flutter_flutter/sky/engine/core/dom/NodeTraversal.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, 2012 Apple Inc. All rights reserved.
 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
 * Copyright (C) 2014 Samsung Electronics. 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 SKY_ENGINE_CORE_DOM_NODETRAVERSAL_H_
#define SKY_ENGINE_CORE_DOM_NODETRAVERSAL_H_

#include "sky/engine/core/dom/ContainerNode.h"
#include "sky/engine/core/dom/Node.h"

namespace blink {

class NodeTraversal {
public:
    // Does a pre-order traversal of the tree to find the next node after this one.
    // This uses the same order that tags appear in the source file. If the stayWithin
    // argument is non-null, the traversal will stop once the specified node is reached.
    // This can be used to restrict traversal to a particular sub-tree.
    static Node* next(const Node& current) { return traverseNextTemplate(current); }
    static Node* next(const ContainerNode& current) { return traverseNextTemplate(current); }
    static Node* next(const Node& current, const Node* stayWithin) { return traverseNextTemplate(current, stayWithin); }
    static Node* next(const ContainerNode& current, const Node* stayWithin) { return traverseNextTemplate(current, stayWithin); }

    // Like next, but skips children and starts with the next sibling.
    static Node* nextSkippingChildren(const Node&);
    static Node* nextSkippingChildren(const Node&, const Node* stayWithin);

    static Node* lastWithin(const ContainerNode&);
    static Node& lastWithinOrSelf(Node&);

    // Does a reverse pre-order traversal to find the node that comes before the current one in document order
    static Node* previous(const Node&, const Node* stayWithin = 0);

    // Like previous, but skips children and starts with the next sibling.
    static Node* previousSkippingChildren(const Node&, const Node* stayWithin = 0);

    // Like next, but visits parents after their children.
    static Node* nextPostOrder(const Node&, const Node* stayWithin = 0);

    // Like previous, but visits parents before their children.
    static Node* previousPostOrder(const Node&, const Node* stayWithin = 0);

    static Node* nextAncestorSibling(const Node&);
    static Node* nextAncestorSibling(const Node&, const Node* stayWithin);
    static Node& highestAncestorOrSelf(Node&);

    // Children traversal.
    static Node* childAt(const Node& parent, unsigned index) { return childAtTemplate(parent, index); }
    static Node* childAt(const ContainerNode& parent, unsigned index) { return childAtTemplate(parent, index); }

private:
    template <class NodeType>
    static Node* traverseNextTemplate(NodeType&);
    template <class NodeType>
    static Node* traverseNextTemplate(NodeType&, const Node* stayWithin);
    template <class NodeType>
    static Node* childAtTemplate(NodeType&, unsigned);
};

template <class NodeType>
inline Node* NodeTraversal::traverseNextTemplate(NodeType& current)
{
    if (current.hasChildren())
        return current.firstChild();
    if (current.nextSibling())
        return current.nextSibling();
    return nextAncestorSibling(current);
}

template <class NodeType>
inline Node* NodeTraversal::traverseNextTemplate(NodeType& current, const Node* stayWithin)
{
    if (current.hasChildren())
        return current.firstChild();
    if (current == stayWithin)
        return 0;
    if (current.nextSibling())
        return current.nextSibling();
    return nextAncestorSibling(current, stayWithin);
}

inline Node* NodeTraversal::nextSkippingChildren(const Node& current)
{
    if (current.nextSibling())
        return current.nextSibling();
    return nextAncestorSibling(current);
}

inline Node* NodeTraversal::nextSkippingChildren(const Node& current, const Node* stayWithin)
{
    if (current == stayWithin)
        return 0;
    if (current.nextSibling())
        return current.nextSibling();
    return nextAncestorSibling(current, stayWithin);
}

inline Node& NodeTraversal::highestAncestorOrSelf(Node& current)
{
    Node* highest = &current;
    while (highest->parentNode())
        highest = highest->parentNode();
    return *highest;
}

template <class NodeType>
inline Node* NodeTraversal::childAtTemplate(NodeType& parent, unsigned index)
{
    Node* child = parent.firstChild();
    while (child && index--)
        child = child->nextSibling();
    return child;
}

} // namespace blink

#endif  // SKY_ENGINE_CORE_DOM_NODETRAVERSAL_H_