From 0188ab88ac363749f1b6c7ba87718245940f45fa Mon Sep 17 00:00:00 2001
From: Mo Morsi <mo@morsi.org>
Date: Thu, 21 Jun 2018 16:47:47 -0400
Subject: [PATCH] Add generic scope support for expressions.

Variables and funcations can now be injected into the expression
scope like so:

  jsonpath.scope({foo:'bar',parseInt:parseInt})

Thus the client can incorporate builtin or custom methods in
jsonpath expressions:

  $..[?(parseInt(@.Amount) > 0)]
---
 lib/handlers.js | 21 ++++++++++++++-------
 lib/index.js    |  4 ++++
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/lib/handlers.js b/lib/handlers.js
index c00e6b0..635d28e 100755
--- a/lib/handlers.js
+++ b/lib/handlers.js
@@ -10,6 +10,11 @@ var Handlers = function() {
 Handlers.prototype.initialize = function() {
   this.traverse = traverser(true);
   this.descend = traverser();
+  this._scope = {};
+}
+
+Handlers.prototype.scope = function(_scope){
+  this._scope = _scope;
 }
 
 Handlers.prototype.keys = Object.keys;
@@ -115,8 +120,9 @@ Handlers.prototype._fns = {
     var src = component.expression.value.slice(2, -1);
     var ast = aesprim.parse(src).body[0].expression;
 
+    var _scope = this._scope;
     var passable = function(key, value) {
-      return evaluate(ast, { '@': value });
+      return evaluate(ast, Object.assign({ '@': value }, _scope));
     }
 
     return this.descend(partial, null, passable, count);
@@ -129,8 +135,9 @@ Handlers.prototype._fns = {
     var src = component.expression.value.slice(2, -1);
     var ast = aesprim.parse(src).body[0].expression;
 
+    var _scope = this._scope;
     var passable = function(key, value) {
-      return evaluate(ast, { '@': value });
+      return evaluate(ast, Object.assign({ '@': value }, _scope));
     }
 
     return this.traverse(partial, null, passable, count);
@@ -138,17 +145,17 @@ Handlers.prototype._fns = {
 
   'subscript-child-script_expression': function(component, partial) {
     var exp = component.expression.value.slice(1, -1);
-    return eval_recurse(partial, exp, '$[{{value}}]');
+    return eval_recurse(partial, exp, '$[{{value}}]', this._scope);
   },
 
   'member-child-script_expression': function(component, partial) {
     var exp = component.expression.value.slice(1, -1);
-    return eval_recurse(partial, exp, '$.{{value}}');
+    return eval_recurse(partial, exp, '$.{{value}}', this._scope);
   },
 
   'member-descendant-script_expression': function(component, partial) {
     var exp = component.expression.value.slice(1, -1);
-    return eval_recurse(partial, exp, '$..value');
+    return eval_recurse(partial, exp, '$..value', this._scope);
   }
 };
 
@@ -159,11 +166,11 @@ Handlers.prototype._fns['member-descendant-numeric_literal'] =
     Handlers.prototype._fns['subscript-descendant-string_literal'] =
     Handlers.prototype._fns['member-descendant-identifier'];
 
-function eval_recurse(partial, src, template) {
+function eval_recurse(partial, src, template, _scope) {
 
   var jp = require('./index');
   var ast = aesprim.parse(src).body[0].expression;
-  var value = evaluate(ast, { '@': partial.value });
+  var value = evaluate(ast, Object.assign({ '@': partial.value }, _scope));
   var path = template.replace(/\{\{\s*value\s*\}\}/g, value);
 
   var results = jp.nodes(partial.value, path);
diff --git a/lib/index.js b/lib/index.js
index 8f5a832..f3d65fc 100755
--- a/lib/index.js
+++ b/lib/index.js
@@ -12,6 +12,10 @@ JSONPath.prototype.initialize = function() {
   this.handlers = new Handlers();
 };
 
+JSONPath.prototype.scope = function(scope){
+  this.handlers.scope(scope);
+}
+
 JSONPath.prototype.parse = function(string) {
   assert.ok(_is_string(string), "we need a path");
   return this.parser.parse(string);