Commons JXPath example source code file (BasicNodeSet.java)

This example Commons JXPath source code file (BasicNodeSet.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

arraylist, arraylist, basicnodeset, list, list, nodeset, pointer, pointer, string, string, util

The Commons JXPath BasicNodeSet.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;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * A simple implementation of {@link NodeSet} that behaves as a collection
 * of pointers.
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
 */
public class BasicNodeSet implements NodeSet {
    private List pointers = new ArrayList();
    private List readOnlyPointers;
    private List nodes;
    private List values;

    /**
     * Add a pointer to this NodeSet.
     * @param pointer to add
     */
    public void add(Pointer pointer) {
        if (pointers.add(pointer)) {
            clearCacheLists();
        }
    }

    /**
     * Add the specified NodeSet to this NodeSet.
     * @param nodeSet to add
     */
    public void add(NodeSet nodeSet) {
        if (pointers.addAll(nodeSet.getPointers())) {
            clearCacheLists();
        }
    }

    /**
     * Remove a pointer from this NodeSet.
     * @param pointer to remove
     */
    public void remove(Pointer pointer) {
        if (pointers.remove(pointer)) {
            clearCacheLists();
        }
    }

    public synchronized List getPointers() {
        if (readOnlyPointers == null) {
            readOnlyPointers = Collections.unmodifiableList(pointers);
        }
        return readOnlyPointers;
    }

    public synchronized List getNodes() {
        if (nodes == null) {
            nodes = new ArrayList();
            for (int i = 0; i < pointers.size(); i++) {
                Pointer pointer = (Pointer) pointers.get(i);
                nodes.add(pointer.getNode());
            }
            nodes = Collections.unmodifiableList(nodes);
        }
        return nodes;
    }

    public synchronized List getValues() {
        if (values == null) {
            values = new ArrayList();
            for (int i = 0; i < pointers.size(); i++) {
                Pointer pointer = (Pointer) pointers.get(i);
                values.add(pointer.getValue());
            }
            values = Collections.unmodifiableList(values);
        }
        return values;
    }

    public String toString() {
        return pointers.toString();
    }

    /**
     * Clear cache list members.
     */
    private synchronized void clearCacheLists() {
        readOnlyPointers = null;
        nodes = null;
        values = null;
    }

}