Add trackIds compiler flag

Allows helpers that care about where a particular field came from derive this data while maintaining backward compatibility with existing helpers.

lib/handlebars/compiler/javascript-compiler.js

@@ -61,6 +61,7 @@ JavaScriptCompiler.prototype = {
     this.environment = environment;
     this.options = options || {};
     this.stringParams = this.options.stringParams;
+    this.trackIds = this.options.trackIds;
 
     log('debug', this.environment.disassemble() + "\n\n");
 
@@ -418,6 +419,9 @@ JavaScriptCompiler.prototype = {
   emptyHash: function() {
     this.pushStackLiteral('{}');
 
+    if (this.trackIds) {
+      this.push('{}'); // hashIds
+    }
     if (this.stringParams) {
       this.push('{}'); // hashContexts
       this.push('{}'); // hashTypes
@@ -427,12 +431,15 @@ JavaScriptCompiler.prototype = {
     if (this.hash) {
       this.hashes.push(this.hash);
     }
-    this.hash = {values: [], types: [], contexts: []};
+    this.hash = {values: [], types: [], contexts: [], ids: []};
   },
   popHash: function() {
     var hash = this.hash;
     this.hash = this.hashes.pop();
 
+    if (this.trackIds) {
+      this.push('{' + hash.ids.join(',') + '}');
+    }
     if (this.stringParams) {
       this.push('{' + hash.contexts.join(',') + '}');
       this.push('{' + hash.types.join(',') + '}');
@@ -589,8 +596,12 @@ JavaScriptCompiler.prototype = {
   assignToHash: function(key) {
     var value = this.popStack(),
         context,
-        type;
+        type,
+        id;
 
+    if (this.trackIds) {
+      id = this.popStack();
+    }
     if (this.stringParams) {
       type = this.popStack();
       context = this.popStack();
@@ -603,9 +614,22 @@ JavaScriptCompiler.prototype = {
     if (type) {
       hash.types.push("'" + key + "': " + type);
     }
+    if (id) {
+      hash.ids.push("'" + key + "': " + id);
+    }
     hash.values.push("'" + key + "': (" + value + ")");
   },
 
+  pushId: function(type, name) {
+    if (type === 'ID' || type === 'DATA') {
+      this.pushString(name);
+    } else if (type === 'sexpr') {
+      this.pushStackLiteral('true');
+    } else {
+      this.pushStackLiteral('null');
+    }
+  },
+
   // HELPERS
 
   compiler: JavaScriptCompiler,
@@ -844,11 +868,14 @@ JavaScriptCompiler.prototype = {
   },
 
   setupOptions: function(helper, paramSize, params) {
-    var options = {}, contexts = [], types = [], param, inverse, program;
+    var options = {}, contexts = [], types = [], ids = [], param, inverse, program;
 
     options.name = this.quotedString(helper);
     options.hash = this.popStack();
 
+    if (this.trackIds) {
+      options.hashIds = this.popStack();
+    }
     if (this.stringParams) {
       options.hashTypes = this.popStack();
       options.hashContexts = this.popStack();
@@ -878,12 +905,18 @@ JavaScriptCompiler.prototype = {
       param = this.popStack();
       params.push(param);
 
+      if (this.trackIds) {
+        ids.push(this.popStack());
+      }
       if (this.stringParams) {
         types.push(this.popStack());
         contexts.push(this.popStack());
       }
     }
 
+    if (this.trackIds) {
+      options.ids = "[" + ids.join(",") + "]";
+    }
     if (this.stringParams) {
       options.types = "[" + types.join(",") + "]";
       options.contexts = "[" + contexts.join(",") + "]";