Source/bindings/v8/V8DOMWrapper.cpp

/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
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 * in the documentation and/or other materials provided with the
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#include "config.h"
#include "bindings/v8/V8DOMWrapper.h"

#include "V8HTMLCollection.h"
#include "V8HTMLDocument.h"
#include "V8Window.h"
#include "bindings/v8/V8Binding.h"
#include "bindings/v8/V8HiddenPropertyName.h"
#include "bindings/v8/V8ObjectConstructor.h"
#include "bindings/v8/V8PerContextData.h"
#include "bindings/v8/V8ScriptRunner.h"

namespace WebCore {

class V8WrapperInstantiationScope {
public:
    explicit V8WrapperInstantiationScope(v8::Handle<v8::Object> creationContext)
        : m_didEnterContext(false)
        , m_context(v8::Context::GetCurrent())
    {
        // FIXME: Remove all empty creationContexts from caller sites.
        // If a creationContext is empty, we will end up creating a new object
        // in the context currently entered. This is wrong.
        if (creationContext.IsEmpty())
            return;
        v8::Handle<v8::Context> contextForWrapper = creationContext->CreationContext();
        // For performance, we enter the context only if the currently running context
        // is different from the context that we are about to enter.
        if (contextForWrapper == m_context)
            return;
        m_context = v8::Local<v8::Context>::New(contextForWrapper);
        m_didEnterContext = true;
        m_context->Enter();
    }

    ~V8WrapperInstantiationScope()
    {
        if (!m_didEnterContext)
            return;
        m_context->Exit();
    }

    v8::Handle<v8::Context> context() const { return m_context; }

private:
    bool m_didEnterContext;
    v8::Handle<v8::Context> m_context;
};

static v8::Local<v8::Object> wrapInShadowTemplate(v8::Local<v8::Object> wrapper, Node* impl, v8::Isolate* isolate)
{
    // This is only for getting a unique pointer which we can pass to privateTemplate.
    static const char* shadowTemplateUniqueKey = "wrapInShadowTemplate";
    WrapperWorldType currentWorldType = worldType(isolate);
    V8PerIsolateData* data = V8PerIsolateData::from(isolate);
    v8::Handle<v8::FunctionTemplate> shadowTemplate = data->privateTemplateIfExists(currentWorldType, &shadowTemplateUniqueKey);
    if (shadowTemplate.IsEmpty()) {
        shadowTemplate = v8::FunctionTemplate::New();
        if (shadowTemplate.IsEmpty())
            return v8::Local<v8::Object>();
        shadowTemplate->SetClassName(v8::String::NewSymbol("HTMLDocument"));
        shadowTemplate->Inherit(V8HTMLDocument::GetTemplate(isolate, currentWorldType));
        shadowTemplate->InstanceTemplate()->SetInternalFieldCount(V8HTMLDocument::internalFieldCount);
        data->setPrivateTemplate(currentWorldType, &shadowTemplateUniqueKey, shadowTemplate);
    }

    v8::Local<v8::Function> shadowConstructor = shadowTemplate->GetFunction();
    if (shadowConstructor.IsEmpty())
        return v8::Local<v8::Object>();

    v8::Local<v8::Object> shadow = V8ScriptRunner::instantiateObject(shadowConstructor);
    if (shadow.IsEmpty())
        return v8::Local<v8::Object>();
    shadow->SetPrototype(wrapper);
    V8DOMWrapper::setNativeInfo(wrapper, &V8HTMLDocument::info, impl);
    return shadow;
}

v8::Local<v8::Object> V8DOMWrapper::createWrapper(v8::Handle<v8::Object> creationContext, WrapperTypeInfo* type, void* impl, v8::Isolate* isolate)
{
    V8WrapperInstantiationScope scope(creationContext);

    V8PerContextData* perContextData = V8PerContextData::from(scope.context());
    v8::Local<v8::Object> wrapper = perContextData ? perContextData->createWrapperFromCache(type) : V8ObjectConstructor::newInstance(type->getTemplate(isolate, worldTypeInMainThread(isolate))->GetFunction());

    if (type == &V8HTMLDocument::info && !wrapper.IsEmpty())
        wrapper = wrapInShadowTemplate(wrapper, static_cast<Node*>(impl), isolate);

    return wrapper;
}

static bool hasInternalField(v8::Handle<v8::Value> value)
{
    if (value.IsEmpty() || !value->IsObject())
        return false;
    return v8::Handle<v8::Object>::Cast(value)->InternalFieldCount();
}

#ifndef NDEBUG
bool V8DOMWrapper::maybeDOMWrapper(v8::Handle<v8::Value> value)
{
    if (!hasInternalField(value))
        return false;

    v8::Handle<v8::Object> object = v8::Handle<v8::Object>::Cast(value);
    ASSERT(object->InternalFieldCount() >= v8DefaultWrapperInternalFieldCount);

    v8::HandleScope scope;
    ASSERT(object->GetAlignedPointerFromInternalField(v8DOMWrapperObjectIndex));

    return true;
}
#endif

bool V8DOMWrapper::isDOMWrapper(v8::Handle<v8::Value> value)
{
    if (value.IsEmpty() || !value->IsObject())
        return false;

    v8::Handle<v8::Object> wrapper = v8::Handle<v8::Object>::Cast(value);
    if (wrapper->InternalFieldCount() < v8DefaultWrapperInternalFieldCount)
        return false;
    ASSERT(wrapper->GetAlignedPointerFromInternalField(v8DOMWrapperObjectIndex));
    ASSERT(wrapper->GetAlignedPointerFromInternalField(v8DOMWrapperTypeIndex));

    // FIXME: Add class id checks.
    return true;
}

bool V8DOMWrapper::isWrapperOfType(v8::Handle<v8::Value> value, WrapperTypeInfo* type)
{
    if (!hasInternalField(value))
        return false;

    v8::Handle<v8::Object> wrapper = v8::Handle<v8::Object>::Cast(value);
    ASSERT(wrapper->InternalFieldCount() >= v8DefaultWrapperInternalFieldCount);
    ASSERT(wrapper->GetAlignedPointerFromInternalField(v8DOMWrapperObjectIndex));

    WrapperTypeInfo* typeInfo = static_cast<WrapperTypeInfo*>(wrapper->GetAlignedPointerFromInternalField(v8DOMWrapperTypeIndex));
    return typeInfo == type;
}

}  // namespace WebCore