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 */
017
018package org.apache.commons.jxpath.ri.axes;
019
020import java.util.ArrayList;
021import java.util.Iterator;
022
023import org.apache.commons.jxpath.BasicNodeSet;
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 of a union operation like (a | b)
029 */
030public class UnionContext extends NodeSetContext {
031
032    private final EvalContext[] contexts;
033    private boolean prepared;
034
035    /**
036     * Constructs a new UnionContext.
037     *
038     * @param parentContext parent context
039     * @param contexts      child contexts
040     */
041    public UnionContext(final EvalContext parentContext, final EvalContext[] contexts) {
042        super(parentContext, new BasicNodeSet());
043        this.contexts = contexts;
044    }
045
046    @Override
047    public int getDocumentOrder() {
048        return contexts.length > 1 ? 1 : super.getDocumentOrder();
049    }
050
051    @Override
052    public boolean setPosition(final int position) {
053        if (!prepared) {
054            prepared = true;
055            final BasicNodeSet nodeSet = (BasicNodeSet) getNodeSet();
056            final ArrayList<NodePointer> pointers = new ArrayList<>();
057            for (final EvalContext ctx : contexts) {
058                while (ctx.nextSet()) {
059                    while (ctx.nextNode()) {
060                        final NodePointer ptr = ctx.getCurrentNodePointer();
061                        if (!pointers.contains(ptr)) {
062                            pointers.add(ptr);
063                        }
064                    }
065                }
066            }
067            sortPointers(pointers);
068            for (final Iterator<NodePointer> it = pointers.iterator(); it.hasNext();) {
069                nodeSet.add(it.next());
070            }
071        }
072        return super.setPosition(position);
073    }
074}