/*
* Copyright 1999-2004 The Apache Software Foundation
*
* 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 org.apache.commons.jxpath.ri.axes;
import org.apache.commons.jxpath.Pointer;
import org.apache.commons.jxpath.ri.EvalContext;
import org.apache.commons.jxpath.ri.compiler.NodeTest;
import org.apache.commons.jxpath.ri.model.NodeIterator;
import org.apache.commons.jxpath.ri.model.NodePointer;
/**
* EvalContext that can walk the "child::", "following-sibling::" and
* "preceding-sibling::" axes.
*
* @author Dmitri Plotnikov
* @version $Revision: 1.16 $ $Date: 2004/03/25 03:49:50 $
*/
public class ChildContext extends EvalContext {
private NodeTest nodeTest;
private boolean startFromParentLocation;
private boolean reverse;
private NodeIterator iterator;
public ChildContext(
EvalContext parentContext,
NodeTest nodeTest,
boolean startFromParentLocation,
boolean reverse)
{
super(parentContext);
this.nodeTest = nodeTest;
this.startFromParentLocation = startFromParentLocation;
this.reverse = reverse;
}
public NodePointer getCurrentNodePointer() {
if (position == 0) {
if (!setPosition(1)) {
return null;
}
}
if (iterator != null) {
return iterator.getNodePointer();
}
else {
return null;
}
}
/**
* This method is called on the last context on the path when only
* one value is needed. Note that this will return the whole property,
* even if it is a collection. It will not extract the first element
* of the collection. For example, "books" will return the collection
* of books rather than the first book from that collection.
*/
public Pointer getSingleNodePointer() {
if (position == 0) {
while (nextSet()) {
prepare();
if (iterator == null) {
return null;
}
// See if there is a property there, singular or collection
NodePointer pointer = iterator.getNodePointer();
if (pointer != null) {
return pointer;
}
}
return null;
}
return getCurrentNodePointer();
}
public boolean nextNode() {
return setPosition(getCurrentPosition() + 1);
}
public void reset() {
super.reset();
iterator = null;
}
public boolean setPosition(int position) {
int oldPosition = getCurrentPosition();
super.setPosition(position);
if (oldPosition == 0) {
prepare();
}
if (iterator == null) {
return false;
}
return iterator.setPosition(position);
}
/**
* Allocates a PropertyIterator.
*/
private void prepare() {
NodePointer parent = parentContext.getCurrentNodePointer();
if (parent == null) {
return;
}
if (startFromParentLocation) {
NodePointer pointer = parent.getParent();
iterator = pointer.childIterator(nodeTest, reverse, parent);
}
else {
iterator = parent.childIterator(nodeTest, reverse, null);
}
}
}