Include parent field/list index in retaining path.

runtime/vm/service.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/service.h"
 
 #include "include/dart_api.h"
 #include "platform/globals.h"
 
 #include "vm/compiler.h"
@@ skipping 963 matching lines @@
     result.PrintJSON(js, true);
     return true;
   } else if (strcmp(action, "retaining_path") == 0) {
     intptr_t limit;
     if (!GetIntegerId(js->LookupOption("limit"), &limit)) {
       PrintError(js, "retaining_path expects a 'limit' option\n",
                  js->num_arguments());
       return true;
     }
     ObjectGraph graph(isolate);
-    Array& path = Array::Handle(Array::New(limit));
+    Array& path = Array::Handle(Array::New(limit * 2));
     intptr_t length = graph.RetainingPath(obj, path);
     JSONObject jsobj(js);
     jsobj.AddProperty("type", "RetainingPath");
     jsobj.AddProperty("id", "retaining_path");
     jsobj.AddProperty("length", length);
     JSONArray elements(&jsobj, "elements");
-    for (intptr_t i = 0; i < path.Length() && i < length; ++i) {
+    Object& element = Object::Handle();
+    Smi& offset_from_parent = Smi::Handle();
+    for (intptr_t i = 0; i < limit && i < length; ++i) {
       JSONObject jselement(&elements);
-      Object& element = Object::Handle();
-      element = path.At(i);
+      element = path.At(i * 2);
       jselement.AddProperty("index", i);
       jselement.AddProperty("value", element);
+      offset_from_parent ^= path.At((i * 2) + 1);
+      // TODO(koda): Interpret offset as field, list index or map entry.
     }
     return true;
   }
 
   PrintError(js, "unrecognized action '%s'\n", action);
   return true;
 }
 
 
 static bool HandleClassesClosures(Isolate* isolate, const Class& cls,
@@ skipping 1261 matching lines @@
   while (current != NULL) {
     if (strcmp(name, current->name()) == 0) {
       return current;
     }
     current = current->next();
   }
   return NULL;
 }
 
 }  // namespace dart