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Commons JXPath example source code file (ChildContext.java)

This example Commons JXPath source code file (ChildContext.java) 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.

Java - Commons JXPath tags/keywords

childcontext, childcontext, evalcontext, evalcontext, nodeiterator, nodepointer, nodepointer, nodetest, nodetest, pointer

The Commons JXPath ChildContext.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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: 652903 $ $Date: 2008-05-02 15:46:32 -0500 (Fri, 02 May 2008) $
 */
public class ChildContext extends EvalContext {
    private NodeTest nodeTest;
    private boolean startFromParentLocation;
    private boolean reverse;
    private NodeIterator iterator;

    /**
     * Create a new ChildContext.
     * @param parentContext parent EvalContext
     * @param nodeTest NodeTest
     * @param startFromParentLocation whether to start from parent location
     * @param reverse whether to iterate in reverse
     */
    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 && !setPosition(1)) {
            return null;
        }
        return iterator == null ? null : iterator.getNodePointer();
    }

    /**
     * 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.
     * @return Pointer
     */
    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();
        }
        return iterator == null ? false : iterator.setPosition(position);
    }

    /**
     * Allocates a PropertyIterator.
     */
    private void prepare() {
        NodePointer parent = parentContext.getCurrentNodePointer();
        if (parent == null) {
            return;
        }
        NodePointer useParent = startFromParentLocation ? parent.getParent() : parent;
        iterator = useParent.childIterator(nodeTest, reverse,
                startFromParentLocation ? parent : null);
    }
}

Other Commons JXPath examples (source code examples)

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