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


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 org.apache.commons.jxpath.ri.EvalContext;
19 import org.apache.commons.jxpath.ri.compiler.NodeTest;
20 import org.apache.commons.jxpath.ri.model.NodePointer;
21
22 /**
23  * EvalContext that walks the "ancestor::" and "ancestor-or-self::" axes.
24  *
25  * @author Dmitri Plotnikov
26  * @version $Revision: 1.15 $ $Date: 2004/03/25 03:49:50 $
27  */
28 public class AncestorContext extends EvalContext {
29     private NodeTest nodeTest;
30     private boolean setStarted = false;
31     private NodePointer currentNodePointer;
32     private boolean includeSelf;
33
34     /**
35      * @param parentContext represents the previous step on the path
36      * @param includeSelf differentiates between "ancestor::" and "ancestor-
37      * or-self::" axes
38      * @param nameTest is the name of the element(s) we are looking for
39      */
40     public AncestorContext(
41         EvalContext parentContext,
42         boolean includeSelf,
43         NodeTest nodeTest)
44     {
45         super(parentContext);
46         this.includeSelf = includeSelf;
47         this.nodeTest = nodeTest;
48     }
49
50     public NodePointer getCurrentNodePointer() {
51         return currentNodePointer;
52     }
53
54     public int getDocumentOrder() {
55         return -1;
56     }
57
58     public void reset() {
59         super.reset();
60         setStarted = false;
61     }
62
63     public boolean setPosition(int position) {
64         if (position < getCurrentPosition()) {
65             reset();
66         }
67
68         while (getCurrentPosition() < position) {
69             if (!nextNode()) {
70                 return false;
71             }
72         }
73         return true;
74     }
75
76     public boolean nextNode() {
77         if (!setStarted) {
78             setStarted = true;
79             currentNodePointer = parentContext.getCurrentNodePointer();
80             if (includeSelf) {
81                 if (currentNodePointer.testNode(nodeTest)) {
82                     position++;
83                     return true;
84                 }
85             }
86         }
87
88         while (true) {
89             currentNodePointer = currentNodePointer.getImmediateParentPointer();
90
91             if (currentNodePointer == null) {
92                 return false;
93             }
94
95             if (currentNodePointer.testNode(nodeTest)) {
96                 position++;
97                 return true;
98             }
99         }
100     }
101 }
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