Expose the content of Maps and WeakMaps through MapMirror.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index d980d327aa89640d2b44cbef8e08b58be0eb3257..0737fef88b7ab35dd35d215f42d09632eebc7b34 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -1706,6 +1706,29 @@ RUNTIME_FUNCTION(Runtime_MapIteratorInitialize) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_GetWeakMapEntries) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSWeakCollection, holder, 0);
+  Handle<ObjectHashTable> table(ObjectHashTable::cast(holder->table()));
+  Handle<FixedArray> entries =
+      isolate->factory()->NewFixedArray(table->NumberOfElements() * 2);
+  int number_of_non_hole_elements = 0;
+  {
+    DisallowHeapAllocation no_gc;
+    for (int i = 0; i < table->Capacity(); i++) {
+      Handle<Object> key(table->KeyAt(i), isolate);
+      if (table->IsKey(*key)) {
+        entries->set(number_of_non_hole_elements * 2, *key);

[aandrey, 2014/07/17 09:42:28]

maybe get rid of multiplications?
entries->set(index++, ...);
entries->set(index++, ...);

[Alexandra Mikhaylova, 2014/07/17 10:21:18]

Done.

+        entries->set(number_of_non_hole_elements * 2 + 1, table->Lookup(key));
+        number_of_non_hole_elements++;
+      }
+    }
+  }
+  return *isolate->factory()->NewJSArrayWithElements(entries);

[aandrey, 2014/07/17 09:42:28]

is it guaranteed that (table->NumberOfElements() * 2 ==
number_of_non_hole_elements) here? maybe an ASSERT?

[Alexandra Mikhaylova, 2014/07/17 10:21:18]

It should be, added an ASSERT.

+}
+
+
 RUNTIME_FUNCTION(Runtime_MapIteratorNext) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 2);