Memoize various API and index functions for performance

Author: movitto

lib/handlers.js

@@ -2,7 +2,10 @@ var aesprim = require('./aesprim');
 var codegen = require('escodegen')
 var slice = require('./slice');
 var Sandbox = require('v8-sandbox').default;
-var _uniq = require('underscore').uniq;
+
+var _ = require('underscore')
+var _uniq = _.uniq;
+var _memoize = _.memoize
 
 // XXX: if this appears in a filter expression, this won't work
 const _AT_SYMBOL_ = '_AT_SYMBOL_'
@@ -266,8 +269,10 @@ function _traverse(passable) {
 
 function evaluate(expression, globals) {
   // Create sandbox JIT for expression evaluation
-  if(!this.sandbox)
+  if(!this.sandbox){
     this.sandbox = new Sandbox()
+    this.sandbox.execute = _memoize(this.sandbox.execute, JSON.stringify)
+  }
 
   var code = 'setResult({value:' + expression + '})';
   var execute = {
@@ -298,7 +303,7 @@ function _parse_nullable_int(val) {
   return sval.match(/^-?[0-9]+$/) ? parseInt(sval) : null;
 }
 
-function _replace_at(src){
+_replace_at = _memoize(function(src){
   var ast = aesprim.parse(src).body[0].expression;
 
   function search_and_replace(_ast){
@@ -318,6 +323,6 @@ function _replace_at(src){
   }
 
   return codegen.generate(search_and_replace(ast))
-}
+})
 
 module.exports = Handlers;

lib/index.js

@@ -2,13 +2,15 @@ var assert = require('assert');
 var dict = require('./dict');
 var Parser = require('./parser');
 var Handlers = require('./handlers');
+var _memoize = require('underscore').memoize;
 
 var JSONPath = function() {
   this.initialize.apply(this, arguments);
 };
 
 JSONPath.prototype.initialize = function() {
   this.parser = new Parser();
+  this.parser.parse = _memoize(this.parser.parse)
   this.handlers = new Handlers();
 };
 
@@ -119,7 +121,8 @@ JSONPath.prototype.nodes = async function(obj, string, count) {
 
   if (count === 0) return [];
 
-  var path = this.parser.parse(string);
+  // slice to copy before manipulating:
+  var path = this.parser.parse(string).slice();
   var handlers = this.handlers;
 
   var partials = [ { path: ['$'], value: obj } ];
@@ -157,7 +160,7 @@ JSONPath.prototype.nodes = async function(obj, string, count) {
   return count ? matches.slice(0, count) : matches;
 };
 
-JSONPath.prototype.stringify = async function(path) {
+JSONPath.prototype._stringify = _memoize(function(path) {
   assert.ok(path, "we need a path");
 
   var string = '$';
@@ -192,9 +195,13 @@ JSONPath.prototype.stringify = async function(path) {
   }
 
   return string;
+}, JSON.stringify)
+
+JSONPath.prototype.stringify = function(path) {
+  return this._stringify(path)
 }
 
-JSONPath.prototype._normalize = function(path) {
+JSONPath.prototype._normalize = _memoize(function(path) {
   assert.ok(path, "we need a path");
 
   if (typeof path == "string") {
@@ -245,7 +252,7 @@ JSONPath.prototype._normalize = function(path) {
   }
 
   throw new Error("couldn't understand path " + path);
-}
+}, JSON.stringify)
 
 function _is_string(obj) {
   return Object.prototype.toString.call(obj) == '[object String]';