Expose the content of Maps and WeakMaps through MapMirror.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 #include <limits>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 1688 matching lines @@
       || kind == JSMapIterator::kKindValues
       || kind == JSMapIterator::kKindEntries);
   Handle<OrderedHashMap> table(OrderedHashMap::cast(map->table()));
   holder->set_table(*table);
   holder->set_index(Smi::FromInt(0));
   holder->set_kind(Smi::FromInt(kind));
   return isolate->heap()->undefined_value();
 }
 
 
+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);
   CONVERT_ARG_CHECKED(JSMapIterator, holder, 0);
   CONVERT_ARG_CHECKED(JSArray, value_array, 1);
   return holder->Next(value_array);
 }
 
 
 static Handle<JSWeakCollection> WeakCollectionInitialize(
@@ skipping 13237 matching lines @@
   }
   return NULL;
 }
 
 
 const Runtime::Function* Runtime::FunctionForId(Runtime::FunctionId id) {
   return &(kIntrinsicFunctions[static_cast<int>(id)]);
 }
 
 } }  // namespace v8::internal