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


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.QName;
20 import org.apache.commons.jxpath.ri.compiler.NodeNameTest;
21 import org.apache.commons.jxpath.ri.compiler.NodeTest;
22 import org.apache.commons.jxpath.ri.model.NodeIterator;
23 import org.apache.commons.jxpath.ri.model.NodePointer;
24
25 /**
26  * EvalContext that walks the "attribute::" axis.
27  *
28  * @author Dmitri Plotnikov
29  * @version $Revision: 1.10 $ $Date: 2004/02/29 14:17:38 $
30  */
31 public class AttributeContext extends EvalContext {
32     private NodeTest nodeTest;
33     private boolean setStarted = false;
34     private NodeIterator iterator;
35     private NodePointer currentNodePointer;
36
37     /**
38      * @param parentContext represents the previous step on the path
39      * @param nameTest is the name of the attribute we are looking for
40      */
41     public AttributeContext(EvalContext parentContext, NodeTest nodeTest) {
42         super(parentContext);
43         this.nodeTest = nodeTest;
44     }
45
46     public NodePointer getCurrentNodePointer() {
47         return currentNodePointer;
48     }
49
50     public void reset() {
51         setStarted = false;
52         iterator = null;
53         super.reset();
54     }
55
56     public boolean setPosition(int position) {
57         if (position < getCurrentPosition()) {
58             reset();
59         }
60
61         while (getCurrentPosition() < position) {
62             if (!nextNode()) {
63                 return false;
64             }
65         }
66         return true;
67     }
68
69     public boolean nextNode() {
70         super.setPosition(getCurrentPosition() + 1);
71         if (!setStarted) {
72             setStarted = true;
73             if (!(nodeTest instanceof NodeNameTest)) {
74                 return false;
75             }
76             QName name = ((NodeNameTest) nodeTest).getNodeName();
77             iterator =
78                 parentContext.getCurrentNodePointer().attributeIterator(name);
79         }
80
81         if (iterator == null) {
82             return false;
83         }
84         if (!iterator.setPosition(iterator.getPosition() + 1)) {
85             return false;
86         }
87         currentNodePointer = iterator.getNodePointer();
88         return true;
89     }
90 }
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