alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

What this is

This file is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Other links

The source code

/*
 * 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);
        }
    }
}
... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2024 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.