From 32d7e52182414ae48ff82d4456d982049f0203a5 Mon Sep 17 00:00:00 2001
From: tomhuda <tomhuda@strobecorp.com>
Date: Fri, 25 Feb 2011 23:01:11 -0800
Subject: [PATCH] Helpers take precedence over context properties with the same
 name. This is useful in scenarios where your context object is inherited from
 another system (such as a framework or JSON API) that may contain properties
 that conflict with helpers you explicitly define.

---
 lib/handlebars/vm.js | 20 +++++++++++++-------
 spec/qunit_spec.js   | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 7 deletions(-)

diff --git a/lib/handlebars/vm.js b/lib/handlebars/vm.js
index 3f44a36f..1c2b4eef 100644
--- a/lib/handlebars/vm.js
+++ b/lib/handlebars/vm.js
@@ -8,7 +8,7 @@ Handlebars.JavaScriptCompiler = function() {};
   Compiler.OPCODE_MAP = {
     appendContent: 1,
     getContext: 2,
-    lookupWithFallback: 3,
+    lookupWithHelpers: 3,
     lookup: 4,
     append: 5,
     invokeMustache: 6,
@@ -25,7 +25,7 @@ Handlebars.JavaScriptCompiler = function() {};
   Compiler.MULTI_PARAM_OPCODES = {
     appendContent: 1,
     getContext: 1,
-    lookupWithFallback: 1,
+    lookupWithHelpers: 1,
     lookup: 1,
     invokeMustache: 2,
     pushString: 1,
@@ -201,7 +201,7 @@ Handlebars.JavaScriptCompiler = function() {};
 
       this.opcode('getContext', id.depth);
 
-      this.opcode('lookupWithFallback', id.parts[0] || null);
+      this.opcode('lookupWithHelpers', id.parts[0] || null);
 
       for(var i=1, l=id.parts.length; i<l; i++) {
         this.opcode('lookup', id.parts[i]);
@@ -432,11 +432,17 @@ Handlebars.JavaScriptCompiler = function() {};
       }
     },
 
-    lookupWithFallback: function(name) {
+    lookupWithHelpers: function(name) {
       if(name) {
-        this.pushStack(this.nameLookup('currentContext', name, 'context'));
-        var topStack = this.topStack();
-        this.source.push("if(" + topStack + " === undefined) { " + topStack + " = " + this.nameLookup('helpers', name, 'helper') + "; }");
+        var topStack = this.nextStack();
+
+        var toPush =  "if('" + name + "' in helpers) { " + topStack +
+                      " = " + this.nameLookup('helpers', name, 'helper') +
+                      "; } else { " + topStack + " = " +
+                      this.nameLookup('currentContext', name, 'context') +
+                      "; }";
+
+        this.source.push(toPush);
       } else {
         this.pushStack("currentContext");
       }
diff --git a/spec/qunit_spec.js b/spec/qunit_spec.js
index 7ec0cf2e..01c1aba0 100644
--- a/spec/qunit_spec.js
+++ b/spec/qunit_spec.js
@@ -632,3 +632,47 @@ test("you can override inherited data when invoking a helper with depth", functi
   equals("sad world?", result);
 });
 
+test("helpers take precedence over same-named context properties", function() {
+  var template = Handlebars.compile("{{goodbye}} {{cruel world}}");
+
+  var helpers = {
+    goodbye: function() {
+      return this.goodbye.toUpperCase();
+    }
+  };
+
+  var context = {
+    cruel: function(world) {
+      return "cruel " + world.toUpperCase();
+    },
+
+    goodbye: "goodbye",
+    world: "world"
+  };
+
+  var result = template(context, helpers);
+  equals(result, "GOODBYE cruel WORLD");
+});
+
+test("helpers take precedence over same-named context properties", function() {
+  var template = Handlebars.compile("{{#goodbye}} {{cruel world}}{{/goodbye}}");
+
+  var helpers = {
+    goodbye: function(fn) {
+      return this.goodbye.toUpperCase() + fn(this);
+    }
+  };
+
+  var context = {
+    cruel: function(world) {
+      return "cruel " + world.toUpperCase();
+    },
+
+    goodbye: "goodbye",
+    world: "world"
+  };
+
+  var result = template(context, helpers);
+  equals(result, "GOODBYE cruel WORLD");
+});
+