third_party/WebKit/Source/core/dom/NodeIterator.cpp

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 * Copyright (C) 2000 Frederik Holljen (frederik.holljen@hig.no)
 * Copyright (C) 2001 Peter Kelly (pmk@post.com)
 * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
 * Copyright (C) 2004, 2008 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.
 *
 */

#include "core/dom/NodeIterator.h"

#include "bindings/core/v8/ExceptionState.h"
#include "core/dom/Attr.h"
#include "core/dom/Document.h"
#include "core/dom/NodeTraversal.h"

namespace blink {

NodeIterator::NodePointer::NodePointer() {}

NodeIterator::NodePointer::NodePointer(Node* n, bool b)
    : node(n), isPointerBeforeNode(b) {}

void NodeIterator::NodePointer::clear() {
  node.clear();
}

bool NodeIterator::NodePointer::moveToNext(Node* root) {
  if (!node)
    return false;
  if (isPointerBeforeNode) {
    isPointerBeforeNode = false;
    return true;
  }
  node = NodeTraversal::next(*node, root);
  return node;
}

bool NodeIterator::NodePointer::moveToPrevious(Node* root) {
  if (!node)
    return false;
  if (!isPointerBeforeNode) {
    isPointerBeforeNode = true;
    return true;
  }
  node = NodeTraversal::previous(*node, root);
  return node;
}

NodeIterator::NodeIterator(Node* rootNode,
                           unsigned whatToShow,
                           NodeFilter* filter)
    : NodeIteratorBase(rootNode, whatToShow, filter),
      m_referenceNode(root(), true) {
  // If NodeIterator target is Attr node, don't subscribe for nodeWillBeRemoved,
  // as it would never have child nodes.
  if (!root()->isAttributeNode())
    root()->document().attachNodeIterator(this);
}

Node* NodeIterator::nextNode(ExceptionState& exceptionState) {
  Node* result = nullptr;

  m_candidateNode = m_referenceNode;
  while (m_candidateNode.moveToNext(root())) {
    // NodeIterators treat the DOM tree as a flat list of nodes.
    // In other words, kFilterReject does not pass over descendants
    // of the rejected node. Hence, kFilterReject is the same as kFilterSkip.
    Node* provisionalResult = m_candidateNode.node;
    bool nodeWasAccepted = acceptNode(provisionalResult, exceptionState) ==
                           NodeFilter::kFilterAccept;
    if (exceptionState.hadException())
      break;
    if (nodeWasAccepted) {
      m_referenceNode = m_candidateNode;
      result = provisionalResult;
      break;
    }
  }

  m_candidateNode.clear();
  return result;
}

Node* NodeIterator::previousNode(ExceptionState& exceptionState) {
  Node* result = nullptr;

  m_candidateNode = m_referenceNode;
  while (m_candidateNode.moveToPrevious(root())) {
    // NodeIterators treat the DOM tree as a flat list of nodes.
    // In other words, kFilterReject does not pass over descendants
    // of the rejected node. Hence, kFilterReject is the same as kFilterSkip.
    Node* provisionalResult = m_candidateNode.node;
    bool nodeWasAccepted = acceptNode(provisionalResult, exceptionState) ==
                           NodeFilter::kFilterAccept;
    if (exceptionState.hadException())
      break;
    if (nodeWasAccepted) {
      m_referenceNode = m_candidateNode;
      result = provisionalResult;
      break;
    }
  }

  m_candidateNode.clear();
  return result;
}

void NodeIterator::detach() {
  // This is now a no-op as per the DOM specification.
}

void NodeIterator::nodeWillBeRemoved(Node& removedNode) {
  updateForNodeRemoval(removedNode, m_candidateNode);
  updateForNodeRemoval(removedNode, m_referenceNode);
}

void NodeIterator::updateForNodeRemoval(Node& removedNode,
                                        NodePointer& referenceNode) const {
  DCHECK_EQ(root()->document(), removedNode.document());

  // Iterator is not affected if the removed node is the reference node and is
  // the root.  or if removed node is not the reference node, or the ancestor of
  // the reference node.
  if (!removedNode.isDescendantOf(root()))
    return;
  bool willRemoveReferenceNode = removedNode == referenceNode.node.get();
  bool willRemoveReferenceNodeAncestor =
      referenceNode.node && referenceNode.node->isDescendantOf(&removedNode);
  if (!willRemoveReferenceNode && !willRemoveReferenceNodeAncestor)
    return;

  if (referenceNode.isPointerBeforeNode) {
    Node* node = NodeTraversal::next(removedNode, root());
    if (node) {
      // Move out from under the node being removed if the new reference
      // node is a descendant of the node being removed.
      while (node && node->isDescendantOf(&removedNode))
        node = NodeTraversal::next(*node, root());
      if (node)
        referenceNode.node = node;
    } else {
      node = NodeTraversal::previous(removedNode, root());
      if (node) {
        // Move out from under the node being removed if the reference node is
        // a descendant of the node being removed.
        if (willRemoveReferenceNodeAncestor) {
          while (node && node->isDescendantOf(&removedNode))
            node = NodeTraversal::previous(*node, root());
        }
        if (node) {
          // Removing last node.
          // Need to move the pointer after the node preceding the
          // new reference node.
          referenceNode.node = node;
          referenceNode.isPointerBeforeNode = false;
        }
      }
    }
  } else {
    Node* node = NodeTraversal::previous(removedNode, root());
    if (node) {
      // Move out from under the node being removed if the reference node is
      // a descendant of the node being removed.
      if (willRemoveReferenceNodeAncestor) {
        while (node && node->isDescendantOf(&removedNode))
          node = NodeTraversal::previous(*node, root());
      }
      if (node)
        referenceNode.node = node;
    } else {
      // FIXME: This branch doesn't appear to have any LayoutTests.
      node = NodeTraversal::next(removedNode, root());
      // Move out from under the node being removed if the reference node is
      // a descendant of the node being removed.
      if (willRemoveReferenceNodeAncestor) {
        while (node && node->isDescendantOf(&removedNode))
          node = NodeTraversal::previous(*node, root());
      }
      if (node)
        referenceNode.node = node;
    }
  }
}

DEFINE_TRACE(NodeIterator) {
  visitor->trace(m_referenceNode);
  visitor->trace(m_candidateNode);
  NodeIteratorBase::trace(visitor);
}

DEFINE_TRACE_WRAPPERS(NodeIterator) {
  NodeIteratorBase::traceWrappers(visitor);
}

}  // namespace blink