perf: improve evaluation speed of conditional queries

Use NodeJS' vm.Script class to cache the script that the context needs to be evaluated against. This provides large speed improvements (~50%) when a path contains conditional or JS logic.
autmporn · Aug 24, 2022 · 258832a · 258832a
1 parent 5d740b3
commit 258832a
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Showing 3 changed files with 41 additions and 25 deletions.
diff --git a/src/jsonpath-browser.js b/src/jsonpath-browser.js
@@ -32,14 32,24 @@ const moveToAnotherArray = function (source, target, conditionCb) {
  }
 };
 
-JSONPath.prototype.vm = {
 /**
  * In-browser replacement for NodeJS' VM.Script.
  */
 class Script {
  /**
  * @param {string} expr Expression to evaluate
  */
  constructor (expr) {
  this.code = expr;
  }
 
  /**
  * @param {PlainObject} context Object whose items will be added
  * to evaluation
  * @returns {EvaluatedResult} Result of evaluated code
  */
- runInNewContext (expr, context) {
  runInNewContext (context) {
  let expr = this.code;
  const keys = Object.keys(context);
  const funcs = [];
  moveToAnotherArray(keys, funcs, (key) => {
@@ -81,6 91,10 @@ JSONPath.prototype.vm = {
  // eslint-disable-next-line no-new-func
  return (new Function(...keys, code))(...values);
  }
 }
 
 JSONPath.prototype.vm = {
  Script
 };
 
 export {JSONPath};
diff --git a/src/jsonpath.js b/src/jsonpath.js
@@ -588,32 588,34 @@ JSONPath.prototype._slice = function (
 JSONPath.prototype._eval = function (
  code, _v, _vname, path, parent, parentPropName
 ) {
- if (code.includes('@parentProperty')) {
- this.currSandbox._$_parentProperty = parentPropName;
- code = code.replace(/@parentProperty/gu, '_$_parentProperty');
- }
- if (code.includes('@parent')) {
- this.currSandbox._$_parent = parent;
- code = code.replace(/@parent/gu, '_$_parent');
- }
- if (code.includes('@property')) {
- this.currSandbox._$_property = _vname;
- code = code.replace(/@property/gu, '_$_property');
- }
- if (code.includes('@path')) {
  this.currSandbox._$_parentProperty = parentPropName;
  this.currSandbox._$_parent = parent;
  this.currSandbox._$_property = _vname;
  this.currSandbox._$_root = this.json;
  this.currSandbox._$_v = _v;
 
  const containsPath = code.includes('@path');
  if (containsPath) {
  this.currSandbox._$_path = JSONPath.toPathString(path.concat([_vname]));
- code = code.replace(/@path/gu, '_$_path');
- }
- if (code.includes('@root')) {
- this.currSandbox._$_root = this.json;
- code = code.replace(/@root/gu, '_$_root');
  }
- if ((/@([.\s)[])/u).test(code)) {
- this.currSandbox._$_v = _v;
- code = code.replace(/@([.\s)[])/gu, '_$_v$1');
 
  const scriptCacheKey = 'script:'   code;
  if (!JSONPath.cache[scriptCacheKey]) {
  let script = code
  .replace(/@parentProperty/gu, '_$_parentProperty')
  .replace(/@parent/gu, '_$_parent')
  .replace(/@property/gu, '_$_property')
  .replace(/@root/gu, '_$_root')
  .replace(/@([.\s)[])/gu, '_$_v$1');
  if (containsPath) {
  script = script.replace(/@path/gu, '_$_path');
  }
 
  JSONPath.cache[scriptCacheKey] = new this.vm.Script(script);
  }
 
  try {
- return this.vm.runInNewContext(code, this.currSandbox);
  return JSONPath.cache[scriptCacheKey].runInNewContext(this.currSandbox);
  } catch (e) {
  throw new Error('jsonPath: '   e.message   ': '   code);
  }

diff --git a/test/test.errors.js b/test/test.errors.js
@@ -20,7 20,7 @@ checkBuiltInVMAndNodeVM(function (vmType, setBuiltInState) {
  it('should throw with a bad filter', () => {
  expect(() => {
  jsonpath({json: {book: []}, path: '$..[?(@.category === category)]'});
- }).to.throw(Error, 'jsonPath: category is not defined: _$_v.category === category');
  }).to.throw(Error, 'jsonPath: category is not defined: @.category === category');
  });
 
  it('should throw with a bad result type', () => {