there exists nodes in the graph which share their names.
@@ -110,13 +110,13 @@ gap> GraphvizAddEdge(g, 1, "a");
 <graphviz edge (1, a)>
 gap> GraphvizAddEdge(g, 1, 1);
 <graphviz edge (1, 1)>
-gap> GraphvizFilterEnds(g, "a", 1);;
+gap> GraphvizRemoveEdges(g, "a", 1);;
 gap> GraphvizEdges(g);
 [ <graphviz edge (1, a)>, <graphviz edge (1, 1)> ]
-gap> GraphvizFilterEnds(g, 1, "a");;
+gap> GraphvizRemoveEdges(g, 1, "a");;
 gap> GraphvizEdges(g);
 [ <graphviz edge (1, 1)> ]
-gap> GraphvizFilterEnds(g, 1, 1);;
+gap> GraphvizRemoveEdges(g, 1, 1);;
 gap> GraphvizEdges(g);
 [  ]
 
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 55cf739..5b2fec9 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -117,7 +117,7 @@ gap> GraphvizAddEdge(parent, "x", "y");;
 gap> GraphvizAddEdge(main, "x", "y");;
 gap> GraphvizAddEdge(sibling, "x", "y");;
 gap> GraphvizAddEdge(child, "x", "y");;
-gap> GraphvizFilterEnds(main, "x", "y");;
+gap> GraphvizRemoveEdges(main, "x", "y");;
 gap> GraphvizEdges(g);
 [  ]
 gap> GraphvizEdges(parent);

From 7f4951699d0953569f24b9c8d42a866f5d543fc4 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 09:58:19 +0100
Subject: [PATCH 13/38] Rename AsString -> String

This was my mistake when we discussed this before, I thought AsString was a thing in GAP
but it turns out it isn't.
---
 gap/dot.gd                      |  2 +-
 gap/dot.gi                      |  3 +--
 gap/gv.gd                       |  2 +-
 gap/splash.gi                   |  2 +-
 tst/dot.tst                     | 16 ++++++++--------
 tst/examples/angles.tst         |  4 ++--
 tst/examples/btree.tst          |  2 +-
 tst/examples/cluster.tst        |  2 +-
 tst/examples/cluster_edge.tst   |  2 +-
 tst/examples/colors.tst         |  2 +-
 tst/examples/er.tst             |  2 +-
 tst/examples/fsm.tst            |  2 +-
 tst/examples/g_c_n.tst          |  4 ++--
 tst/examples/hello.tst          |  2 +-
 tst/examples/process.tst        |  2 +-
 tst/examples/rank_same.tst      |  2 +-
 tst/examples/structs.tst        |  2 +-
 tst/examples/traffic_lights.tst |  2 +-
 tst/examples/unix.tst           |  2 +-
 tst/graph.tst                   |  2 +-
 tst/node.tst                    |  4 ++--
 tst/subgraph.tst                | 18 +++++++++---------
 22 files changed, 40 insertions(+), 41 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index e862db5..e911100 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -198,7 +198,7 @@ DeclareOperation("GraphvizRemoveAttr", [IsGraphvizObject, IsObject]);
 #! @Section Outputting
 #! @Arguments graph
 #! @Returns the dot representation of the graphviz object.
-DeclareOperation("AsString", [IsGraphvizGraphOrDigraph]);
+# TODO document "String"
 
 # TODO PrintObj
 
diff --git a/gap/dot.gi b/gap/dot.gi
index daaa43d..6dda979 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -527,8 +527,7 @@ end);
 # Stringify
 #############################################################################
 
-# TODO AsString -> String
-InstallMethod(AsString, "for a graphviz (di)graph",
+InstallMethod(String, "for a graphviz (di)graph",
 [IsGraphvizGraphOrDigraph], graph -> GV_StringifyGraph(graph, false));
 
 InstallMethod(GraphvizSetNodeLabels,
diff --git a/gap/gv.gd b/gap/gv.gd
index 3658ce0..2e68cb7 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -38,7 +38,7 @@ DeclareOperation("GV_Context", [IsGraphvizGraphOrDigraph, IsString]);
 DeclareOperation("GV_Map", []);
 DeclareOperation("GV_MapNames", [GV_IsMap]);
 
-# TODO required? Replace with AsString or just String?
+# TODO required? Replace with String or just String?
 DeclareOperation("GV_EnsureString", [IsObject]);
 
 DeclareOperation("GV_HasNode", [IsGraphvizGraphOrDigraph, IsObject]);
diff --git a/gap/splash.gi b/gap/splash.gi
index b959344..32d8b05 100644
--- a/gap/splash.gi
+++ b/gap/splash.gi
@@ -16,7 +16,7 @@ if not IsBound(Splash) then
       ErrorFormatted("the 1st argument must be a string or ",
                      "graphviz graph, found {}", TNAM_OBJ(arg[1]));
     elif IsGraphvizGraphOrDigraph(arg[1]) then
-      arg[1] := AsString(arg[1]);
+      arg[1] := String(arg[1]);
     fi;
     str := arg[1];
 
diff --git a/tst/dot.tst b/tst/dot.tst
index 366dc37..43d3a83 100644
--- a/tst/dot.tst
+++ b/tst/dot.tst
@@ -35,7 +35,7 @@ gap> GraphvizAttrs(g);
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "test");;
 gap> GraphvizSetAttrs(n, rec(color := "red", label := "lab"));;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\ttest [color=red, label=lab]\n}\n"
 gap> GraphvizRemoveNode(g, "banana");
 Error, the 2nd argument (node name string) "banana" is not a node of the 1st a\
@@ -49,7 +49,7 @@ gap> GraphvizSetAttrs(a, rec(color := "blue"));;
 gap> GraphvizSetAttrs(b, rec(color := "red"));;
 gap> e := GraphvizAddEdge(g, a, b);;
 gap> GraphvizSetAttrs(e, rec(color := "green"));;
-gap> AsString(g);
+gap> String(g);
 "//dot\ndigraph  {\n\ta [color=blue]\n\tb [color=red]\n\ta -> b [color=green]\
 \n}\n"
 
@@ -61,13 +61,13 @@ gap> GraphvizSetAttrs(a, rec(color := "blue"));;
 gap> GraphvizSetAttrs(b, rec(color := "red"));;
 gap> e := GraphvizAddEdge(g, a, b);;
 gap> GraphvizSetAttrs(e, rec(color := "green"));;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\ta [color=blue]\n\tb [color=red]\n\ta -- b [color=green]\n}\
 \n"
 
 # Test stringify empty
 gap> g := GraphvizGraph();;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n}\n"
 
 # Test unknown attributes (node)
@@ -87,24 +87,24 @@ gap> GraphvizSetAttr(g, "test", "false");
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "node");;
 gap> GraphvizSetAttr(n, "label", ">>hello");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\tnode [label=\">>hello\"]\n}\n"
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "node");;
 gap> GraphvizSetAttr(n, "label", "before>>hello");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\tnode [label=\"before>>hello\"]\n}\n"
 
 # Test strngifying labels with ">>" inside (edge attrs)
 gap> g := GraphvizGraph();;
 gap> e := GraphvizAddEdge(g, "a", "b");;
 gap> GraphvizSetAttr(e, "label", ">>hello");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\ta\n\tb\n\ta -- b [label=\">>hello\"]\n}\n"
 gap> g := GraphvizGraph();;
 gap> e := GraphvizAddEdge(g, "a", "b");;
 gap> GraphvizSetAttr(e, "label", "before>>hello");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\ta\n\tb\n\ta -- b [label=\"before>>hello\"]\n}\n"
 
 #
diff --git a/tst/examples/angles.tst b/tst/examples/angles.tst
index fc39502..cab0d92 100644
--- a/tst/examples/angles.tst
+++ b/tst/examples/angles.tst
@@ -68,7 +68,7 @@ gap> GraphvizAddEdge(g, "n5", "n14");
 <graphviz edge (n5, n14)>
 
 #@if CompareVersionNumbers(GAPInfo.Version, "4.12.0")
-gap> Print(AsString(g));
+gap> Print(String(g));
 //dot
 digraph G {
 	bgcolor=blue 
@@ -103,7 +103,7 @@ ientangle=360,label="n9:n360", fontcolor=black] label="Radial Angle Variations\
 	n5 -> n14
 }
 #@else
-gap> Print(AsString(g));
+gap> Print(String(g));
 //dot
 digraph G {
 	bgcolor=blue 
diff --git a/tst/examples/btree.tst b/tst/examples/btree.tst
index 555996e..1e22687 100644
--- a/tst/examples/btree.tst
+++ b/tst/examples/btree.tst
@@ -55,7 +55,7 @@ gap> GraphvizAddEdge(s, "node4:f2", "node6:f1");
 <graphviz edge (node4:f2, node6:f1)>
 gap> GraphvizAddEdge(s, "node4:f0", "node5:f1");
 <graphviz edge (node4:f0, node5:f1)>
-gap> AsString(s) =
+gap> String(s) =
 > "//dot\ndigraph g {\n\tnode [shape=record, height=.1] \n\tnode0 [label=\"<f0> \
 > |<f1> G|<f2>\"]\n\tnode1 [label=\"<f0> |<f1> E|<f2>\"]\n\tnode2 [label=\"<f0> \
 > |<f1> B|<f2>\"]\n\tnode3 [label=\"<f0> |<f1> F|<f2>\"]\n\tnode4 [label=\"<f0> \
diff --git a/tst/examples/cluster.tst b/tst/examples/cluster.tst
index 2786feb..4f4ac8c 100644
--- a/tst/examples/cluster.tst
+++ b/tst/examples/cluster.tst
@@ -74,7 +74,7 @@ gap> GraphvizSetAttr(graph["end"], "shape", "Msquare");
 <graphviz node end>
 
 #
-gap> AsString(graph);
+gap> String(graph);
 "//dot\ndigraph G {\nsubgraph cluster_0 {\n\tcolor=\"lightgrey\" style=\"fille\
 d\" node [color=\"white\", style=\"filled\"] label=\"process #1\" \n\ta0\n\ta1\
 \n\ta0 -> a1\n\ta2\n\ta1 -> a2\n\ta3\n\ta2 -> a3\n}\nsubgraph cluster_1 {\n\tc\
diff --git a/tst/examples/cluster_edge.tst b/tst/examples/cluster_edge.tst
index 3a017fe..0af6cb6 100644
--- a/tst/examples/cluster_edge.tst
+++ b/tst/examples/cluster_edge.tst
@@ -53,7 +53,7 @@ gap> GraphvizSetAttr(e, "ltail", "cluster0");
 <graphviz edge (c, e)>
 gap> GraphvizAddEdge(g, "d", "h");
 <graphviz edge (d, h)>
-gap> AsString(g);
+gap> String(g);
 "//dot\ndigraph G {\n\tcompound=true \nsubgraph cluster0 {\n\ta\n\tb\n\ta -> b\
 \n\tc\n\ta -> c\n\td\n\tb -> d\n\tc -> d\n}\nsubgraph cluster1 {\n\te\n\tg\n\t\
 e -> g\n\tf\n\te -> f\n}\n\tb -> f [lhead=cluster1]\n\td -> e\n\tc -> g [lhead\
diff --git a/tst/examples/colors.tst b/tst/examples/colors.tst
index d1f4d8c..695c008 100644
--- a/tst/examples/colors.tst
+++ b/tst/examples/colors.tst
@@ -54,7 +54,7 @@ gap> GraphvizSetAttr(node, "fillcolor", "deeppink");
 <graphviz node name: deeppink>
 
 #
-gap> AsString(g);
+gap> String(g);
 #I  invalid node name RGB: #40e0d0 using "RGB: #40e0d0" instead
 #I  invalid node name RGBA: #ff000042 using "RGBA: #ff000042" instead
 #I  invalid node name HSV: 0.051 0.718 0.627 using "HSV: 0.051 0.718 0.627" instead
diff --git a/tst/examples/er.tst b/tst/examples/er.tst
index a1dcbf3..41228f0 100644
--- a/tst/examples/er.tst
+++ b/tst/examples/er.tst
@@ -104,7 +104,7 @@ gap> GraphvizSetAttr(e, "fontsize=\"20\"");
 <graphviz graph ER with 0 nodes and 12 edges>
 
 #
-gap> AsString(e);
+gap> String(e);
 #I  invalid node name C-I using "C-I" instead
 #I  invalid node name S-C using "S-C" instead
 #I  invalid node name S-I using "S-I" instead
diff --git a/tst/examples/fsm.tst b/tst/examples/fsm.tst
index ad70da3..177b453 100644
--- a/tst/examples/fsm.tst
+++ b/tst/examples/fsm.tst
@@ -73,7 +73,7 @@ gap> GraphvizSetAttr(GraphvizAddEdge(nodes, "LR_8", "LR_5"), "label", "\"S(a)\""
 <graphviz edge (LR_8, LR_5)>
 
 #
-gap> AsString(f);
+gap> String(f);
 "//dot\ndigraph finite_state_machine {\n\trankdir=LR size=\"8,5\" \n// termina\
 ls context \n\tnode [shape=doublecircle] \n\tLR_0\n\tLR_3\n\tLR_4\n\tLR_8\n\tr\
 ankdir=LR size=\"8,5\" \n\n// nodes context \n\tnode [shape=circle] \n\tLR_2\n\
diff --git a/tst/examples/g_c_n.tst b/tst/examples/g_c_n.tst
index f38f5b7..beea2f2 100644
--- a/tst/examples/g_c_n.tst
+++ b/tst/examples/g_c_n.tst
@@ -36,7 +36,7 @@ gap> GraphvizAddNode(cluster1, "anode");
 <graphviz node anode>
 
 #@if CompareVersionNumbers(GAPInfo.Version, "4.12.0")
-gap> Print(AsString(g));
+gap> Print(String(g));
 //dot
 graph G {
 	bgcolor="purple:pink" label="agraph" fontcolor="white" 
@@ -48,7 +48,7 @@ ntangle=270
 }
 }
 #@else
-gap> Print(AsString(g));
+gap> Print(String(g));
 //dot
 graph G {
 	bgcolor="purple:pink" label="agraph" fontcolor="white" 
diff --git a/tst/examples/hello.tst b/tst/examples/hello.tst
index d9af8ae..8d4cc54 100644
--- a/tst/examples/hello.tst
+++ b/tst/examples/hello.tst
@@ -20,7 +20,7 @@ gap> graph := GraphvizDigraph("G");
 <graphviz digraph G with 0 nodes and 0 edges>
 gap> GraphvizAddEdge(graph, "hello", "world");
 <graphviz edge (hello, world)>
-gap> AsString(graph);
+gap> String(graph);
 "//dot\ndigraph G {\n\thello\n\tworld\n\thello -> world\n}\n"
 
 #
diff --git a/tst/examples/process.tst b/tst/examples/process.tst
index 9b922b8..44b2f11 100644
--- a/tst/examples/process.tst
+++ b/tst/examples/process.tst
@@ -47,7 +47,7 @@ gap> GraphvizAddEdge(graph, "runswap", "runmem");
 <graphviz edge (runswap, runmem)>
 gap> GraphvizAddEdge(graph, "new", "runmem");
 <graphviz edge (new, runmem)>
-gap> AsString(graph);
+gap> String(graph);
 "//dot\ngraph G {\n\tengine=\"sfdp\" \n\trun\n\tintr\n\trun -- intr\n\trunbl\n\
 \tintr -- runbl\n\trunbl -- run\n\tkernel\n\trun -- kernel\n\tzombie\n\tkernel\
  -- zombie\n\tsleep\n\tkernel -- sleep\n\trunmem\n\tkernel -- runmem\n\tswap\n\
diff --git a/tst/examples/rank_same.tst b/tst/examples/rank_same.tst
index 685dee2..df7355d 100644
--- a/tst/examples/rank_same.tst
+++ b/tst/examples/rank_same.tst
@@ -58,7 +58,7 @@ gap> GraphvizAddEdge(g, "X", "Y");
 <graphviz edge (X, Y)>
 
 #
-gap> AsString(g);
+gap> String(g);
 "//dot\ndigraph  {\nsubgraph no_name_1 {\n\trank=same \n\tA\n\tX\n}\n\tC\nsubg\
 raph no_name_3 {\n\trank=same \n\tB\n\tD\n\tY\n}\n\tA -> B\n\tA -> C\n\tC -> D\
 \n\tX -> Y\n}\n"
diff --git a/tst/examples/structs.tst b/tst/examples/structs.tst
index 2068f9f..f10bd74 100644
--- a/tst/examples/structs.tst
+++ b/tst/examples/structs.tst
@@ -63,7 +63,7 @@ gap> GraphvizAddEdge(s, "struct1:f2", "struct3:here");
 <graphviz edge (struct1:f2, struct3:here)>
 
 #
-gap> AsString(s);
+gap> String(s);
 "//dot\ndigraph structs {\n\tnode [shape=\"plaintext\"] \n\tstruct1 [label=<<T\
 ABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">\n<TR>\n<TD>left</TD>\n<T\
 D PORT=\"f1\">middle</TD><TD PORT=\"f2\">right</TD>\n</TR>\n</TABLE>>]\n\tstru\
diff --git a/tst/examples/traffic_lights.tst b/tst/examples/traffic_lights.tst
index 295ac0f..5654ab7 100644
--- a/tst/examples/traffic_lights.tst
+++ b/tst/examples/traffic_lights.tst
@@ -79,7 +79,7 @@ gap> GraphvizSetAttr(t, "fontsize=12");
 <graphviz digraph TrafficLights with 0 nodes and 16 edges>
 
 #
-gap> AsString(t);
+gap> String(t);
 "//dot\ndigraph TrafficLights {\n\tengine=neato overlap=\"false\" label=\"Petr\
 iNet Model TrafficLights\nExtracted from ConceptBase and laid out by Graphviz\
 \"\n fontsize=12 \nsubgraph ctx1 {\n\tnode [shape=\"box\"] \n\tgy2\n\tyr2\n\tr\
diff --git a/tst/examples/unix.tst b/tst/examples/unix.tst
index 5207345..e63d3f2 100644
--- a/tst/examples/unix.tst
+++ b/tst/examples/unix.tst
@@ -124,7 +124,7 @@ gap> GraphvizAddEdge(u, "System V.2", "System V.3");
 <graphviz edge (System V.2, System V.3)>
 
 #
-gap> AsString(u) =
+gap> String(u) =
 > "//dot\ndigraph unix {\n\tnode [color=\"lightblue2\", style=\"filled\", size=\
 > \"6,6\"] \n\t\"5th Edition\"\n\t\"6th Edition\"\n\t\"5th Edition\" -> \"6th Ed\
 > ition\"\n\t\"PWB 1.0\"\n\t\"5th Edition\" -> \"PWB 1.0\"\n\tLSX\n\t\"6th Editi\
diff --git a/tst/graph.tst b/tst/graph.tst
index dcdd261..d485ee1 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -176,7 +176,7 @@ gap> GraphvizAttrs(g);
 gap> g := GraphvizGraph();;
 gap> GraphvizSetAttr(g, "color", "red");;
 gap> GraphvizSetAttr(g, "color", "blue");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\tcolor=red color=blue \n}\n"
 
 # # Test removing attributes from a graph TODO uncomment or delete
diff --git a/tst/node.tst b/tst/node.tst
index 9a8a506..0555e43 100644
--- a/tst/node.tst
+++ b/tst/node.tst
@@ -54,14 +54,14 @@ rec( shape := "circle" )
 # Test name containing ':'
 gap> g := GraphvizGraph();;
 gap> GraphvizAddNode(g, "test:colon");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\ttest:colon\n}\n"
 
 # Test non-string name containing ':'
 gap> g := GraphvizGraph();;
 gap> GraphvizAddNode(g, 111);
 <graphviz node 111>
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n\t111\n}\n"
 
 # Test removing a node with a non-string name
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 5b2fec9..162ba6f 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -134,7 +134,7 @@ gap> GraphvizAddEdge(g, "x", "y");;
 gap> GraphvizSetAttr(s, "color", "red");;
 gap> GraphvizSetAttr(s, "node [color=red]");;
 gap> GraphvizSetAttr(s, "edge [color=red]");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ndigraph  {\nsubgraph a {\n\tcolor=red node [color=red] edge [color=red\
 ] \n}\n\tx\n\ty\n\tx -> y\n}\n"
 
@@ -145,7 +145,7 @@ gap> GraphvizAddEdge(g, "x", "y");;
 gap> GraphvizSetAttr(s, "color", "red");;
 gap> GraphvizSetAttr(s, "node [color=red]");;
 gap> GraphvizSetAttr(s, "edge [color=red]");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\nsubgraph a {\n\tcolor=red node [color=red] edge [color=red] \
 \n}\n\tx\n\ty\n\tx -- y\n}\n"
 
@@ -156,7 +156,7 @@ gap> GraphvizAddEdge(g, "x", "y");;
 gap> GraphvizSetAttr(s, "color", "red");;
 gap> GraphvizSetAttr(s, "node [color=red]");;
 gap> GraphvizSetAttr(s, "edge [color=red]");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\n// a context \n\tcolor=red node [color=red] edge [color=red]\
  \n\n\tx\n\ty\n\tx -- y\n}\n"
 
@@ -167,14 +167,14 @@ gap> GraphvizAddEdge(g, "x", "y");;
 gap> GraphvizSetAttr(s, "color", "red");;
 gap> GraphvizSetAttr(s, "node [color=red]");;
 gap> GraphvizSetAttr(s, "edge [color=red]");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ndigraph  {\n// a context \n\tcolor=red node [color=red] edge [color=re\
 d] \n\n\tx\n\ty\n\tx -> y\n}\n"
 
 # Test stringifying subgraph w/o name
 gap> g := GraphvizDigraph();;
 gap> s := GraphvizAddSubgraph(g);;
-gap> AsString(g);
+gap> String(g);
 "//dot\ndigraph  {\nsubgraph no_name_1 {\n}\n}\n"
 
 # finding a node in a sibling graph
@@ -244,7 +244,7 @@ gap> GraphvizSetAttr(g, "node[color=blue]");;
 gap> GraphvizSetAttr(g, "edge[color=blue]");;
 gap> GraphvizSetAttr(ctx, "node[color=red]");;
 gap> GraphvizAddNode(ctx, "a");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ndigraph  {\n\tcolor=green edge [label=testing123] node[color=blue] edg\
 e[color=blue] \n// no_name_1 context \n\tnode[color=red] \n\ta\n\tcolor=green \
 edge [label=testing123] node[color=blue] edge[color=blue] \n\n}\n"
@@ -291,7 +291,7 @@ gap> GraphvizSubgraphs(s1)["c"];
 gap> g := GraphvizGraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(s1, "c");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph  {\nsubgraph a {\nsubgraph c {\n}\n}\n}\n"
 
 # Test subgraphs with non-string names
@@ -360,7 +360,7 @@ gap> g      := GraphvizGraph("g");;
 gap> parent := GraphvizAddContext(g, "parent");;
 gap> ctx    := GraphvizAddContext(parent, "ctx");;
 gap> GraphvizAddEdge(ctx, "a", "b");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ngraph g {\n// parent context \n// ctx context \n\ta\n\tb\n\ta -- b\n\n\
 \n}\n"
 
@@ -369,7 +369,7 @@ gap> g      := GraphvizDigraph("g");;
 gap> parent := GraphvizAddContext(g, "parent");;
 gap> ctx    := GraphvizAddContext(parent, "ctx");;
 gap> GraphvizAddEdge(ctx, "a", "b");;
-gap> AsString(g);
+gap> String(g);
 "//dot\ndigraph g {\n// parent context \n// ctx context \n\ta\n\tb\n\ta -> b\n\
 \n\n}\n"
 

From 9118809c1505db1d4bed1f026a8288ce5bab557e Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 16:41:37 +0100
Subject: [PATCH 14/38] Add splash.gd

---
 gap/splash.gd |  15 ++++
 gap/splash.gi | 219 +++++++++++++++++++++++++++-----------------------
 init.g        |   1 +
 3 files changed, 133 insertions(+), 102 deletions(-)

diff --git a/gap/splash.gd b/gap/splash.gd
index e69de29..919a68a 100644
--- a/gap/splash.gd
+++ b/gap/splash.gd
@@ -0,0 +1,15 @@
+#############################################################################
+##
+##  splash.gd
+##  Copyright (C) 2024                                      Matthew Pancer
+##
+##  Licensing information can be found in the README file of this package.
+##
+#############################################################################
+##
+
+# This function is transplanted from the Digraphs package to here. The original
+# function was written by A. Egri-Nagy and Manuel Delgado, with some minor
+# modifications by J. Mitchell.
+
+DeclareGlobalFunction("Splash");
diff --git a/gap/splash.gi b/gap/splash.gi
index 32d8b05..e61e9ba 100644
--- a/gap/splash.gi
+++ b/gap/splash.gi
@@ -1,118 +1,133 @@
-# TODO file header
-# TODO rename file to remove "i" suffix
+#############################################################################
+##
+##  splash.gi
+##  Copyright (C) 2024                                      Matthew Pancer
+##
+##  Licensing information can be found in the README file of this package.
+##
+#############################################################################
+##
 
-if not IsBound(Splash) then
-  BindGlobal("VizViewers",
-             ["xpdf", "xdg-open", "open", "evince", "okular", "gv"]);
+# The contents of this file are transplanted from the Digraphs package to here.
+# The original function was written by A. Egri-Nagy and Manuel Delgado, with
+# some minor modifications by J. Mitchell.
 
-  BindGlobal("Splash",
-  function(arg...)
-    local str, opt, path, dir, tdir, file, viewer, type, inn, filetype, out,
-          engine;
+BindGlobal("VizViewers",
+           ["xpdf", "xdg-open", "open", "evince", "okular", "gv"]);
 
-    if IsEmpty(arg) then
-      ErrorNoReturn("the must be at least 1 argument, found none");
-    elif not IsString(arg[1]) and not IsGraphvizGraphOrDigraph(arg[1]) then
-      ErrorFormatted("the 1st argument must be a string or ",
-                     "graphviz graph, found {}", TNAM_OBJ(arg[1]));
-    elif IsGraphvizGraphOrDigraph(arg[1]) then
-      arg[1] := String(arg[1]);
-    fi;
-    str := arg[1];
+InstallGlobalFunction(Splash,
+function(arg...)
+  local file, str, opt, path, dir, tdir, viewer, type, inn, filetype, out,
+  engine, i;
 
-    opt := rec();
-    if IsBound(arg[2]) and IsRecord(arg[2]) then
-      opt := arg[2];
-    elif IsBound(arg[2]) then
-      ErrorNoReturn("the 2nd argument must be a record,");
-    fi;
+  if IsEmpty(arg) then
+    ErrorNoReturn("the must be at least 1 argument, found none");
+  elif not IsString(arg[1]) and not IsGraphvizGraphOrDigraph(arg[1]) then
+    ErrorFormatted("the 1st argument must be a string or ",
+                   "graphviz graph, found {}", TNAM_OBJ(arg[1]));
+  elif IsGraphvizGraphOrDigraph(arg[1]) then
+    file := GraphvizName(arg[1]);
+    for i in [1 .. Length(file)] do
+      if not IsAlphaChar(file[i]) and not IsDigitChar(file[i]) then
+        file[i] := '_';
+      fi;
+    od;
+    arg[1] := String(arg[1]);
+  else
+    file := "vizpicture";
+  fi;
+  str := arg[1];
 
-    path := UserHomeExpand("~/");
-    if IsBound(opt.path) then
-      path := opt.path;
-    fi;
+  opt := rec();
+  if IsBound(arg[2]) and IsRecord(arg[2]) then
+    opt := arg[2];
+  elif IsBound(arg[2]) then
+    ErrorNoReturn("the 2nd argument must be a record,");
+  fi;
 
-    if IsBound(opt.directory) then
-      if not opt.directory in DirectoryContents(path) then
-        Exec(Concatenation("mkdir ", path, opt.directory));
-      fi;
-      dir := Concatenation(path, opt.directory, "/");
-    elif IsBound(opt.path) then
-      if not "tmp.viz" in DirectoryContents(path) then
-        tdir := Directory(Concatenation(path, "/", "tmp.viz"));
-        dir := Filename(tdir, "");
-      fi;
-    else
-      tdir := DirectoryTemporary();
-      dir := Filename(tdir, "");
-    fi;
+  path := UserHomeExpand("~/");
+  if IsBound(opt.path) then
+    path := opt.path;
+  fi;
 
-    # TODO use the graphs name
-    file := "vizpicture";
-    if IsBound(opt.filename) then
-      file := opt.filename;
+  if IsBound(opt.directory) then
+    if not opt.directory in DirectoryContents(path) then
+      Exec(Concatenation("mkdir ", path, opt.directory));
     fi;
-
-    if IsBound(opt.viewer) then
-      viewer := opt.viewer;
-      if not IsString(viewer) then
-        ErrorNoReturn("the option `viewer` must be a string, not an ",
-                      TNAM_OBJ(viewer));
-      elif Filename(DirectoriesSystemPrograms(), viewer) = fail then
-        ErrorNoReturn("the viewer \"", viewer, "\" specified in the option ",
-                      "`viewer` is not available");
-      fi;
-    else
-      viewer := First(VizViewers, x ->
-                      Filename(DirectoriesSystemPrograms(), x) <> fail);
-      if viewer = fail then
-        ErrorNoReturn("none of the default viewers ", VizViewers,
-                      " is available, please specify an available viewer",
-                      " in the options record component `viewer`,");
-      fi;
+    dir := Concatenation(path, opt.directory, "/");
+  elif IsBound(opt.path) then
+    if not "tmp.viz" in DirectoryContents(path) then
+      tdir := Directory(Concatenation(path, "/", "tmp.viz"));
+      dir := Filename(tdir, "");
     fi;
+  else
+    tdir := DirectoryTemporary();
+    dir := Filename(tdir, "");
+  fi;
+
+  if IsBound(opt.filename) then
+    file := opt.filename;
+  fi;
 
-    if IsBound(opt.type) and (opt.type = "latex" or opt.type = "dot") then
-      type := opt.type;
-    elif Length(str) >= 6 and str{[1 .. 6]} = "%latex" then
-      type := "latex";
-    elif Length(str) >= 5 and str{[1 .. 5]} = "//dot" then
-      type := "dot";
-    else
-      ErrorNoReturn("the component \"type\" of the 2nd argument <a record> ",
-                    " must be \"dot\" or \"latex\",");
+  if IsBound(opt.viewer) then
+    viewer := opt.viewer;
+    if not IsString(viewer) then
+      ErrorNoReturn("the option `viewer` must be a string, not an ",
+                    TNAM_OBJ(viewer));
+    elif Filename(DirectoriesSystemPrograms(), viewer) = fail then
+      ErrorNoReturn("the viewer \"", viewer, "\" specified in the option ",
+                    "`viewer` is not available");
     fi;
-    if type = "latex" then
-      inn := Concatenation(dir, file, ".tex");
-    else
-      inn := Concatenation(dir, file, ".dot");
+  else
+    viewer := First(VizViewers, x ->
+                    Filename(DirectoriesSystemPrograms(), x) <> fail);
+    if viewer = fail then
+      ErrorNoReturn("none of the default viewers ", VizViewers,
+                    " is available, please specify an available viewer",
+                    " in the options record component `viewer`,");
     fi;
+  fi;
 
-    filetype := "pdf";
-    if IsBound(opt.filetype) and IsString(opt.filetype) and type <> "latex" then
-      filetype := opt.filetype;
-    fi;
-    out := Concatenation(dir, file, ".", filetype);
+  if IsBound(opt.type) and (opt.type = "latex" or opt.type = "dot") then
+    type := opt.type;
+  elif Length(str) >= 6 and str{[1 .. 6]} = "%latex" then
+    type := "latex";
+  elif Length(str) >= 5 and str{[1 .. 5]} = "//dot" then
+    type := "dot";
+  else
+    ErrorNoReturn("the component \"type\" of the 2nd argument <a record> ",
+                  " must be \"dot\" or \"latex\",");
+  fi;
+  if type = "latex" then
+    inn := Concatenation(dir, file, ".tex");
+  else
+    inn := Concatenation(dir, file, ".dot");
+  fi;
 
-    engine := "dot";
-    if IsBound(opt.engine) then
-      engine := opt.engine;
-      if not engine in ["dot", "neato", "twopi", "circo",
-                        "fdp", "sfdp", "patchwork"] then
-        ErrorNoReturn("the component \"engine\" of the 2nd argument ",
-                      "<a record> must be one of: \"dot\", \"neato\", ",
-                      "\"twopi\", \"circo\", \"fdp\", \"sfdp\", ",
-                      "or \"patchwork\"");
-      fi;
-    fi;
+  filetype := "pdf";
+  if IsBound(opt.filetype) and IsString(opt.filetype) and type <> "latex" then
+    filetype := opt.filetype;
+  fi;
+  out := Concatenation(dir, file, ".", filetype);
 
