/*
    Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
    Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
    Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.

    This class provides all functionality needed for loading images, style sheets and html
    pages from the web. It has a memory cache for these objects.
*/

#ifndef ResourceClientOrObserverWalker_h
#define ResourceClientOrObserverWalker_h

#include "core/fetch/ResourceClient.h"
#include "wtf/Allocator.h"
#include "wtf/HashCountedSet.h"
#include "wtf/Vector.h"

namespace blink {

// Call this "walker" instead of iterator so people won't expect Qt or STL-style iterator interface.
// Just keep calling next() on this. It's safe from deletions of items.
// ClientOrObserver is either ResourceClient or ImageResourceObserver, so that
// this walker can be used both for ResourceClient and ImageResourceObserver.
template<typename ClientOrObserver, typename T>
class ResourceClientOrObserverWalker {
    STACK_ALLOCATED();
public:
    explicit ResourceClientOrObserverWalker(const HashCountedSet<ClientOrObserver*>& set)
        : m_clientSet(set), m_clientVector(set.size()), m_index(0)
    {
        size_t clientIndex = 0;
        for (const auto& resourceClient : set)
            m_clientVector[clientIndex++] = resourceClient.key;
    }

    T* next()
    {
        size_t size = m_clientVector.size();
        while (m_index < size) {
            ClientOrObserver* next = m_clientVector[m_index++];
            if (m_clientSet.contains(next)) {
                ASSERT(T::isExpectedType(next));
                return static_cast<T*>(next);
            }
        }

        return 0;
    }
private:
    const HashCountedSet<ClientOrObserver*>& m_clientSet;
    Vector<ClientOrObserver*> m_clientVector;
    size_t m_index;
};

template<typename T>
struct ResourceClientWalker : public ResourceClientOrObserverWalker<ResourceClient, T> {
public:
    explicit ResourceClientWalker(const HashCountedSet<ResourceClient*>& set)
        : ResourceClientOrObserverWalker<ResourceClient, T>(set) { }
};

} // namespace blink

#endif