Commons JXPath example source code file (CollectionNodeIterator.java)

This example Commons JXPath source code file (CollectionNodeIterator.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, collectionnodeiterator, collectionnodeiterator, collectionpointer, collectionpointer, invalid, jxpathexception, list, nodeiterator, nodeiterator, nodepointer, nodepointer, util

The Commons JXPath CollectionNodeIterator.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.model.beans;

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

import org.apache.commons.jxpath.JXPathException;
import org.apache.commons.jxpath.ri.model.NodeIterator;
import org.apache.commons.jxpath.ri.model.NodePointer;

/**
 * Combines node iterators of all elements of a collection into one
 * aggregate node iterator.
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
 */
public abstract class CollectionNodeIterator implements NodeIterator {
    private CollectionPointer pointer;
    private boolean reverse;
    private NodePointer startWith;
    private int position;
    private List collection;

    /**
     * Create a new CollectionNodeIterator.
     * @param pointer collection pointer
     * @param reverse iteration order
     * @param startWith starting pointer
     */
    protected CollectionNodeIterator(
        CollectionPointer pointer,
        boolean reverse,
        NodePointer startWith) {
        this.pointer = pointer;
        this.reverse = reverse;
        this.startWith = startWith;
    }

    /**
     * Implemented by subclasses to produce child/attribute node iterators.
     * @param elementPointer owning pointer
     * @return NodeIterator
     */
    protected abstract NodeIterator
            getElementNodeIterator(NodePointer elementPointer);

    public int getPosition() {
        return position;
    }

    public boolean setPosition(int position) {
        if (collection == null) {
            prepare();
        }

        if (position < 1 || position > collection.size()) {
            return false;
        }
        this.position = position;
        return true;
    }

    public NodePointer getNodePointer() {
        if (position == 0) {
            return null;
        }
        return (NodePointer) collection.get(position - 1);
    }

    /**
     * Prepare...
     */
    private void prepare() {
        collection = new ArrayList();
        NodePointer ptr = (NodePointer) pointer.clone();
        int length = ptr.getLength();
        for (int i = 0; i < length; i++) {
            ptr.setIndex(i);
            NodePointer elementPointer = ptr.getValuePointer();
            NodeIterator iter = getElementNodeIterator(elementPointer);

            for (int j = 1; iter.setPosition(j); j++) {
                NodePointer childPointer = iter.getNodePointer();
                if (reverse) {
                    collection.add(0, childPointer);
                }
                else {
                    collection.add(childPointer);
                }
            }
        }
        if (startWith != null) {
            int index = collection.indexOf(startWith);
            if (index == -1) {
                throw new JXPathException(
                    "Invalid starting pointer for iterator: " + startWith);
            }
            while (collection.size() > index) {
                if (!reverse) {
                    collection.remove(collection.size() - 1);
                }
                else {
                    collection.remove(0);
                }
            }
        }
    }
}