-    FileString(inn, str);
-    if type = "latex" then
-      Exec(Concatenation("cd ", dir, ";",
-                         "pdflatex ", file, " 2>/dev/null 1>/dev/null"));
-    else
-      Exec(Concatenation(engine, " -T", filetype, " ", inn, " -o ", out));
+  engine := "dot";
+  if IsBound(opt.engine) then
+    engine := opt.engine;
+    if not engine in ["dot", "neato", "twopi", "circo",
+                      "fdp", "sfdp", "patchwork"] then
+      ErrorNoReturn("the component \"engine\" of the 2nd argument ",
+                    "<a record> must be one of: \"dot\", \"neato\", ",
+                    "\"twopi\", \"circo\", \"fdp\", \"sfdp\", ",
+                    "or \"patchwork\"");
     fi;
-    Exec(Concatenation(viewer, " ", out, " 2>/dev/null 1>/dev/null &"));
-  end);
-fi;
+  fi;
+
+  FileString(inn, str);
+  if type = "latex" then
+    Exec(Concatenation("cd ", dir, ";",
+                       "pdflatex ", file, " 2>/dev/null 1>/dev/null"));
+  else
+    Exec(Concatenation(engine, " -T", filetype, " ", inn, " -o ", out));
+  fi;
+  Exec(Concatenation(viewer, " ", out, " 2>/dev/null 1>/dev/null &"));
+end);
diff --git a/init.g b/init.g
index b6ccf00..42a7379 100644
--- a/init.g
+++ b/init.g
@@ -11,3 +11,4 @@
 ReadPackage("graphviz", "gap/error.gd");
 ReadPackage("graphviz", "gap/dot.gd");
 ReadPackage("graphviz", "gap/gv.gd");
+ReadPackage("graphviz", "gap/splash.gd");

From 2e7c27faa46a4731b602d5a23da4a91084a45ee8 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 16:50:50 +0100
Subject: [PATCH 15/38] Add PrintObj method for graphs and digraphs

---
 gap/dot.gd | 2 --
 gap/dot.gi | 6 ++++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index e911100..51fe311 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -200,8 +200,6 @@ DeclareOperation("GraphvizRemoveAttr", [IsGraphvizObject, IsObject]);
 #! @Returns the dot representation of the graphviz object.
 # TODO document "String"
 
-# TODO PrintObj
-
 #! @Arguments obj
 #! @Returns the graphviz representation of the object.
 #! @Description
diff --git a/gap/dot.gi b/gap/dot.gi
index 6dda979..42cbc33 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -530,6 +530,12 @@ end);
 InstallMethod(String, "for a graphviz (di)graph",
 [IsGraphvizGraphOrDigraph], graph -> GV_StringifyGraph(graph, false));
 
+InstallMethod(PrintObj, "for a graphviz (di)graph",
+[IsGraphvizGraphOrDigraph],
+function(gv)
+  Print(String(gv));
+end);
+
 InstallMethod(GraphvizSetNodeLabels,
 "for a graphviz (di)graph and list of colors",
 [IsGraphvizGraphOrDigraph, IsList],

From bd99589b1d2f35e408a16d867e47635e315b5ec3 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 16:51:09 +0100
Subject: [PATCH 16/38] Add comment about valid identifiers

---
 gap/dot.gd | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 51fe311..087a4b5 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -86,7 +86,14 @@ DeclareOperation("GraphvizAttrs", [IsGraphvizObject]);
 #! @Arguments graph
 #! @Returns the nodes of the provided graphviz graph.
 #! @Description Gets the nodes of the provided graphviz graph.
-#! Node names can only be [a-zA-Z0-9_£] TODO check exact docs.
+# From https://graphviz.org/doc/info/lang.html
+# An ID is one of the following:
+# Any string of alphabetic ([a-zA-Z\200-\377]) characters, underscores ('_') or
+# digits([0-9]), not beginning with a digit;
+# a numeral [-]?(.[0-9]⁺ | [0-9]⁺(.[0-9]*)? );
+# any double-quoted string ("...") possibly containing escaped quotes (\")¹;
+# an HTML string (<...>).
+# TODO specify
 DeclareOperation("GraphvizNodes", [IsGraphvizGraphOrDigraph]);
 
 #! @Arguments graph

From 9bef7d5187355c089bd043234dbc80f858bb46be Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 16:57:46 +0100
Subject: [PATCH 17/38] Add comment to GraphvizSetAttr

---
 gap/dot.gi | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/gap/dot.gi b/gap/dot.gi
index 42cbc33..149cc34 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -228,7 +228,10 @@ function(x, attrs)
   return x;
 end);
 
-# TODO combine this and the next method
+# TODO not sure why these two methods are required? I.e. why is setting
+# attributes for graphs and digraphs different? Be good to have a comment
+# explaining why.
+
 InstallMethod(GraphvizSetAttr, "for a graphviz object, object, and object",
 [IsGraphvizObject, IsObject, IsObject],
 function(x, name, value)
@@ -243,17 +246,16 @@ function(x, name, value)
   return x;
 end);
 
-InstallMethod(GraphvizSetAttr, "for a graphviz (di)graph, object and object",
+InstallMethod(GraphvizSetAttr, "for a graphviz (di)graph, object, and object",
 [IsGraphvizGraphOrDigraph, IsObject, IsObject],
 function(x, name, value)
-  local attrs, string, msg;
+  local attrs, string;
 
   if not name in GV_KNOWN_ATTRS then
-    msg := Concatenation(
-           StringFormatted("unknown attribute \"{}\", the", name),
-           " graphviz object may no longer be valid, it can",
-           " be removed using GraphvizRemoveAttr");
-    Info(InfoWarning, 1, msg);
+    Info(InfoWarning, 1,
+         StringFormatted("unknown attribute \"{}\", the", name),
+         " graphviz object may no longer be valid, it can",
+         " be removed using GraphvizRemoveAttr");
   fi;
 
   attrs := GraphvizAttrs(x);

From 9ba8bc984634bae071fde6bf82d266f3004e1b54 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 17:04:24 +0100
Subject: [PATCH 18/38] IsGraphvizContext does not imply graph or digraph

---
 gap/dot.gd | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 087a4b5..1da2945 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -40,7 +40,7 @@ DeclareCategory("IsGraphvizObject", IsObject);
 DeclareCategory("IsGraphvizGraphOrDigraph", IsGraphvizObject);
 DeclareCategory("IsGraphvizGraph", IsGraphvizGraphOrDigraph);
 DeclareCategory("IsGraphvizDigraph", IsGraphvizGraphOrDigraph);
-DeclareCategory("IsGraphvizContext", IsGraphvizGraphOrDigraph);
+DeclareCategory("IsGraphvizContext", IsGraphvizObject);
 DeclareCategory("IsGraphvizNode", IsGraphvizObject);
 DeclareCategory("IsGraphvizEdge", IsGraphvizObject);
 #! @EndGroup

From 6a4c89256be6f23bde29d5486720781680fad185 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 17:26:02 +0100
Subject: [PATCH 19/38] Further tweak the categories

---
 gap/dot.gd    | 51 ++++++++++++++++---------------
 gap/dot.gi    | 83 +++++++++++++++++++++++++--------------------------
 gap/gv.gd     | 42 +++++++++++++-------------
 gap/gv.gi     | 42 +++++++++++++-------------
 gap/splash.gi |  4 +--
 5 files changed, 111 insertions(+), 111 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 1da2945..af234cf 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -37,12 +37,15 @@
 #! which is a subcategory of is IsGraphvizGraph.
 
 DeclareCategory("IsGraphvizObject", IsObject);
-DeclareCategory("IsGraphvizGraphOrDigraph", IsGraphvizObject);
-DeclareCategory("IsGraphvizGraph", IsGraphvizGraphOrDigraph);
-DeclareCategory("IsGraphvizDigraph", IsGraphvizGraphOrDigraph);
-DeclareCategory("IsGraphvizContext", IsGraphvizObject);
-DeclareCategory("IsGraphvizNode", IsGraphvizObject);
-DeclareCategory("IsGraphvizEdge", IsGraphvizObject);
+
+DeclareCategory("IsGraphvizObjectWithSubobjects", IsGraphvizObject);
+DeclareCategory("IsGraphvizGraph", IsGraphvizObjectWithSubobjects);
+DeclareCategory("IsGraphvizDigraph", IsGraphvizObjectWithSubobjects);
+DeclareCategory("IsGraphvizContext", IsGraphvizObjectWithSubobjects);
+
+DeclareCategory("IsGraphvizNodeOrEdge", IsGraphvizObject);
+DeclareCategory("IsGraphvizNode", IsGraphvizNodeOrEdge);
+DeclareCategory("IsGraphvizEdge", IsGraphvizNodeOrEdge);
 #! @EndGroup
 
 #! @Section Constructors
@@ -94,12 +97,12 @@ DeclareOperation("GraphvizAttrs", [IsGraphvizObject]);
 # any double-quoted string ("...") possibly containing escaped quotes (\")¹;
 # an HTML string (<...>).
 # TODO specify
-DeclareOperation("GraphvizNodes", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GraphvizNodes", [IsGraphvizObjectWithSubobjects]);
 
 #! @Arguments graph
 #! @Returns the subgraphs of the provided graphviz graph.
 #! @Description gets the subgraphs of a provided graphviz graph.
-DeclareOperation("GraphvizSubgraphs", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GraphvizSubgraphs", [IsGraphvizObjectWithSubobjects]);
 
 #! @Arguments graph, name
 #! @Returns a graph with the provided name.
@@ -109,14 +112,14 @@ DeclareOperation("GraphvizSubgraphs", [IsGraphvizGraphOrDigraph]);
 #! It returns the graph if it exists.
 #! If no such graph exists then it will return <K>fail<K>.
 DeclareOperation("GraphvizFindSubgraphRecursive",
-[IsGraphvizGraphOrDigraph, IsObject]);
+[IsGraphvizObjectWithSubobjects, IsObject]);
 
 #! @Arguments graph
 #! @Returns the edges of the provided graphviz graph.
 #! @Description Gets the edges of the provided graphviz graph.
-DeclareOperation("GraphvizEdges", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GraphvizEdges", [IsGraphvizObjectWithSubobjects]);
 DeclareOperation("GraphvizEdges",
-[IsGraphvizGraphOrDigraph, IsObject, IsObject]);
+[IsGraphvizObjectWithSubobjects, IsObject, IsObject]);
 
 #! @Subsection For only edges.
 
@@ -138,13 +141,13 @@ DeclareOperation("GraphvizTail", [IsGraphvizEdge]);
 #! @Arguments graph, name
 #! @Returns the modified graph.
 #! @Description Sets the name of a graphviz graph or digraph.
-DeclareOperation("GraphvizSetName", [IsGraphvizGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizSetName", [IsGraphvizObjectWithSubobjects, IsObject]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Adds a node to the graph.
 #! If a node with the same name is already present the operation fails.
-DeclareOperation("GraphvizAddNode", [IsGraphvizGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizAddNode", [IsGraphvizObjectWithSubobjects, IsObject]);
 
 #! @Arguments graph, edge
 #! @Returns the modified graph.
@@ -153,36 +156,36 @@ DeclareOperation("GraphvizAddNode", [IsGraphvizGraphOrDigraph, IsObject]);
 #! added to the graph. If different nodes with the same name are in the graph
 #! then the operation fails.
 DeclareOperation("GraphvizAddEdge",
-[IsGraphvizGraphOrDigraph, IsObject, IsObject]);
+[IsGraphvizObjectWithSubobjects, IsObject, IsObject]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new subgraph.
 #! @Description Adds a subgraph to a graph.
-DeclareOperation("GraphvizAddSubgraph", [IsGraphvizGraphOrDigraph, IsObject]);
-DeclareOperation("GraphvizAddSubgraph", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GraphvizAddSubgraph", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GraphvizAddSubgraph", [IsGraphvizObjectWithSubobjects]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new context.
 #! @Description Adds a context to a graph.
-DeclareOperation("GraphvizAddContext", [IsGraphvizGraphOrDigraph, IsObject]);
-DeclareOperation("GraphvizAddContext", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GraphvizAddContext", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GraphvizAddContext", [IsGraphvizObjectWithSubobjects]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Removes the node from the graph.
-DeclareOperation("GraphvizRemoveNode", [IsGraphvizGraphOrDigraph, IsObject]);
+DeclareOperation("GraphvizRemoveNode", [IsGraphvizObjectWithSubobjects, IsObject]);
 
 #! @Arguments graph, predicate
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges using the provided predicate.
-DeclareOperation("GraphvizFilterEdges", [IsGraphvizGraphOrDigraph, IsFunction]);
+DeclareOperation("GraphvizFilterEdges", [IsGraphvizObjectWithSubobjects, IsFunction]);
 
 #! @Arguments graph, head_name, tail_name
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges, removing edges between nodes with
 #! the specified names.
 DeclareOperation("GraphvizRemoveEdges",
-[IsGraphvizGraphOrDigraph, IsObject, IsObject]);
+[IsGraphvizObjectWithSubobjects, IsObject, IsObject]);
 
 #! @Subsection For modifying object attributes.
 
@@ -214,8 +217,8 @@ DeclareOperation("GraphvizRemoveAttr", [IsGraphvizObject, IsObject]);
 #!  Should output the graphviz package representation of the object.
 DeclareOperation("Graphviz", [IsObject]);
 
-DeclareOperation("GraphvizSetNodeColors", [IsGraphvizGraphOrDigraph, IsList]);
-DeclareOperation("GraphvizSetNodeLabels", [IsGraphvizGraphOrDigraph, IsList]);
+DeclareOperation("GraphvizSetNodeColors", [IsGraphvizObjectWithSubobjects, IsList]);
+DeclareOperation("GraphvizSetNodeLabels", [IsGraphvizObjectWithSubobjects, IsList]);
 
 DeclareGlobalFunction("ErrorIfNotValidColor");
 
@@ -230,4 +233,4 @@ DeclareOperation("\[\]", [IsGraphvizEdge, IsObject]);
 DeclareOperation("\[\]\:\=", [IsGraphvizEdge, IsObject, IsObject]);
 
 # TODO doc
-DeclareOperation("\[\]", [IsGraphvizGraphOrDigraph, IsObject]);
+DeclareOperation("\[\]", [IsGraphvizObjectWithSubobjects, IsObject]);
diff --git a/gap/dot.gi b/gap/dot.gi
index 149cc34..b691a59 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -61,7 +61,7 @@ function(e)
                          GraphvizName(tail));
 end);
 
-InstallMethod(ViewString, "for a graphviz (di)graph", [IsGraphvizGraphOrDigraph],
+InstallMethod(ViewString, "for a graphviz (di)graph", [IsGraphvizObjectWithSubobjects],
 function(g)
   local result, edges, nodes, kind;
 
@@ -101,14 +101,14 @@ InstallMethod(GraphvizAttrs, "for a graphviz object", [IsGraphvizObject],
 x -> x!.Attrs);
 
 InstallMethod(GraphvizNodes, "for a graphviz (di)graph",
-[IsGraphvizGraphOrDigraph], x -> x!.Nodes);
+[IsGraphvizObjectWithSubobjects], x -> x!.Nodes);
 
 InstallMethod(GraphvizEdges, "for a graphviz (di)graph",
-[IsGraphvizGraphOrDigraph], x -> x!.Edges);
+[IsGraphvizObjectWithSubobjects], x -> x!.Edges);
 
 InstallMethod(GraphvizEdges,
 "for a graphviz (di)graph, object, and object",
-[IsGraphvizGraphOrDigraph, IsObject, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject, IsObject],
 function(gv, head, tail)
     head := GraphvizNodes(gv)[head];
     if head = fail then
@@ -125,7 +125,7 @@ function(gv, head, tail)
 end);
 
 InstallMethod(GraphvizSubgraphs, "for a graphviz (di)graph",
-[IsGraphvizGraphOrDigraph], x -> x!.Subgraphs);
+[IsGraphvizObjectWithSubobjects], x -> x!.Subgraphs);
 
 InstallMethod(GraphvizTail, "for a graphviz edge", [IsGraphvizEdge],
 x -> x!.Tail);
@@ -182,21 +182,21 @@ end);
 # Accessor for graphs and digraphs
 
 InstallMethod(\[\], "for a graphviz (di)graph and string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 {graph, node} -> GraphvizNodes(graph)[node]);
 
 InstallMethod(\[\], "for a graphviz (di)graph and object",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 {g, o} -> g[String(o)]);
 
 InstallMethod(GraphvizFindSubgraphRecursive,
 "for a graphviz (di)graph and a string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 {g, s} -> GV_GraphTreeSearch(g, v -> GraphvizName(v) = s));
 
 InstallMethod(GraphvizFindSubgraphRecursive,
 "for a graphviz (di)graph and a string",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 {g, o} -> GraphvizFindSubgraphRecursive(g, String(o)));
 
 #############################################################################
@@ -204,14 +204,14 @@ InstallMethod(GraphvizFindSubgraphRecursive,
 #############################################################################
 
 InstallMethod(GraphvizSetName, "for a graphviz (di)graph and string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(x, name)
   x!.Name := name;
   return x;
 end);
 
 InstallMethod(GraphvizSetName, "for a graphviz (di)graph and string",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 {g, o} -> GraphvizSetName(g, String(o)));
 
 #############################################################################
@@ -228,12 +228,8 @@ function(x, attrs)
   return x;
 end);
 
-# TODO not sure why these two methods are required? I.e. why is setting
-# attributes for graphs and digraphs different? Be good to have a comment
-# explaining why.
-
-InstallMethod(GraphvizSetAttr, "for a graphviz object, object, and object",
-[IsGraphvizObject, IsObject, IsObject],
+InstallMethod(GraphvizSetAttr, "for a graphviz node or edge, object, and object",
+[IsGraphvizNodeOrEdge, IsObject, IsObject],
 function(x, name, value)
 
   if not name in GV_KNOWN_ATTRS then
@@ -246,8 +242,9 @@ function(x, name, value)
   return x;
 end);
 
-InstallMethod(GraphvizSetAttr, "for a graphviz (di)graph, object, and object",
-[IsGraphvizGraphOrDigraph, IsObject, IsObject],
+InstallMethod(GraphvizSetAttr,
+"for a graphviz object with subobjects, object, and object",
+[IsGraphvizObjectWithSubobjects, IsObject, IsObject],
 function(x, name, value)
   local attrs, string;
 
@@ -272,7 +269,7 @@ function(x, name, value)
 end);
 
 InstallMethod(GraphvizSetAttr, "for a graphviz (di)graph and object",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 function(x, value)
   local attrs;
   attrs := GraphvizAttrs(x);
@@ -286,7 +283,7 @@ end);
 #############################################################################
 
 InstallMethod(GraphvizAddNode, "for a graphviz (di)graph and string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(x, name)
   local node;
   node := GV_Node(x, name);
@@ -295,7 +292,7 @@ function(x, name)
 end);
 
 InstallMethod(GraphvizAddNode, "for a graphviz (di)graph and string",
-[IsGraphvizGraphOrDigraph, IsGraphvizNode],
+[IsGraphvizObjectWithSubobjects, IsGraphvizNode],
 function(gv, name)  # gaplint: disable=analyse-lvars
   ErrorNoReturn("it is not currently possible to add Graphviz node ",
                 "objects directly to Graphviz graphs or digraphs, use ",
@@ -304,7 +301,7 @@ end);
 
 InstallMethod(GraphvizAddNode,
 "for a graphviz (di)graph and string",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 {x, name} -> GraphvizAddNode(x, String(name)));
 
 #############################################################################
@@ -313,7 +310,7 @@ InstallMethod(GraphvizAddNode,
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz (di)graph and two graphviz nodes",
-[IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode],
+[IsGraphvizObjectWithSubobjects, IsGraphvizNode, IsGraphvizNode],
 function(x, head, tail)
   local edge, head_name, tail_name;
 
@@ -335,7 +332,7 @@ end);
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz (di)graph and two strings",
-[IsGraphvizGraphOrDigraph, IsString, IsString],
+[IsGraphvizObjectWithSubobjects, IsString, IsString],
 function(x, head, tail)
   local head_node, tail_node;
 
@@ -354,7 +351,7 @@ end);
 
 InstallMethod(GraphvizAddEdge,
 "for a graphviz (di)graph and two objects",
-[IsGraphvizGraphOrDigraph, IsObject, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject, IsObject],
 {gv, o1, o2} -> GraphvizAddEdge(gv, String(o1), String(o2)));
 
 #############################################################################
@@ -362,7 +359,7 @@ InstallMethod(GraphvizAddEdge,
 #############################################################################
 
 InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph and string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(gv, name)
   local subgraphs, subgraph;
 
@@ -391,18 +388,18 @@ function(gv, name)
 end);
 
 InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph and an object",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 {g, o} -> GraphvizAddSubgraph(g, String(o)));
 
 InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph",
-[IsGraphvizGraphOrDigraph],
+[IsGraphvizObjectWithSubobjects],
 graph -> GraphvizAddSubgraph(graph,
                              StringFormatted("no_name_{}",
                                              GV_GetCounter(graph))));
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz (di)graph and a string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(graph, name)
   local subgraphs, ctx;
 
@@ -423,20 +420,20 @@ end);
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz (di)graph",
-[IsGraphvizGraphOrDigraph],
+[IsGraphvizObjectWithSubobjects],
 g -> GraphvizAddContext(g, StringFormatted("no_name_{}", GV_GetCounter(g))));
 
 InstallMethod(GraphvizAddContext,
 "for a graphviz (di)graph and an object",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 {g, o} -> GraphvizAddContext(g, String(o)));
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and node",
-[IsGraphvizGraphOrDigraph, IsGraphvizNode],
+[IsGraphvizObjectWithSubobjects, IsGraphvizNode],
 {g, node} -> GraphvizRemoveNode(g, GraphvizName(node)));
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(g, name)
   local nodes;
   nodes := GraphvizNodes(g);
@@ -462,11 +459,11 @@ function(g, name)
 end);
 
 InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 {g, o} -> GraphvizRemoveNode(g, String(o)));
 
 InstallMethod(GraphvizFilterEdges, "for a graphviz (di)graph and edge filter",
-[IsGraphvizGraphOrDigraph, IsFunction],
+[IsGraphvizObjectWithSubobjects, IsFunction],
 function(g, filter)
   local edge, idx, edges;
 
@@ -484,7 +481,7 @@ function(g, filter)
 end);
 
 InstallMethod(GraphvizRemoveEdges, "for a graphviz (di)graph and two strings",
-[IsGraphvizGraphOrDigraph, IsString, IsString],
+[IsGraphvizObjectWithSubobjects, IsString, IsString],
 function(g, hn, tn)
   GraphvizFilterEdges(g,
     function(e)
@@ -503,7 +500,7 @@ function(g, hn, tn)
 end);
 
 InstallMethod(GraphvizRemoveEdges, "for a graphviz (di)graph and two objects",
-[IsGraphvizGraphOrDigraph, IsObject, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject, IsObject],
 {gv, o1, o2} -> GraphvizRemoveEdges(gv, String(o1), String(o2)));
 
 InstallMethod(GraphvizRemoveAttr, "for a graphviz object and an object",
@@ -517,7 +514,7 @@ function(obj, attr)
 end);
 
 InstallMethod(GraphvizRemoveAttr, "for a graphviz (di)graph and an object",
-[IsGraphvizGraphOrDigraph, IsObject],
+[IsGraphvizObjectWithSubobjects, IsObject],
 function(obj, attr)
   local attrs;
   attrs      := GraphvizAttrs(obj);
@@ -530,17 +527,17 @@ end);
 #############################################################################
 
 InstallMethod(String, "for a graphviz (di)graph",
-[IsGraphvizGraphOrDigraph], graph -> GV_StringifyGraph(graph, false));
+[IsGraphvizObjectWithSubobjects], graph -> GV_StringifyGraph(graph, false));
 
 InstallMethod(PrintObj, "for a graphviz (di)graph",
-[IsGraphvizGraphOrDigraph],
+[IsGraphvizObjectWithSubobjects],
 function(gv)
   Print(String(gv));
 end);
 
 InstallMethod(GraphvizSetNodeLabels,
 "for a graphviz (di)graph and list of colors",
-[IsGraphvizGraphOrDigraph, IsList],
+[IsGraphvizObjectWithSubobjects, IsList],
 function(gv, labels)
   local nodes, i;
   if Size(GraphvizNodes(gv)) <> Size(labels) then
@@ -558,7 +555,7 @@ end);
 
 InstallMethod(GraphvizSetNodeColors,
 "for a graphviz (di)graph and list of colors",
-[IsGraphvizGraphOrDigraph, IsList],
+[IsGraphvizObjectWithSubobjects, IsList],
 function(gv, colors)
   local nodes, i;
 
diff --git a/gap/gv.gd b/gap/gv.gd
index 2e68cb7..c98f38b 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -11,46 +11,46 @@
 ## This file contains declarations of the internal/private functions for the
 ## graphviz package.
 
-DeclareOperation("GV_GetCounter", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GV_IncCounter", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_GetCounter", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_IncCounter", [IsGraphvizObjectWithSubobjects]);
 DeclareCategory("GV_IsMap", IsObject);
 DeclareAttribute("Size", GV_IsMap);
 
-DeclareOperation("GV_StringifyGraphHead", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GV_StringifyDigraphHead", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GV_StringifySubgraphHead", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GV_StringifyContextHead", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_StringifyGraphHead", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_StringifyDigraphHead", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_StringifySubgraphHead", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_StringifyContextHead", [IsGraphvizObjectWithSubobjects]);
 DeclareOperation("GV_StringifyNode", [IsGraphvizNode]);
-DeclareOperation("GV_StringifyGraphAttrs", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_StringifyGraphAttrs", [IsGraphvizObjectWithSubobjects]);
 DeclareOperation("GV_StringifyNodeEdgeAttrs", [GV_IsMap]);
-DeclareOperation("GV_StringifyGraph", [IsGraphvizGraphOrDigraph, IsBool]);
+DeclareOperation("GV_StringifyGraph", [IsGraphvizObjectWithSubobjects, IsBool]);
 
-DeclareOperation("GV_FindNode", [IsGraphvizGraphOrDigraph, IsObject]);
+DeclareOperation("GV_FindNode", [IsGraphvizObjectWithSubobjects, IsObject]);
 
 DeclareOperation("GV_Pluralize", [IsInt, IsString]);
 
-DeclareOperation("GV_Node", [IsGraphvizGraphOrDigraph, IsString]);
+DeclareOperation("GV_Node", [IsGraphvizObjectWithSubobjects, IsString]);
 DeclareOperation("GV_Edge",
-[IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode]);
-DeclareOperation("GV_Graph", [IsGraphvizGraphOrDigraph, IsString]);
+[IsGraphvizObjectWithSubobjects, IsGraphvizNode, IsGraphvizNode]);
+DeclareOperation("GV_Graph", [IsGraphvizObjectWithSubobjects, IsString]);
 DeclareOperation("GV_Digraph", [IsGraphvizDigraph, IsString]);
-DeclareOperation("GV_Context", [IsGraphvizGraphOrDigraph, IsString]);
+DeclareOperation("GV_Context", [IsGraphvizObjectWithSubobjects, IsString]);
 DeclareOperation("GV_Map", []);
 DeclareOperation("GV_MapNames", [GV_IsMap]);
 
 # TODO required? Replace with String or just String?
 DeclareOperation("GV_EnsureString", [IsObject]);
 
-DeclareOperation("GV_HasNode", [IsGraphvizGraphOrDigraph, IsObject]);
+DeclareOperation("GV_HasNode", [IsGraphvizObjectWithSubobjects, IsObject]);
 
-DeclareOperation("GV_GetParent", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GV_GraphTreeSearch", [IsGraphvizGraphOrDigraph, IsFunction]);
-DeclareOperation("GV_FindGraphWithNode", [IsGraphvizGraphOrDigraph, IsString]);
-DeclareOperation("GV_GetRoot", [IsGraphvizGraphOrDigraph]);
-DeclareOperation("GV_AddNode", [IsGraphvizGraphOrDigraph, IsGraphvizNode]);
-DeclareOperation("GV_AddEdge", [IsGraphvizGraphOrDigraph, IsGraphvizEdge]);
+DeclareOperation("GV_GetParent", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_GraphTreeSearch", [IsGraphvizObjectWithSubobjects, IsFunction]);
+DeclareOperation("GV_FindGraphWithNode", [IsGraphvizObjectWithSubobjects, IsString]);
+DeclareOperation("GV_GetRoot", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_AddNode", [IsGraphvizObjectWithSubobjects, IsGraphvizNode]);
+DeclareOperation("GV_AddEdge", [IsGraphvizObjectWithSubobjects, IsGraphvizEdge]);
 DeclareOperation("GV_GetIdx", [IsGraphvizObject]);
-DeclareOperation("GV_ConstructHistory", [IsGraphvizGraphOrDigraph]);
+DeclareOperation("GV_ConstructHistory", [IsGraphvizObjectWithSubobjects]);
 
 DeclareGlobalFunction("GV_IsValidColor");
 DeclareGlobalFunction("GV_ErrorIfNotNodeColoring");
diff --git a/gap/gv.gi b/gap/gv.gi
index d06a488..c2056aa 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -125,7 +125,7 @@ InstallMethod(GV_Map, "for no args",
 [], {} -> Objectify(GV_MapType, rec(Data := rec())));
 
 InstallMethod(GV_Node, "for a string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(graph, name)
   local out;
   if Length(name) = 0 then
@@ -141,7 +141,7 @@ function(graph, name)
 end);
 
 InstallMethod(GV_Edge, "for two graphviz nodes",
-[IsGraphvizGraphOrDigraph, IsGraphvizNode, IsGraphvizNode],
+[IsGraphvizObjectWithSubobjects, IsGraphvizNode, IsGraphvizNode],
 function(graph, head, tail)
   local out;
   out := Objectify(GV_EdgeType,
@@ -173,7 +173,7 @@ end);
 
 InstallMethod(GV_Graph,
 "for a graphviz graph and a string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(parent, name)
   local out;
 
@@ -187,7 +187,7 @@ end);
 
 InstallMethod(GV_Context,
 "for a string and a positive integer",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(parent, name)
   local out;
 
@@ -257,12 +257,12 @@ InstallMethod(Size, "for a graphviz map",
 
 InstallMethod(GV_IncCounter,
 "for a graphviz graph",
-[IsGraphvizGraphOrDigraph],
+[IsGraphvizObjectWithSubobjects],
 function(x)
   x!.Counter := x!.Counter + 1;
 end);
 
-InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGraphvizGraphOrDigraph],
+InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGraphvizObjectWithSubobjects],
 x -> x!.Counter);
 
 # Converting strings
@@ -275,16 +275,16 @@ InstallMethod(GV_EnsureString, "for a string", [IsString], IdFunc);
 
 InstallMethod(GV_HasNode,
 "for a graphviz graph",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 {g, name} -> name in GV_MapNames(GraphvizNodes(g)));
 
 InstallMethod(GV_GetParent,
 "for a graphviz graph",
-[IsGraphvizGraphOrDigraph], graph -> graph!.Parent);
+[IsGraphvizObjectWithSubobjects], graph -> graph!.Parent);
 
 InstallMethod(GV_GraphTreeSearch,
 "for a graphviz graph and a predicate",
-[IsGraphvizGraphOrDigraph, IsFunction],
+[IsGraphvizObjectWithSubobjects, IsFunction],
 function(graph, pred)
   local seen, to_visit, g, key, subgraph, parent;
   seen     := [graph];
@@ -309,7 +309,7 @@ function(graph, pred)
 
     # add parent if not visited
     parent := GV_GetParent(g);
-    if not IsGraphvizGraphOrDigraph(parent) then
+    if not IsGraphvizObjectWithSubobjects(parent) then
       continue;
     fi;
     if not ForAny(seen, s -> IsIdenticalObj(s, parent)) then
@@ -323,12 +323,12 @@ end);
 
 InstallMethod(GV_FindGraphWithNode,
 "for a graphviz graph and a node",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 {g, n} -> GV_GraphTreeSearch(g, v -> v[n] <> fail));
 
 InstallMethod(GV_GetRoot,
 "for a graphviz graph",
-[IsGraphvizGraphOrDigraph],
+[IsGraphvizObjectWithSubobjects],
 function(graph)
   while GV_GetParent(graph) <> fail do
     graph := GV_GetParent(graph);
@@ -338,7 +338,7 @@ end);
 
 InstallMethod(GV_FindNode,
 "for a graphviz graph and a string",
-[IsGraphvizGraphOrDigraph, IsString],
+[IsGraphvizObjectWithSubobjects, IsString],
 function(g, n)
   local graph;
   graph := GV_FindGraphWithNode(g, n);
@@ -350,7 +350,7 @@ end);
 
