Avoid to list internal Arrays in _GetRetainingPath api

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 "include/dart_native_api.h"
 #include "platform/globals.h"
 
@@ skipping 1988 matching lines @@
   Array& path = Array::Handle(Array::New(limit * 2));
   intptr_t length = graph.RetainingPath(obj, path);
   JSONObject jsobj(js);
   jsobj.AddProperty("type", "RetainingPath");
   jsobj.AddProperty("length", length);
   JSONArray elements(&jsobj, "elements");
   Object& element = Object::Handle();
   Smi& slot_offset = Smi::Handle();
   Class& element_class = Class::Handle();
   Array& element_field_map = Array::Handle();
+  LinkedHashMap& map = LinkedHashMap::Handle();
+  Array& map_data = Array::Handle();
   Field& field = Field::Handle();
   limit = Utils::Minimum(limit, length);
   for (intptr_t i = 0; i < limit; ++i) {
     JSONObject jselement(&elements);
     element = path.At(i * 2);
-    jselement.AddProperty("index", i);
     jselement.AddProperty("value", element);
-    // Interpret the word offset from parent as list index or instance field.
-    // TODO(koda): User-friendly interpretation for map entries.
+    // Interpret the word offset from parent as list index, map key
+    // or instance field.
     if (i > 0) {
       slot_offset ^= path.At((i * 2) - 1);
-      if (element.IsArray()) {
+      jselement.AddProperty("offset", slot_offset.Value());
+      if (element.IsArray() || element.IsGrowableObjectArray()) {
         intptr_t element_index = slot_offset.Value() -
             (Array::element_offset(0) >> kWordSizeLog2);
         jselement.AddProperty("parentListIndex", element_index);
+      } else if (element.IsLinkedHashMap()) {
+        map = static_cast<RawLinkedHashMap*>(path.At(i * 2));
+        map_data = map.data();
+        intptr_t element_index = slot_offset.Value() -
+            (Array::element_offset(0) >> kWordSizeLog2);
+        LinkedHashMap::Iterator iterator(map);
+        while (iterator.MoveNext()) {
+          if (iterator.CurrentKey() == map_data.At(element_index) ||
+              iterator.CurrentValue() == map_data.At(element_index)) {
+            element = iterator.CurrentKey();
+            jselement.AddProperty("parentMapKey", element);
+            break;
+          }
+        }
       } else if (element.IsInstance()) {
         element_class ^= element.clazz();
         element_field_map = element_class.OffsetToFieldMap();
         intptr_t offset = slot_offset.Value();
         if (offset > 0 && offset < element_field_map.Length()) {
           field ^= element_field_map.At(offset);
           jselement.AddProperty("parentField", field);
         }
       } else {
         intptr_t element_index = slot_offset.Value();
@@ skipping 2090 matching lines @@
     if (strcmp(method_name, method.name) == 0) {
       return &method;
     }
   }
   return NULL;
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart