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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "config.h"
      6 #include "bindings/core/v8/ScriptWrappable.h"
      7 
      8 #include "bindings/core/v8/DOMDataStore.h"
      9 #include "bindings/core/v8/V8DOMWrapper.h"
     10 
     11 namespace blink {
     12 
     13 #if COMPILER(MSVC)
     14 __declspec(align(4))
     15 #endif
     16 struct SameSizeAsScriptWrappableBase { };
     17 
     18 COMPILE_ASSERT(sizeof(ScriptWrappableBase) <= sizeof(SameSizeAsScriptWrappableBase), ScriptWrappableBase_should_stay_small);
     19 
     20 struct SameSizeAsScriptWrappable : public ScriptWrappableBase {
     21     virtual ~SameSizeAsScriptWrappable() { }
     22     v8::Object* m_wrapper;
     23 };
     24 
     25 COMPILE_ASSERT(sizeof(ScriptWrappable) <= sizeof(SameSizeAsScriptWrappable), ScriptWrappable_should_stay_small);
     26 
     27 namespace {
     28 
     29 class ScriptWrappableBaseProtector FINAL {
     30     WTF_MAKE_NONCOPYABLE(ScriptWrappableBaseProtector);
     31 public:
     32     ScriptWrappableBaseProtector(ScriptWrappableBase* scriptWrappableBase, const WrapperTypeInfo* wrapperTypeInfo)
     33         : m_scriptWrappableBase(scriptWrappableBase), m_wrapperTypeInfo(wrapperTypeInfo)
     34     {
     35         m_wrapperTypeInfo->refObject(m_scriptWrappableBase);
     36     }
     37     ~ScriptWrappableBaseProtector()
     38     {
     39         m_wrapperTypeInfo->derefObject(m_scriptWrappableBase);
     40     }
     41 
     42 private:
     43     ScriptWrappableBase* m_scriptWrappableBase;
     44     const WrapperTypeInfo* m_wrapperTypeInfo;
     45 };
     46 
     47 } // namespace
     48 
     49 v8::Handle<v8::Object> ScriptWrappable::wrap(v8::Handle<v8::Object> creationContext, v8::Isolate* isolate)
     50 {
     51     const WrapperTypeInfo* wrapperTypeInfo = this->wrapperTypeInfo();
     52 
     53     // It's possible that no one except for the new wrapper owns this object at
     54     // this moment, so we have to prevent GC to collect this object until the
     55     // object gets associated with the wrapper.
     56     ScriptWrappableBaseProtector protect(this, wrapperTypeInfo);
     57 
     58     ASSERT(!DOMDataStore::containsWrapperNonTemplate(this, isolate));
     59 
     60     v8::Handle<v8::Object> wrapper = V8DOMWrapper::createWrapper(creationContext, wrapperTypeInfo, toScriptWrappableBase(), isolate);
     61     if (UNLIKELY(wrapper.IsEmpty()))
     62         return wrapper;
     63 
     64     wrapperTypeInfo->installConditionallyEnabledProperties(wrapper, isolate);
     65     return associateWithWrapper(wrapperTypeInfo, wrapper, isolate);
     66 }
     67 
     68 v8::Handle<v8::Object> ScriptWrappable::associateWithWrapper(const WrapperTypeInfo* wrapperTypeInfo, v8::Handle<v8::Object> wrapper, v8::Isolate* isolate)
     69 {
     70     return V8DOMWrapper::associateObjectWithWrapperNonTemplate(this, wrapperTypeInfo, wrapper, isolate);
     71 }
     72 
     73 } // namespace blink
     74