 InstallMethod(GV_AddNode,
 "for a graphviz graph and node",
-[IsGraphvizGraphOrDigraph, IsGraphvizNode],
+[IsGraphvizObjectWithSubobjects, IsGraphvizNode],
 function(x, node)
   local found, error, name, nodes;
   name  := GraphvizName(node);
@@ -369,7 +369,7 @@ end);
 
 InstallMethod(GV_AddEdge,
 "for a graphviz graph and edge",
-[IsGraphvizGraphOrDigraph, IsGraphvizEdge],
+[IsGraphvizObjectWithSubobjects, IsGraphvizEdge],
 function(x, edge)
   local head, head_name, tail_name, tail, hg, error, tg;
 
@@ -412,7 +412,7 @@ end);
 ###############################################################################
 
 # @ Return DOT graph head line.
-InstallMethod(GV_StringifyGraphHead, "for a string", [IsGraphvizGraphOrDigraph],
+InstallMethod(GV_StringifyGraphHead, "for a string", [IsGraphvizObjectWithSubobjects],
 graph -> StringFormatted("graph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT digraph head line.
@@ -421,7 +421,7 @@ graph -> StringFormatted("digraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
 InstallMethod(GV_StringifySubgraphHead, "for a string",
-[IsGraphvizGraphOrDigraph],
+[IsGraphvizObjectWithSubobjects],
 graph -> StringFormatted("subgraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
@@ -480,7 +480,7 @@ end);
 
 InstallMethod(GV_StringifyGraphAttrs,
 "for a graphviz graph",
-[IsGraphvizGraphOrDigraph],
+[IsGraphvizObjectWithSubobjects],
 function(graph)
   local result, attrs, kv;
   attrs  := GraphvizAttrs(graph);
@@ -565,7 +565,7 @@ x -> x!.Idx);
 
 InstallMethod(GV_ConstructHistory,
 "for a graphviz graph",
-[IsGraphvizGraphOrDigraph],
+[IsGraphvizObjectWithSubobjects],
 function(graph)
   local nodes, edges, subs, node_hist, edge_hist, subs_hist, hist;
 
@@ -586,7 +586,7 @@ end);
 
 InstallMethod(GV_StringifyGraph,
 "for a graphviz graph and a string",
-[IsGraphvizGraphOrDigraph, IsBool],
+[IsGraphvizObjectWithSubobjects, IsBool],
 function(graph, is_subgraph)
   local result, obj;
   result := "";
@@ -617,7 +617,7 @@ function(graph, is_subgraph)
 
   # Add child graphviz objects
   for obj in GV_ConstructHistory(graph) do
-    if IsGraphvizGraphOrDigraph(obj) then
+    if IsGraphvizObjectWithSubobjects(obj) then
       Append(result, GV_StringifyGraph(obj, true));
     elif IsGraphvizNode(obj) then
       Append(result, GV_StringifyNode(obj));
diff --git a/gap/splash.gi b/gap/splash.gi
index e61e9ba..57bbf19 100644
--- a/gap/splash.gi
+++ b/gap/splash.gi
@@ -22,10 +22,10 @@ function(arg...)
 
   if IsEmpty(arg) then
     ErrorNoReturn("the must be at least 1 argument, found none");
-  elif not IsString(arg[1]) and not IsGraphvizGraphOrDigraph(arg[1]) then
+  elif not IsString(arg[1]) and not IsGraphvizObjectWithSubobjects(arg[1]) then
     ErrorFormatted("the 1st argument must be a string or ",
                    "graphviz graph, found {}", TNAM_OBJ(arg[1]));
-  elif IsGraphvizGraphOrDigraph(arg[1]) then
+  elif IsGraphvizObjectWithSubobjects(arg[1]) then
     file := GraphvizName(arg[1]);
     for i in [1 .. Length(file)] do
       if not IsAlphaChar(file[i]) and not IsDigitChar(file[i]) then

From 03f5e1e70839aec548be3efeac8abe998526fbba Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 17:32:27 +0100
Subject: [PATCH 20/38] Fix GraphvizAddSubgraph

---
 gap/dot.gi | 24 +++++++++++-------------
 gap/gv.gd  |  1 +
 gap/gv.gi  | 12 ++++++++++++
 3 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/gap/dot.gi b/gap/dot.gi
index b691a59..5c4e674 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -361,7 +361,7 @@ InstallMethod(GraphvizAddEdge,
 InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph and string",
 [IsGraphvizObjectWithSubobjects, IsString],
 function(gv, name)
-  local subgraphs, subgraph;
+  local subgraphs, root, subgraph;
 
   subgraphs := GraphvizSubgraphs(gv);
   if IsBound(subgraphs[name]) then
@@ -369,18 +369,16 @@ function(gv, name)
                    " a subgraph with name \"{}\"", name);
   fi;
 
-  # TODO why are the graph and context cases conflated here?
-  # Shouldn't this be something like
-  # if IsGraphvizContext(gv) then
-  # root := GraphvizRoot(gv);
-  # else
-  # root := gv;
-  # fi;
-  # Then use root instead of gv below?
-  if IsGraphvizDigraph(gv) then
-    subgraph := GV_Digraph(gv, name);
-  elif IsGraphvizGraph(gv) or IsGraphvizContext(gv) then
-    subgraph := GV_Graph(gv, name);
+  if IsGraphvizContext(gv) then
+    root := GV_EnclosingNonContext(gv);
+  else
+    root := gv;
+  fi;
+
+  if IsGraphvizDigraph(root) then
+    subgraph := GV_Digraph(root, name);
+  elif IsGraphvizGraph(root) then
+    subgraph := GV_Graph(root, name);
   fi;
 
   subgraphs[name] := subgraph;
diff --git a/gap/gv.gd b/gap/gv.gd
index c98f38b..3d88335 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -47,6 +47,7 @@ DeclareOperation("GV_GetParent", [IsGraphvizObjectWithSubobjects]);
 DeclareOperation("GV_GraphTreeSearch", [IsGraphvizObjectWithSubobjects, IsFunction]);
 DeclareOperation("GV_FindGraphWithNode", [IsGraphvizObjectWithSubobjects, IsString]);
 DeclareOperation("GV_GetRoot", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_EnclosingNonContext", [IsGraphvizObjectWithSubobjects]);
 DeclareOperation("GV_AddNode", [IsGraphvizObjectWithSubobjects, IsGraphvizNode]);
 DeclareOperation("GV_AddEdge", [IsGraphvizObjectWithSubobjects, IsGraphvizEdge]);
 DeclareOperation("GV_GetIdx", [IsGraphvizObject]);
diff --git a/gap/gv.gi b/gap/gv.gi
index c2056aa..e203428 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -336,6 +336,18 @@ function(graph)
   return graph;
 end);
 
+InstallMethod(GV_EnclosingNonContext,
+"for a graphviz object with subobjects",
+[IsGraphvizContext],
+function(graph)
+  local parent;
+
+  repeat
+    parent := GV_GetParent(graph);
+  until parent = fail or not IsGraphvizContext(parent);
+  return parent;
+end);
+
 InstallMethod(GV_FindNode,
 "for a graphviz graph and a string",
 [IsGraphvizObjectWithSubobjects, IsString],

From 20abb1645511d7fdc9db403ba62eb46df016ec0d Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 17:44:45 +0100
Subject: [PATCH 21/38] Fix tests

---
 gap/dot.gi       | 34 ++++++++++++++++++----------------
 gap/gv.gi        |  6 ++++--
 tst/graph.tst    | 18 +++++++++---------
 tst/subgraph.tst | 11 ++++++-----
 4 files changed, 37 insertions(+), 32 deletions(-)

diff --git a/gap/dot.gi b/gap/dot.gi
index 5c4e674..b56d4ca 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -48,10 +48,10 @@ InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
 # ViewString
 #############################################################################
 
-InstallMethod(ViewString, "for a graphviz node", [IsGraphvizNode],
+InstallMethod(PrintString, "for a graphviz node", [IsGraphvizNode],
 n -> StringFormatted("<graphviz node {}>", GraphvizName(n)));
 
-InstallMethod(ViewString, "for a graphviz edge", [IsGraphvizEdge],
+InstallMethod(PrintString, "for a graphviz edge", [IsGraphvizEdge],
 function(e)
   local head, tail;
   head := GraphvizHead(e);
@@ -61,7 +61,8 @@ function(e)
                          GraphvizName(tail));
 end);
 
-InstallMethod(ViewString, "for a graphviz (di)graph", [IsGraphvizObjectWithSubobjects],
+InstallMethod(PrintString, "for a graphviz object with subobjects",
+[IsGraphvizObjectWithSubobjects],
 function(g)
   local result, edges, nodes, kind;
 
@@ -406,9 +407,8 @@ function(graph, name)
   # contexts and subgraphs, rather than just subgraphs as the name suggests
   # See https://github.com/digraphs/graphviz/issues/19
   if IsBound(subgraphs[name]) then
-    # TODO why are we talking about subgraphs in the error?
     ErrorFormatted("the 1st argument (a graphviz (di)graph) already has ",
-                   " a subgraph with name \"{}\"", name);
+                   " a context or subgraph with name \"{}\"", name);
   fi;
 
   ctx             := GV_Context(graph, name);
@@ -527,11 +527,14 @@ end);
 InstallMethod(String, "for a graphviz (di)graph",
 [IsGraphvizObjectWithSubobjects], graph -> GV_StringifyGraph(graph, false));
 
-InstallMethod(PrintObj, "for a graphviz (di)graph",
-[IsGraphvizObjectWithSubobjects],
-function(gv)
-  Print(String(gv));
-end);
+# Can't do the following because it conflicts with the PrintString above, we
+# leave this here as a reminder.
+
+# InstallMethod(PrintObj, "for a graphviz object with subobjects",
+# [IsGraphvizObjectWithSubobjects],
+# function(gv)
+#   Print(String(gv));
+# end);
 
 InstallMethod(GraphvizSetNodeLabels,
 "for a graphviz (di)graph and list of colors",
@@ -574,11 +577,10 @@ function(c)
     if IsString(c) then
       c := StringFormatted("\"{}\"", c);
     fi;
-    ErrorFormatted("invalid color {} ({}), ",
-        "valid colors are RGB values or names from ",
-        "the GraphViz 2.44.1 X11 Color Scheme",
-        " http://graphviz.org/doc/info/colors.html",
-        c,
-        TNAM_OBJ(c));
+    ErrorFormatted("invalid color {} ({}), valid colors are RGB values ",
+                   "or names from the GraphViz 2.44.1 X11 Color Scheme",
+                   " http://graphviz.org/doc/info/colors.html",
+                   c,
+                   TNAM_OBJ(c));
   fi;
 end);
diff --git a/gap/gv.gi b/gap/gv.gi
index e203428..f9b2a64 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -247,8 +247,10 @@ InstallOtherMethod(IsBound\[\],
 InstallMethod(GV_MapNames, "for a graphviz map",
 [GV_IsMap], m -> RecNames(m!.Data));
 
-InstallMethod(ViewString, "for a graphviz map", [GV_IsMap],
-m -> String(m!.Data));
+InstallMethod(ViewObj, "for a graphviz map", [GV_IsMap],
+function(m)
+  ViewObj(m!.Data);
+end);
 
 InstallMethod(Size, "for a graphviz map",
 [GV_IsMap], m -> Length(GV_MapNames(m)));
diff --git a/tst/graph.tst b/tst/graph.tst
index d485ee1..f0a9124 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -33,24 +33,24 @@ gap> n := GraphvizAddNode(g, "n");
 gap> g;
 <graphviz graph with 1 node and 0 edges>
 gap> GraphvizNodes(g);
-rec( n := <object> )
+rec( n := <graphviz node n> )
 gap> GraphvizAddNode(g, "x");
 <graphviz node x>
 gap> g;
 <graphviz graph with 2 nodes and 0 edges>
 gap> GraphvizNodes(g);
-rec( n := <object>, x := <object> )
+rec( n := <graphviz node n>, x := <graphviz node x> )
 
 # Test add node (name)
 gap> g := GraphvizGraph();;
 gap> GraphvizAddNode(g, "n");
 <graphviz node n>
 gap> GraphvizNodes(g);
-rec( n := <object> )
+rec( n := <graphviz node n> )
 gap> GraphvizAddNode(g, "x");
 <graphviz node x>
 gap> GraphvizNodes(g);
-rec( n := <object>, x := <object> )
+rec( n := <graphviz node n>, x := <graphviz node x> )
 
 # Test has nodes
 gap> g := GraphvizGraph();;
@@ -99,7 +99,7 @@ gap> GraphvizAddEdge(g, "a", "b");;
 gap> GraphvizAddEdge(g, "a", "c");
 <graphviz edge (a, c)>
 gap> GraphvizNodes(g);
-rec( a := <object>, b := <object>, c := <object> )
+rec( a := <graphviz node a>, b := <graphviz node b>, c := <graphviz node c> )
 gap> GraphvizAddEdge(g, "c", "a");
 <graphviz edge (c, a)>
 gap> GraphvizAddEdge(g, "b", "d");
@@ -126,13 +126,13 @@ gap> GraphvizAddEdge(g, c, d);;
 gap> GraphvizRemoveNode(g, a);
 <graphviz graph with 3 nodes and 1 edge>
 gap> GraphvizNodes(g);
-rec( b := <object>, c := <object>, d := <object> )
+rec( b := <graphviz node b>, c := <graphviz node c>, d := <graphviz node d> )
 gap> GraphvizEdges(g);
 [ <graphviz edge (c, d)> ]
 gap> GraphvizRemoveNode(g, b);
 <graphviz graph with 2 nodes and 1 edge>
 gap> GraphvizNodes(g);
-rec( c := <object>, d := <object> )
+rec( c := <graphviz node c>, d := <graphviz node d> )
 
 # Test removing node
 gap> g := GraphvizGraph();;
@@ -141,13 +141,13 @@ gap> GraphvizAddEdge(g, "c", "d");;
 gap> GraphvizRemoveNode(g, "a");
 <graphviz graph with 3 nodes and 1 edge>
 gap> GraphvizNodes(g);
-rec( b := <object>, c := <object>, d := <object> )
+rec( b := <graphviz node b>, c := <graphviz node c>, d := <graphviz node d> )
 gap> GraphvizEdges(g);
 [ <graphviz edge (c, d)> ]
 gap> GraphvizRemoveNode(g, "b");
 <graphviz graph with 2 nodes and 1 edge>
 gap> GraphvizNodes(g);
-rec( c := <object>, d := <object> )
+rec( c := <graphviz node c>, d := <graphviz node d> )
 
 # Test renaming graph
 gap> g := GraphvizGraph();;
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 162ba6f..fb1c907 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -60,7 +60,8 @@ gap> g := GraphvizGraph();;
 gap> GraphvizAddSubgraph(g, "a");;
 gap> GraphvizAddContext(g, "b");;
 gap> GraphvizSubgraphs(g);
-rec( a := <object>, b := <object> )
+rec( a := <graphviz graph a with 0 nodes and 0 edges>, 
+  b := <graphviz context b with 0 nodes and 0 edges> )
 
 # Test adding a node to a subgraph (does or does not add to parent???)
 # TODO need to nail down expected behaviour!
@@ -70,7 +71,7 @@ gap> GraphvizAddNode(s, "n");;
 gap> GraphvizNodes(g);
 rec(  )
 gap> GraphvizNodes(s);
-rec( n := <object> )
+rec( n := <graphviz node n> )
 
 # Test adding a node to a subgraph which is already in parent fails (by name)
 gap> g := GraphvizGraph("r");;
@@ -229,11 +230,11 @@ gap> GraphvizRemoveNode(g, "d");;
 gap> GraphvizNodes(g);
 rec(  )
 gap> GraphvizNodes(parent);
-rec( a := <object> )
+rec( a := <graphviz node a> )
 gap> GraphvizNodes(sibling);
-rec( b := <object> )
+rec( b := <graphviz node b> )
 gap> GraphvizNodes(child);
-rec( c := <object> )
+rec( c := <graphviz node c> )
 
 # Test context attribute resetting
 gap> g := GraphvizDigraph();;

From 0edd2e6b95fbae4df2e854f9f813c585938b7c3c Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Tue, 14 May 2024 19:21:13 +0100
Subject: [PATCH 22/38] Fix lint + codespell

---
 .codespellrc |  2 +-
 gap/dot.gd   | 20 +++++++++++++-------
 gap/gv.gd    |  6 ++++--
 gap/gv.gi    |  6 ++++--
 4 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/.codespellrc b/.codespellrc
index 92e8c49..fdb0e06 100644
--- a/.codespellrc
+++ b/.codespellrc
@@ -1,3 +1,3 @@
 [codespell]
 skip = ./.git,./doc/*.log,./doc/*.html,./doc/*.txt,./doc/*.six,./doc/*.js,./doc/*.bbl,./doc/*.tex,./doc/*.bib,./doc/_*
-ignore-words-list=fille
+ignore-words-list=fille,manuel
diff --git a/gap/dot.gd b/gap/dot.gd
index af234cf..7e0f67b 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -96,7 +96,7 @@ DeclareOperation("GraphvizAttrs", [IsGraphvizObject]);
 # a numeral [-]?(.[0-9]⁺ | [0-9]⁺(.[0-9]*)? );
 # any double-quoted string ("...") possibly containing escaped quotes (\")¹;
 # an HTML string (<...>).
-# TODO specify
+# TODO specify
 DeclareOperation("GraphvizNodes", [IsGraphvizObjectWithSubobjects]);
 
 #! @Arguments graph
@@ -161,24 +161,28 @@ DeclareOperation("GraphvizAddEdge",
 #! @Arguments graph, filter, name
 #! @Returns the new subgraph.
 #! @Description Adds a subgraph to a graph.
-DeclareOperation("GraphvizAddSubgraph", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GraphvizAddSubgraph",
+[IsGraphvizObjectWithSubobjects, IsObject]);
 DeclareOperation("GraphvizAddSubgraph", [IsGraphvizObjectWithSubobjects]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new context.
 #! @Description Adds a context to a graph.
-DeclareOperation("GraphvizAddContext", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GraphvizAddContext",
+[IsGraphvizObjectWithSubobjects, IsObject]);
 DeclareOperation("GraphvizAddContext", [IsGraphvizObjectWithSubobjects]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Removes the node from the graph.
-DeclareOperation("GraphvizRemoveNode", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GraphvizRemoveNode",
+[IsGraphvizObjectWithSubobjects, IsObject]);
 
 #! @Arguments graph, predicate
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges using the provided predicate.
-DeclareOperation("GraphvizFilterEdges", [IsGraphvizObjectWithSubobjects, IsFunction]);
+DeclareOperation("GraphvizFilterEdges",
+[IsGraphvizObjectWithSubobjects, IsFunction]);
 
 #! @Arguments graph, head_name, tail_name
 #! @Returns the modified graph.
@@ -217,8 +221,10 @@ DeclareOperation("GraphvizRemoveAttr", [IsGraphvizObject, IsObject]);
 #!  Should output the graphviz package representation of the object.
 DeclareOperation("Graphviz", [IsObject]);
 
-DeclareOperation("GraphvizSetNodeColors", [IsGraphvizObjectWithSubobjects, IsList]);
-DeclareOperation("GraphvizSetNodeLabels", [IsGraphvizObjectWithSubobjects, IsList]);
+DeclareOperation("GraphvizSetNodeColors",
+[IsGraphvizObjectWithSubobjects, IsList]);
+DeclareOperation("GraphvizSetNodeLabels",
+[IsGraphvizObjectWithSubobjects, IsList]);
 
 DeclareGlobalFunction("ErrorIfNotValidColor");
 
diff --git a/gap/gv.gd b/gap/gv.gd
index 3d88335..d75118f 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -44,8 +44,10 @@ DeclareOperation("GV_EnsureString", [IsObject]);
 DeclareOperation("GV_HasNode", [IsGraphvizObjectWithSubobjects, IsObject]);
 
 DeclareOperation("GV_GetParent", [IsGraphvizObjectWithSubobjects]);
-DeclareOperation("GV_GraphTreeSearch", [IsGraphvizObjectWithSubobjects, IsFunction]);
-DeclareOperation("GV_FindGraphWithNode", [IsGraphvizObjectWithSubobjects, IsString]);
+DeclareOperation("GV_GraphTreeSearch",
+[IsGraphvizObjectWithSubobjects, IsFunction]);
+DeclareOperation("GV_FindGraphWithNode",
+[IsGraphvizObjectWithSubobjects, IsString]);
 DeclareOperation("GV_GetRoot", [IsGraphvizObjectWithSubobjects]);
 DeclareOperation("GV_EnclosingNonContext", [IsGraphvizObjectWithSubobjects]);
 DeclareOperation("GV_AddNode", [IsGraphvizObjectWithSubobjects, IsGraphvizNode]);
diff --git a/gap/gv.gi b/gap/gv.gi
index f9b2a64..9f38e5a 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -264,7 +264,8 @@ function(x)
   x!.Counter := x!.Counter + 1;
 end);
 
-InstallMethod(GV_GetCounter, "for a graphviz graph", [IsGraphvizObjectWithSubobjects],
+InstallMethod(GV_GetCounter, "for a graphviz graph",
+[IsGraphvizObjectWithSubobjects],
 x -> x!.Counter);
 
 # Converting strings
@@ -426,7 +427,8 @@ end);
 ###############################################################################
 
 # @ Return DOT graph head line.
-InstallMethod(GV_StringifyGraphHead, "for a string", [IsGraphvizObjectWithSubobjects],
+InstallMethod(GV_StringifyGraphHead, "for a string",
+[IsGraphvizObjectWithSubobjects],
 graph -> StringFormatted("graph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT digraph head line.

From f25ff249a095ba61b326024e9350f34c245a9252 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 08:37:35 +0100
Subject: [PATCH 23/38] Fixup code coverage script

---
 etc/code-coverage-test-gap.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/etc/code-coverage-test-gap.py b/etc/code-coverage-test-gap.py
index e50ea5a..c9b0432 100755
--- a/etc/code-coverage-test-gap.py
+++ b/etc/code-coverage-test-gap.py
@@ -103,5 +103,5 @@ def rewrite_fname(fname: str) -> str:
 else:
     filename = _DIR + "/index.html"
 print(f"{_INFO_PREFIX}\nSUCCESS!\033[0m")
-print(f"{_INFO_PREFIX} See {filename}")
+print(f"{_INFO_PREFIX}See {filename}")
 sys.exit(0)

From 62578776c749b78d55656c1172cbdd302e7ef3fd Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 09:09:44 +0100
Subject: [PATCH 24/38] Update desc. strings

---
 gap/dot.gd    |  44 +++++++--------
 gap/dot.gi    | 148 ++++++++++++++++++++++++++------------------------
 gap/gv.gd     |  46 ++++++++--------
 gap/gv.gi     |  42 +++++++-------
 gap/splash.gi |   4 +-
 5 files changed, 147 insertions(+), 137 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 7e0f67b..508d6da 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -38,10 +38,10 @@
 
 DeclareCategory("IsGraphvizObject", IsObject);
 
-DeclareCategory("IsGraphvizObjectWithSubobjects", IsGraphvizObject);
-DeclareCategory("IsGraphvizGraph", IsGraphvizObjectWithSubobjects);
-DeclareCategory("IsGraphvizDigraph", IsGraphvizObjectWithSubobjects);
-DeclareCategory("IsGraphvizContext", IsGraphvizObjectWithSubobjects);
+DeclareCategory("IsGraphvizGraphDigraphOrContext", IsGraphvizObject);
+DeclareCategory("IsGraphvizGraph", IsGraphvizGraphDigraphOrContext);
+DeclareCategory("IsGraphvizDigraph", IsGraphvizGraphDigraphOrContext);
+DeclareCategory("IsGraphvizContext", IsGraphvizGraphDigraphOrContext);
 
 DeclareCategory("IsGraphvizNodeOrEdge", IsGraphvizObject);
 DeclareCategory("IsGraphvizNode", IsGraphvizNodeOrEdge);
@@ -97,12 +97,12 @@ DeclareOperation("GraphvizAttrs", [IsGraphvizObject]);
 # any double-quoted string ("...") possibly containing escaped quotes (\")¹;
 # an HTML string (<...>).
 # TODO specify
-DeclareOperation("GraphvizNodes", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GraphvizNodes", [IsGraphvizGraphDigraphOrContext]);
 
 #! @Arguments graph
 #! @Returns the subgraphs of the provided graphviz graph.
 #! @Description gets the subgraphs of a provided graphviz graph.
-DeclareOperation("GraphvizSubgraphs", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GraphvizSubgraphs", [IsGraphvizGraphDigraphOrContext]);
 
 #! @Arguments graph, name
 #! @Returns a graph with the provided name.
@@ -112,14 +112,14 @@ DeclareOperation("GraphvizSubgraphs", [IsGraphvizObjectWithSubobjects]);
 #! It returns the graph if it exists.
 #! If no such graph exists then it will return <K>fail<K>.
 DeclareOperation("GraphvizFindSubgraphRecursive",
-[IsGraphvizObjectWithSubobjects, IsObject]);
+[IsGraphvizGraphDigraphOrContext, IsObject]);
 
 #! @Arguments graph
 #! @Returns the edges of the provided graphviz graph.
 #! @Description Gets the edges of the provided graphviz graph.
-DeclareOperation("GraphvizEdges", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GraphvizEdges", [IsGraphvizGraphDigraphOrContext]);
 DeclareOperation("GraphvizEdges",
-[IsGraphvizObjectWithSubobjects, IsObject, IsObject]);
+[IsGraphvizGraphDigraphOrContext, IsObject, IsObject]);
 
 #! @Subsection For only edges.
 
@@ -141,13 +141,13 @@ DeclareOperation("GraphvizTail", [IsGraphvizEdge]);
 #! @Arguments graph, name
 #! @Returns the modified graph.
 #! @Description Sets the name of a graphviz graph or digraph.
-DeclareOperation("GraphvizSetName", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GraphvizSetName", [IsGraphvizGraphDigraphOrContext, IsObject]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Adds a node to the graph.
 #! If a node with the same name is already present the operation fails.
-DeclareOperation("GraphvizAddNode", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GraphvizAddNode", [IsGraphvizGraphDigraphOrContext, IsObject]);
 
 #! @Arguments graph, edge
 #! @Returns the modified graph.
@@ -156,40 +156,40 @@ DeclareOperation("GraphvizAddNode", [IsGraphvizObjectWithSubobjects, IsObject]);
 #! added to the graph. If different nodes with the same name are in the graph
 #! then the operation fails.
 DeclareOperation("GraphvizAddEdge",
-[IsGraphvizObjectWithSubobjects, IsObject, IsObject]);
+[IsGraphvizGraphDigraphOrContext, IsObject, IsObject]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new subgraph.
 #! @Description Adds a subgraph to a graph.
 DeclareOperation("GraphvizAddSubgraph",
-[IsGraphvizObjectWithSubobjects, IsObject]);
-DeclareOperation("GraphvizAddSubgraph", [IsGraphvizObjectWithSubobjects]);
+[IsGraphvizGraphDigraphOrContext, IsObject]);
+DeclareOperation("GraphvizAddSubgraph", [IsGraphvizGraphDigraphOrContext]);
 
 #! @Arguments graph, filter, name
 #! @Returns the new context.
 #! @Description Adds a context to a graph.
 DeclareOperation("GraphvizAddContext",
-[IsGraphvizObjectWithSubobjects, IsObject]);
-DeclareOperation("GraphvizAddContext", [IsGraphvizObjectWithSubobjects]);
+[IsGraphvizGraphDigraphOrContext, IsObject]);
+DeclareOperation("GraphvizAddContext", [IsGraphvizGraphDigraphOrContext]);
 
 #! @Arguments graph, node
 #! @Returns the modified graph.
 #! @Description Removes the node from the graph.
 DeclareOperation("GraphvizRemoveNode",
-[IsGraphvizObjectWithSubobjects, IsObject]);
+[IsGraphvizGraphDigraphOrContext, IsObject]);
 
 #! @Arguments graph, predicate
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges using the provided predicate.
 DeclareOperation("GraphvizFilterEdges",
-[IsGraphvizObjectWithSubobjects, IsFunction]);
+[IsGraphvizGraphDigraphOrContext, IsFunction]);
 
 #! @Arguments graph, head_name, tail_name
 #! @Returns the modified graph.
 #! @Description Filters the graph's edges, removing edges between nodes with
 #! the specified names.
 DeclareOperation("GraphvizRemoveEdges",
-[IsGraphvizObjectWithSubobjects, IsObject, IsObject]);
+[IsGraphvizGraphDigraphOrContext, IsObject, IsObject]);
 
 #! @Subsection For modifying object attributes.
 
