    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    package org.apache.commons.jxpath.ri.axes;
    018
    019    import java.util.ArrayList;
    020    import java.util.Iterator;
    021
    022    import org.apache.commons.jxpath.BasicNodeSet;
    023    import org.apache.commons.jxpath.Pointer;
    024    import org.apache.commons.jxpath.ri.EvalContext;
    025    import 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: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
    033     */
    034    public 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 = (EvalContext) 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    }