001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.jxpath.ri.axes;
018
019import java.util.ArrayList;
020import java.util.Iterator;
021
022import org.apache.commons.jxpath.BasicNodeSet;
023import org.apache.commons.jxpath.Pointer;
024import org.apache.commons.jxpath.ri.EvalContext;
025import org.apache.commons.jxpath.ri.model.NodePointer;
026
027/**
028 * EvalContext that represents a union between other contexts - result
029 * of a union operation like (a | b)
030 *
031 * @author Dmitri Plotnikov
032 * @version $Revision: 1523199 $ $Date: 2013-09-14 11:45:47 +0200 (Sa, 14 Sep 2013) $
033 */
034public class UnionContext extends NodeSetContext {
035    private EvalContext[] contexts;
036    private boolean prepared;
037
038    /**
039     * Create a new UnionContext.
040     * @param parentContext parent context
041     * @param contexts child contexts
042     */
043    public UnionContext(EvalContext parentContext, EvalContext[] contexts) {
044        super(parentContext, new BasicNodeSet());
045        this.contexts = contexts;
046    }
047
048    public int getDocumentOrder() {
049        return contexts.length > 1 ? 1 : super.getDocumentOrder();
050    }
051
052    public boolean setPosition(int position) {
053        if (!prepared) {
054            prepared = true;
055            BasicNodeSet nodeSet = (BasicNodeSet) getNodeSet();
056            ArrayList pointers = new ArrayList();
057            for (int i = 0; i < contexts.length; i++) {
058                EvalContext ctx = contexts[i];
059                while (ctx.nextSet()) {
060                    while (ctx.nextNode()) {
061                        NodePointer ptr = ctx.getCurrentNodePointer();
062                        if (!pointers.contains(ptr)) {
063                            pointers.add(ptr);
064                        }
065                    }
066                }
067            }
068            sortPointers(pointers);
069
070            for (Iterator it = pointers.iterator(); it.hasNext();) {
071                nodeSet.add((Pointer) it.next());
072            }
073        }
074        return super.setPosition(position);
075    }
076}