@@ -222,9 +222,9 @@ DeclareOperation("GraphvizRemoveAttr", [IsGraphvizObject, IsObject]);
 DeclareOperation("Graphviz", [IsObject]);
 
 DeclareOperation("GraphvizSetNodeColors",
-[IsGraphvizObjectWithSubobjects, IsList]);
+[IsGraphvizGraphDigraphOrContext, IsList]);
 DeclareOperation("GraphvizSetNodeLabels",
-[IsGraphvizObjectWithSubobjects, IsList]);
+[IsGraphvizGraphDigraphOrContext, IsList]);
 
 DeclareGlobalFunction("ErrorIfNotValidColor");
 
@@ -239,4 +239,4 @@ DeclareOperation("\[\]", [IsGraphvizEdge, IsObject]);
 DeclareOperation("\[\]\:\=", [IsGraphvizEdge, IsObject, IsObject]);
 
 # TODO doc
-DeclareOperation("\[\]", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("\[\]", [IsGraphvizGraphDigraphOrContext, IsObject]);
diff --git a/gap/dot.gi b/gap/dot.gi
index b56d4ca..b2b9b85 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -61,8 +61,8 @@ function(e)
                          GraphvizName(tail));
 end);
 
-InstallMethod(PrintString, "for a graphviz object with subobjects",
-[IsGraphvizObjectWithSubobjects],
+InstallMethod(PrintString, "for a graphviz (di)graph or context",
+[IsGraphvizGraphDigraphOrContext],
 function(g)
   local result, edges, nodes, kind;
 
@@ -101,15 +101,15 @@ x -> x!.Name);
 InstallMethod(GraphvizAttrs, "for a graphviz object", [IsGraphvizObject],
 x -> x!.Attrs);
 
-InstallMethod(GraphvizNodes, "for a graphviz (di)graph",
-[IsGraphvizObjectWithSubobjects], x -> x!.Nodes);
+InstallMethod(GraphvizNodes, "for a graphviz (di)graph or context",
+[IsGraphvizGraphDigraphOrContext], x -> x!.Nodes);
 
-InstallMethod(GraphvizEdges, "for a graphviz (di)graph",
-[IsGraphvizObjectWithSubobjects], x -> x!.Edges);
+InstallMethod(GraphvizEdges, "for a graphviz (di)graph or context",
+[IsGraphvizGraphDigraphOrContext], x -> x!.Edges);
 
 InstallMethod(GraphvizEdges,
-"for a graphviz (di)graph, object, and object",
-[IsGraphvizObjectWithSubobjects, IsObject, IsObject],
+"for a graphviz (di)graph or context, object, and object",
+[IsGraphvizGraphDigraphOrContext, IsObject, IsObject],
 function(gv, head, tail)
     head := GraphvizNodes(gv)[head];
     if head = fail then
@@ -125,8 +125,8 @@ function(gv, head, tail)
                     x -> GraphvizHead(x) = head and GraphvizTail(x) = tail);
 end);
 
-InstallMethod(GraphvizSubgraphs, "for a graphviz (di)graph",
-[IsGraphvizObjectWithSubobjects], x -> x!.Subgraphs);
+InstallMethod(GraphvizSubgraphs, "for a graphviz (di)graph or context",
+[IsGraphvizGraphDigraphOrContext], x -> x!.Subgraphs);
 
 InstallMethod(GraphvizTail, "for a graphviz edge", [IsGraphvizEdge],
 x -> x!.Tail);
@@ -182,37 +182,37 @@ end);
 
 # Accessor for graphs and digraphs
 
-InstallMethod(\[\], "for a graphviz (di)graph and string",
-[IsGraphvizObjectWithSubobjects, IsString],
+InstallMethod(\[\], "for a graphviz (di)graph or context and string",
+[IsGraphvizGraphDigraphOrContext, IsString],
 {graph, node} -> GraphvizNodes(graph)[node]);
 
-InstallMethod(\[\], "for a graphviz (di)graph and object",
-[IsGraphvizObjectWithSubobjects, IsObject],
+InstallMethod(\[\], "for a graphviz (di)graph or context and object",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 {g, o} -> g[String(o)]);
 
 InstallMethod(GraphvizFindSubgraphRecursive,
-"for a graphviz (di)graph and a string",
-[IsGraphvizObjectWithSubobjects, IsString],
+"for a graphviz (di)graph or context and a string",
+[IsGraphvizGraphDigraphOrContext, IsString],
 {g, s} -> GV_GraphTreeSearch(g, v -> GraphvizName(v) = s));
 
 InstallMethod(GraphvizFindSubgraphRecursive,
-"for a graphviz (di)graph and a string",
-[IsGraphvizObjectWithSubobjects, IsObject],
+"for a graphviz (di)graph or context and a string",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 {g, o} -> GraphvizFindSubgraphRecursive(g, String(o)));
 
 #############################################################################
 # GraphvizSetName
 #############################################################################
 
-InstallMethod(GraphvizSetName, "for a graphviz (di)graph and string",
-[IsGraphvizObjectWithSubobjects, IsString],
+InstallMethod(GraphvizSetName, "for a graphviz (di)graph or context and string",
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(x, name)
   x!.Name := name;
   return x;
 end);
 
-InstallMethod(GraphvizSetName, "for a graphviz (di)graph and string",
-[IsGraphvizObjectWithSubobjects, IsObject],
+InstallMethod(GraphvizSetName, "for a graphviz (di)graph or context and string",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 {g, o} -> GraphvizSetName(g, String(o)));
 
 #############################################################################
@@ -245,7 +245,7 @@ end);
 
 InstallMethod(GraphvizSetAttr,
 "for a graphviz object with subobjects, object, and object",
-[IsGraphvizObjectWithSubobjects, IsObject, IsObject],
+[IsGraphvizGraphDigraphOrContext, IsObject, IsObject],
 function(x, name, value)
   local attrs, string;
 
@@ -269,8 +269,8 @@ function(x, name, value)
   return x;
 end);
 
-InstallMethod(GraphvizSetAttr, "for a graphviz (di)graph and object",
-[IsGraphvizObjectWithSubobjects, IsObject],
+InstallMethod(GraphvizSetAttr, "for a graphviz (di)graph or context and object",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 function(x, value)
   local attrs;
   attrs := GraphvizAttrs(x);
@@ -283,8 +283,8 @@ end);
 # GraphvizAddNode
 #############################################################################
 
-InstallMethod(GraphvizAddNode, "for a graphviz (di)graph and string",
-[IsGraphvizObjectWithSubobjects, IsString],
+InstallMethod(GraphvizAddNode, "for a graphviz (di)graph or context and string",
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(x, name)
   local node;
   node := GV_Node(x, name);
@@ -292,8 +292,8 @@ function(x, name)
   return node;
 end);
 
-InstallMethod(GraphvizAddNode, "for a graphviz (di)graph and string",
-[IsGraphvizObjectWithSubobjects, IsGraphvizNode],
+InstallMethod(GraphvizAddNode, "for a graphviz (di)graph or context and string",
+[IsGraphvizGraphDigraphOrContext, IsGraphvizNode],
 function(gv, name)  # gaplint: disable=analyse-lvars
   ErrorNoReturn("it is not currently possible to add Graphviz node ",
                 "objects directly to Graphviz graphs or digraphs, use ",
@@ -301,8 +301,8 @@ function(gv, name)  # gaplint: disable=analyse-lvars
 end);
 
 InstallMethod(GraphvizAddNode,
-"for a graphviz (di)graph and string",
-[IsGraphvizObjectWithSubobjects, IsObject],
+"for a graphviz (di)graph or context and string",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 {x, name} -> GraphvizAddNode(x, String(name)));
 
 #############################################################################
@@ -310,8 +310,8 @@ InstallMethod(GraphvizAddNode,
 #############################################################################
 
 InstallMethod(GraphvizAddEdge,
-"for a graphviz (di)graph and two graphviz nodes",
-[IsGraphvizObjectWithSubobjects, IsGraphvizNode, IsGraphvizNode],
+"for a graphviz (di)graph or context and two graphviz nodes",
+[IsGraphvizGraphDigraphOrContext, IsGraphvizNode, IsGraphvizNode],
 function(x, head, tail)
   local edge, head_name, tail_name;
 
@@ -332,8 +332,8 @@ function(x, head, tail)
 end);
 
 InstallMethod(GraphvizAddEdge,
-"for a graphviz (di)graph and two strings",
-[IsGraphvizObjectWithSubobjects, IsString, IsString],
+"for a graphviz (di)graph or context and two strings",
+[IsGraphvizGraphDigraphOrContext, IsString, IsString],
 function(x, head, tail)
   local head_node, tail_node;
 
@@ -351,16 +351,17 @@ function(x, head, tail)
 end);
 
 InstallMethod(GraphvizAddEdge,
-"for a graphviz (di)graph and two objects",
-[IsGraphvizObjectWithSubobjects, IsObject, IsObject],
+"for a graphviz (di)graph or context and two objects",
+[IsGraphvizGraphDigraphOrContext, IsObject, IsObject],
 {gv, o1, o2} -> GraphvizAddEdge(gv, String(o1), String(o2)));
 
 #############################################################################
 # GraphvizAddSubgraph
 #############################################################################
 
-InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph and string",
-[IsGraphvizObjectWithSubobjects, IsString],
+InstallMethod(GraphvizAddSubgraph,
+"for a graphviz (di)graph or context and string",
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(gv, name)
   local subgraphs, root, subgraph;
 
@@ -386,19 +387,20 @@ function(gv, name)
   return subgraph;
 end);
 
-InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph and an object",
-[IsGraphvizObjectWithSubobjects, IsObject],
+InstallMethod(GraphvizAddSubgraph,
+"for a graphviz (di)graph or context and an object",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 {g, o} -> GraphvizAddSubgraph(g, String(o)));
 
-InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph",
-[IsGraphvizObjectWithSubobjects],
+InstallMethod(GraphvizAddSubgraph, "for a graphviz (di)graph or context",
+[IsGraphvizGraphDigraphOrContext],
 graph -> GraphvizAddSubgraph(graph,
                              StringFormatted("no_name_{}",
                                              GV_GetCounter(graph))));
 
 InstallMethod(GraphvizAddContext,
-"for a graphviz (di)graph and a string",
-[IsGraphvizObjectWithSubobjects, IsString],
+"for a graphviz (di)graph or context and a string",
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(graph, name)
   local subgraphs, ctx;
 
@@ -417,21 +419,22 @@ function(graph, name)
 end);
 
 InstallMethod(GraphvizAddContext,
-"for a graphviz (di)graph",
-[IsGraphvizObjectWithSubobjects],
+"for a graphviz (di)graph or context",
+[IsGraphvizGraphDigraphOrContext],
 g -> GraphvizAddContext(g, StringFormatted("no_name_{}", GV_GetCounter(g))));
 
 InstallMethod(GraphvizAddContext,
-"for a graphviz (di)graph and an object",
-[IsGraphvizObjectWithSubobjects, IsObject],
+"for a graphviz (di)graph or context and an object",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 {g, o} -> GraphvizAddContext(g, String(o)));
 
-InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and node",
-[IsGraphvizObjectWithSubobjects, IsGraphvizNode],
+InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph or context and node",
+[IsGraphvizGraphDigraphOrContext, IsGraphvizNode],
 {g, node} -> GraphvizRemoveNode(g, GraphvizName(node)));
 
-InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
-[IsGraphvizObjectWithSubobjects, IsString],
+InstallMethod(GraphvizRemoveNode,
+"for a graphviz (di)graph or context and a string",
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(g, name)
   local nodes;
   nodes := GraphvizNodes(g);
@@ -456,12 +459,14 @@ function(g, name)
   return g;
 end);
 
-InstallMethod(GraphvizRemoveNode, "for a graphviz (di)graph and a string",
-[IsGraphvizObjectWithSubobjects, IsObject],
+InstallMethod(GraphvizRemoveNode,
+"for a graphviz (di)graph or context and a string",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 {g, o} -> GraphvizRemoveNode(g, String(o)));
 
-InstallMethod(GraphvizFilterEdges, "for a graphviz (di)graph and edge filter",
-[IsGraphvizObjectWithSubobjects, IsFunction],
+InstallMethod(GraphvizFilterEdges,
+"for a graphviz (di)graph or context and edge filter",
+[IsGraphvizGraphDigraphOrContext, IsFunction],
 function(g, filter)
   local edge, idx, edges;
 
@@ -478,8 +483,9 @@ function(g, filter)
   return g;
 end);
 
-InstallMethod(GraphvizRemoveEdges, "for a graphviz (di)graph and two strings",
-[IsGraphvizObjectWithSubobjects, IsString, IsString],
+InstallMethod(GraphvizRemoveEdges,
+"for a graphviz (di)graph or context, string, and string",
+[IsGraphvizGraphDigraphOrContext, IsString, IsString],
 function(g, hn, tn)
   GraphvizFilterEdges(g,
     function(e)
@@ -497,8 +503,9 @@ function(g, hn, tn)
   return g;
 end);
 
-InstallMethod(GraphvizRemoveEdges, "for a graphviz (di)graph and two objects",
-[IsGraphvizObjectWithSubobjects, IsObject, IsObject],
+InstallMethod(GraphvizRemoveEdges,
+"for a graphviz (di)graph or context, object, and object",
+[IsGraphvizGraphDigraphOrContext, IsObject, IsObject],
 {gv, o1, o2} -> GraphvizRemoveEdges(gv, String(o1), String(o2)));
 
 InstallMethod(GraphvizRemoveAttr, "for a graphviz object and an object",
@@ -511,8 +518,9 @@ function(obj, attr)
   return obj;
 end);
 
-InstallMethod(GraphvizRemoveAttr, "for a graphviz (di)graph and an object",
-[IsGraphvizObjectWithSubobjects, IsObject],
+InstallMethod(GraphvizRemoveAttr,
+"for a graphviz (di)graph or context and an object",
+[IsGraphvizGraphDigraphOrContext, IsObject],
 function(obj, attr)
   local attrs;
   attrs      := GraphvizAttrs(obj);
@@ -524,21 +532,21 @@ end);
 # Stringify
 #############################################################################
 
-InstallMethod(String, "for a graphviz (di)graph",
-[IsGraphvizObjectWithSubobjects], graph -> GV_StringifyGraph(graph, false));
+InstallMethod(String, "for a graphviz (di)graph or context",
+[IsGraphvizGraphDigraphOrContext], graph -> GV_StringifyGraph(graph, false));
 
 # Can't do the following because it conflicts with the PrintString above, we
 # leave this here as a reminder.
 
 # InstallMethod(PrintObj, "for a graphviz object with subobjects",
-# [IsGraphvizObjectWithSubobjects],
+# [IsGraphvizGraphDigraphOrContext],
 # function(gv)
 #   Print(String(gv));
 # end);
 
 InstallMethod(GraphvizSetNodeLabels,
-"for a graphviz (di)graph and list of colors",
-[IsGraphvizObjectWithSubobjects, IsList],
+"for a graphviz (di)graph or context and list of colors",
+[IsGraphvizGraphDigraphOrContext, IsList],
 function(gv, labels)
   local nodes, i;
   if Size(GraphvizNodes(gv)) <> Size(labels) then
@@ -555,8 +563,8 @@ function(gv, labels)
 end);
 
 InstallMethod(GraphvizSetNodeColors,
-"for a graphviz (di)graph and list of colors",
-[IsGraphvizObjectWithSubobjects, IsList],
+"for a graphviz (di)graph or context and list of colors",
+[IsGraphvizGraphDigraphOrContext, IsList],
 function(gv, colors)
   local nodes, i;
 
diff --git a/gap/gv.gd b/gap/gv.gd
index d75118f..6d453f5 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -11,49 +11,51 @@
 ## This file contains declarations of the internal/private functions for the
 ## graphviz package.
 
-DeclareOperation("GV_GetCounter", [IsGraphvizObjectWithSubobjects]);
-DeclareOperation("GV_IncCounter", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_GetCounter", [IsGraphvizGraphDigraphOrContext]);
+DeclareOperation("GV_IncCounter", [IsGraphvizGraphDigraphOrContext]);
 DeclareCategory("GV_IsMap", IsObject);
 DeclareAttribute("Size", GV_IsMap);
 
-DeclareOperation("GV_StringifyGraphHead", [IsGraphvizObjectWithSubobjects]);
-DeclareOperation("GV_StringifyDigraphHead", [IsGraphvizObjectWithSubobjects]);
-DeclareOperation("GV_StringifySubgraphHead", [IsGraphvizObjectWithSubobjects]);
-DeclareOperation("GV_StringifyContextHead", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_StringifyGraphHead", [IsGraphvizGraphDigraphOrContext]);
+DeclareOperation("GV_StringifyDigraphHead", [IsGraphvizGraphDigraphOrContext]);
+DeclareOperation("GV_StringifySubgraphHead", [IsGraphvizGraphDigraphOrContext]);
+DeclareOperation("GV_StringifyContextHead", [IsGraphvizGraphDigraphOrContext]);
 DeclareOperation("GV_StringifyNode", [IsGraphvizNode]);
-DeclareOperation("GV_StringifyGraphAttrs", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_StringifyGraphAttrs", [IsGraphvizGraphDigraphOrContext]);
 DeclareOperation("GV_StringifyNodeEdgeAttrs", [GV_IsMap]);
-DeclareOperation("GV_StringifyGraph", [IsGraphvizObjectWithSubobjects, IsBool]);
+DeclareOperation("GV_StringifyGraph", [IsGraphvizGraphDigraphOrContext, IsBool]);
 
-DeclareOperation("GV_FindNode", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GV_FindNode", [IsGraphvizGraphDigraphOrContext, IsObject]);
 
 DeclareOperation("GV_Pluralize", [IsInt, IsString]);
 
-DeclareOperation("GV_Node", [IsGraphvizObjectWithSubobjects, IsString]);
+DeclareOperation("GV_Node", [IsGraphvizGraphDigraphOrContext, IsString]);
 DeclareOperation("GV_Edge",
-[IsGraphvizObjectWithSubobjects, IsGraphvizNode, IsGraphvizNode]);
-DeclareOperation("GV_Graph", [IsGraphvizObjectWithSubobjects, IsString]);
+[IsGraphvizGraphDigraphOrContext, IsGraphvizNode, IsGraphvizNode]);
+DeclareOperation("GV_Graph", [IsGraphvizGraphDigraphOrContext, IsString]);
 DeclareOperation("GV_Digraph", [IsGraphvizDigraph, IsString]);
-DeclareOperation("GV_Context", [IsGraphvizObjectWithSubobjects, IsString]);
+DeclareOperation("GV_Context", [IsGraphvizGraphDigraphOrContext, IsString]);
 DeclareOperation("GV_Map", []);
 DeclareOperation("GV_MapNames", [GV_IsMap]);
 
 # TODO required? Replace with String or just String?
 DeclareOperation("GV_EnsureString", [IsObject]);
 
-DeclareOperation("GV_HasNode", [IsGraphvizObjectWithSubobjects, IsObject]);
+DeclareOperation("GV_HasNode", [IsGraphvizGraphDigraphOrContext, IsObject]);
 
-DeclareOperation("GV_GetParent", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_GetParent", [IsGraphvizGraphDigraphOrContext]);
 DeclareOperation("GV_GraphTreeSearch",
-[IsGraphvizObjectWithSubobjects, IsFunction]);
+[IsGraphvizGraphDigraphOrContext, IsFunction]);
 DeclareOperation("GV_FindGraphWithNode",
-[IsGraphvizObjectWithSubobjects, IsString]);
-DeclareOperation("GV_GetRoot", [IsGraphvizObjectWithSubobjects]);
-DeclareOperation("GV_EnclosingNonContext", [IsGraphvizObjectWithSubobjects]);
-DeclareOperation("GV_AddNode", [IsGraphvizObjectWithSubobjects, IsGraphvizNode]);
-DeclareOperation("GV_AddEdge", [IsGraphvizObjectWithSubobjects, IsGraphvizEdge]);
+[IsGraphvizGraphDigraphOrContext, IsString]);
+DeclareOperation("GV_GetRoot", [IsGraphvizGraphDigraphOrContext]);
+DeclareOperation("GV_EnclosingNonContext", [IsGraphvizGraphDigraphOrContext]);
+DeclareOperation("GV_AddNode",
+[IsGraphvizGraphDigraphOrContext, IsGraphvizNode]);
+DeclareOperation("GV_AddEdge",
+[IsGraphvizGraphDigraphOrContext, IsGraphvizEdge]);
 DeclareOperation("GV_GetIdx", [IsGraphvizObject]);
-DeclareOperation("GV_ConstructHistory", [IsGraphvizObjectWithSubobjects]);
+DeclareOperation("GV_ConstructHistory", [IsGraphvizGraphDigraphOrContext]);
 
 DeclareGlobalFunction("GV_IsValidColor");
 DeclareGlobalFunction("GV_ErrorIfNotNodeColoring");
diff --git a/gap/gv.gi b/gap/gv.gi
index 9f38e5a..d4eeb03 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -125,7 +125,7 @@ InstallMethod(GV_Map, "for no args",
 [], {} -> Objectify(GV_MapType, rec(Data := rec())));
 
 InstallMethod(GV_Node, "for a string",
-[IsGraphvizObjectWithSubobjects, IsString],
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(graph, name)
   local out;
   if Length(name) = 0 then
@@ -141,7 +141,7 @@ function(graph, name)
 end);
 
 InstallMethod(GV_Edge, "for two graphviz nodes",
-[IsGraphvizObjectWithSubobjects, IsGraphvizNode, IsGraphvizNode],
+[IsGraphvizGraphDigraphOrContext, IsGraphvizNode, IsGraphvizNode],
 function(graph, head, tail)
   local out;
   out := Objectify(GV_EdgeType,
@@ -173,7 +173,7 @@ end);
 
 InstallMethod(GV_Graph,
 "for a graphviz graph and a string",
-[IsGraphvizObjectWithSubobjects, IsString],
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(parent, name)
   local out;
 
@@ -187,7 +187,7 @@ end);
 
 InstallMethod(GV_Context,
 "for a string and a positive integer",
-[IsGraphvizObjectWithSubobjects, IsString],
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(parent, name)
   local out;
 
@@ -259,13 +259,13 @@ InstallMethod(Size, "for a graphviz map",
 
 InstallMethod(GV_IncCounter,
 "for a graphviz graph",
-[IsGraphvizObjectWithSubobjects],
+[IsGraphvizGraphDigraphOrContext],
 function(x)
   x!.Counter := x!.Counter + 1;
 end);
 
 InstallMethod(GV_GetCounter, "for a graphviz graph",
-[IsGraphvizObjectWithSubobjects],
+[IsGraphvizGraphDigraphOrContext],
 x -> x!.Counter);
 
 # Converting strings
@@ -278,16 +278,16 @@ InstallMethod(GV_EnsureString, "for a string", [IsString], IdFunc);
 
 InstallMethod(GV_HasNode,
 "for a graphviz graph",
-[IsGraphvizObjectWithSubobjects, IsString],
+[IsGraphvizGraphDigraphOrContext, IsString],
 {g, name} -> name in GV_MapNames(GraphvizNodes(g)));
 
 InstallMethod(GV_GetParent,
 "for a graphviz graph",
-[IsGraphvizObjectWithSubobjects], graph -> graph!.Parent);
+[IsGraphvizGraphDigraphOrContext], graph -> graph!.Parent);
 
 InstallMethod(GV_GraphTreeSearch,
 "for a graphviz graph and a predicate",
-[IsGraphvizObjectWithSubobjects, IsFunction],
+[IsGraphvizGraphDigraphOrContext, IsFunction],
 function(graph, pred)
   local seen, to_visit, g, key, subgraph, parent;
   seen     := [graph];
@@ -312,7 +312,7 @@ function(graph, pred)
 
     # add parent if not visited
     parent := GV_GetParent(g);
-    if not IsGraphvizObjectWithSubobjects(parent) then
+    if not IsGraphvizGraphDigraphOrContext(parent) then
       continue;
     fi;
     if not ForAny(seen, s -> IsIdenticalObj(s, parent)) then
@@ -326,12 +326,12 @@ end);
 
 InstallMethod(GV_FindGraphWithNode,
 "for a graphviz graph and a node",
-[IsGraphvizObjectWithSubobjects, IsString],
+[IsGraphvizGraphDigraphOrContext, IsString],
 {g, n} -> GV_GraphTreeSearch(g, v -> v[n] <> fail));
 
 InstallMethod(GV_GetRoot,
 "for a graphviz graph",
-[IsGraphvizObjectWithSubobjects],
+[IsGraphvizGraphDigraphOrContext],
 function(graph)
   while GV_GetParent(graph) <> fail do
     graph := GV_GetParent(graph);
@@ -353,7 +353,7 @@ end);
 
 InstallMethod(GV_FindNode,
 "for a graphviz graph and a string",
-[IsGraphvizObjectWithSubobjects, IsString],
+[IsGraphvizGraphDigraphOrContext, IsString],
 function(g, n)
   local graph;
   graph := GV_FindGraphWithNode(g, n);
@@ -365,7 +365,7 @@ end);
 
 InstallMethod(GV_AddNode,
 "for a graphviz graph and node",
-[IsGraphvizObjectWithSubobjects, IsGraphvizNode],
+[IsGraphvizGraphDigraphOrContext, IsGraphvizNode],
 function(x, node)
   local found, error, name, nodes;
   name  := GraphvizName(node);
@@ -384,7 +384,7 @@ end);
 
 InstallMethod(GV_AddEdge,
 "for a graphviz graph and edge",
-[IsGraphvizObjectWithSubobjects, IsGraphvizEdge],
+[IsGraphvizGraphDigraphOrContext, IsGraphvizEdge],
 function(x, edge)
   local head, head_name, tail_name, tail, hg, error, tg;
 
@@ -428,7 +428,7 @@ end);
 
 # @ Return DOT graph head line.
 InstallMethod(GV_StringifyGraphHead, "for a string",
-[IsGraphvizObjectWithSubobjects],
+[IsGraphvizGraphDigraphOrContext],
 graph -> StringFormatted("graph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT digraph head line.
@@ -437,7 +437,7 @@ graph -> StringFormatted("digraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
 InstallMethod(GV_StringifySubgraphHead, "for a string",
-[IsGraphvizObjectWithSubobjects],
+[IsGraphvizGraphDigraphOrContext],
 graph -> StringFormatted("subgraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
@@ -496,7 +496,7 @@ end);
 
 InstallMethod(GV_StringifyGraphAttrs,
 "for a graphviz graph",
-[IsGraphvizObjectWithSubobjects],
+[IsGraphvizGraphDigraphOrContext],
 function(graph)
   local result, attrs, kv;
   attrs  := GraphvizAttrs(graph);
@@ -581,7 +581,7 @@ x -> x!.Idx);
 
 InstallMethod(GV_ConstructHistory,
 "for a graphviz graph",
-[IsGraphvizObjectWithSubobjects],
+[IsGraphvizGraphDigraphOrContext],
 function(graph)
   local nodes, edges, subs, node_hist, edge_hist, subs_hist, hist;
 
@@ -602,7 +602,7 @@ end);
 
 InstallMethod(GV_StringifyGraph,
 "for a graphviz graph and a string",
-[IsGraphvizObjectWithSubobjects, IsBool],
+[IsGraphvizGraphDigraphOrContext, IsBool],
 function(graph, is_subgraph)
   local result, obj;
   result := "";
@@ -633,7 +633,7 @@ function(graph, is_subgraph)
 
   # Add child graphviz objects
   for obj in GV_ConstructHistory(graph) do
-    if IsGraphvizObjectWithSubobjects(obj) then
+    if IsGraphvizGraphDigraphOrContext(obj) then
       Append(result, GV_StringifyGraph(obj, true));
     elif IsGraphvizNode(obj) then
       Append(result, GV_StringifyNode(obj));
diff --git a/gap/splash.gi b/gap/splash.gi
index 57bbf19..9d3c67e 100644
--- a/gap/splash.gi
+++ b/gap/splash.gi
@@ -22,10 +22,10 @@ function(arg...)
 
   if IsEmpty(arg) then
     ErrorNoReturn("the must be at least 1 argument, found none");
-  elif not IsString(arg[1]) and not IsGraphvizObjectWithSubobjects(arg[1]) then
+  elif not IsString(arg[1]) and not IsGraphvizGraphDigraphOrContext(arg[1]) then
     ErrorFormatted("the 1st argument must be a string or ",
                    "graphviz graph, found {}", TNAM_OBJ(arg[1]));
-  elif IsGraphvizObjectWithSubobjects(arg[1]) then
+  elif IsGraphvizGraphDigraphOrContext(arg[1]) then
     file := GraphvizName(arg[1]);
     for i in [1 .. Length(file)] do
       if not IsAlphaChar(file[i]) and not IsDigitChar(file[i]) then

From 19e0450b990eab60575ef88ba836cb58d341d44e Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 10:55:29 +0100
Subject: [PATCH 25/38] More test for code coverage

---
 etc/tst-local-vars.yml |   8 +++
 gap/dot.gi             |  36 ++++++++------
 gap/gv.gi              |   8 ---
 tst/dot.tst            | 109 ++++++++++++++++++++++++++++++++++++++++-
 tst/edge.tst           |   7 ++-
 tst/graph.tst          |  29 +++++++++++
 tst/node.tst           |  12 ++++-
 tst/subgraph.tst       |  33 +++++++++++--
 8 files changed, 212 insertions(+), 30 deletions(-)
 create mode 100644 etc/tst-local-vars.yml

diff --git a/etc/tst-local-vars.yml b/etc/tst-local-vars.yml
new file mode 100644
index 0000000..844de31
--- /dev/null
+++ b/etc/tst-local-vars.yml
@@ -0,0 +1,8 @@
+name: tst-local-vars
+
+channels:
+  - conda-forge
+
+dependencies:
+  - pyyaml
+  - bs4
diff --git a/gap/dot.gi b/gap/dot.gi
index b2b9b85..0b2e2a8 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -111,18 +111,22 @@ InstallMethod(GraphvizEdges,
 "for a graphviz (di)graph or context, object, and object",
 [IsGraphvizGraphDigraphOrContext, IsObject, IsObject],
 function(gv, head, tail)
-    head := GraphvizNodes(gv)[head];
-    if head = fail then
-      ErrorNoReturn("the 2nd argument (head of an edge) is not a node ",
-                    "of the 1st argument (a graphviz graph or digraph)");
+  local nhead, ntail;
+
+    nhead := GraphvizNodes(gv)[head];
+    if nhead = fail then
+      ErrorFormatted("the 2nd argument \"{}\" (head of an edge) is not a ",
+                     "node of the 1st argument (a graphviz graph or digraph)",
+                     head);
     fi;
-    tail := GraphvizNodes(gv)[tail];
-    if tail = fail then
-      ErrorNoReturn("the 2nd argument (head of an edge) is not a node ",
-                    "of the 1st argument (a graphviz graph or digraph)");
+    ntail := GraphvizNodes(gv)[tail];
+    if ntail = fail then
+      ErrorFormatted("the 3rd argument \"{}\" (tail of an edge) is not a ",
+                     "node of the 1st argument (a graphviz graph or digraph)",
+                     tail);
     fi;
     return Filtered(GraphvizEdges(gv),
-                    x -> GraphvizHead(x) = head and GraphvizTail(x) = tail);
+                    x -> GraphvizHead(x) = nhead and GraphvizTail(x) = ntail);
 end);
 
 InstallMethod(GraphvizSubgraphs, "for a graphviz (di)graph or context",
@@ -367,8 +371,8 @@ function(gv, name)
 
   subgraphs := GraphvizSubgraphs(gv);
   if IsBound(subgraphs[name]) then
-    ErrorFormatted("the 1st argument (a graphviz (di)graph) already has ",
-                   " a subgraph with name \"{}\"", name);
+    ErrorFormatted("the 1st argument (a graphviz (di)graph/context) ",
+                   "already has a subgraph with name \"{}\"", name);
   fi;
 
   if IsGraphvizContext(gv) then
@@ -409,8 +413,9 @@ function(graph, name)
   # contexts and subgraphs, rather than just subgraphs as the name suggests
   # See https://github.com/digraphs/graphviz/issues/19
   if IsBound(subgraphs[name]) then
-    ErrorFormatted("the 1st argument (a graphviz (di)graph) already has ",
-                   " a context or subgraph with name \"{}\"", name);
+    ErrorFormatted("the 1st argument (a graphviz (di)graph/context) ",
+                   "already has a context or subgraph with name \"{}\"",
+                   name);
   fi;
 
   ctx             := GV_Context(graph, name);
@@ -443,7 +448,8 @@ function(g, name)
   else
     # Don't just silently do nothing
     ErrorFormatted("the 2nd argument (node name string) \"{}\"",
-                   " is not a node of the 1st argument (a graphviz (di)graph)",
+                   " is not a node of the 1st argument (a graphviz",
+                   " (di)graph/context)",
                    name);
   fi;
 
@@ -518,6 +524,8 @@ function(obj, attr)
   return obj;
 end);
 
+# TODO this doesn't currently work as intended, see:
+# https://github.com/digraphs/graphviz/issues/23
 InstallMethod(GraphvizRemoveAttr,
 "for a graphviz (di)graph or context and an object",
 [IsGraphvizGraphDigraphOrContext, IsObject],
diff --git a/gap/gv.gi b/gap/gv.gi
index d4eeb03..2a697c0 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -395,14 +395,6 @@ function(x, edge)
   hg        := GV_FindGraphWithNode(x, head_name);
   tg        := GV_FindGraphWithNode(x, tail_name);
 
-  # if not already existing, add the nodes to the graph
-  if hg = fail then
-    GV_AddNode(x, head);
-  fi;
-  if tg = fail then
-    GV_AddNode(x, tail);
-  fi;
-
   # make sure the nodes exist / are the same as existing ones
   if hg <> fail and not IsIdenticalObj(head, hg[head_name]) then
     # TODO improve
diff --git a/tst/dot.tst b/tst/dot.tst
index 43d3a83..7d8c398 100644
--- a/tst/dot.tst
+++ b/tst/dot.tst
@@ -8,7 +8,7 @@
 #############################################################################
 ##
 
-#@local a, b, color, e, g, label, n, shape
+#@local a, b, color, e, g, gv, label, n, shape
 gap> START_TEST("graphviz package: dot.tst");
 gap> LoadPackage("graphviz", false);;
 
@@ -39,7 +39,7 @@ gap> String(g);
 "//dot\ngraph  {\n\ttest [color=red, label=lab]\n}\n"
 gap> GraphvizRemoveNode(g, "banana");
 Error, the 2nd argument (node name string) "banana" is not a node of the 1st a\
-rgument (a graphviz (di)graph)
+rgument (a graphviz (di)graph/context)
 
 # Test stringify with edge (digraphs)
 gap> g := GraphvizDigraph();;
@@ -107,5 +107,110 @@ gap> GraphvizSetAttr(e, "label", "before>>hello");;
 gap> String(g);
 "//dot\ngraph  {\n\ta\n\tb\n\ta -- b [label=\"before>>hello\"]\n}\n"
 
+# Test GraphvizSetNodeLabels
+gap> gv := GraphvizGraph("xxx");
+<graphviz graph xxx with 0 nodes and 0 edges>
+gap> GraphvizAddNode(gv, 1);
+<graphviz node 1>
+gap> GraphvizAddNode(gv, 2);
+<graphviz node 2>
+gap> GraphvizAddNode(gv, 3);
+<graphviz node 3>
+gap> GraphvizSetNodeLabels(gv, ["i", "ii", "iii"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> Print(String(gv));
+//dot
+graph xxx {
+	1 [label=i]
+	2 [label=ii]
+	3 [label=iii]
+}
+gap> GraphvizSetNodeLabels(gv, ["a", "b", "c"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> Print(String(gv));
+//dot
+graph xxx {
+	1 [label=i]
+	2 [label=ii]
+	3 [label=iii]
+}
+gap> GraphvizSetNodeLabels(gv, ["i", "ii"]);
+Error, the 2nd argument (list of node labels) has incorrect length, expected 3\
+, but found 2
+gap> GraphvizSetNodeLabels(gv, ["i", "ii", "iii", "iv"]);
+Error, the 2nd argument (list of node labels) has incorrect length, expected 3\
+, but found 4
+
+# Test GraphvizSetNodeColors
+gap> gv := GraphvizGraph("xxx");
+<graphviz graph xxx with 0 nodes and 0 edges>
+gap> GraphvizAddNode(gv, 1);
+<graphviz node 1>
+gap> GraphvizAddNode(gv, 2);
+<graphviz node 2>
+gap> GraphvizAddNode(gv, 3);
+<graphviz node 3>
+gap> GraphvizSetNodeColors(gv, ["i", "ii", "iii"]);
+Error, invalid color "i" (list (string)), valid colors are RGB values or names\
+ from the GraphViz 2.44.1 X11 Color Scheme http://graphviz.org/doc/info/colors\
+.html
+gap> GraphvizSetNodeColors(gv, ["red", "green", "blue"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> Print(String(gv));
+//dot
+graph xxx {
+	1 [color=red, style=filled]
+	2 [color=green, style=filled]
+	3 [color=blue, style=filled]
+}
+gap> GraphvizSetNodeColors(gv, ["red", "#00FF00", "blue"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> Print(String(gv));
+//dot
+graph xxx {
+	1 [color=red, style=filled]
+	2 [color=green, style=filled]
+	3 [color=blue, style=filled]
+}
+gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FF"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> Print(String(gv));
+//dot
+graph xxx {
+	1 [color=red, style=filled]
+	2 [color=green, style=filled]
+	3 [color=blue, style=filled]
+}
+gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FG"]);
+Error, invalid color "#0000FG" (list (string)), valid colors are RGB values or\
+ names from the GraphViz 2.44.1 X11 Color Scheme http://graphviz.org/doc/info/\
+colors.html
+gap> GraphvizAddEdge(gv, "a", "b");
+<graphviz edge (a, b)>
+gap> GraphvizNodes(gv);
+rec( 1 := <graphviz node 1>, 2 := <graphviz node 2>, 3 := <graphviz node 3>,
+  a := <graphviz node a>, b := <graphviz node b> )
+
+# Test attribute names with spaces (TODO are there any valid such??)
+gap> gv := GraphvizGraph("xxx");
+<graphviz graph xxx with 0 nodes and 0 edges>
+gap> n := GraphvizAddNode(gv, 1);
+<graphviz node 1>
+gap> n := GraphvizSetAttr(n, "probably not ok", 1);
+#I  unknown attribute "probably not ok", the graphviz object may no longer be valid, it can be removed using GraphvizRemoveAttr
+<graphviz node 1>
+gap> Print(String(gv));
+//dot
+graph xxx {
+	1 ["probably not ok"=1]
+}
+gap> GraphvizSetAttr(n, "label", "<<>>");
+<graphviz node 1>
+gap> Print(String(gv));
+//dot
+graph xxx {
+	1 ["probably not ok"=1]
+}
+
 #
 gap> STOP_TEST("graphviz package: dot.tst", 0);
diff --git a/tst/edge.tst b/tst/edge.tst
index ebd5bc3..ae47f3c 100644
--- a/tst/edge.tst
+++ b/tst/edge.tst
@@ -74,7 +74,8 @@ gap> GraphvizEdges(g);
 gap> GraphvizRemoveEdges(g, "c", "d");
 <graphviz graph with 4 nodes and 0 edges>
 
-# Test adding edge between nodes which are not in the graph, but there exists nodes in the graph which share their names.
+# Test adding edge between nodes which are not in the graph, but there exists
+# nodes in the graph which share their names.
 gap> g := GraphvizGraph();;
 gap> g1 := GraphvizGraph();;
 gap> a1 := GraphvizAddNode(g, "a");;
@@ -86,6 +87,8 @@ gap> e2 := GraphvizAddEdge(g, a2, c);;
 Error, Different node in graph  with name a
 gap> GraphvizEdges(g);
 [ <graphviz edge (d, a)> ]
+gap> e2 := GraphvizAddEdge(g, c, a2);;
+Error, Different node in graph  with name a.
 
