Source/core/fetch/ResourceOwner.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 */

#ifndef ResourceOwner_h
#define ResourceOwner_h

#include "core/fetch/ResourcePtr.h"

namespace WebCore {


template<class R, class C = typename R::ClientType>
class ResourceOwner : public C {
public:
    typedef R ResourceType;

    virtual ~ResourceOwner();
    ResourceType* resource() const { return m_resource.get(); }

protected:
    ResourceOwner();
    ResourceOwner(const ResourceOwner& other) { setResource(other.resource()); }
    explicit ResourceOwner(const ResourcePtr<ResourceType>&);

    void setResource(const ResourcePtr<ResourceType>&);
    void clearResource();

    ResourceOwner& operator=(const ResourceOwner& other);

private:
    ResourcePtr<ResourceType> m_resource;
};

template<class R, class C>
inline ResourceOwner<R, C>::ResourceOwner()
{
}

template<class R, class C>
inline ResourceOwner<R, C>::~ResourceOwner()
{
    clearResource();
}

template<class R, class C>
inline ResourceOwner<R, C>::ResourceOwner(const ResourcePtr<R>& resource)
    : m_resource(resource)
{
    if (m_resource)
        m_resource->addClient(this);
}

template<class R, class C>
inline void ResourceOwner<R, C>::setResource(const ResourcePtr<R>& newResource)
{
    if (newResource == m_resource)
        return;

    // Some ResourceClient implementations reenter this so
    // we need to prevent double removal.
    if (ResourcePtr<ResourceType> oldResource = m_resource) {
        m_resource.clear();
        oldResource->removeClient(this);
    }

    if (newResource) {
        m_resource = newResource;
        m_resource->addClient(this);
    }
}

template<class R, class C>
inline void ResourceOwner<R, C>::clearResource()
{
    setResource(0);
}

template<class R, class C>
inline ResourceOwner<R, C>& ResourceOwner<R, C>::operator=(const ResourceOwner<R, C>& other)
{
    if (this == &other)
        return *this;
    setResource(other.resource());
    return *this;
}

} // namespace WebCore

#endif