V8BindingPerContextData.h   [plain text]

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
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#ifndef V8BindingPerContextData_h
#define V8BindingPerContextData_h

#include "OwnHandle.h"
#include "WrapperTypeInfo.h"
#include <v8.h>
#include <wtf/HashMap.h>
#include <wtf/PassOwnPtr.h>

namespace WebCore {

class V8BindingPerContextData {
public:
    static PassOwnPtr<V8BindingPerContextData> create(v8::Handle<v8::Context> context)
    {
        return adoptPtr(new V8BindingPerContextData(context));
    }

    ~V8BindingPerContextData()
    {
        dispose();
    }

    bool init();

    // To create JS Wrapper objects, we create a cache of a 'boiler plate'
    // object, and then simply Clone that object each time we need a new one.
    // This is faster than going through the full object creation process.
    v8::Local<v8::Object> createWrapperFromCache(WrapperTypeInfo* type)
    {
        v8::Persistent<v8::Object> boilerplate = m_wrapperBoilerplates.get(type);
        return !boilerplate.IsEmpty() ? boilerplate->Clone() : createWrapperFromCacheSlowCase(type);
    }

    v8::Local<v8::Function> constructorForType(WrapperTypeInfo* type)
    {
        v8::Persistent<v8::Function> function = m_constructorMap.get(type);
        if (!function.IsEmpty())
            return v8::Local<v8::Function>::New(function);
        return constructorForTypeSlowCase(type);
    }

private:
    explicit V8BindingPerContextData(v8::Handle<v8::Context> context)
        : m_context(context)
    {
    }

    void dispose();

    v8::Local<v8::Object> createWrapperFromCacheSlowCase(WrapperTypeInfo*);
    v8::Local<v8::Function> constructorForTypeSlowCase(WrapperTypeInfo*);

    // For each possible type of wrapper, we keep a boilerplate object.
    // The boilerplate is used to create additional wrappers of the same type.
    typedef WTF::HashMap<WrapperTypeInfo*, v8::Persistent<v8::Object> > WrapperBoilerplateMap;
    WrapperBoilerplateMap m_wrapperBoilerplates;

    typedef WTF::HashMap<WrapperTypeInfo*, v8::Persistent<v8::Function> > ConstructorMap;
    ConstructorMap m_constructorMap;

    v8::Handle<v8::Context> m_context;
    OwnHandle<v8::Value> m_objectPrototype;
};

} // namespace WebCore

#endif // V8BindingPerContextData_h