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/*
* © Copyright IBM Corp. 2012
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.ibm.commons.xml;
import java.util.*;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.ranges.Range;
/**
*
* Iterator over the objects in a Range.
*
* @author dloverin
* Jun 9, 2006
*
*/
public class RangeIterator implements ListIterator {
private Node _currentNode; // hold place for traversal
private int _currentOffset; // current offset in container of _currentNode
private Node _commonAncestor; // derived from _range
private Range _range;
private Map _descentPath; // descent from the common ancestor to the starting container
private int _currentIndex; // index of iterator
private boolean _firstChild; // if true start at first child, not common ancestor
/**
* NOT READY FOR USE YET. PLEASE DO NOT USE!
*
* Create a new iterator that will return each node encounters while
* walking the dom tree from the beginning of the range to the end of
* the range.
* The walk of the range begins at the common ancestor of the range endpoints
* and continues in a depth first traversal of the tree.
*
* Parent containers are included in the iteration after reaching the last child in
* a container.
*
* @param range
*/
public RangeIterator(Range range) {
this(range, false);
}
/**
* Same iterator with an option to start the iterator at the range's first node.
* @param range - range must be normalized.
* @param firstChild - if true start the the range's first child instead of
* the common ancestor.
*/
public RangeIterator(Range range, boolean firstChild) {
if (range == null || range.getStartContainer() == null ||
range.getEndContainer() == null) {
throw new NullPointerException();
}
_range = range;
_firstChild = firstChild;
initIterator();
}
public boolean hasNext() {
if (_commonAncestor == null) {
return false;
}
if (_currentNode == null) {
return true;
}
if (isAtEndOfRange(_currentNode, _currentOffset)) {
return false;
}
return true;
}
public Object next() {
if (_commonAncestor == null) {
throw new NoSuchElementException();
}
if (_currentNode == null) {
if (_firstChild) {
_currentNode = _range.getStartContainer();
if (_currentNode.hasChildNodes()) {
_currentNode = _currentNode.getChildNodes().item(_range.getStartOffset());
_currentOffset = 0;
}
else {
_currentOffset = _range.getStartOffset();
}
}
else {
_currentNode = _commonAncestor;
_currentOffset = ((Integer)_descentPath.get(_commonAncestor)).intValue();
}
_currentIndex++;
return _currentNode;
}
if (isAtEndOfRange(_currentNode, _currentOffset)) {
throw new NoSuchElementException();
}
if (_currentNode.hasChildNodes()) {
Integer offsetInt = (Integer)_descentPath.get(_currentNode);
if (offsetInt == null) {
_currentNode = _currentNode.getFirstChild();
_currentIndex++;
_currentOffset = 0;
return _currentNode;
}
else {
Node tempNode = _currentNode.getChildNodes().item(offsetInt.intValue());
if (tempNode != null) {
_currentNode = tempNode;
_currentIndex++;
offsetInt = (Integer)_descentPath.get(_currentNode);
_currentOffset = (offsetInt == null) ? 0 : offsetInt.intValue();
return _currentNode;
}
}
}
// when we are at the end of the sibling for a node,
// go to the parent and get the next sibing in the parent.
Node nextNode = _currentNode.getNextSibling();
_currentOffset++;
while (nextNode == null) {
_currentNode = _currentNode.getParentNode();
if (_currentNode == _commonAncestor) {
throw new NoSuchElementException();
}
nextNode = _currentNode.getNextSibling();
_currentOffset = 0;
}
_currentNode = nextNode;
_currentIndex++;
return _currentNode;
}
/**
* currently not supported
*/
public void remove() {
throw new UnsupportedOperationException();
}
/**
* init state of this iterator
*
*/
private void initIterator() {
_currentIndex = 0;
// init the common ascestor
_commonAncestor = _range.getCommonAncestorContainer();
// this can hapend when an element has been removed from the model
// but the changes have not been flushed.
if (_commonAncestor == null) {
return;
}
// create a map of nodes to child index to create a path
// to descend the tree from the common ancestor to the
// starting container
_descentPath = new HashMap();
Node node = _range.getStartContainer();
int offset = _range.getStartOffset();
Node ancestorParent = _commonAncestor.getParentNode();
while (node != ancestorParent) {
_descentPath.put(node, Integer.valueOf(offset));
offset = getOffsetInContainer(node);
node = node.getParentNode();
}
}
/**
* Helper method to get the offset of a given node with respect to its
* parent.
*
* @param node -
* may not be null
* @return int - zero-based offset of node in its container or -1 if the
* node as no container.
*/
public static int getOffsetInContainer(Node node) {
Node parent = node.getParentNode();
if (parent != null) {
NodeList children = parent.getChildNodes();
for (int i = 0; i < children.getLength(); i++) {
Node child = (Node) children.item(i);
if (child == node) {
return i;
}
}
throw new IllegalStateException(); // how could the child not be found?
}
return -1;
}
/**
* NOT SUPPORTED
* @param arg0
*/
public void add(Object arg0) {
throw new UnsupportedOperationException();
}
public boolean hasPrevious() {
return _currentIndex == 0 ? true : false;
}
public int nextIndex() {
return _currentIndex + 1;
}
public Object previous() {
if (_currentIndex == 0) {
throw new NoSuchElementException();
}
// return the current node
Node retNode = _currentNode;
// update the position of the current node for the next operation
Node prev = _currentNode.getPreviousSibling();
if (prev == null) {
_currentNode = _currentNode.getParentNode();
}
else {
// get the last child of this node if it has children
if (prev.hasChildNodes()) {
NodeList children = prev.getChildNodes();
_currentNode = children.item(children.getLength() - 1);
}
else {
_currentNode = prev;
}
}
_currentIndex--;
return retNode;
}
public int previousIndex() {
return _currentIndex - 1;
}
/**
* NOT SUPPORTED
*
* @param arg0
*/
public void set(Object arg0) {
throw new UnsupportedOperationException();
}
/**
* Test if node is at the end of the range of this iterator.
* @param node
* @return true node is the last node in the range.
*/
private boolean isAtEndOfRange(Node node, int offset) {
// don't compare offsets on the text node since we are jumping node to node.
if (node.getNodeType() == Node.TEXT_NODE && node == _range.getEndContainer()) {
return true;
}
int result = DOMUtil.compareLocations(node, offset, _range.getEndContainer(), _range.getEndOffset());
if (result >= 0) {
return true;
}
Node currentNode = node;
Node endNode = _range.getEndContainer();
if (currentNode.hasChildNodes()) {
return false;
}
// check if all the parents between the current node and the end node are at their last child.
// if so then we are done.
Node parent = currentNode.getParentNode();
while (parent != null) {
NodeList children = parent.getChildNodes();
if (children.item(children.getLength() - 1) != currentNode) {
break;
}
if (parent == endNode) {
return true; // found no nodes to iterate to
}
currentNode = parent;
parent = currentNode.getParentNode();
}
return false;
}
/**
* Map a node and offset into an actual node.
*
* @param node
* @param offset
* @return
*/
// private Node getEffectiveNode(Node node, int offset) {
// if (node.hasChildNodes()) {
// NodeList children = node.getChildNodes();
// if (offset == children.getLength()) {
// offset--;
// }
// node = children.item(offset);
// }
//
// return node;
// }
//
}
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