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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;
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 set = new HashSet();
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  }