text: /*
   * 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.
   *     * Neither the name of Google Inc. 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 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,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_ORDER_ITERATOR_H_
  #define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_ORDER_ITERATOR_H_
  
  #include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
  
  #include <set>
  
  namespace blink {
  
  class LayoutBox;
  
  class OrderIterator {
    DISALLOW_NEW();
  
   public:
    friend class OrderIteratorPopulator;
  
    explicit OrderIterator(const LayoutBox*);
    OrderIterator(const OrderIterator&) = delete;
    OrderIterator& operator=(const OrderIterator&) = delete;
  
    LayoutBox* CurrentChild() { return current_child_; }
    const LayoutBox* CurrentChild() const { return current_child_; }
    LayoutBox* First();
    const LayoutBox* First() const {
      return const_cast<OrderIterator*>(this)->First();
    }
    LayoutBox* Next();
    const LayoutBox* Next() const {
      return const_cast<OrderIterator*>(this)->Next();
    }
  
   private:
    void Reset();
  
    // Returns the order to use for |child|.
    int ResolvedOrder(const LayoutBox& child) const;
  
    const LayoutBox* container_box_;
  
    LayoutBox* current_child_ = nullptr;
  
    using OrderValues = std::set<int>;
    OrderValues order_values_;
    OrderValues::const_iterator order_values_iterator_;
    // Set by |Reset()|, triggers iteration to start from the beginning.
    bool is_reset_ = false;
  };
  
  class OrderIteratorPopulator {
    STACK_ALLOCATED();
  
   public:
    explicit OrderIteratorPopulator(OrderIterator& iterator)
        : iterator_(iterator) {
      iterator_.order_values_.clear();
    }
  
    ~OrderIteratorPopulator();
  
    void CollectChild(const LayoutBox*);
  
   private:
    OrderIterator& iterator_;
  };
  
  }  // namespace blink
  
  #endif  // THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_ORDER_ITERATOR_H_
  