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Java > Open Source Codes > org > apache > commons > jxpath > ri > axes > UnionContext


1 /*
2  * Copyright 1999-2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.jxpath.ri.axes;
17
18 import java.util.HashSet JavaDoc;
19
20 import org.apache.commons.jxpath.BasicNodeSet;
21 import org.apache.commons.jxpath.ri.EvalContext;
22 import org.apache.commons.jxpath.ri.model.NodePointer;
23
24 /**
25  * EvalContext that represents a union between other contexts - result
26  * of a union operation like (a | b)
27  *
28  * @author Dmitri Plotnikov
29  * @version $Revision: 1.12 $ $Date: 2004/02/29 14:17:38 $
30  */
31 public class UnionContext extends NodeSetContext {
32     private boolean startedSet = false;
33     private EvalContext contexts[];
34     private boolean prepared = false;
35
36     public UnionContext(EvalContext parentContext, EvalContext contexts[]) {
37         super(parentContext, new BasicNodeSet());
38         this.contexts = contexts;
39     }
40
41     public int getDocumentOrder() {
42         if (contexts.length > 1) {
43             return 1;
44         }
45         return super.getDocumentOrder();
46     }
47
48     public boolean setPosition(int position) {
49         if (!prepared) {
50             prepared = true;
51             BasicNodeSet nodeSet = (BasicNodeSet) getNodeSet();
52             HashSet JavaDoc set = new HashSet JavaDoc();
53             for (int i = 0; i < contexts.length; i++) {
54                 EvalContext ctx = (EvalContext) contexts[i];
55                 while (ctx.nextSet()) {
56                     while (ctx.nextNode()) {
57                         NodePointer ptr = ctx.getCurrentNodePointer();
58                         if (!set.contains(ptr)) {
59                             nodeSet.add(ptr);
60                             set.add(ptr);
61                         }
62                     }
63                 }
64             }
65         }
66         return super.setPosition(position);
67     }
68 }
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