Implement recursive field lookup in compat mode

Provides the mustache behavior of recursive lookup without the use of depthed paths.

Note that this does incur a fairly dramatic performance penalty for depthed queries.

2 files changed, 24 insertions, 8 deletions

diff --git a/lib/handlebars/compiler/compiler.js b/lib/handlebars/compiler/compiler.js
index 48575d4..ffddec4 100644
--- a/lib/handlebars/compiler/compiler.js
+++ b/lib/handlebars/compiler/compiler.js
@@ -308,7 +308,7 @@ Compiler.prototype = {
       // Context reference, i.e. `{{foo .}}` or `{{foo ..}}`
       this.opcode('pushContext');
     } else {
-      this.opcode('lookupOnContext', id.parts, id.falsy);
+      this.opcode('lookupOnContext', id.parts, id.falsy, id.isScoped);
     }
   },
 
@@ -424,6 +424,9 @@ export function precompile(input, options, env) {
   if (!('data' in options)) {
     options.data = true;
   }
+  if (options.compat) {
+    options.useDepths = true;
+  }
 
   var ast = env.parse(input);
   var environment = new env.Compiler().compile(ast, options);
@@ -440,6 +443,9 @@ export function compile(input, options, env) {
   if (!('data' in options)) {
     options.data = true;
   }
+  if (options.compat) {
+    options.useDepths = true;
+  }
 
   var compiled;
 
diff --git a/lib/handlebars/compiler/javascript-compiler.js b/lib/handlebars/compiler/javascript-compiler.js
index f1b6d36..b9b858d 100644
--- a/lib/handlebars/compiler/javascript-compiler.js
+++ b/lib/handlebars/compiler/javascript-compiler.js
@@ -17,6 +17,11 @@ JavaScriptCompiler.prototype = {
       return parent + "['" + name + "']";
     }
   },
+  depthedLookup: function(name) {
+    this.aliases.lookup = 'this.lookup';
+
+    return 'lookup(depths, "' + name + '")';
+  },
 
   compilerInfo: function() {
     var revision = COMPILER_REVISION,
@@ -69,7 +74,7 @@ JavaScriptCompiler.prototype = {
 
     this.compileChildren(environment, options);
 
-    this.useDepths = this.useDepths || environment.depths.list.length;
+    this.useDepths = this.useDepths || environment.depths.list.length || this.options.compat;
 
     var opcodes = environment.opcodes,
         opcode,
@@ -356,15 +361,20 @@ JavaScriptCompiler.prototype = {
   //
   // Looks up the value of `name` on the current context and pushes
   // it onto the stack.
-  lookupOnContext: function(parts, falsy) {
+  lookupOnContext: function(parts, falsy, scoped) {
     /*jshint -W083 */
-    this.pushContext();
-    if (!parts) {
-      return;
+    var i = 0,
+        len = parts.length;
+
+    if (!scoped && this.isChild && this.options.compat && !this.lastContext) {
+      // The depthed query is expected to handle the undefined logic for the root level that
+      // is implemented below, so we evaluate that directly in compat mode
+      this.pushStackLiteral(this.depthedLookup(parts[i++]));
+    } else {
+      this.pushContext();
     }
 
-    var len = parts.length;
-    for (var i = 0; i < len; i++) {
+    for (; i < len; i++) {
       this.replaceStack(function(current) {
         var lookup = this.nameLookup(current, parts[i], 'context');
         // We want to ensure that zero and false are handled properly for the first element