sky/engine/wtf/PassTraits.h

/*
 * Copyright (C) 2011 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
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 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 */

#ifndef SKY_ENGINE_WTF_PASSTRAITS_H_
#define SKY_ENGINE_WTF_PASSTRAITS_H_

#include "sky/engine/wtf/OwnPtr.h"
#include "sky/engine/wtf/RefPtr.h"

// The PassTraits template exists to help optimize (or make possible) use
// of WTF data structures with WTF smart pointers that have a Pass
// variant for transfer of ownership

namespace WTF {

template<typename T> struct PassTraits {
    typedef T Type;
    typedef T PassType;
    static Type& transfer(Type& value) { return value; }
};

template<typename T> struct PassTraits<OwnPtr<T> > {
    typedef OwnPtr<T> Type;
    typedef PassOwnPtr<T> PassType;
    static PassType transfer(Type& value) { return value.release(); }
};

template<typename T> struct PassTraits<RefPtr<T> > {
    typedef RefPtr<T> Type;
    typedef PassRefPtr<T> PassType;
    static PassType transfer(Type& value) { return value.release(); }
};

} // namespace WTF

using WTF::PassTraits;

#endif  // SKY_ENGINE_WTF_PASSTRAITS_H_