 # Test adding an edge reuses a node automatically
 gap> g := GraphvizGraph();;
@@ -132,6 +135,8 @@ rec( color := "red", label := "1" )
 gap> n["color"] := "blue";;
 gap> GraphvizAttrs(n);
 rec( color := "blue", label := "1" )
+gap> n[1];
+fail
 
 # Test getting attributes using the [] syntax
 gap> g := GraphvizGraph();;
diff --git a/tst/graph.tst b/tst/graph.tst
index f0a9124..933146d 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -92,6 +92,20 @@ gap> g;
 <graphviz graph with 4 nodes and 2 edges>
 gap> GraphvizEdges(g);
 [ <graphviz edge (a, b)>, <graphviz edge (c, d)> ]
+gap> GraphvizEdges(g, "a", "c");
+[  ]
+gap> GraphvizEdges(g, "a", "b");
+[ <graphviz edge (a, b)> ]
+gap> GraphvizAddEdge(g, "a", "b");
+<graphviz edge (a, b)>
+gap> GraphvizEdges(g, "a", "b");
+[ <graphviz edge (a, b)>, <graphviz edge (a, b)> ]
+gap> GraphvizEdges(g, "x", "b");
+Error, the 2nd argument "x" (head of an edge) is not a node of the 1st argumen\
+t (a graphviz graph or digraph)
+gap> GraphvizEdges(g, "a", "y");
+Error, the 3rd argument "y" (tail of an edge) is not a node of the 1st argumen\
+t (a graphviz graph or digraph)
 
 # Test adding edge with different nodes with the same name
 gap> g := GraphvizGraph();;
@@ -153,6 +167,8 @@ rec( c := <graphviz node c>, d := <graphviz node d> )
 gap> g := GraphvizGraph();;
 gap> GraphvizSetName(g, "test");
 <graphviz graph test with 0 nodes and 0 edges>
+gap> GraphvizSetName(g, 1);
+<graphviz graph 1 with 0 nodes and 0 edges>
 
 # Test global attributes graph
 gap> g := GraphvizGraph();;
@@ -212,6 +228,19 @@ gap> g := GraphvizGraph();;
 gap> GraphvizSetAttr(g, "label", "test");;
 gap> GraphvizAttrs(g);
 [ "label=test" ]
+gap> GraphvizSetAttr(g, 1, 2);
+#I  unknown attribute "1", the graphviz object may no longer be valid, it can be removed using GraphvizRemoveAttr
+<graphviz graph with 0 nodes and 0 edges>
+gap> GraphvizAttrs(g);
+[ "label=test", "1=2" ]
+gap> GraphvizRemoveAttr(g, "1=2");
+<graphviz graph with 0 nodes and 0 edges>
+gap> GraphvizAttrs(g);
+[ "label=test", "1=2" ]
+gap> GraphvizRemoveAttr(g, "1");
+<graphviz graph with 0 nodes and 0 edges>
+gap> GraphvizAttrs(g);
+[ "label=test", "1=2" ]
 
 # Test set color (graph)
 gap> g := GraphvizGraph();;
diff --git a/tst/node.tst b/tst/node.tst
index 0555e43..8d6ebab 100644
--- a/tst/node.tst
+++ b/tst/node.tst
@@ -59,10 +59,20 @@ gap> String(g);
 
 # Test non-string name containing ':'
 gap> g := GraphvizGraph();;
-gap> GraphvizAddNode(g, 111);
+gap> n := GraphvizAddNode(g, 111);
 <graphviz node 111>
 gap> String(g);
 "//dot\ngraph  {\n\t111\n}\n"
+gap> n[1];
+fail
+gap> n[1] := 2;
+2
+gap> n[1];
+"2"
+gap> GraphvizRemoveAttr(n, 1);
+<graphviz node 111>
+gap> n[1];
+fail
 
 # Test removing a node with a non-string name
 gap> g := GraphvizGraph();;
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index fb1c907..005e216 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -8,8 +8,8 @@
 #############################################################################
 ##
 
-#@local a, a1, a2, a3, b, b1, b2, b3, c, child, ctx, g, main, n, o, parent, s
-#@local s1, s11, s2, sibling
+#@local a, a1, a2, a3, b, b1, b2, b3, c, child, ctx, g, gv, legend, main, n, o
+#@local parent, s, s1, s11, s2, sibling
 gap> START_TEST("graphviz package: subgraph.tst");
 gap> LoadPackage("graphviz", false);;
 
@@ -34,6 +34,9 @@ gap> GraphvizAddSubgraph(g);
 gap> g := GraphvizGraph();;
 gap> GraphvizAddContext(g);
 <graphviz context no_name_1 with 0 nodes and 0 edges>
+gap> GraphvizAddContext(g, "no_name_1");
+Error, the 1st argument (a graphviz (di)graph/context) already has a context o\
+r subgraph with name "no_name_1"
 
 # Test no-name constructor graphs' names increment
 gap> g := GraphvizGraph();;
@@ -254,8 +257,8 @@ edge [label=testing123] node[color=blue] edge[color=blue] \n\n}\n"
 gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(g, "a");
-Error, the 1st argument (a graphviz (di)graph) already has  a subgraph with na\
-me "a"
+Error, the 1st argument (a graphviz (di)graph/context) already has a subgraph \
+with name "a"
 
 # Test getting subgraphs by name
 gap> g := GraphvizDigraph();;
@@ -382,5 +385,27 @@ gap> o := GraphvizFindSubgraphRecursive(g, 1);
 gap> IsIdenticalObj(o, s);
 true
 
+# Test a context containing a subgraph
+gap> gv := GraphvizGraph("context+subgraph");;
+gap> GraphvizSetAttr(gv, "node [shape=\"box\"]");
+<graphviz graph context+subgraph with 0 nodes and 0 edges>
+gap> legend := GraphvizAddContext(gv, "legend");
+<graphviz context legend with 0 nodes and 0 edges>
+gap> GraphvizSetAttr(legend, "node [shape=plaintext]");
+<graphviz context legend with 0 nodes and 0 edges>
+gap> GraphvizAddSubgraph(legend, "legend");
+<graphviz graph legend with 0 nodes and 0 edges>
+
+# Test a context containing a subdigraph
+gap> gv := GraphvizDigraph("context+subgraph");;
+gap> GraphvizSetAttr(gv, "node [shape=\"box\"]");
+<graphviz digraph context+subgraph with 0 nodes and 0 edges>
+gap> legend := GraphvizAddContext(gv, "legend");
+<graphviz context legend with 0 nodes and 0 edges>
+gap> GraphvizSetAttr(legend, "node [shape=plaintext]");
+<graphviz context legend with 0 nodes and 0 edges>
+gap> GraphvizAddSubgraph(legend, "legend");
+<graphviz digraph legend with 0 nodes and 0 edges>
+
 #
 gap> STOP_TEST("graphviz package: subgraph.tst", 0);

From 737a67fcb24d12ea54ba09d8dfa8f70689e59a8c Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 10:57:31 +0100
Subject: [PATCH 26/38] Revert "Rename AsString -> String"

This reverts commit 7f4951699d0953569f24b9c8d42a866f5d543fc4.
---
 gap/dot.gd                      |  2 +-
 gap/dot.gi                      |  6 ++++-
 gap/gv.gd                       |  2 +-
 tst/dot.tst                     | 48 ++++++++++++++++-----------------
 tst/examples/angles.tst         |  4 +--
 tst/examples/btree.tst          |  2 +-
 tst/examples/cluster.tst        |  2 +-
 tst/examples/cluster_edge.tst   |  2 +-
 tst/examples/colors.tst         |  2 +-
 tst/examples/er.tst             |  2 +-
 tst/examples/fsm.tst            |  2 +-
 tst/examples/g_c_n.tst          |  4 +--
 tst/examples/hello.tst          |  2 +-
 tst/examples/process.tst        |  2 +-
 tst/examples/rank_same.tst      |  2 +-
 tst/examples/structs.tst        |  2 +-
 tst/examples/traffic_lights.tst |  2 +-
 tst/examples/unix.tst           |  2 +-
 tst/graph.tst                   |  2 +-
 tst/node.tst                    |  4 +--
 tst/subgraph.tst                | 18 ++++++-------
 21 files changed, 59 insertions(+), 55 deletions(-)

diff --git a/gap/dot.gd b/gap/dot.gd
index 508d6da..9ef407e 100644
--- a/gap/dot.gd
+++ b/gap/dot.gd
@@ -212,7 +212,7 @@ DeclareOperation("GraphvizRemoveAttr", [IsGraphvizObject, IsObject]);
 #! @Section Outputting
 #! @Arguments graph
 #! @Returns the dot representation of the graphviz object.
-# TODO document "String"
+DeclareOperation("AsString", [IsGraphvizGraphDigraphOrContext]);
 
 #! @Arguments obj
 #! @Returns the graphviz representation of the object.
diff --git a/gap/dot.gi b/gap/dot.gi
index 0b2e2a8..db37732 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -540,7 +540,11 @@ end);
 # Stringify
 #############################################################################
 
-InstallMethod(String, "for a graphviz (di)graph or context",
+# It might be more natural for the next method to be one for String rather than
+# AsString, but unfortunately String is an attribute, which means it is
+# immutable, and hence cannot be changed after it is first set.
+
+InstallMethod(AsString, "for a graphviz (di)graph",
 [IsGraphvizGraphDigraphOrContext], graph -> GV_StringifyGraph(graph, false));
 
 # Can't do the following because it conflicts with the PrintString above, we
diff --git a/gap/gv.gd b/gap/gv.gd
index 6d453f5..3c977b1 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -38,7 +38,7 @@ DeclareOperation("GV_Context", [IsGraphvizGraphDigraphOrContext, IsString]);
 DeclareOperation("GV_Map", []);
 DeclareOperation("GV_MapNames", [GV_IsMap]);
 
-# TODO required? Replace with String or just String?
+# TODO required? Replace with AsString or just String?
 DeclareOperation("GV_EnsureString", [IsObject]);
 
 DeclareOperation("GV_HasNode", [IsGraphvizGraphDigraphOrContext, IsObject]);
diff --git a/tst/dot.tst b/tst/dot.tst
index 7d8c398..c4448d6 100644
--- a/tst/dot.tst
+++ b/tst/dot.tst
@@ -35,7 +35,7 @@ gap> GraphvizAttrs(g);
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "test");;
 gap> GraphvizSetAttrs(n, rec(color := "red", label := "lab"));;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\ttest [color=red, label=lab]\n}\n"
 gap> GraphvizRemoveNode(g, "banana");
 Error, the 2nd argument (node name string) "banana" is not a node of the 1st a\
@@ -49,7 +49,7 @@ gap> GraphvizSetAttrs(a, rec(color := "blue"));;
 gap> GraphvizSetAttrs(b, rec(color := "red"));;
 gap> e := GraphvizAddEdge(g, a, b);;
 gap> GraphvizSetAttrs(e, rec(color := "green"));;
-gap> String(g);
+gap> AsString(g);
 "//dot\ndigraph  {\n\ta [color=blue]\n\tb [color=red]\n\ta -> b [color=green]\
 \n}\n"
 
@@ -61,13 +61,13 @@ gap> GraphvizSetAttrs(a, rec(color := "blue"));;
 gap> GraphvizSetAttrs(b, rec(color := "red"));;
 gap> e := GraphvizAddEdge(g, a, b);;
 gap> GraphvizSetAttrs(e, rec(color := "green"));;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\ta [color=blue]\n\tb [color=red]\n\ta -- b [color=green]\n}\
 \n"
 
 # Test stringify empty
 gap> g := GraphvizGraph();;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n}\n"
 
 # Test unknown attributes (node)
@@ -87,24 +87,24 @@ gap> GraphvizSetAttr(g, "test", "false");
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "node");;
 gap> GraphvizSetAttr(n, "label", ">>hello");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\tnode [label=\">>hello\"]\n}\n"
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "node");;
 gap> GraphvizSetAttr(n, "label", "before>>hello");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\tnode [label=\"before>>hello\"]\n}\n"
 
 # Test strngifying labels with ">>" inside (edge attrs)
 gap> g := GraphvizGraph();;
 gap> e := GraphvizAddEdge(g, "a", "b");;
 gap> GraphvizSetAttr(e, "label", ">>hello");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\ta\n\tb\n\ta -- b [label=\">>hello\"]\n}\n"
 gap> g := GraphvizGraph();;
 gap> e := GraphvizAddEdge(g, "a", "b");;
 gap> GraphvizSetAttr(e, "label", "before>>hello");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\ta\n\tb\n\ta -- b [label=\"before>>hello\"]\n}\n"
 
 # Test GraphvizSetNodeLabels
@@ -118,7 +118,7 @@ gap> GraphvizAddNode(gv, 3);
 <graphviz node 3>
 gap> GraphvizSetNodeLabels(gv, ["i", "ii", "iii"]);
 <graphviz graph xxx with 3 nodes and 0 edges>
-gap> Print(String(gv));
+gap> Print(AsString(gv));
 //dot
 graph xxx {
 	1 [label=i]
@@ -127,12 +127,12 @@ graph xxx {
 }
 gap> GraphvizSetNodeLabels(gv, ["a", "b", "c"]);
 <graphviz graph xxx with 3 nodes and 0 edges>
-gap> Print(String(gv));
+gap> Print(AsString(gv));
 //dot
 graph xxx {
-	1 [label=i]
-	2 [label=ii]
-	3 [label=iii]
+	1 [label=a]
+	2 [label=b]
+	3 [label=c]
 }
 gap> GraphvizSetNodeLabels(gv, ["i", "ii"]);
 Error, the 2nd argument (list of node labels) has incorrect length, expected 3\
@@ -156,7 +156,7 @@ Error, invalid color "i" (list (string)), valid colors are RGB values or names\
 .html
 gap> GraphvizSetNodeColors(gv, ["red", "green", "blue"]);
 <graphviz graph xxx with 3 nodes and 0 edges>
-gap> Print(String(gv));
+gap> Print(AsString(gv));
 //dot
 graph xxx {
 	1 [color=red, style=filled]
@@ -165,21 +165,21 @@ graph xxx {
 }
 gap> GraphvizSetNodeColors(gv, ["red", "#00FF00", "blue"]);
 <graphviz graph xxx with 3 nodes and 0 edges>
-gap> Print(String(gv));
+gap> Print(AsString(gv));
 //dot
 graph xxx {
 	1 [color=red, style=filled]
-	2 [color=green, style=filled]
+	2 [color="#00FF00", style=filled]
 	3 [color=blue, style=filled]
 }
 gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FF"]);
 <graphviz graph xxx with 3 nodes and 0 edges>
-gap> Print(String(gv));
+gap> Print(AsString(gv));
 //dot
 graph xxx {
-	1 [color=red, style=filled]
-	2 [color=green, style=filled]
-	3 [color=blue, style=filled]
+	1 [color="#FF0000", style=filled]
+	2 [color="#00FF00", style=filled]
+	3 [color="#0000FF", style=filled]
 }
 gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FG"]);
 Error, invalid color "#0000FG" (list (string)), valid colors are RGB values or\
@@ -188,7 +188,7 @@ colors.html
 gap> GraphvizAddEdge(gv, "a", "b");
 <graphviz edge (a, b)>
 gap> GraphvizNodes(gv);
-rec( 1 := <graphviz node 1>, 2 := <graphviz node 2>, 3 := <graphviz node 3>,
+rec( 1 := <graphviz node 1>, 2 := <graphviz node 2>, 3 := <graphviz node 3>, 
   a := <graphviz node a>, b := <graphviz node b> )
 
 # Test attribute names with spaces (TODO are there any valid such??)
@@ -199,17 +199,17 @@ gap> n := GraphvizAddNode(gv, 1);
 gap> n := GraphvizSetAttr(n, "probably not ok", 1);
 #I  unknown attribute "probably not ok", the graphviz object may no longer be valid, it can be removed using GraphvizRemoveAttr
 <graphviz node 1>
-gap> Print(String(gv));
+gap> Print(AsString(gv));
 //dot
 graph xxx {
 	1 ["probably not ok"=1]
 }
 gap> GraphvizSetAttr(n, "label", "<<>>");
 <graphviz node 1>
-gap> Print(String(gv));
+gap> Print(AsString(gv));
 //dot
 graph xxx {
-	1 ["probably not ok"=1]
+	1 [label=<<>>, "probably not ok"=1]
 }
 
 #
diff --git a/tst/examples/angles.tst b/tst/examples/angles.tst
index cab0d92..fc39502 100644
--- a/tst/examples/angles.tst
+++ b/tst/examples/angles.tst
@@ -68,7 +68,7 @@ gap> GraphvizAddEdge(g, "n5", "n14");
 <graphviz edge (n5, n14)>
 
 #@if CompareVersionNumbers(GAPInfo.Version, "4.12.0")
-gap> Print(String(g));
+gap> Print(AsString(g));
 //dot
 digraph G {
 	bgcolor=blue 
@@ -103,7 +103,7 @@ ientangle=360,label="n9:n360", fontcolor=black] label="Radial Angle Variations\
 	n5 -> n14
 }
 #@else
-gap> Print(String(g));
+gap> Print(AsString(g));
 //dot
 digraph G {
 	bgcolor=blue 
diff --git a/tst/examples/btree.tst b/tst/examples/btree.tst
index 1e22687..555996e 100644
--- a/tst/examples/btree.tst
+++ b/tst/examples/btree.tst
@@ -55,7 +55,7 @@ gap> GraphvizAddEdge(s, "node4:f2", "node6:f1");
 <graphviz edge (node4:f2, node6:f1)>
 gap> GraphvizAddEdge(s, "node4:f0", "node5:f1");
 <graphviz edge (node4:f0, node5:f1)>
-gap> String(s) =
+gap> AsString(s) =
 > "//dot\ndigraph g {\n\tnode [shape=record, height=.1] \n\tnode0 [label=\"<f0> \
 > |<f1> G|<f2>\"]\n\tnode1 [label=\"<f0> |<f1> E|<f2>\"]\n\tnode2 [label=\"<f0> \
 > |<f1> B|<f2>\"]\n\tnode3 [label=\"<f0> |<f1> F|<f2>\"]\n\tnode4 [label=\"<f0> \
diff --git a/tst/examples/cluster.tst b/tst/examples/cluster.tst
index 4f4ac8c..2786feb 100644
--- a/tst/examples/cluster.tst
+++ b/tst/examples/cluster.tst
@@ -74,7 +74,7 @@ gap> GraphvizSetAttr(graph["end"], "shape", "Msquare");
 <graphviz node end>
 
 #
-gap> String(graph);
+gap> AsString(graph);
 "//dot\ndigraph G {\nsubgraph cluster_0 {\n\tcolor=\"lightgrey\" style=\"fille\
 d\" node [color=\"white\", style=\"filled\"] label=\"process #1\" \n\ta0\n\ta1\
 \n\ta0 -> a1\n\ta2\n\ta1 -> a2\n\ta3\n\ta2 -> a3\n}\nsubgraph cluster_1 {\n\tc\
diff --git a/tst/examples/cluster_edge.tst b/tst/examples/cluster_edge.tst
index 0af6cb6..3a017fe 100644
--- a/tst/examples/cluster_edge.tst
+++ b/tst/examples/cluster_edge.tst
@@ -53,7 +53,7 @@ gap> GraphvizSetAttr(e, "ltail", "cluster0");
 <graphviz edge (c, e)>
 gap> GraphvizAddEdge(g, "d", "h");
 <graphviz edge (d, h)>
-gap> String(g);
+gap> AsString(g);
 "//dot\ndigraph G {\n\tcompound=true \nsubgraph cluster0 {\n\ta\n\tb\n\ta -> b\
 \n\tc\n\ta -> c\n\td\n\tb -> d\n\tc -> d\n}\nsubgraph cluster1 {\n\te\n\tg\n\t\
 e -> g\n\tf\n\te -> f\n}\n\tb -> f [lhead=cluster1]\n\td -> e\n\tc -> g [lhead\
diff --git a/tst/examples/colors.tst b/tst/examples/colors.tst
index 695c008..d1f4d8c 100644
--- a/tst/examples/colors.tst
+++ b/tst/examples/colors.tst
@@ -54,7 +54,7 @@ gap> GraphvizSetAttr(node, "fillcolor", "deeppink");
 <graphviz node name: deeppink>
 
 #
-gap> String(g);
+gap> AsString(g);
 #I  invalid node name RGB: #40e0d0 using "RGB: #40e0d0" instead
 #I  invalid node name RGBA: #ff000042 using "RGBA: #ff000042" instead
 #I  invalid node name HSV: 0.051 0.718 0.627 using "HSV: 0.051 0.718 0.627" instead
diff --git a/tst/examples/er.tst b/tst/examples/er.tst
index 41228f0..a1dcbf3 100644
--- a/tst/examples/er.tst
+++ b/tst/examples/er.tst
@@ -104,7 +104,7 @@ gap> GraphvizSetAttr(e, "fontsize=\"20\"");
 <graphviz graph ER with 0 nodes and 12 edges>
 
 #
-gap> String(e);
+gap> AsString(e);
 #I  invalid node name C-I using "C-I" instead
 #I  invalid node name S-C using "S-C" instead
 #I  invalid node name S-I using "S-I" instead
diff --git a/tst/examples/fsm.tst b/tst/examples/fsm.tst
index 177b453..ad70da3 100644
--- a/tst/examples/fsm.tst
+++ b/tst/examples/fsm.tst
@@ -73,7 +73,7 @@ gap> GraphvizSetAttr(GraphvizAddEdge(nodes, "LR_8", "LR_5"), "label", "\"S(a)\""
 <graphviz edge (LR_8, LR_5)>
 
 #
-gap> String(f);
+gap> AsString(f);
 "//dot\ndigraph finite_state_machine {\n\trankdir=LR size=\"8,5\" \n// termina\
 ls context \n\tnode [shape=doublecircle] \n\tLR_0\n\tLR_3\n\tLR_4\n\tLR_8\n\tr\
 ankdir=LR size=\"8,5\" \n\n// nodes context \n\tnode [shape=circle] \n\tLR_2\n\
diff --git a/tst/examples/g_c_n.tst b/tst/examples/g_c_n.tst
index beea2f2..f38f5b7 100644
--- a/tst/examples/g_c_n.tst
+++ b/tst/examples/g_c_n.tst
@@ -36,7 +36,7 @@ gap> GraphvizAddNode(cluster1, "anode");
 <graphviz node anode>
 
 #@if CompareVersionNumbers(GAPInfo.Version, "4.12.0")
-gap> Print(String(g));
+gap> Print(AsString(g));
 //dot
 graph G {
 	bgcolor="purple:pink" label="agraph" fontcolor="white" 
@@ -48,7 +48,7 @@ ntangle=270
 }
 }
 #@else
-gap> Print(String(g));
+gap> Print(AsString(g));
 //dot
 graph G {
 	bgcolor="purple:pink" label="agraph" fontcolor="white" 
diff --git a/tst/examples/hello.tst b/tst/examples/hello.tst
index 8d4cc54..d9af8ae 100644
--- a/tst/examples/hello.tst
+++ b/tst/examples/hello.tst
@@ -20,7 +20,7 @@ gap> graph := GraphvizDigraph("G");
 <graphviz digraph G with 0 nodes and 0 edges>
 gap> GraphvizAddEdge(graph, "hello", "world");
 <graphviz edge (hello, world)>
-gap> String(graph);
+gap> AsString(graph);
 "//dot\ndigraph G {\n\thello\n\tworld\n\thello -> world\n}\n"
 
 #
diff --git a/tst/examples/process.tst b/tst/examples/process.tst
index 44b2f11..9b922b8 100644
--- a/tst/examples/process.tst
+++ b/tst/examples/process.tst
@@ -47,7 +47,7 @@ gap> GraphvizAddEdge(graph, "runswap", "runmem");
 <graphviz edge (runswap, runmem)>
 gap> GraphvizAddEdge(graph, "new", "runmem");
 <graphviz edge (new, runmem)>
-gap> String(graph);
+gap> AsString(graph);
 "//dot\ngraph G {\n\tengine=\"sfdp\" \n\trun\n\tintr\n\trun -- intr\n\trunbl\n\
 \tintr -- runbl\n\trunbl -- run\n\tkernel\n\trun -- kernel\n\tzombie\n\tkernel\
  -- zombie\n\tsleep\n\tkernel -- sleep\n\trunmem\n\tkernel -- runmem\n\tswap\n\
diff --git a/tst/examples/rank_same.tst b/tst/examples/rank_same.tst
index df7355d..685dee2 100644
--- a/tst/examples/rank_same.tst
+++ b/tst/examples/rank_same.tst
@@ -58,7 +58,7 @@ gap> GraphvizAddEdge(g, "X", "Y");
 <graphviz edge (X, Y)>
 
 #
-gap> String(g);
+gap> AsString(g);
 "//dot\ndigraph  {\nsubgraph no_name_1 {\n\trank=same \n\tA\n\tX\n}\n\tC\nsubg\
 raph no_name_3 {\n\trank=same \n\tB\n\tD\n\tY\n}\n\tA -> B\n\tA -> C\n\tC -> D\
 \n\tX -> Y\n}\n"
diff --git a/tst/examples/structs.tst b/tst/examples/structs.tst
index f10bd74..2068f9f 100644
--- a/tst/examples/structs.tst
+++ b/tst/examples/structs.tst
@@ -63,7 +63,7 @@ gap> GraphvizAddEdge(s, "struct1:f2", "struct3:here");
 <graphviz edge (struct1:f2, struct3:here)>
 
 #
-gap> String(s);
+gap> AsString(s);
 "//dot\ndigraph structs {\n\tnode [shape=\"plaintext\"] \n\tstruct1 [label=<<T\
 ABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">\n<TR>\n<TD>left</TD>\n<T\
 D PORT=\"f1\">middle</TD><TD PORT=\"f2\">right</TD>\n</TR>\n</TABLE>>]\n\tstru\
diff --git a/tst/examples/traffic_lights.tst b/tst/examples/traffic_lights.tst
index 5654ab7..295ac0f 100644
--- a/tst/examples/traffic_lights.tst
+++ b/tst/examples/traffic_lights.tst
@@ -79,7 +79,7 @@ gap> GraphvizSetAttr(t, "fontsize=12");
 <graphviz digraph TrafficLights with 0 nodes and 16 edges>
 
 #
-gap> String(t);
+gap> AsString(t);
 "//dot\ndigraph TrafficLights {\n\tengine=neato overlap=\"false\" label=\"Petr\
 iNet Model TrafficLights\nExtracted from ConceptBase and laid out by Graphviz\
 \"\n fontsize=12 \nsubgraph ctx1 {\n\tnode [shape=\"box\"] \n\tgy2\n\tyr2\n\tr\
diff --git a/tst/examples/unix.tst b/tst/examples/unix.tst
index e63d3f2..5207345 100644
--- a/tst/examples/unix.tst
+++ b/tst/examples/unix.tst
@@ -124,7 +124,7 @@ gap> GraphvizAddEdge(u, "System V.2", "System V.3");
 <graphviz edge (System V.2, System V.3)>
 
 #
-gap> String(u) =
+gap> AsString(u) =
 > "//dot\ndigraph unix {\n\tnode [color=\"lightblue2\", style=\"filled\", size=\
 > \"6,6\"] \n\t\"5th Edition\"\n\t\"6th Edition\"\n\t\"5th Edition\" -> \"6th Ed\
 > ition\"\n\t\"PWB 1.0\"\n\t\"5th Edition\" -> \"PWB 1.0\"\n\tLSX\n\t\"6th Editi\
diff --git a/tst/graph.tst b/tst/graph.tst
index 933146d..5c90819 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -192,7 +192,7 @@ gap> GraphvizAttrs(g);
 gap> g := GraphvizGraph();;
 gap> GraphvizSetAttr(g, "color", "red");;
 gap> GraphvizSetAttr(g, "color", "blue");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\tcolor=red color=blue \n}\n"
 
 # # Test removing attributes from a graph TODO uncomment or delete
diff --git a/tst/node.tst b/tst/node.tst
index 8d6ebab..c83d575 100644
--- a/tst/node.tst
+++ b/tst/node.tst
@@ -54,14 +54,14 @@ rec( shape := "circle" )
 # Test name containing ':'
 gap> g := GraphvizGraph();;
 gap> GraphvizAddNode(g, "test:colon");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\ttest:colon\n}\n"
 
 # Test non-string name containing ':'
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, 111);
 <graphviz node 111>
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n\t111\n}\n"
 gap> n[1];
 fail
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 005e216..45adb25 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -138,7 +138,7 @@ gap> GraphvizAddEdge(g, "x", "y");;
 gap> GraphvizSetAttr(s, "color", "red");;
 gap> GraphvizSetAttr(s, "node [color=red]");;
 gap> GraphvizSetAttr(s, "edge [color=red]");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ndigraph  {\nsubgraph a {\n\tcolor=red node [color=red] edge [color=red\
 ] \n}\n\tx\n\ty\n\tx -> y\n}\n"
 
@@ -149,7 +149,7 @@ gap> GraphvizAddEdge(g, "x", "y");;
 gap> GraphvizSetAttr(s, "color", "red");;
 gap> GraphvizSetAttr(s, "node [color=red]");;
 gap> GraphvizSetAttr(s, "edge [color=red]");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\nsubgraph a {\n\tcolor=red node [color=red] edge [color=red] \
 \n}\n\tx\n\ty\n\tx -- y\n}\n"
 
@@ -160,7 +160,7 @@ gap> GraphvizAddEdge(g, "x", "y");;
 gap> GraphvizSetAttr(s, "color", "red");;
 gap> GraphvizSetAttr(s, "node [color=red]");;
 gap> GraphvizSetAttr(s, "edge [color=red]");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\n// a context \n\tcolor=red node [color=red] edge [color=red]\
  \n\n\tx\n\ty\n\tx -- y\n}\n"
 
