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 }