third_party/WebKit/Source/core/dom/LayoutTreeBuilder.h

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
 * rights reserved.
 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
 * (http://www.torchmobile.com/)
 * Copyright (C) 2011 Google 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.
 *
 */

#ifndef LayoutTreeBuilder_h
#define LayoutTreeBuilder_h

#include "core/dom/Document.h"
#include "core/dom/LayoutTreeBuilderTraversal.h"
#include "core/dom/Node.h"
#include "core/dom/Text.h"
#include "core/layout/LayoutObject.h"
#include "wtf/RefPtr.h"

namespace blink {

class ComputedStyle;

template <typename NodeType>
class LayoutTreeBuilder {
  STACK_ALLOCATED();

 protected:
  LayoutTreeBuilder(NodeType& node, LayoutObject* layoutObjectParent)
      : m_node(node), m_layoutObjectParent(layoutObjectParent) {
    DCHECK(!node.layoutObject());
    DCHECK(node.needsAttach());
    DCHECK(node.document().inStyleRecalc());
    DCHECK(node.inActiveDocument());
  }

  LayoutObject* nextLayoutObject() const {
    DCHECK(m_layoutObjectParent);

    // Avoid an O(N^2) walk over the children when reattaching all children of a
    // node.
    if (m_layoutObjectParent->node() &&
        m_layoutObjectParent->node()->needsAttach())
      return 0;

    return LayoutTreeBuilderTraversal::nextSiblingLayoutObject(*m_node);
  }

  Member<NodeType> m_node;
  LayoutObject* m_layoutObjectParent;
};

class LayoutTreeBuilderForElement : public LayoutTreeBuilder<Element> {
 public:
  LayoutTreeBuilderForElement(Element&, ComputedStyle*);

  void createLayoutObjectIfNeeded() {
    if (shouldCreateLayoutObject())
      createLayoutObject();
  }

 private:
  LayoutObject* parentLayoutObject() const;
  LayoutObject* nextLayoutObject() const;
  bool shouldCreateLayoutObject() const;
  ComputedStyle& style() const;
  void createLayoutObject();

  mutable RefPtr<ComputedStyle> m_style;
};

class LayoutTreeBuilderForText : public LayoutTreeBuilder<Text> {
 public:
  LayoutTreeBuilderForText(Text& text, LayoutObject* layoutParent)
      : LayoutTreeBuilder(text, layoutParent) {}

  void createLayoutObject();
};

}  // namespace blink

#endif