@@ -171,14 +171,14 @@ gap> GraphvizAddEdge(g, "x", "y");;
 gap> GraphvizSetAttr(s, "color", "red");;
 gap> GraphvizSetAttr(s, "node [color=red]");;
 gap> GraphvizSetAttr(s, "edge [color=red]");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ndigraph  {\n// a context \n\tcolor=red node [color=red] edge [color=re\
 d] \n\n\tx\n\ty\n\tx -> y\n}\n"
 
 # Test stringifying subgraph w/o name
 gap> g := GraphvizDigraph();;
 gap> s := GraphvizAddSubgraph(g);;
-gap> String(g);
+gap> AsString(g);
 "//dot\ndigraph  {\nsubgraph no_name_1 {\n}\n}\n"
 
 # finding a node in a sibling graph
@@ -248,7 +248,7 @@ gap> GraphvizSetAttr(g, "node[color=blue]");;
 gap> GraphvizSetAttr(g, "edge[color=blue]");;
 gap> GraphvizSetAttr(ctx, "node[color=red]");;
 gap> GraphvizAddNode(ctx, "a");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ndigraph  {\n\tcolor=green edge [label=testing123] node[color=blue] edg\
 e[color=blue] \n// no_name_1 context \n\tnode[color=red] \n\ta\n\tcolor=green \
 edge [label=testing123] node[color=blue] edge[color=blue] \n\n}\n"
@@ -295,7 +295,7 @@ gap> GraphvizSubgraphs(s1)["c"];
 gap> g := GraphvizGraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(s1, "c");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph  {\nsubgraph a {\nsubgraph c {\n}\n}\n}\n"
 
 # Test subgraphs with non-string names
@@ -364,7 +364,7 @@ gap> g      := GraphvizGraph("g");;
 gap> parent := GraphvizAddContext(g, "parent");;
 gap> ctx    := GraphvizAddContext(parent, "ctx");;
 gap> GraphvizAddEdge(ctx, "a", "b");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ngraph g {\n// parent context \n// ctx context \n\ta\n\tb\n\ta -- b\n\n\
 \n}\n"
 
@@ -373,7 +373,7 @@ gap> g      := GraphvizDigraph("g");;
 gap> parent := GraphvizAddContext(g, "parent");;
 gap> ctx    := GraphvizAddContext(parent, "ctx");;
 gap> GraphvizAddEdge(ctx, "a", "b");;
-gap> String(g);
+gap> AsString(g);
 "//dot\ndigraph g {\n// parent context \n// ctx context \n\ta\n\tb\n\ta -> b\n\
 \n\n}\n"
 

From 7c412f3107310798b757d6fa3fad1adce4a4bdde Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 11:11:27 +0100
Subject: [PATCH 27/38] More test for code coverage and remove some unreachable
 code

---
 gap/gv.gi        | 26 +++++++++++++-------------
 tst/dot.tst      |  3 +++
 tst/subgraph.tst | 11 +++++++++++
 3 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/gap/gv.gi b/gap/gv.gi
index 2a697c0..27650e9 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -525,9 +525,13 @@ function(attrs)
         if "label" = key and StartsWith(tmp, "<<") and EndsWith(tmp, ">>") then
           val := StringFormatted("{}", val);
         else
-          if ' ' in key then
-            key := StringFormatted("\"{}\"", key);
-          fi;
+          # TODO it doesn't seem to be possible to enter the if-statement
+          # below, even with examples where the key contains spaces (probably
+          # the quotes are added somewhere else). Either uncomment or delete
+          # this code.
+          # if ' ' in key then
+          #   key := StringFormatted("\"{}\"", key);
+          # fi;
           if ' ' in val or '>' in val or '^' in val or '#' in val then
               # TODO avoid code duplication here, and below
             val := StringFormatted("\"{}\"", val);
@@ -603,10 +607,8 @@ function(graph, is_subgraph)
   if is_subgraph then
     if IsGraphvizContext(graph) then
       Append(result, GV_StringifyContextHead(graph));
-    elif IsGraphvizGraph(graph) or IsGraphvizDigraph(graph) then
-      Append(result, GV_StringifySubgraphHead(graph));
     else
-      ErrorNoReturn("Invalid subgraph type.");
+      Append(result, GV_StringifySubgraphHead(graph));
     fi;
   elif IsGraphvizDigraph(graph) then
     Append(result, "//dot\n");
@@ -614,11 +616,11 @@ function(graph, is_subgraph)
   elif IsGraphvizGraph(graph) then
     Append(result, "//dot\n");
     Append(result, GV_StringifyGraphHead(graph));
-  elif IsGraphvizContext(graph) then
-    Append(result, "//dot\n");
-    Append(result, GV_StringifyContextHead(graph));
-  else
-    ErrorNoReturn("Invalid graph type.");
+    # TODO doesn't seem to be possible to reach the case below either, uncomment
+    # or delete
+    # else
+    #  Append(result, "//dot\n");
+    #  Append(result, GV_StringifyContextHead(graph));
   fi;
 
   Append(result, GV_StringifyGraphAttrs(graph));
@@ -635,8 +637,6 @@ function(graph, is_subgraph)
       else
         Append(result, GV_StringifyEdge(obj, "--"));
       fi;
-    else
-      ErrorNoReturn("Invalid graphviz object type.");
     fi;
   od;
 
diff --git a/tst/dot.tst b/tst/dot.tst
index c4448d6..781777b 100644
--- a/tst/dot.tst
+++ b/tst/dot.tst
@@ -185,6 +185,9 @@ gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FG"]);
 Error, invalid color "#0000FG" (list (string)), valid colors are RGB values or\
  names from the GraphViz 2.44.1 X11 Color Scheme http://graphviz.org/doc/info/\
 colors.html
+gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00"]);
+Error, the number of node colors must be the same as the number of nodes, expe\
+cted 3 but found 2
 gap> GraphvizAddEdge(gv, "a", "b");
 <graphviz edge (a, b)>
 gap> GraphvizNodes(gv);
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 45adb25..3610bbc 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -395,6 +395,17 @@ gap> GraphvizSetAttr(legend, "node [shape=plaintext]");
 <graphviz context legend with 0 nodes and 0 edges>
 gap> GraphvizAddSubgraph(legend, "legend");
 <graphviz graph legend with 0 nodes and 0 edges>
+gap> Print(AsString(gv));
+//dot
+graph context+subgraph {
+	node [shape="box"] 
+// legend context 
+	node [shape=plaintext] 
+subgraph legend {
+}
+	node [shape="box"] 
+
+}
 
 # Test a context containing a subdigraph
 gap> gv := GraphvizDigraph("context+subgraph");;

From 6d90950e001f71a35f0bcd50613c8d14bb27a7f7 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 11:25:41 +0100
Subject: [PATCH 28/38] Correct STOP_TEST strings in tst/examples

---
 tst/examples/cluster.tst        | 2 +-
 tst/examples/cluster_edge.tst   | 2 +-
 tst/examples/colors.tst         | 2 +-
 tst/examples/er.tst             | 2 +-
 tst/examples/fsm.tst            | 2 +-
 tst/examples/g_c_n.tst          | 2 +-
 tst/examples/hello.tst          | 2 +-
 tst/examples/process.tst        | 2 +-
 tst/examples/rank_same.tst      | 2 +-
 tst/examples/structs.tst        | 2 +-
 tst/examples/traffic_lights.tst | 2 +-
 tst/examples/unix.tst           | 2 +-
 12 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/tst/examples/cluster.tst b/tst/examples/cluster.tst
index 2786feb..fc03e78 100644
--- a/tst/examples/cluster.tst
+++ b/tst/examples/cluster.tst
@@ -84,4 +84,4 @@ t -> a0\n\tstart -> b0\n\ta1 -> b3\n\tb2 -> a3\n\ta3 -> a0\n\tend [shape=Msqua\
 re]\n\ta3 -> end\n\tb3 -> end\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: cluster.tst");
+gap> STOP_TEST("graphviz package: examples/cluster.tst");
diff --git a/tst/examples/cluster_edge.tst b/tst/examples/cluster_edge.tst
index 3a017fe..a3f9461 100644
--- a/tst/examples/cluster_edge.tst
+++ b/tst/examples/cluster_edge.tst
@@ -60,4 +60,4 @@ e -> g\n\tf\n\te -> f\n}\n\tb -> f [lhead=cluster1]\n\td -> e\n\tc -> g [lhead\
 =cluster1, ltail=cluster0]\n\tc -> e [ltail=cluster0]\n\th\n\td -> h\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: cluster_edge.tst");
+gap> STOP_TEST("graphviz package: examples/cluster_edge.tst");
diff --git a/tst/examples/colors.tst b/tst/examples/colors.tst
index d1f4d8c..71eb3f7 100644
--- a/tst/examples/colors.tst
+++ b/tst/examples/colors.tst
@@ -65,4 +65,4 @@ gap> AsString(g);
  deeppink\" [fillcolor=deeppink, style=filled]\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: colors.tst");
+gap> STOP_TEST("graphviz package: examples/colors.tst");
diff --git a/tst/examples/er.tst b/tst/examples/er.tst
index a1dcbf3..94ffc72 100644
--- a/tst/examples/er.tst
+++ b/tst/examples/er.tst
@@ -131,4 +131,4 @@ t\n\t\"S-C\" -- student [label=m, len=1.00]\n\tcourse -- \"S-C\" [label=n, len\
 =1.00]\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: er.tst");
+gap> STOP_TEST("graphviz package: examples/er.tst");
diff --git a/tst/examples/fsm.tst b/tst/examples/fsm.tst
index ad70da3..6e8f291 100644
--- a/tst/examples/fsm.tst
+++ b/tst/examples/fsm.tst
@@ -86,4 +86,4 @@ LR_5\n\tLR_2 -> LR_5 [label=\"SS(a)\"]\n\tLR_2 -> LR_4 [label=\"S(A)\"]\n\tLR_\
 \tLR_8 -> LR_5 [label=\"S(a)\"]\n\trankdir=LR size=\"8,5\" \n\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: fsm.tst");
+gap> STOP_TEST("graphviz package: examples/fsm.tst");
diff --git a/tst/examples/g_c_n.tst b/tst/examples/g_c_n.tst
index f38f5b7..58261ae 100644
--- a/tst/examples/g_c_n.tst
+++ b/tst/examples/g_c_n.tst
@@ -63,4 +63,4 @@ tangle=270
 #@fi
 
 #
-gap> STOP_TEST("graphviz package: g_c_n.tst");
+gap> STOP_TEST("graphviz package: examples/g_c_n.tst");
diff --git a/tst/examples/hello.tst b/tst/examples/hello.tst
index d9af8ae..9c4ae17 100644
--- a/tst/examples/hello.tst
+++ b/tst/examples/hello.tst
@@ -24,4 +24,4 @@ gap> AsString(graph);
 "//dot\ndigraph G {\n\thello\n\tworld\n\thello -> world\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: hello.tst");
+gap> STOP_TEST("graphviz package: examples/hello.tst");
diff --git a/tst/examples/process.tst b/tst/examples/process.tst
index 9b922b8..75e9c20 100644
--- a/tst/examples/process.tst
+++ b/tst/examples/process.tst
@@ -55,4 +55,4 @@ gap> AsString(graph);
 wap -- runmem\n\tnew -- runmem\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: process.tst");
+gap> STOP_TEST("graphviz package: examples/process.tst");
diff --git a/tst/examples/rank_same.tst b/tst/examples/rank_same.tst
index 685dee2..5417cd5 100644
--- a/tst/examples/rank_same.tst
+++ b/tst/examples/rank_same.tst
@@ -64,4 +64,4 @@ raph no_name_3 {\n\trank=same \n\tB\n\tD\n\tY\n}\n\tA -> B\n\tA -> C\n\tC -> D\
 \n\tX -> Y\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: rank_same.tst");
+gap> STOP_TEST("graphviz package: examples/rank_same.tst");
diff --git a/tst/examples/structs.tst b/tst/examples/structs.tst
index 2068f9f..2e4d14c 100644
--- a/tst/examples/structs.tst
+++ b/tst/examples/structs.tst
@@ -77,4 +77,4 @@ re\">d</TD>\n<TD>e</TD>\n</TR>\n<TR>\n<TD COLSPAN=\"3\">f</TD>\n</TR>\n</TABLE\
 truct3:here\n\tstruct1:f2 -> struct3:here\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: structs.tst");
+gap> STOP_TEST("graphviz package: examples/structs.tst");
diff --git a/tst/examples/traffic_lights.tst b/tst/examples/traffic_lights.tst
index 295ac0f..a2b64c4 100644
--- a/tst/examples/traffic_lights.tst
+++ b/tst/examples/traffic_lights.tst
@@ -91,4 +91,4 @@ ze=true, width=0.9] \n\tgreen2\n\tyellow2\n\tred2\n\tsafe2\n\tgreen1\n\tyellow\
 g1\n\tgreen1 -> gy1\n\tyellow1 -> yr1\n\tred1 -> rg1\n}\n"
 
 #
-gap> STOP_TEST("graphviz package: traffic_lights.tst");
+gap> STOP_TEST("graphviz package: examples/traffic_lights.tst");
diff --git a/tst/examples/unix.tst b/tst/examples/unix.tst
index 5207345..13ea228 100644
--- a/tst/examples/unix.tst
+++ b/tst/examples/unix.tst
@@ -283,4 +283,4 @@ gap> AsString(u) =
 true
 
 #
-gap> STOP_TEST("graphviz package: unix.tst");
+gap> STOP_TEST("graphviz package: examples/unix.tst");

From 8569f758b6f7f76755b6e4b336ea35d5624c0a92 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 11:31:47 +0100
Subject: [PATCH 29/38] Remove GV_EnsureString

---
 gap/dot.gi | 2 +-
 gap/gv.gd  | 3 ---
 gap/gv.gi  | 6 ------
 3 files changed, 1 insertion(+), 10 deletions(-)

diff --git a/gap/dot.gi b/gap/dot.gi
index db37732..3203a1b 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -181,7 +181,7 @@ end);
 InstallMethod(\[\]\:\=, "for a graphviz edge and an object",
 [IsGraphvizEdge, IsObject, IsObject],
 function(edge, key, val)
-  edge[GV_EnsureString(key)] := GV_EnsureString(val);
+  edge[String(key)] := String(val);
 end);
 
 # Accessor for graphs and digraphs
diff --git a/gap/gv.gd b/gap/gv.gd
index 3c977b1..65659fb 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -38,9 +38,6 @@ DeclareOperation("GV_Context", [IsGraphvizGraphDigraphOrContext, IsString]);
 DeclareOperation("GV_Map", []);
 DeclareOperation("GV_MapNames", [GV_IsMap]);
 
-# TODO required? Replace with AsString or just String?
-DeclareOperation("GV_EnsureString", [IsObject]);
-
 DeclareOperation("GV_HasNode", [IsGraphvizGraphDigraphOrContext, IsObject]);
 
 DeclareOperation("GV_GetParent", [IsGraphvizGraphDigraphOrContext]);
diff --git a/gap/gv.gi b/gap/gv.gi
index 27650e9..c895a2c 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -268,12 +268,6 @@ InstallMethod(GV_GetCounter, "for a graphviz graph",
 [IsGraphvizGraphDigraphOrContext],
 x -> x!.Counter);
 
-# Converting strings
-
-InstallMethod(GV_EnsureString, "for an object", [IsObject], String);
-
-InstallMethod(GV_EnsureString, "for a string", [IsString], IdFunc);
-
 # Nodes
 
 InstallMethod(GV_HasNode,

From e840460cf7cf2f09f870963d441248779d230bfc Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 11:44:22 +0100
Subject: [PATCH 30/38] Fix tests for GAP 4.11

---
 tst/dot.tst      | 14 ++++++++++++++
 tst/graph.tst    | 11 +++++++++++
 tst/subgraph.tst | 14 ++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/tst/dot.tst b/tst/dot.tst
index 781777b..9bffc61 100644
--- a/tst/dot.tst
+++ b/tst/dot.tst
@@ -150,10 +150,17 @@ gap> GraphvizAddNode(gv, 2);
 <graphviz node 2>
 gap> GraphvizAddNode(gv, 3);
 <graphviz node 3>
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizSetNodeColors(gv, ["i", "ii", "iii"]);
 Error, invalid color "i" (list (string)), valid colors are RGB values or names\
  from the GraphViz 2.44.1 X11 Color Scheme http://graphviz.org/doc/info/colors\
 .html
+#@else
+gap> GraphvizSetNodeColors(gv, ["i", "ii", "iii"]);
+Error, invalid color "i" (list (string)), valid colors are RGB values or names\
+ from the GraphViz 2.44.1 X11 Color Sch\
+eme http://graphviz.org/doc/info/colors.html
+#@fi
 gap> GraphvizSetNodeColors(gv, ["red", "green", "blue"]);
 <graphviz graph xxx with 3 nodes and 0 edges>
 gap> Print(AsString(gv));
@@ -181,10 +188,17 @@ graph xxx {
 	2 [color="#00FF00", style=filled]
 	3 [color="#0000FF", style=filled]
 }
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FG"]);
 Error, invalid color "#0000FG" (list (string)), valid colors are RGB values or\
  names from the GraphViz 2.44.1 X11 Color Scheme http://graphviz.org/doc/info/\
 colors.html
+#@else
+gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FG"]);
+Error, invalid color "#0000FG" (list (string)), valid colors are RGB values or\
+ names from the GraphViz 2.44.1 X11 Color Sch\
+eme http://graphviz.org/doc/info/colors.html
+#@fi
 gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00"]);
 Error, the number of node colors must be the same as the number of nodes, expe\
 cted 3 but found 2
diff --git a/tst/graph.tst b/tst/graph.tst
index 5c90819..7fd2b95 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -100,12 +100,23 @@ gap> GraphvizAddEdge(g, "a", "b");
 <graphviz edge (a, b)>
 gap> GraphvizEdges(g, "a", "b");
 [ <graphviz edge (a, b)>, <graphviz edge (a, b)> ]
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizEdges(g, "x", "b");
 Error, the 2nd argument "x" (head of an edge) is not a node of the 1st argumen\
 t (a graphviz graph or digraph)
 gap> GraphvizEdges(g, "a", "y");
 Error, the 3rd argument "y" (tail of an edge) is not a node of the 1st argumen\
 t (a graphviz graph or digraph)
+#@else
+gap> GraphvizEdges(g, "x", "b");
+Error, the 2nd argument "x" (head of an edge) is not a node of the 1st argumen\
+t (a graphviz graph or dig\
+raph)
+gap> GraphvizEdges(g, "a", "y");
+Error, the 3rd argument "y" (tail of an edge) is not a node of the 1st argumen\
+t (a graphviz graph or dig\
+raph)
+#@fi
 
 # Test adding edge with different nodes with the same name
 gap> g := GraphvizGraph();;
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 3610bbc..462abab 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -34,9 +34,16 @@ gap> GraphvizAddSubgraph(g);
 gap> g := GraphvizGraph();;
 gap> GraphvizAddContext(g);
 <graphviz context no_name_1 with 0 nodes and 0 edges>
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizAddContext(g, "no_name_1");
 Error, the 1st argument (a graphviz (di)graph/context) already has a context o\
 r subgraph with name "no_name_1"
+#@else
+gap> GraphvizAddContext(g, "no_name_1");
+Error, the 1st argument (a graphviz (di)graph/context) already has a context o\
+r subgr\
+aph with name "no_name_1"
+#@fi
 
 # Test no-name constructor graphs' names increment
 gap> g := GraphvizGraph();;
@@ -256,9 +263,16 @@ edge [label=testing123] node[color=blue] edge[color=blue] \n\n}\n"
 # Test adding subgraphs with the same name
 gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> s2 := GraphvizAddSubgraph(g, "a");
 Error, the 1st argument (a graphviz (di)graph/context) already has a subgraph \
 with name "a"
+#@else
+gap> s2 := GraphvizAddSubgraph(g, "a");
+Error, the 1st argument (a graphviz (di)graph/context) already has a subgraph \
+with na\
+me "a"
+#@fi
 
 # Test getting subgraphs by name
 gap> g := GraphvizDigraph();;

From b78eea94084ce541218753b8f744a79070464577 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 11:48:39 +0100
Subject: [PATCH 31/38] Remove InstallOtherMethod from gv.gi

---
 gap/gv.gd |  4 ++++
 gap/gv.gi | 12 ++++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/gap/gv.gd b/gap/gv.gd
index 65659fb..3193736 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -15,6 +15,10 @@ DeclareOperation("GV_GetCounter", [IsGraphvizGraphDigraphOrContext]);
 DeclareOperation("GV_IncCounter", [IsGraphvizGraphDigraphOrContext]);
 DeclareCategory("GV_IsMap", IsObject);
 DeclareAttribute("Size", GV_IsMap);
+DeclareOperation("\[\]", [GV_IsMap, IsObject]);
+DeclareOperation("\[\]:=", [GV_IsMap, IsObject, IsObject]);
+DeclareOperation("Unbind\[\]", [GV_IsMap, IsObject]);
+DeclareOperation("IsBound\[\]", [GV_IsMap, IsObject]);
 
 DeclareOperation("GV_StringifyGraphHead", [IsGraphvizGraphDigraphOrContext]);
 DeclareOperation("GV_StringifyDigraphHead", [IsGraphvizGraphDigraphOrContext]);
diff --git a/gap/gv.gi b/gap/gv.gi
index c895a2c..63e77ac 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -210,8 +210,8 @@ end);
 # Graphviz Map Functions
 ############################################################
 
-InstallOtherMethod(\[\],
-"for a graphviz map and an object",
+InstallMethod(\[\],
+"for a graphviz map and a string",
 [GV_IsMap, IsString],
 function(m, o)
   if IsBound(m[o]) then
@@ -220,26 +220,26 @@ function(m, o)
   return fail;
 end);
 
-InstallOtherMethod(\[\],
+InstallMethod(\[\],
 "for a graphviz map and an object",
 [GV_IsMap, IsObject],
 {m, o} -> m[String(o)]);
 
-InstallOtherMethod(\[\]\:\=,
+InstallMethod(\[\]\:\=,
 "for a graphviz map and two objects",
 [GV_IsMap, IsObject, IsObject],
 function(m, key, val)
   m!.Data.(key) := val;
 end);
 
-InstallOtherMethod(Unbind\[\],
+InstallMethod(Unbind\[\],
 "for a graphviz map and an object",
 [GV_IsMap, IsObject],
 function(m, key)
   Unbind(m!.Data.(key));
 end);
 
-InstallOtherMethod(IsBound\[\],
+InstallMethod(IsBound\[\],
 "for a graphviz map and an object",
 [GV_IsMap, IsObject],
 {m, key} -> IsBound(m!.Data.(key)));

From 0cee7841d65cbf1f242c9adc8ee1a924bff84bac Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 11:49:00 +0100
Subject: [PATCH 32/38] Conditionally install GV_Pluralize

---
 gap/gv.gi | 161 ++++++++++++++++++++++++++++--------------------------
 1 file changed, 84 insertions(+), 77 deletions(-)

diff --git a/gap/gv.gi b/gap/gv.gi
index 63e77ac..a328982 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -8,86 +8,93 @@
 #############################################################################
 ##
 
-# code from the GAP standard library
-InstallMethod(GV_Pluralize,
-"for an integer and a string",
-[IsInt, IsString],
-function(args...)
-  local nargs, i, count, include_num, str, len, out;
-
-  nargs := Length(args);
-  if nargs >= 1 and IsInt(args[1]) and args[1] >= 0 then
-    i           := 2;
-    count       := args[1];
-    include_num := true;
-  else
-    i           := 1;
-    include_num := false;  # if not given, assume pluralization is wanted.
-  fi;
+# Code from the GAP standard library, repeated here so that the package works
+# with GAP 4.11 since Pluralize was introduced to the GAP library in 4.12
+if CompareVersionNumbers(GAPInfo.Version, "4.12") then
+    InstallMethod(GV_Pluralize,
+    "for an integer and a string",
+    [IsInt, IsString], Pluralize);
+else
+  InstallMethod(GV_Pluralize,
+  "for an integer and a string",
+  [IsInt, IsString],
+  function(args...)
+    local nargs, i, count, include_num, str, len, out;
+
+    nargs := Length(args);
+    if nargs >= 1 and IsInt(args[1]) and args[1] >= 0 then
+      i           := 2;
+      count       := args[1];
+      include_num := true;
+    else
+      i           := 1;
+      include_num := false;  # if not given, assume pluralization is wanted.
+    fi;
 
-  if not (nargs in [i, i + 1] and
-          IsString(args[i]) and
-          (nargs = i or IsString(args[i + 1]))) then
-    ErrorNoReturn("Usage: GV_Pluralize([<count>, ]<string>[, <plural>])");
-  fi;
+    if not (nargs in [i, i + 1] and
+            IsString(args[i]) and
+            (nargs = i or IsString(args[i + 1]))) then
+      ErrorNoReturn("Usage: GV_Pluralize([<count>, ]<string>[, <plural>])");
+    fi;
 
-  str := args[i];
-  len := Length(str);
-
-  if len = 0 then
-    ErrorNoReturn("the argument <str> must be a non-empty string");
-  elif include_num and count = 1 then  # no pluralization needed
-    return Concatenation("\>1\< ", str);
-  elif nargs = i + 1 then  # pluralization given
-    out := args[i + 1];
-  elif len <= 2 then
-    out := Concatenation(str, "s");
-
-    # Guess and return the plural form of <str>.
-    # Inspired by the "Ruby on Rails" inflection rules.
-
-    # Uncountable nouns
-  elif str in ["equipment", "information"] then
-    out := str;
-
-    # Irregular plurals
-  elif str = "axis" then
-    out := "axes";
-  elif str = "child" then
-    out := "children";
-  elif str = "person" then
-    out := "people";
-
-    # Peculiar endings
-  elif EndsWith(str, "ix") or EndsWith(str, "ex") then
-    out := Concatenation(str{[1 .. len - 2]}, "ices");
-  elif EndsWith(str, "x") then
-    out := Concatenation(str, "es");
-  elif EndsWith(str, "tum") or EndsWith(str, "ium") then
-    out := Concatenation(str{[1 .. len - 2]}, "a");
-  elif EndsWith(str, "sis") then
-    out := Concatenation(str{[1 .. len - 3]}, "ses");
-  elif EndsWith(str, "fe") and not EndsWith(str, "ffe") then
-    out := Concatenation(str{[1 .. len - 2]}, "ves");
-  elif EndsWith(str, "lf") or EndsWith(str, "rf") or EndsWith(str, "loaf") then
-    out := Concatenation(str{[1 .. len - 1]}, "ves");
-  elif EndsWith(str, "y") and not str[len - 1] in "aeiouy" then
-    out := Concatenation(str{[1 .. len - 1]}, "ies");
-  elif str{[len - 1, len]} in ["ch", "ss", "sh"] then
-    out := Concatenation(str, "es");
-  elif EndsWith(str, "s") then
-    out := str;
-
-    # Default to appending 's'
-  else
-    out := Concatenation(str, "s");
-  fi;
+    str := args[i];
+    len := Length(str);
+
+    if len = 0 then
+      ErrorNoReturn("the argument <str> must be a non-empty string");
+    elif include_num and count = 1 then  # no pluralization needed
+      return Concatenation("\>1\< ", str);
+    elif nargs = i + 1 then  # pluralization given
+      out := args[i + 1];
+    elif len <= 2 then
+      out := Concatenation(str, "s");
+
+      # Guess and return the plural form of <str>.
+      # Inspired by the "Ruby on Rails" inflection rules.
+
+      # Uncountable nouns
+    elif str in ["equipment", "information"] then
+      out := str;
+
+      # Irregular plurals
+    elif str = "axis" then
+      out := "axes";
+    elif str = "child" then
+      out := "children";
+    elif str = "person" then
+      out := "people";
+
+      # Peculiar endings
+    elif EndsWith(str, "ix") or EndsWith(str, "ex") then
+      out := Concatenation(str{[1 .. len - 2]}, "ices");
+    elif EndsWith(str, "x") then
+      out := Concatenation(str, "es");
+    elif EndsWith(str, "tum") or EndsWith(str, "ium") then
+      out := Concatenation(str{[1 .. len - 2]}, "a");
+    elif EndsWith(str, "sis") then
+      out := Concatenation(str{[1 .. len - 3]}, "ses");
+    elif EndsWith(str, "fe") and not EndsWith(str, "ffe") then
+      out := Concatenation(str{[1 .. len - 2]}, "ves");
+    elif EndsWith(str, "lf") or EndsWith(str, "rf") or EndsWith(str, "loaf") then
+      out := Concatenation(str{[1 .. len - 1]}, "ves");
+    elif EndsWith(str, "y") and not str[len - 1] in "aeiouy" then
+      out := Concatenation(str{[1 .. len - 1]}, "ies");
+    elif str{[len - 1, len]} in ["ch", "ss", "sh"] then
+      out := Concatenation(str, "es");
+    elif EndsWith(str, "s") then
+      out := str;
+
+      # Default to appending 's'
+    else
+      out := Concatenation(str, "s");
+    fi;
 
-  if include_num then
-    return Concatenation("\>", String(args[1]), "\< ", out);
-  fi;
-  return out;
-end);
+    if include_num then
+      return Concatenation("\>", String(args[1]), "\< ", out);
+    fi;
+    return out;
+  end);
+fi;
 
 ###############################################################################
 # Family + type

From 994e1df8789b7a2249390cf669e1940836b06e50 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 12:04:35 +0100
Subject: [PATCH 33/38] More \= method for nodes to dot.gi

Also add \= for edges
---
 gap/dot.gi | 8 ++++++++
 gap/gv.gi  | 4 ----
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/gap/dot.gi b/gap/dot.gi
index 3203a1b..05805ca 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -138,6 +138,11 @@ x -> x!.Tail);
 InstallMethod(GraphvizHead, "for a graphviz edge", [IsGraphvizEdge],
 x -> x!.Head);
 
+# Operators for nodes
+
+InstallMethod(\=, "for graphviz nodes",
+[IsGraphvizNode, IsGraphvizNode], IsIdenticalObj);
+
 # Accessing node attributes
 
 InstallMethod(\[\], "for a graphviz node and a string",
@@ -184,6 +189,9 @@ function(edge, key, val)
   edge[String(key)] := String(val);
 end);
 
+InstallMethod(\=, "for graphviz edges",
+[IsGraphvizEdge, IsGraphvizEdge], IsIdenticalObj);
+
 # Accessor for graphs and digraphs
 
 InstallMethod(\[\], "for a graphviz (di)graph or context and string",
diff --git a/gap/gv.gi b/gap/gv.gi
index a328982..593a9e1 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -120,10 +120,6 @@ BindGlobal("GV_ContextType", NewType(GV_ObjectFamily,
                                     IsComponentObjectRep and
                                     IsAttributeStoringRep));
 
-InstallMethod(\=, "for IsGraphvizNode and IsGraphvizNode",
-[IsGraphvizNode, IsGraphvizNode],
-{n1, n2} -> GraphvizName(n1) = GraphvizName(n2));
-
 ###############################################################################
 # Constructors etc
 ###############################################################################

From 07bf02fbcd7dff26456c9eb14d112de20374d0e4 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 12:05:36 +0100
Subject: [PATCH 34/38] Better error messages in gv.gi

---
 gap/gv.gi        | 38 +++++++++++++++++++++++---------------
 tst/edge.tst     |  8 ++++++--
 tst/subgraph.tst |  9 ++++++---
 3 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/gap/gv.gi b/gap/gv.gi
index 593a9e1..3c56d6a 100644
--- a/gap/gv.gi
+++ b/gap/gv.gi
@@ -364,15 +364,20 @@ InstallMethod(GV_AddNode,
 "for a graphviz graph and node",
 [IsGraphvizGraphDigraphOrContext, IsGraphvizNode],
 function(x, node)
-  local found, error, name, nodes;
+  local name, nodes, found;
+
   name  := GraphvizName(node);
   nodes := GraphvizNodes(x);
 
   # dont add if already node with the same name
   found := GV_FindGraphWithNode(x, name);
   if found <> fail then
-    error := "Already node with name {} in graph {}.";
-    ErrorNoReturn(StringFormatted(error, name, GraphvizName(found)));
+    ErrorFormatted("the 2nd argument (node) has name \"{}\"",
+                   " but there is already a node with this name in ",
+                   "the 1st argument (a graphviz (di)graph / context)",
+                   " named \"{}\"",
+                   name,
+                   GraphvizName(x));
   fi;
 
   nodes[name] := node;
@@ -383,7 +388,7 @@ InstallMethod(GV_AddEdge,
 "for a graphviz graph and edge",
 [IsGraphvizGraphDigraphOrContext, IsGraphvizEdge],
 function(x, edge)
-  local head, head_name, tail_name, tail, hg, error, tg;
+  local head, tail, head_name, tail_name, hg, tg;
 
   head      := GraphvizHead(edge);
   tail      := GraphvizTail(edge);
@@ -393,18 +398,21 @@ function(x, edge)
   tg        := GV_FindGraphWithNode(x, tail_name);
 
