Source/core/rendering/OrderIterator.h

/*
 * Copyright (C) 2011 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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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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 */

#ifndef OrderIterator_h
#define OrderIterator_h

#include "wtf/Noncopyable.h"
#include "wtf/Vector.h"

namespace WebCore {

class RenderBox;

class OrderIterator {
    WTF_MAKE_NONCOPYABLE(OrderIterator);
public:
    friend class OrderIteratorPopulator;

    OrderIterator(const RenderBox*);

    RenderBox* currentChild() const { return m_currentChild; }
    RenderBox* first();
    RenderBox* next();
    void reset();

private:
    RenderBox* firstChildBox();
    RenderBox* nextSiblingBox();

    // If |m_children| is not empty, we will use it to iterate over this fixed subset.
    const RenderBox* m_containerBox;
    Vector<RenderBox*> m_children;

    RenderBox* m_currentChild;
    size_t m_childIndex;

    // The inline capacity for a single item is used to cover the most
    // common case by far: if we only have the default 'order' value 0.
    typedef Vector<int, 1> OrderValues;
    OrderValues m_orderValues;
    Vector<int>::const_iterator m_orderValuesIterator;
};

class OrderIteratorPopulator {
public:
    OrderIteratorPopulator(OrderIterator& iterator)
        : m_iterator(iterator)
        , m_anyChildHasDefaultOrderValue(false)
    {
        // Note that we don't release the memory here, we only invalidate the size.
        // This avoids unneeded reallocation if the size ends up not changing.
        m_iterator.m_orderValues.shrink(0);
    }

    ~OrderIteratorPopulator();

    void storeChild(RenderBox*);
    void collectChild(const RenderBox*);

private:
    void removeDuplicatedOrderValues();

    OrderIterator& m_iterator;
    bool m_anyChildHasDefaultOrderValue;
};

} // namespace WebCore

#endif //  OrderIterator_h