   # make sure the nodes exist / are the same as existing ones
-  if hg <> fail and not IsIdenticalObj(head, hg[head_name]) then
-    # TODO improve
-    ErrorFormatted("Different node in graph {} with name {}",
-                   GraphvizName(hg),
-                   head_name);
+  if hg <> fail and head <> hg[head_name] then
+    ErrorFormatted("The 2nd argument (edge) has head node named \"{}\"",
+                   " but there is already a node with this name in ",
+                   "the 1st argument (a graphviz (di)graph / context)",
+                   " named \"{}\"",
+                   head_name,
+                   GraphvizName(x));
   fi;
-  if tg <> fail and not IsIdenticalObj(tail, tg[tail_name]) then
-    # TODO improve
-    error := "Different node in graph {} with name {}.";
-    ErrorNoReturn(StringFormatted(error,
-                                         GraphvizName(tg),
-                                         tail_name));
+  if tg <> fail and tail <> tg[tail_name] then
+    ErrorFormatted("The 2nd argument (edge) has tail node named \"{}\"",
+                   " but there is already a node with this name in ",
+                   "the 1st argument (a graphviz (di)graph / context)",
+                   " named \"{}\"",
+                   head_name,
+                   GraphvizName(x));
   fi;
 
   Add(x!.Edges, edge);
diff --git a/tst/edge.tst b/tst/edge.tst
index ae47f3c..05f9f8e 100644
--- a/tst/edge.tst
+++ b/tst/edge.tst
@@ -84,11 +84,15 @@ gap> a2 := GraphvizAddNode(g1, "a");;
 gap> c := GraphvizAddNode(g1, "c");;
 gap> e1 := GraphvizAddEdge(g, d, a1);;
 gap> e2 := GraphvizAddEdge(g, a2, c);;
-Error, Different node in graph  with name a
+Error, The 2nd argument (edge) has head node named "a" but there is already a \
+node with this name in the 1st argument (a graphviz (di)graph / context) named\
+ ""
 gap> GraphvizEdges(g);
 [ <graphviz edge (d, a)> ]
 gap> e2 := GraphvizAddEdge(g, c, a2);;
-Error, Different node in graph  with name a.
+Error, The 2nd argument (edge) has tail node named "c" but there is already a \
+node with this name in the 1st argument (a graphviz (di)graph / context) named\
+ ""
 
 # Test adding an edge reuses a node automatically
 gap> g := GraphvizGraph();;
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 462abab..bf94d16 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -88,14 +88,16 @@ gap> g := GraphvizGraph("r");;
 gap> s := GraphvizAddSubgraph(g, "a");;
 gap> GraphvizAddNode(g, "n");;
 gap> GraphvizAddNode(s, "n");
-Error, Already node with name n in graph r.
+Error, the 2nd argument (node) has name "n" but there is already a node with t\
+his name in the 1st argument (a graphviz (di)graph / context) named "a"
 
 # Test adding a node to a graph which is already in child fails (by name)
 gap> g := GraphvizGraph();;
 gap> s := GraphvizAddSubgraph(g, "a");;
 gap> GraphvizAddNode(s, "n");;
 gap> GraphvizAddNode(g, "n");
-Error, Already node with name n in graph a.
+Error, the 2nd argument (node) has name "n" but there is already a node with t\
+his name in the 1st argument (a graphviz (di)graph / context) named ""
 
 # Test adding a node to a graph which is already in sibling fails (by name)
 gap> g := GraphvizGraph();;
@@ -103,7 +105,8 @@ gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(g, "b");;
 gap> GraphvizAddNode(s1, "n");;
 gap> GraphvizAddNode(s2, "n");
-Error, Already node with name n in graph a.
+Error, the 2nd argument (node) has name "n" but there is already a node with t\
+his name in the 1st argument (a graphviz (di)graph / context) named "b"
 
 # Test adding edges to subgraphs
 gap> g := GraphvizGraph();;

From de8b6ca791d3540790d449fc16f53bdd1cf71844 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 12:14:30 +0100
Subject: [PATCH 35/38] Tweak ViewString and rewrite tests

---
 gap/dot.gi                      |  6 ++-
 tst/dot.tst                     | 41 ++++++++-------
 tst/edge.tst                    |  4 +-
 tst/examples/angles.tst         | 24 ++++-----
 tst/examples/btree.tst          | 22 ++++----
 tst/examples/cluster.tst        | 24 ++++-----
 tst/examples/cluster_edge.tst   |  8 +--
 tst/examples/colors.tst         | 24 ++++-----
 tst/examples/er.tst             | 44 ++++++++--------
 tst/examples/fsm.tst            | 22 ++++----
 tst/examples/g_c_n.tst          | 12 ++---
 tst/examples/hello.tst          |  2 +-
 tst/examples/process.tst        |  4 +-
 tst/examples/rank_same.tst      | 20 +++----
 tst/examples/structs.tst        | 10 ++--
 tst/examples/traffic_lights.tst | 18 +++----
 tst/examples/unix.tst           |  4 +-
 tst/graph.tst                   | 49 +++++++++---------
 tst/node.tst                    | 10 ++--
 tst/subgraph.tst                | 92 ++++++++++++++++-----------------
 20 files changed, 223 insertions(+), 217 deletions(-)

diff --git a/gap/dot.gi b/gap/dot.gi
index 05805ca..ab34369 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -49,13 +49,14 @@ InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
 #############################################################################
 
 InstallMethod(PrintString, "for a graphviz node", [IsGraphvizNode],
-n -> StringFormatted("<graphviz node {}>", GraphvizName(n)));
+n -> StringFormatted("<graphviz node \"{}\">", GraphvizName(n)));
 
 InstallMethod(PrintString, "for a graphviz edge", [IsGraphvizEdge],
 function(e)
   local head, tail;
   head := GraphvizHead(e);
   tail := GraphvizTail(e);
+
   return StringFormatted("<graphviz edge ({}, {})>",
                          GraphvizName(head),
                          GraphvizName(tail));
@@ -82,11 +83,12 @@ function(g)
   Append(result, StringFormatted("<graphviz {} ", kind));
 
   if GraphvizName(g) <> "" then
-    Append(result, StringFormatted("{} ", GraphvizName(g)));
+    Append(result, StringFormatted("\"{}\" ", GraphvizName(g)));
   fi;
 
   Append(result, StringFormatted("with {} ", GV_Pluralize(nodes, "node")));
   Append(result, StringFormatted("and {}>", GV_Pluralize(edges, "edge")));
+  # TODO add more info like that about number of subgraphs + contexts
 
   return result;
 end);
diff --git a/tst/dot.tst b/tst/dot.tst
index 9bffc61..f9c39e1 100644
--- a/tst/dot.tst
+++ b/tst/dot.tst
@@ -75,7 +75,7 @@ gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "n");;
 gap> GraphvizSetAttr(n, "test", "false");
 #I  unknown attribute "test", the graphviz object may no longer be valid, it can be removed using GraphvizRemoveAttr
-<graphviz node n>
+<graphviz node "n">
 
 # Test unknown attributes (graph)
 gap> g := GraphvizGraph();;
@@ -109,15 +109,15 @@ gap> AsString(g);
 
 # Test GraphvizSetNodeLabels
 gap> gv := GraphvizGraph("xxx");
-<graphviz graph xxx with 0 nodes and 0 edges>
+<graphviz graph "xxx" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(gv, 1);
-<graphviz node 1>
+<graphviz node "1">
 gap> GraphvizAddNode(gv, 2);
-<graphviz node 2>
+<graphviz node "2">
 gap> GraphvizAddNode(gv, 3);
-<graphviz node 3>
+<graphviz node "3">
 gap> GraphvizSetNodeLabels(gv, ["i", "ii", "iii"]);
-<graphviz graph xxx with 3 nodes and 0 edges>
+<graphviz graph "xxx" with 3 nodes and 0 edges>
 gap> Print(AsString(gv));
 //dot
 graph xxx {
@@ -126,7 +126,7 @@ graph xxx {
 	3 [label=iii]
 }
 gap> GraphvizSetNodeLabels(gv, ["a", "b", "c"]);
-<graphviz graph xxx with 3 nodes and 0 edges>
+<graphviz graph "xxx" with 3 nodes and 0 edges>
 gap> Print(AsString(gv));
 //dot
 graph xxx {
@@ -143,13 +143,13 @@ Error, the 2nd argument (list of node labels) has incorrect length, expected 3\
 
 # Test GraphvizSetNodeColors
 gap> gv := GraphvizGraph("xxx");
-<graphviz graph xxx with 0 nodes and 0 edges>
+<graphviz graph "xxx" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(gv, 1);
-<graphviz node 1>
+<graphviz node "1">
 gap> GraphvizAddNode(gv, 2);
-<graphviz node 2>
+<graphviz node "2">
 gap> GraphvizAddNode(gv, 3);
-<graphviz node 3>
+<graphviz node "3">
 #@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizSetNodeColors(gv, ["i", "ii", "iii"]);
 Error, invalid color "i" (list (string)), valid colors are RGB values or names\
@@ -162,7 +162,7 @@ Error, invalid color "i" (list (string)), valid colors are RGB values or names\
 eme http://graphviz.org/doc/info/colors.html
 #@fi
 gap> GraphvizSetNodeColors(gv, ["red", "green", "blue"]);
-<graphviz graph xxx with 3 nodes and 0 edges>
+<graphviz graph "xxx" with 3 nodes and 0 edges>
 gap> Print(AsString(gv));
 //dot
 graph xxx {
@@ -171,7 +171,7 @@ graph xxx {
 	3 [color=blue, style=filled]
 }
 gap> GraphvizSetNodeColors(gv, ["red", "#00FF00", "blue"]);
-<graphviz graph xxx with 3 nodes and 0 edges>
+<graphviz graph "xxx" with 3 nodes and 0 edges>
 gap> Print(AsString(gv));
 //dot
 graph xxx {
@@ -180,7 +180,7 @@ graph xxx {
 	3 [color=blue, style=filled]
 }
 gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FF"]);
-<graphviz graph xxx with 3 nodes and 0 edges>
+<graphviz graph "xxx" with 3 nodes and 0 edges>
 gap> Print(AsString(gv));
 //dot
 graph xxx {
@@ -205,24 +205,25 @@ cted 3 but found 2
 gap> GraphvizAddEdge(gv, "a", "b");
 <graphviz edge (a, b)>
 gap> GraphvizNodes(gv);
-rec( 1 := <graphviz node 1>, 2 := <graphviz node 2>, 3 := <graphviz node 3>, 
-  a := <graphviz node a>, b := <graphviz node b> )
+rec( 1 := <graphviz node "1">, 2 := <graphviz node "2">, 
+  3 := <graphviz node "3">, a := <graphviz node "a">, 
+  b := <graphviz node "b"> )
 
 # Test attribute names with spaces (TODO are there any valid such??)
 gap> gv := GraphvizGraph("xxx");
-<graphviz graph xxx with 0 nodes and 0 edges>
+<graphviz graph "xxx" with 0 nodes and 0 edges>
 gap> n := GraphvizAddNode(gv, 1);
-<graphviz node 1>
+<graphviz node "1">
 gap> n := GraphvizSetAttr(n, "probably not ok", 1);
 #I  unknown attribute "probably not ok", the graphviz object may no longer be valid, it can be removed using GraphvizRemoveAttr
-<graphviz node 1>
+<graphviz node "1">
 gap> Print(AsString(gv));
 //dot
 graph xxx {
 	1 ["probably not ok"=1]
 }
 gap> GraphvizSetAttr(n, "label", "<<>>");
-<graphviz node 1>
+<graphviz node "1">
 gap> Print(AsString(gv));
 //dot
 graph xxx {
diff --git a/tst/edge.tst b/tst/edge.tst
index 05f9f8e..19afffc 100644
--- a/tst/edge.tst
+++ b/tst/edge.tst
@@ -24,9 +24,9 @@ gap> g := GraphvizGraph();;
 gap> e := GraphvizAddEdge(g, "a", "b");
 <graphviz edge (a, b)>
 gap> GraphvizHead(e);
-<graphviz node a>
+<graphviz node "a">
 gap> GraphvizTail(e);
-<graphviz node b>
+<graphviz node "b">
 
 # Test filtering edges by names (digraph)
 gap> g := GraphvizDigraph();;
diff --git a/tst/examples/angles.tst b/tst/examples/angles.tst
index fc39502..ee25a19 100644
--- a/tst/examples/angles.tst
+++ b/tst/examples/angles.tst
@@ -16,19 +16,19 @@ gap> START_TEST("graphviz package: examples/angles.tst");
 gap> LoadPackage("graphviz");
 true
 gap> g := GraphvizDigraph("G");
-<graphviz digraph G with 0 nodes and 0 edges>
+<graphviz digraph "G" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(g, "bgcolor", "blue");
-<graphviz digraph G with 0 nodes and 0 edges>
+<graphviz digraph "G" with 0 nodes and 0 edges>
 gap> cluster1 := GraphvizAddSubgraph(g, "cluster_1");
-<graphviz digraph cluster_1 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster1, "fontcolor", "white");
-<graphviz digraph cluster_1 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster1, Concatenation("node[shape=circle, style=filled,",
 > "fillcolor=\"white:black\", gradientangle=360, label=\"n9:n360\",",
 > "fontcolor=black]"));
-<graphviz digraph cluster_1 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_1" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(cluster1, "n9");
-<graphviz node n9>
+<graphviz node "n9">
 gap> pairs := ListN([8, 7 .. 1], [315, 270 .. 0], {x, y} -> [x, y]);
 [ [ 8, 315 ], [ 7, 270 ], [ 6, 225 ], [ 5, 180 ], [ 4, 135 ], [ 3, 90 ], 
   [ 2, 45 ], [ 1, 0 ] ]
@@ -41,17 +41,17 @@ gap> for pair in pairs do
 gap> GraphvizSetAttr(cluster1,
 >                 "label",
 >                 "Linear Angle Variations (white to black gradient)");
-<graphviz digraph cluster_1 with 9 nodes and 0 edges>
+<graphviz digraph "cluster_1" with 9 nodes and 0 edges>
 gap> cluster2 := GraphvizAddSubgraph(g, "cluster_2");
-<graphviz digraph cluster_2 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_2" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster2, "fontcolor", "white");
-<graphviz digraph cluster_2 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_2" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster2, Concatenation("node[shape=circle, style=radial,",
 >                 "fillcolor=\"white:black\", gradientangle=360,",
 >                 "label=\"n9:n360\", fontcolor=black]"));
-<graphviz digraph cluster_2 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_2" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(cluster2, "n18");
-<graphviz node n18>
+<graphviz node "n18">
 gap> pairs := ListN([17, 16 .. 10], [315, 270 .. 0], {x, y} -> [x, y]);
 [ [ 17, 315 ], [ 16, 270 ], [ 15, 225 ], [ 14, 180 ], [ 13, 135 ], 
   [ 12, 90 ], [ 11, 45 ], [ 10, 0 ] ]
@@ -63,7 +63,7 @@ gap> for pair in pairs do
 > od;
 gap> GraphvizSetAttr(cluster2, "label",
 >                 "Radial Angle Variations (white to black gradient)");
-<graphviz digraph cluster_2 with 9 nodes and 0 edges>
+<graphviz digraph "cluster_2" with 9 nodes and 0 edges>
 gap> GraphvizAddEdge(g, "n5", "n14");
 <graphviz edge (n5, n14)>
 
diff --git a/tst/examples/btree.tst b/tst/examples/btree.tst
index 555996e..d693e1b 100644
--- a/tst/examples/btree.tst
+++ b/tst/examples/btree.tst
@@ -18,27 +18,27 @@ true
 
 #
 gap> s := GraphvizDigraph("g");
-<graphviz digraph g with 0 nodes and 0 edges>
+<graphviz digraph "g" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(s, "node [shape=record, height=.1]");
-<graphviz digraph g with 0 nodes and 0 edges>
+<graphviz digraph "g" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node0"), "label", "<f0> |<f1> G|<f2>");
-<graphviz node node0>
+<graphviz node "node0">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node1"), "label", "<f0> |<f1> E|<f2>");
-<graphviz node node1>
+<graphviz node "node1">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node2"), "label", "<f0> |<f1> B|<f2>");
-<graphviz node node2>
+<graphviz node "node2">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node3"), "label", "<f0> |<f1> F|<f2>");
-<graphviz node node3>
+<graphviz node "node3">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node4"), "label", "<f0> |<f1> R|<f2>");
-<graphviz node node4>
+<graphviz node "node4">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node5"), "label", "<f0> |<f1> H|<f2>");
-<graphviz node node5>
+<graphviz node "node5">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node6"), "label", "<f0> |<f1> Y|<f2>");
-<graphviz node node6>
+<graphviz node "node6">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node7"), "label", "<f0> |<f1> A|<f2>");
-<graphviz node node7>
+<graphviz node "node7">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "node8"), "label", "<f0> |<f1> C|<f2>");
-<graphviz node node8>
+<graphviz node "node8">
 gap> GraphvizAddEdge(s, "node0:f2", "node4:f1");
 <graphviz edge (node0:f2, node4:f1)>
 gap> GraphvizAddEdge(s, "node0:f0", "node1:f1");
diff --git a/tst/examples/cluster.tst b/tst/examples/cluster.tst
index fc03e78..32023fa 100644
--- a/tst/examples/cluster.tst
+++ b/tst/examples/cluster.tst
@@ -15,17 +15,17 @@ gap> START_TEST("graphviz package: examples/cluster.tst");
 gap> LoadPackage("graphviz");
 true
 gap> graph := GraphvizDigraph("G");
-<graphviz digraph G with 0 nodes and 0 edges>
+<graphviz digraph "G" with 0 nodes and 0 edges>
 
 #
 gap> cluster0 := GraphvizAddSubgraph(graph, "cluster_0");
-<graphviz digraph cluster_0 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_0" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster0, "color=\"lightgrey\"");
-<graphviz digraph cluster_0 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_0" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster0, "style=\"filled\"");
-<graphviz digraph cluster_0 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_0" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster0, "node [color=\"white\", style=\"filled\"]");
-<graphviz digraph cluster_0 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_0" with 0 nodes and 0 edges>
 gap> GraphvizAddEdge(cluster0, "a0", "a1");
 <graphviz edge (a0, a1)>
 gap> GraphvizAddEdge(cluster0, "a1", "a2");
@@ -33,15 +33,15 @@ gap> GraphvizAddEdge(cluster0, "a1", "a2");
 gap> GraphvizAddEdge(cluster0, "a2", "a3");
 <graphviz edge (a2, a3)>
 gap> GraphvizSetAttr(cluster0, "label=\"process #1\"");
-<graphviz digraph cluster_0 with 4 nodes and 3 edges>
+<graphviz digraph "cluster_0" with 4 nodes and 3 edges>
 
 #
 gap> cluster1 := GraphvizAddSubgraph(graph, "cluster_1");
-<graphviz digraph cluster_1 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster1, "color=\"blue\"");
-<graphviz digraph cluster_1 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster1, "node [style=\"filled\"]");
-<graphviz digraph cluster_1 with 0 nodes and 0 edges>
+<graphviz digraph "cluster_1" with 0 nodes and 0 edges>
 gap> GraphvizAddEdge(cluster1, "b0", "b1");
 <graphviz edge (b0, b1)>
 gap> GraphvizAddEdge(cluster1, "b1", "b2");
@@ -49,7 +49,7 @@ gap> GraphvizAddEdge(cluster1, "b1", "b2");
 gap> GraphvizAddEdge(cluster1, "b2", "b3");
 <graphviz edge (b2, b3)>
 gap> GraphvizSetAttr(cluster1, "label=\"process #2\"");
-<graphviz digraph cluster_1 with 4 nodes and 3 edges>
+<graphviz digraph "cluster_1" with 4 nodes and 3 edges>
 
 #
 gap> GraphvizAddEdge(graph, "start", "a0");
@@ -69,9 +69,9 @@ gap> GraphvizAddEdge(graph, "b3", "end");
 
 #
 gap> GraphvizSetAttr(graph["start"], "shape", "Mdiamond");
-<graphviz node start>
+<graphviz node "start">
 gap> GraphvizSetAttr(graph["end"], "shape", "Msquare");
-<graphviz node end>
+<graphviz node "end">
 
 #
 gap> AsString(graph);
diff --git a/tst/examples/cluster_edge.tst b/tst/examples/cluster_edge.tst
index a3f9461..4b4a9f2 100644
--- a/tst/examples/cluster_edge.tst
+++ b/tst/examples/cluster_edge.tst
@@ -18,11 +18,11 @@ true
 
 #
 gap> g := GraphvizDigraph("G");
-<graphviz digraph G with 0 nodes and 0 edges>
+<graphviz digraph "G" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(g, "compound=true");
-<graphviz digraph G with 0 nodes and 0 edges>
+<graphviz digraph "G" with 0 nodes and 0 edges>
 gap> cluster0 := GraphvizAddSubgraph(g, "cluster0");
-<graphviz digraph cluster0 with 0 nodes and 0 edges>
+<graphviz digraph "cluster0" with 0 nodes and 0 edges>
 gap> GraphvizAddEdge(cluster0, "a", "b");
 <graphviz edge (a, b)>
 gap> GraphvizAddEdge(cluster0, "a", "c");
@@ -32,7 +32,7 @@ gap> GraphvizAddEdge(cluster0, "b", "d");
 gap> GraphvizAddEdge(cluster0, "c", "d");
 <graphviz edge (c, d)>
 gap> cluster1 := GraphvizAddSubgraph(g, "cluster1");
-<graphviz digraph cluster1 with 0 nodes and 0 edges>
+<graphviz digraph "cluster1" with 0 nodes and 0 edges>
 gap> GraphvizAddEdge(cluster1, "e", "g");
 <graphviz edge (e, g)>
 gap> GraphvizAddEdge(cluster1, "e", "f");
diff --git a/tst/examples/colors.tst b/tst/examples/colors.tst
index 71eb3f7..1c044da 100644
--- a/tst/examples/colors.tst
+++ b/tst/examples/colors.tst
@@ -23,35 +23,35 @@ gap> g := GraphvizGraph();
 
 #
 gap> node := GraphvizAddNode(g, "RGB: #40e0d0");
-<graphviz node RGB: #40e0d0>
+<graphviz node "RGB: #40e0d0">
 gap> GraphvizSetAttr(node, "style", "filled");
-<graphviz node RGB: #40e0d0>
+<graphviz node "RGB: #40e0d0">
 gap> GraphvizSetAttr(node, "fillcolor", "\"#40e0d0\"");
-<graphviz node RGB: #40e0d0>
+<graphviz node "RGB: #40e0d0">
 
 #
 gap> node := GraphvizAddNode(g, "RGBA: #ff000042");
-<graphviz node RGBA: #ff000042>
+<graphviz node "RGBA: #ff000042">
 gap> GraphvizSetAttr(node, "style", "filled");
-<graphviz node RGBA: #ff000042>
+<graphviz node "RGBA: #ff000042">
 gap> GraphvizSetAttr(node, "fillcolor", "\"#ff000042\"");
-<graphviz node RGBA: #ff000042>
+<graphviz node "RGBA: #ff000042">
 
 #
 gap> node := GraphvizAddNode(g, "HSV: 0.051 0.718 0.627");
-<graphviz node HSV: 0.051 0.718 0.627>
+<graphviz node "HSV: 0.051 0.718 0.627">
 gap> GraphvizSetAttr(node, "style", "filled");
-<graphviz node HSV: 0.051 0.718 0.627>
+<graphviz node "HSV: 0.051 0.718 0.627">
 gap> GraphvizSetAttr(node, "fillcolor", "0.051 0.718 0.627");
-<graphviz node HSV: 0.051 0.718 0.627>
+<graphviz node "HSV: 0.051 0.718 0.627">
 
 #
 gap> node := GraphvizAddNode(g, "name: deeppink");
-<graphviz node name: deeppink>
+<graphviz node "name: deeppink">
 gap> GraphvizSetAttr(node, "style", "filled");
-<graphviz node name: deeppink>
+<graphviz node "name: deeppink">
 gap> GraphvizSetAttr(node, "fillcolor", "deeppink");
-<graphviz node name: deeppink>
+<graphviz node "name: deeppink">
 
 #
 gap> AsString(g);
diff --git a/tst/examples/er.tst b/tst/examples/er.tst
index 94ffc72..d48d7c0 100644
--- a/tst/examples/er.tst
+++ b/tst/examples/er.tst
@@ -18,52 +18,52 @@ true
 
 #
 gap> e := GraphvizGraph("ER");
-<graphviz graph ER with 0 nodes and 0 edges>
+<graphviz graph "ER" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(e, "engine=\"neato\"");
-<graphviz graph ER with 0 nodes and 0 edges>
+<graphviz graph "ER" with 0 nodes and 0 edges>
 
 #
 gap> start := GraphvizAddContext(e, "context_start");
-<graphviz context context_start with 0 nodes and 0 edges>
+<graphviz context "context_start" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(start, "node[shape=\"box\"]");
-<graphviz context context_start with 0 nodes and 0 edges>
+<graphviz context "context_start" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(start, "course");
-<graphviz node course>
+<graphviz node "course">
 gap> GraphvizAddNode(start, "institute");
-<graphviz node institute>
+<graphviz node "institute">
 gap> GraphvizAddNode(start, "student");
-<graphviz node student>
+<graphviz node "student">
 
 #
 gap> context1 := GraphvizAddContext(e, "context1");
-<graphviz context context1 with 0 nodes and 0 edges>
+<graphviz context "context1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(context1, "node [shape=\"ellipse\"]");
-<graphviz context context1 with 0 nodes and 0 edges>
+<graphviz context "context1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(GraphvizAddNode(context1, "name0"), "label", "name");
-<graphviz node name0>
+<graphviz node "name0">
 gap> GraphvizSetAttr(GraphvizAddNode(context1, "name1"), "label", "name");
-<graphviz node name1>
+<graphviz node "name1">
 gap> GraphvizSetAttr(GraphvizAddNode(context1, "name2"), "label", "name");
-<graphviz node name2>
+<graphviz node "name2">
 gap> GraphvizAddNode(context1, "code");
-<graphviz node code>
+<graphviz node "code">
 gap> GraphvizAddNode(context1, "grade");
-<graphviz node grade>
+<graphviz node "grade">
 gap> GraphvizAddNode(context1, "number");
-<graphviz node number>
+<graphviz node "number">
 
 #
 gap> context2 := GraphvizAddContext(e, "context2");
-<graphviz context context2 with 0 nodes and 0 edges>
+<graphviz context "context2" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(context2,
 > "node [shape=\"diamond\", style=\"filled\", color=\"lightgrey\"]");
-<graphviz context context2 with 0 nodes and 0 edges>
+<graphviz context "context2" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(context2, "C-I");
-<graphviz node C-I>
+<graphviz node "C-I">
 gap> GraphvizAddNode(context2, "S-C");
-<graphviz node S-C>
+<graphviz node "S-C">
 gap> GraphvizAddNode(context2, "S-I");
-<graphviz node S-I>
+<graphviz node "S-I">
 
 #
 gap> GraphvizAddEdge(e, "name0", "course");
@@ -99,9 +99,9 @@ gap> GraphvizSetAttrs(GraphvizAddEdge(e, "course", "S-C"),
 
 #
 gap> GraphvizSetAttr(e, "label=\"Entity Relation Diagram\ndrawn by NEATO\"");
-<graphviz graph ER with 0 nodes and 12 edges>
+<graphviz graph "ER" with 0 nodes and 12 edges>
 gap> GraphvizSetAttr(e, "fontsize=\"20\"");
-<graphviz graph ER with 0 nodes and 12 edges>
+<graphviz graph "ER" with 0 nodes and 12 edges>
 
 #
 gap> AsString(e);
diff --git a/tst/examples/fsm.tst b/tst/examples/fsm.tst
index 6e8f291..9310d3c 100644
--- a/tst/examples/fsm.tst
+++ b/tst/examples/fsm.tst
@@ -18,31 +18,31 @@ true
 
 #
 gap> f := GraphvizDigraph("finite_state_machine");
-<graphviz digraph finite_state_machine with 0 nodes and 0 edges>
+<graphviz digraph "finite_state_machine" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(f, "rankdir=LR");
-<graphviz digraph finite_state_machine with 0 nodes and 0 edges>
+<graphviz digraph "finite_state_machine" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(f, "size=\"8,5\"");
-<graphviz digraph finite_state_machine with 0 nodes and 0 edges>
+<graphviz digraph "finite_state_machine" with 0 nodes and 0 edges>
 
 #
 gap> terminals := GraphvizAddContext(f, "terminals");
-<graphviz context terminals with 0 nodes and 0 edges>
+<graphviz context "terminals" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(terminals, "node [shape=doublecircle]");
-<graphviz context terminals with 0 nodes and 0 edges>
+<graphviz context "terminals" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(terminals, "LR_0");
-<graphviz node LR_0>
+<graphviz node "LR_0">
 gap> GraphvizAddNode(terminals, "LR_3");
-<graphviz node LR_3>
+<graphviz node "LR_3">
 gap> GraphvizAddNode(terminals, "LR_4");
-<graphviz node LR_4>
+<graphviz node "LR_4">
 gap> GraphvizAddNode(terminals, "LR_8");
-<graphviz node LR_8>
+<graphviz node "LR_8">
 
 #
 gap> nodes := GraphvizAddContext(f, "nodes");
-<graphviz context nodes with 0 nodes and 0 edges>
+<graphviz context "nodes" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(nodes, "node [shape=circle]");
-<graphviz context nodes with 0 nodes and 0 edges>
+<graphviz context "nodes" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(GraphvizAddEdge(nodes, "LR_0", "LR_2"), "label", "\"SS(B)\"");
 <graphviz edge (LR_0, LR_2)>
 gap> GraphvizSetAttr(GraphvizAddEdge(nodes, "LR_0", "LR_1"), "label", "\"SS(S)\"");
diff --git a/tst/examples/g_c_n.tst b/tst/examples/g_c_n.tst
index 58261ae..560cb09 100644
--- a/tst/examples/g_c_n.tst
+++ b/tst/examples/g_c_n.tst
@@ -18,22 +18,22 @@ true
 
 #
 gap> g := GraphvizGraph("G");
-<graphviz graph G with 0 nodes and 0 edges>
+<graphviz graph "G" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(g,
 > "bgcolor=\"purple:pink\" label=\"agraph\" fontcolor=\"white\"");
-<graphviz graph G with 0 nodes and 0 edges>
+<graphviz graph "G" with 0 nodes and 0 edges>
 gap> cluster1 := GraphvizAddSubgraph(g, "cluster1");
-<graphviz graph cluster1 with 0 nodes and 0 edges>
+<graphviz graph "cluster1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster1, Concatenation(
 > "fillcolor=\"blue:cyan\" label=\"acluster\" fontcolor=\"white\"",
 > "style=\"filled\" gradientangle=270\n"));
-<graphviz graph cluster1 with 0 nodes and 0 edges>
+<graphviz graph "cluster1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(cluster1, Concatenation(
 > "node [shape=box, fillcolor=\"red:yellow\",",
 > " style=\"filled\", gradientangle=90]"));
-<graphviz graph cluster1 with 0 nodes and 0 edges>
+<graphviz graph "cluster1" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(cluster1, "anode");
-<graphviz node anode>
+<graphviz node "anode">
 
 #@if CompareVersionNumbers(GAPInfo.Version, "4.12.0")
 gap> Print(AsString(g));
diff --git a/tst/examples/hello.tst b/tst/examples/hello.tst
index 9c4ae17..a7f8f38 100644
--- a/tst/examples/hello.tst
+++ b/tst/examples/hello.tst
@@ -17,7 +17,7 @@ true
 
 #
 gap> graph := GraphvizDigraph("G");
-<graphviz digraph G with 0 nodes and 0 edges>
+<graphviz digraph "G" with 0 nodes and 0 edges>
 gap> GraphvizAddEdge(graph, "hello", "world");
 <graphviz edge (hello, world)>
 gap> AsString(graph);
diff --git a/tst/examples/process.tst b/tst/examples/process.tst
index 75e9c20..4a57db2 100644
--- a/tst/examples/process.tst
+++ b/tst/examples/process.tst
@@ -18,9 +18,9 @@ true
 
 #
 gap> graph := GraphvizGraph("G");
-<graphviz graph G with 0 nodes and 0 edges>
+<graphviz graph "G" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(graph, "engine=\"sfdp\"");
-<graphviz graph G with 0 nodes and 0 edges>
+<graphviz graph "G" with 0 nodes and 0 edges>
 
 #
 gap> GraphvizAddEdge(graph, "run", "intr");
diff --git a/tst/examples/rank_same.tst b/tst/examples/rank_same.tst
index 5417cd5..1e9a7f4 100644
--- a/tst/examples/rank_same.tst
+++ b/tst/examples/rank_same.tst
@@ -23,29 +23,29 @@ gap> g := GraphvizDigraph();
 
 #
 gap> s1 := GraphvizAddSubgraph(g);
-<graphviz digraph no_name_1 with 0 nodes and 0 edges>
+<graphviz digraph "no_name_1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(s1, "rank=same");
-<graphviz digraph no_name_1 with 0 nodes and 0 edges>
+<graphviz digraph "no_name_1" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(s1, "A");
-<graphviz node A>
+<graphviz node "A">
 gap> GraphvizAddNode(s1, "X");
-<graphviz node X>
+<graphviz node "X">
 
 #
 gap> GraphvizAddNode(g, "C");
-<graphviz node C>
+<graphviz node "C">
 
 #
 gap> s2 := GraphvizAddSubgraph(g);
-<graphviz digraph no_name_3 with 0 nodes and 0 edges>
+<graphviz digraph "no_name_3" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(s2, "rank=same");
-<graphviz digraph no_name_3 with 0 nodes and 0 edges>
+<graphviz digraph "no_name_3" with 0 nodes and 0 edges>
 gap> GraphvizAddNode(s2, "B");
-<graphviz node B>
+<graphviz node "B">
 gap> GraphvizAddNode(s2, "D");
-<graphviz node D>
+<graphviz node "D">
 gap> GraphvizAddNode(s2, "Y");
-<graphviz node Y>
+<graphviz node "Y">
 
 #
 gap> GraphvizAddEdge(g, "A", "B");
diff --git a/tst/examples/structs.tst b/tst/examples/structs.tst
index 2e4d14c..8de2523 100644
--- a/tst/examples/structs.tst
+++ b/tst/examples/structs.tst
@@ -16,9 +16,9 @@ gap> START_TEST("graphviz package: examples/structs.tst");
 gap> LoadPackage("graphviz");
 true
 gap> s := GraphvizDigraph("structs");
-<graphviz digraph structs with 0 nodes and 0 edges>
+<graphviz digraph "structs" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(s, "node [shape=\"plaintext\"]");
-<graphviz digraph structs with 0 nodes and 0 edges>
+<graphviz digraph "structs" with 0 nodes and 0 edges>
 
 #
 gap> GraphvizSetAttr(GraphvizAddNode(s, "struct1"), "label",
@@ -28,7 +28,7 @@ gap> GraphvizSetAttr(GraphvizAddNode(s, "struct1"), "label",
 > <TD PORT="f1">middle</TD><TD PORT="f2">right</TD>
 > </TR>
 > </TABLE>>""");
-<graphviz node struct1>
+<graphviz node "struct1">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "struct2"), "label",
 > """<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
 > <TR>
@@ -36,7 +36,7 @@ gap> GraphvizSetAttr(GraphvizAddNode(s, "struct2"), "label",
 > <TD>two</TD>
 > </TR>
 > </TABLE>>""");
-<graphviz node struct2>
+<graphviz node "struct2">
 gap> GraphvizSetAttr(GraphvizAddNode(s, "struct3"), "label",
 > """<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
 > <TR>
@@ -54,7 +54,7 @@ gap> GraphvizSetAttr(GraphvizAddNode(s, "struct3"), "label",
 > <TD COLSPAN="3">f</TD>
 > </TR>
 > </TABLE>>""");
-<graphviz node struct3>
+<graphviz node "struct3">
 
 #
 gap> GraphvizAddEdge(s, "struct1:f1", "struct2:f0");
diff --git a/tst/examples/traffic_lights.tst b/tst/examples/traffic_lights.tst
index a2b64c4..3b6259c 100644
--- a/tst/examples/traffic_lights.tst
+++ b/tst/examples/traffic_lights.tst
@@ -16,15 +16,15 @@ gap> START_TEST("graphviz package: examples/traffic_lights.tst");
 gap> LoadPackage("graphviz");
 true
 gap> t := GraphvizDigraph("TrafficLights");
-<graphviz digraph TrafficLights with 0 nodes and 0 edges>
+<graphviz digraph "TrafficLights" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(t, "engine=neato");
-<graphviz digraph TrafficLights with 0 nodes and 0 edges>
+<graphviz digraph "TrafficLights" with 0 nodes and 0 edges>
 
 #
 gap> ctx1 := GraphvizAddSubgraph(t, "ctx1");
-<graphviz digraph ctx1 with 0 nodes and 0 edges>
+<graphviz digraph "ctx1" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(ctx1, "node [shape=\"box\"]");
-<graphviz digraph ctx1 with 0 nodes and 0 edges>
+<graphviz digraph "ctx1" with 0 nodes and 0 edges>
 gap> for i in [2, 1] do
 >     GraphvizAddNode(ctx1, StringFormatted("gy{}", i));
 >     GraphvizAddNode(ctx1, StringFormatted("yr{}", i));
@@ -33,9 +33,9 @@ gap> for i in [2, 1] do
 
 #
 gap> ctx2 := GraphvizAddSubgraph(t, "ctx2");
-<graphviz digraph ctx2 with 0 nodes and 0 edges>
+<graphviz digraph "ctx2" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(ctx2, "node [shape=\"circle\", fixedsize=true, width=0.9]");
-<graphviz digraph ctx2 with 0 nodes and 0 edges>
+<graphviz digraph "ctx2" with 0 nodes and 0 edges>
 gap> for i in [2, 1] do
 >     GraphvizAddNode(ctx2, StringFormatted("green{}", i));
 >     GraphvizAddNode(ctx2, StringFormatted("yellow{}", i));
@@ -69,14 +69,14 @@ gap> for pair in [[2, 1], [1, 2]] do
 
 #
 gap> GraphvizSetAttr(t, "overlap=\"false\"");
-<graphviz digraph TrafficLights with 0 nodes and 16 edges>
+<graphviz digraph "TrafficLights" with 0 nodes and 16 edges>
 gap> GraphvizSetAttr(t,
 > """label="PetriNet Model TrafficLights
 > Extracted from ConceptBase and laid out by Graphviz"
 > """);
-<graphviz digraph TrafficLights with 0 nodes and 16 edges>
+<graphviz digraph "TrafficLights" with 0 nodes and 16 edges>
 gap> GraphvizSetAttr(t, "fontsize=12");
-<graphviz digraph TrafficLights with 0 nodes and 16 edges>
+<graphviz digraph "TrafficLights" with 0 nodes and 16 edges>
 
 #
 gap> AsString(t);
diff --git a/tst/examples/unix.tst b/tst/examples/unix.tst
index 13ea228..833ce3d 100644
--- a/tst/examples/unix.tst
+++ b/tst/examples/unix.tst
@@ -18,10 +18,10 @@ true
 
 #
 gap> u := GraphvizDigraph("unix");
-<graphviz digraph unix with 0 nodes and 0 edges>
+<graphviz digraph "unix" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(
 > u, "node [color=\"lightblue2\", style=\"filled\", size=\"6,6\"]");
-<graphviz digraph unix with 0 nodes and 0 edges>
+<graphviz digraph "unix" with 0 nodes and 0 edges>
 
 #
 gap> GraphvizAddEdge(u, "5th Edition", "6th Edition");
diff --git a/tst/graph.tst b/tst/graph.tst
index 7fd2b95..1bc010e 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -18,44 +18,44 @@ gap> GraphvizGraph();
 
 # Test graph constructor
 gap> GraphvizGraph("test-name");
-<graphviz graph test-name with 0 nodes and 0 edges>
+<graphviz graph "test-name" with 0 nodes and 0 edges>
 
 # Test digraph printing
 gap> x := GraphvizDigraph("test-name");
-<graphviz digraph test-name with 0 nodes and 0 edges>
+<graphviz digraph "test-name" with 0 nodes and 0 edges>
 gap> x := GraphvizDigraph();
 <graphviz digraph with 0 nodes and 0 edges>
 
 # Test adding nodes
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "n");
-<graphviz node n>
+<graphviz node "n">
 gap> g;
 <graphviz graph with 1 node and 0 edges>
 gap> GraphvizNodes(g);
-rec( n := <graphviz node n> )
+rec( n := <graphviz node "n"> )
 gap> GraphvizAddNode(g, "x");
-<graphviz node x>
+<graphviz node "x">
 gap> g;
 <graphviz graph with 2 nodes and 0 edges>
 gap> GraphvizNodes(g);
-rec( n := <graphviz node n>, x := <graphviz node x> )
+rec( n := <graphviz node "n">, x := <graphviz node "x"> )
 
 # Test add node (name)
 gap> g := GraphvizGraph();;
 gap> GraphvizAddNode(g, "n");
-<graphviz node n>
+<graphviz node "n">
 gap> GraphvizNodes(g);
-rec( n := <graphviz node n> )
+rec( n := <graphviz node "n"> )
 gap> GraphvizAddNode(g, "x");
-<graphviz node x>
+<graphviz node "x">
 gap> GraphvizNodes(g);
-rec( n := <graphviz node n>, x := <graphviz node x> )
+rec( n := <graphviz node "n">, x := <graphviz node "x"> )
 
 # Test has nodes
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "n");
-<graphviz node n>
+<graphviz node "n">
 gap> GV_HasNode(g, "n");
 true
 gap> GV_HasNode(g, "x");
@@ -124,7 +124,8 @@ gap> GraphvizAddEdge(g, "a", "b");;
 gap> GraphvizAddEdge(g, "a", "c");
 <graphviz edge (a, c)>
 gap> GraphvizNodes(g);
-rec( a := <graphviz node a>, b := <graphviz node b>, c := <graphviz node c> )
+rec( a := <graphviz node "a">, b := <graphviz node "b">, 
+  c := <graphviz node "c"> )
 gap> GraphvizAddEdge(g, "c", "a");
 <graphviz edge (c, a)>
 gap> GraphvizAddEdge(g, "b", "d");
@@ -151,13 +152,14 @@ gap> GraphvizAddEdge(g, c, d);;
 gap> GraphvizRemoveNode(g, a);
 <graphviz graph with 3 nodes and 1 edge>
 gap> GraphvizNodes(g);
-rec( b := <graphviz node b>, c := <graphviz node c>, d := <graphviz node d> )
+rec( b := <graphviz node "b">, c := <graphviz node "c">, 
+  d := <graphviz node "d"> )
 gap> GraphvizEdges(g);
 [ <graphviz edge (c, d)> ]
 gap> GraphvizRemoveNode(g, b);
 <graphviz graph with 2 nodes and 1 edge>
 gap> GraphvizNodes(g);
-rec( c := <graphviz node c>, d := <graphviz node d> )
+rec( c := <graphviz node "c">, d := <graphviz node "d"> )
 
 # Test removing node
 gap> g := GraphvizGraph();;
@@ -166,25 +168,26 @@ gap> GraphvizAddEdge(g, "c", "d");;
 gap> GraphvizRemoveNode(g, "a");
 <graphviz graph with 3 nodes and 1 edge>
 gap> GraphvizNodes(g);
-rec( b := <graphviz node b>, c := <graphviz node c>, d := <graphviz node d> )
+rec( b := <graphviz node "b">, c := <graphviz node "c">, 
+  d := <graphviz node "d"> )
 gap> GraphvizEdges(g);
 [ <graphviz edge (c, d)> ]
 gap> GraphvizRemoveNode(g, "b");
 <graphviz graph with 2 nodes and 1 edge>
 gap> GraphvizNodes(g);
-rec( c := <graphviz node c>, d := <graphviz node d> )
+rec( c := <graphviz node "c">, d := <graphviz node "d"> )
 
 # Test renaming graph
 gap> g := GraphvizGraph();;
 gap> GraphvizSetName(g, "test");
-<graphviz graph test with 0 nodes and 0 edges>
+<graphviz graph "test" with 0 nodes and 0 edges>
 gap> GraphvizSetName(g, 1);
-<graphviz graph 1 with 0 nodes and 0 edges>
+<graphviz graph "1" with 0 nodes and 0 edges>
 
 # Test global attributes graph
 gap> g := GraphvizGraph();;
 gap> GraphvizSetName(g, "test");
-<graphviz graph test with 0 nodes and 0 edges>
+<graphviz graph "test" with 0 nodes and 0 edges>
 
 # Test global attributes graph
 gap> g := GraphvizGraph();;
@@ -223,18 +226,18 @@ gap> g := GraphvizGraph();;
 gap> n1 := GraphvizAddNode(g, "test");;
 gap> n2 := GraphvizAddNode(g, "abc");;
 gap> g["test"];
-<graphviz node test>
+<graphviz node "test">
 gap> g["abc"];
-<graphviz node abc>
+<graphviz node "abc">
 
 # Test getting a node with a non-string name using bracket notation
 gap> g := GraphvizGraph();;
 gap> n1 := GraphvizAddNode(g, 1);;
 gap> n2 := GraphvizAddNode(g, ["a"]);;
 gap> g[1];
-<graphviz node 1>
+<graphviz node "1">
 gap> g[["a"]];
-<graphviz node [ "a" ]>
+<graphviz node "[ "a" ]">
 gap> g := GraphvizGraph();;
 gap> GraphvizSetAttr(g, "label", "test");;
 gap> GraphvizAttrs(g);
diff --git a/tst/node.tst b/tst/node.tst
index c83d575..cbf9313 100644
--- a/tst/node.tst
+++ b/tst/node.tst
@@ -14,7 +14,7 @@ gap> LoadPackage("graphviz", false);;
 
 # Test node constructor
 gap> GraphvizAddNode(GraphvizGraph(), "test-node");
-<graphviz node test-node>
+<graphviz node "test-node">
 
 # Test renaming nodes fails
 gap> n := GraphvizAddNode(GraphvizGraph(), "a");;
@@ -24,7 +24,7 @@ Error, no 1st choice method found for `GraphvizName' on 2 arguments
 
 # Test making a node with an all whitespace name
 gap> n := GraphvizAddNode(GraphvizGraph(), "  ");
-<graphviz node   >
+<graphviz node "  ">
 
 # Test making a node with empty name fails
 gap> n := GraphvizAddNode(GraphvizGraph(), "");
@@ -32,7 +32,7 @@ Error, the 2nd argument (string/node name) cannot be empty
 
 # Test whitespace in node names
 gap> n := GraphvizAddNode(GraphvizGraph(), "a  a   ");
-<graphviz node a  a   >
+<graphviz node "a  a   ">
 
 # Test modifying attributes
 gap> n := GraphvizAddNode(GraphvizGraph(), "t");;
@@ -60,7 +60,7 @@ gap> AsString(g);
 # Test non-string name containing ':'
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, 111);
-<graphviz node 111>
+<graphviz node "111">
 gap> AsString(g);
 "//dot\ngraph  {\n\t111\n}\n"
 gap> n[1];
@@ -70,7 +70,7 @@ gap> n[1] := 2;
 gap> n[1];
 "2"
 gap> GraphvizRemoveAttr(n, 1);
-<graphviz node 111>
+<graphviz node "111">
 gap> n[1];
 fail
 
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index bf94d16..9545fde 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -16,24 +16,24 @@ gap> LoadPackage("graphviz", false);;
 # Test creating subgraphs (named)
 gap> g := GraphvizGraph();;
 gap> GraphvizAddSubgraph(g, "test-graph");
-<graphviz graph test-graph with 0 nodes and 0 edges>
+<graphviz graph "test-graph" with 0 nodes and 0 edges>
 gap> g := GraphvizDigraph();;
 gap> GraphvizAddSubgraph(g, "test-digraph");
-<graphviz digraph test-digraph with 0 nodes and 0 edges>
+<graphviz digraph "test-digraph" with 0 nodes and 0 edges>
 gap> g := GraphvizGraph();;
 gap> GraphvizAddContext(g, "test-context");
-<graphviz context test-context with 0 nodes and 0 edges>
+<graphviz context "test-context" with 0 nodes and 0 edges>
 
 # Test no-name constructors
 gap> g := GraphvizGraph();;
 gap> GraphvizAddSubgraph(g);
-<graphviz graph no_name_1 with 0 nodes and 0 edges>
+<graphviz graph "no_name_1" with 0 nodes and 0 edges>
 gap> g := GraphvizDigraph();;
 gap> GraphvizAddSubgraph(g);
-<graphviz digraph no_name_1 with 0 nodes and 0 edges>
+<graphviz digraph "no_name_1" with 0 nodes and 0 edges>
 gap> g := GraphvizGraph();;
 gap> GraphvizAddContext(g);
-<graphviz context no_name_1 with 0 nodes and 0 edges>
+<graphviz context "no_name_1" with 0 nodes and 0 edges>
 #@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizAddContext(g, "no_name_1");
 Error, the 1st argument (a graphviz (di)graph/context) already has a context o\
@@ -48,30 +48,30 @@ aph with name "no_name_1"
 # Test no-name constructor graphs' names increment
 gap> g := GraphvizGraph();;
 gap> GraphvizAddSubgraph(g);
-<graphviz graph no_name_1 with 0 nodes and 0 edges>
+<graphviz graph "no_name_1" with 0 nodes and 0 edges>
 gap> GraphvizAddSubgraph(g);
-<graphviz graph no_name_2 with 0 nodes and 0 edges>
+<graphviz graph "no_name_2" with 0 nodes and 0 edges>
 gap> GraphvizAddSubgraph(g);
-<graphviz graph no_name_3 with 0 nodes and 0 edges>
+<graphviz graph "no_name_3" with 0 nodes and 0 edges>
 gap> GraphvizAddContext(g);
-<graphviz context no_name_4 with 0 nodes and 0 edges>
+<graphviz context "no_name_4" with 0 nodes and 0 edges>
 
 # Test no-name constructor graphs' names increment (contexts)
 gap> g := GraphvizGraph();;
 gap> GraphvizAddContext(g);
-<graphviz context no_name_1 with 0 nodes and 0 edges>
+<graphviz context "no_name_1" with 0 nodes and 0 edges>
 gap> GraphvizAddContext(g);
-<graphviz context no_name_2 with 0 nodes and 0 edges>
+<graphviz context "no_name_2" with 0 nodes and 0 edges>
 gap> GraphvizAddContext(g);
-<graphviz context no_name_3 with 0 nodes and 0 edges>
+<graphviz context "no_name_3" with 0 nodes and 0 edges>
 
 # Test getting subgraphs
 gap> g := GraphvizGraph();;
 gap> GraphvizAddSubgraph(g, "a");;
 gap> GraphvizAddContext(g, "b");;
 gap> GraphvizSubgraphs(g);
-rec( a := <graphviz graph a with 0 nodes and 0 edges>, 
-  b := <graphviz context b with 0 nodes and 0 edges> )
+rec( a := <graphviz graph "a" with 0 nodes and 0 edges>, 
+  b := <graphviz context "b" with 0 nodes and 0 edges> )
 
 # Test adding a node to a subgraph (does or does not add to parent???)
 # TODO need to nail down expected behaviour!
@@ -81,7 +81,7 @@ gap> GraphvizAddNode(s, "n");;
 gap> GraphvizNodes(g);
 rec(  )
 gap> GraphvizNodes(s);
-rec( n := <graphviz node n> )
+rec( n := <graphviz node "n"> )
 
 # Test adding a node to a subgraph which is already in parent fails (by name)
 gap> g := GraphvizGraph("r");;
@@ -197,7 +197,7 @@ gap> s1 := GraphvizAddSubgraph(g);;
 gap> GraphvizAddNode(s1, "a");;
 gap> s2 := GraphvizAddSubgraph(g);;
 gap> GV_FindNode(s2, "a");
-<graphviz node a>
+<graphviz node "a">
 gap> GV_FindNode(s2, "b");
 fail
 
@@ -206,7 +206,7 @@ gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g);;
 gap> GraphvizAddNode(s1, "a");;
 gap> GV_FindNode(g, "a");
-<graphviz node a>
+<graphviz node "a">
 gap> GV_FindNode(g, "b");
 fail
 
@@ -215,7 +215,7 @@ gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g);;
 gap> GraphvizAddNode(g, "a");;
 gap> GV_FindNode(s1, "a");
-<graphviz node a>
+<graphviz node "a">
 gap> GV_FindNode(s1, "b");
 fail
 
@@ -226,7 +226,7 @@ gap> s2 := GraphvizAddSubgraph(g);;
 gap> s11 := GraphvizAddSubgraph(s1);;
 gap> GraphvizAddNode(s2, "a");;
 gap> GV_FindNode(s11, "a");
-<graphviz node a>
+<graphviz node "a">
 gap> GV_FindNode(s11, "b");
 fail
 
@@ -243,11 +243,11 @@ gap> GraphvizRemoveNode(g, "d");;
 gap> GraphvizNodes(g);
 rec(  )
 gap> GraphvizNodes(parent);
-rec( a := <graphviz node a> )
+rec( a := <graphviz node "a"> )
 gap> GraphvizNodes(sibling);
-rec( b := <graphviz node b> )
+rec( b := <graphviz node "b"> )
 gap> GraphvizNodes(child);
-rec( c := <graphviz node c> )
+rec( c := <graphviz node "c"> )
 
 # Test context attribute resetting
 gap> g := GraphvizDigraph();;
@@ -282,9 +282,9 @@ gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(g, "b");;
 gap> GraphvizSubgraphs(g)["a"];
-<graphviz digraph a with 0 nodes and 0 edges>
+<graphviz digraph "a" with 0 nodes and 0 edges>
 gap> GraphvizSubgraphs(g)["b"];
-<graphviz digraph b with 0 nodes and 0 edges>
+<graphviz digraph "b" with 0 nodes and 0 edges>
 gap> GraphvizSubgraphs(g)["d"];
 fail
 
@@ -293,20 +293,20 @@ gap> g := GraphvizDigraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddContext(g, "c");;
 gap> GraphvizSubgraphs(g)["a"];
-<graphviz digraph a with 0 nodes and 0 edges>
+<graphviz digraph "a" with 0 nodes and 0 edges>
 gap> GraphvizSubgraphs(g)["c"];
-<graphviz context c with 0 nodes and 0 edges>
+<graphviz context "c" with 0 nodes and 0 edges>
 
 # Test adding a nested subgraph
 gap> g := GraphvizGraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(s1, "c");;
 gap> GraphvizSubgraphs(g)["a"];
-<graphviz graph a with 0 nodes and 0 edges>
+<graphviz graph "a" with 0 nodes and 0 edges>
 gap> GraphvizSubgraphs(g)["c"];
 fail
 gap> GraphvizSubgraphs(s1)["c"];
-<graphviz graph c with 0 nodes and 0 edges>
+<graphviz graph "c" with 0 nodes and 0 edges>
 
 # Test displaying a nested subgraph
 gap> g := GraphvizGraph();;
@@ -318,24 +318,24 @@ gap> AsString(g);
 # Test subgraphs with non-string names
 gap> g := GraphvizGraph();;
 gap> GraphvizAddSubgraph(g, 11);
-<graphviz graph 11 with 0 nodes and 0 edges>
+<graphviz graph "11" with 0 nodes and 0 edges>
 
 # Test contexts with non-string names
 gap> g := GraphvizGraph();;
 gap> GraphvizAddContext(g, 11);
-<graphviz context 11 with 0 nodes and 0 edges>
+<graphviz context "11" with 0 nodes and 0 edges>
 
 # Test getting subgraphs with non-string names
 gap> g := GraphvizGraph();;
 gap> GraphvizAddContext(g, ["a"]);;
 gap> GraphvizSubgraphs(g)[["a"]];
-<graphviz context [ "a" ] with 0 nodes and 0 edges>
+<graphviz context "[ "a" ]" with 0 nodes and 0 edges>
 
 # Test finding subgraph (parent)
 gap> g := GraphvizGraph("a");;
 gap> s := GraphvizAddSubgraph(g, "b");;
 gap> o := GraphvizFindSubgraphRecursive(s, "a");
-<graphviz graph a with 0 nodes and 0 edges>
+<graphviz graph "a" with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, g);
 true
 
@@ -343,7 +343,7 @@ true
 gap> g := GraphvizGraph("a");;
 gap> s := GraphvizAddSubgraph(g, "b");;
 gap> o := GraphvizFindSubgraphRecursive(g, "b");
-<graphviz graph b with 0 nodes and 0 edges>
+<graphviz graph "b" with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, s);
 true
 
@@ -352,14 +352,14 @@ gap> g  := GraphvizGraph("a");;
 gap> s  := GraphvizAddSubgraph(g, "b");;
 gap> s2 := GraphvizAddSubgraph(g, "c");;
 gap> o  := GraphvizFindSubgraphRecursive(s, "c");
-<graphviz graph c with 0 nodes and 0 edges>
+<graphviz graph "c" with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, s2);
 true
 
 # Test finding subgraph (self)
 gap> g := GraphvizGraph("a");;
 gap> o := GraphvizFindSubgraphRecursive(g, "a");
-<graphviz graph a with 0 nodes and 0 edges>
+<graphviz graph "a" with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, g);
 true
 
@@ -372,7 +372,7 @@ gap> b1 := GraphvizAddSubgraph(g, "b1");;
 gap> b2 := GraphvizAddSubgraph(b1, "b2");;
 gap> b3 := GraphvizAddSubgraph(b2, "b3");;
 gap> o  := GraphvizFindSubgraphRecursive(a3, "b3");
-<graphviz graph b3 with 0 nodes and 0 edges>
+<graphviz graph "b3" with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, b3);
 true
 
@@ -398,20 +398,20 @@ gap> AsString(g);
 gap> g := GraphvizGraph("r");;
 gap> s := GraphvizAddSubgraph(g, 1);;
 gap> o := GraphvizFindSubgraphRecursive(g, 1);
-<graphviz graph 1 with 0 nodes and 0 edges>
+<graphviz graph "1" with 0 nodes and 0 edges>
 gap> IsIdenticalObj(o, s);
 true
 
 # Test a context containing a subgraph
 gap> gv := GraphvizGraph("context+subgraph");;
 gap> GraphvizSetAttr(gv, "node [shape=\"box\"]");
-<graphviz graph context+subgraph with 0 nodes and 0 edges>
+<graphviz graph "context+subgraph" with 0 nodes and 0 edges>
 gap> legend := GraphvizAddContext(gv, "legend");
-<graphviz context legend with 0 nodes and 0 edges>
+<graphviz context "legend" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(legend, "node [shape=plaintext]");
-<graphviz context legend with 0 nodes and 0 edges>
+<graphviz context "legend" with 0 nodes and 0 edges>
 gap> GraphvizAddSubgraph(legend, "legend");
-<graphviz graph legend with 0 nodes and 0 edges>
+<graphviz graph "legend" with 0 nodes and 0 edges>
 gap> Print(AsString(gv));
 //dot
 graph context+subgraph {
@@ -427,13 +427,13 @@ subgraph legend {
 # Test a context containing a subdigraph
 gap> gv := GraphvizDigraph("context+subgraph");;
 gap> GraphvizSetAttr(gv, "node [shape=\"box\"]");
-<graphviz digraph context+subgraph with 0 nodes and 0 edges>
+<graphviz digraph "context+subgraph" with 0 nodes and 0 edges>
 gap> legend := GraphvizAddContext(gv, "legend");
-<graphviz context legend with 0 nodes and 0 edges>
+<graphviz context "legend" with 0 nodes and 0 edges>
 gap> GraphvizSetAttr(legend, "node [shape=plaintext]");
-<graphviz context legend with 0 nodes and 0 edges>
+<graphviz context "legend" with 0 nodes and 0 edges>
 gap> GraphvizAddSubgraph(legend, "legend");
-<graphviz digraph legend with 0 nodes and 0 edges>
+<graphviz digraph "legend" with 0 nodes and 0 edges>
 
 #
 gap> STOP_TEST("graphviz package: subgraph.tst", 0);

From 57f2736f3cd2df0c61f2ccff80ff4bd73d3e1aba Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 12:19:05 +0100
Subject: [PATCH 36/38] Add comment

---
 gap/gv.gd | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gap/gv.gd b/gap/gv.gd
index 3193736..ddaef86 100644
--- a/gap/gv.gd
+++ b/gap/gv.gd
@@ -61,14 +61,17 @@ DeclareOperation("GV_ConstructHistory", [IsGraphvizGraphDigraphOrContext]);
 DeclareGlobalFunction("GV_IsValidColor");
 DeclareGlobalFunction("GV_ErrorIfNotNodeColoring");
 
+# TODO move to dot? and make public?
 BindGlobal("GV_ObjectFamily",
            NewFamily("GV_ObjectFamily", IsGraphvizObject));
 
+# TODO move to dot? and make public?
 BindGlobal("GV_DigraphType", NewType(GV_ObjectFamily,
                                     IsGraphvizDigraph and
                                     IsComponentObjectRep and
                                     IsAttributeStoringRep));
 
+# TODO move to dot? and make public?
 BindGlobal("GV_GraphType", NewType(GV_ObjectFamily,
                                     IsGraphvizGraph and
                                     IsComponentObjectRep and

From 910639c82867d4d31d9d19ca441764e193d3f77a Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 12:21:45 +0100
Subject: [PATCH 37/38] Fix tests for GAP 4.11 again

---
 tst/edge.tst     | 4 ++++
 tst/subgraph.tst | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/tst/edge.tst b/tst/edge.tst
index 19afffc..6381a04 100644
--- a/tst/edge.tst
+++ b/tst/edge.tst
@@ -83,16 +83,20 @@ gap> d := GraphvizAddNode(g, "d");;
 gap> a2 := GraphvizAddNode(g1, "a");;
 gap> c := GraphvizAddNode(g1, "c");;
 gap> e1 := GraphvizAddEdge(g, d, a1);;
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> e2 := GraphvizAddEdge(g, a2, c);;
 Error, The 2nd argument (edge) has head node named "a" but there is already a \
 node with this name in the 1st argument (a graphviz (di)graph / context) named\
  ""
+#@fi
 gap> GraphvizEdges(g);
 [ <graphviz edge (d, a)> ]
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> e2 := GraphvizAddEdge(g, c, a2);;
 Error, The 2nd argument (edge) has tail node named "c" but there is already a \
 node with this name in the 1st argument (a graphviz (di)graph / context) named\
  ""
+#@fi
 
 # Test adding an edge reuses a node automatically
 gap> g := GraphvizGraph();;
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 9545fde..de7eede 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -87,26 +87,32 @@ rec( n := <graphviz node "n"> )
 gap> g := GraphvizGraph("r");;
 gap> s := GraphvizAddSubgraph(g, "a");;
 gap> GraphvizAddNode(g, "n");;
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizAddNode(s, "n");
 Error, the 2nd argument (node) has name "n" but there is already a node with t\
 his name in the 1st argument (a graphviz (di)graph / context) named "a"
+#@fi
 
 # Test adding a node to a graph which is already in child fails (by name)
 gap> g := GraphvizGraph();;
 gap> s := GraphvizAddSubgraph(g, "a");;
 gap> GraphvizAddNode(s, "n");;
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizAddNode(g, "n");
 Error, the 2nd argument (node) has name "n" but there is already a node with t\
 his name in the 1st argument (a graphviz (di)graph / context) named ""
+#@fi
 
 # Test adding a node to a graph which is already in sibling fails (by name)
 gap> g := GraphvizGraph();;
 gap> s1 := GraphvizAddSubgraph(g, "a");;
 gap> s2 := GraphvizAddSubgraph(g, "b");;
 gap> GraphvizAddNode(s1, "n");;
+#@if CompareVersionNumbers(GAPInfo.Version, "4.12")
 gap> GraphvizAddNode(s2, "n");
 Error, the 2nd argument (node) has name "n" but there is already a node with t\
 his name in the 1st argument (a graphviz (di)graph / context) named "b"
+#@fi
 
 # Test adding edges to subgraphs
 gap> g := GraphvizGraph();;

From 2785ab5cd16eb8fab0986c1162a830b22e5450c6 Mon Sep 17 00:00:00 2001
From: "James D. Mitchell" <jdm3@st-andrews.ac.uk>
Date: Wed, 15 May 2024 13:04:33 +0100
Subject: [PATCH 38/38] Fix codespell

---
 .codespellrc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.codespellrc b/.codespellrc
index fdb0e06..ff818f3 100644
--- a/.codespellrc
+++ b/.codespellrc
@@ -1,3 +1,3 @@
 [codespell]
-skip = ./.git,./doc/*.log,./doc/*.html,./doc/*.txt,./doc/*.six,./doc/*.js,./doc/*.bbl,./doc/*.tex,./doc/*.bib,./doc/_*
-ignore-words-list=fille,manuel
+skip = ./.git,./doc/*.log,./doc/*.html,./doc/*.txt,./doc/*.six,./doc/*.js,./doc/*.bbl,./doc/*.tex,./doc/*.bib,./doc/_*,./tst/*
+ignore-words-list=manuel