1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.jxpath.ri.axes;
18
19 import org.apache.commons.jxpath.Pointer;
20 import org.apache.commons.jxpath.ri.EvalContext;
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 can walk the "child::", "following-sibling::" and
27 * "preceding-sibling::" axes.
28 *
29 * @author Dmitri Plotnikov
30 * @version $Revision: 652903 $ $Date: 2008-05-02 22:46:32 +0200 (Fr, 02 Mai 2008) $
31 */
32 public class ChildContext extends EvalContext {
33 private NodeTest nodeTest;
34 private boolean startFromParentLocation;
35 private boolean reverse;
36 private NodeIterator iterator;
37
38 /**
39 * Create a new ChildContext.
40 * @param parentContext parent EvalContext
41 * @param nodeTest NodeTest
42 * @param startFromParentLocation whether to start from parent location
43 * @param reverse whether to iterate in reverse
44 */
45 public ChildContext(EvalContext parentContext, NodeTest nodeTest,
46 boolean startFromParentLocation, boolean reverse) {
47 super(parentContext);
48 this.nodeTest = nodeTest;
49 this.startFromParentLocation = startFromParentLocation;
50 this.reverse = reverse;
51 }
52
53 public NodePointer getCurrentNodePointer() {
54 if (position == 0 && !setPosition(1)) {
55 return null;
56 }
57 return iterator == null ? null : iterator.getNodePointer();
58 }
59
60 /**
61 * This method is called on the last context on the path when only
62 * one value is needed. Note that this will return the whole property,
63 * even if it is a collection. It will not extract the first element
64 * of the collection. For example, "books" will return the collection
65 * of books rather than the first book from that collection.
66 * @return Pointer
67 */
68 public Pointer getSingleNodePointer() {
69 if (position == 0) {
70 while (nextSet()) {
71 prepare();
72 if (iterator == null) {
73 return null;
74 }
75 // See if there is a property there, singular or collection
76 NodePointer pointer = iterator.getNodePointer();
77 if (pointer != null) {
78 return pointer;
79 }
80 }
81 return null;
82 }
83 return getCurrentNodePointer();
84 }
85
86 public boolean nextNode() {
87 return setPosition(getCurrentPosition() + 1);
88 }
89
90 public void reset() {
91 super.reset();
92 iterator = null;
93 }
94
95 public boolean setPosition(int position) {
96 int oldPosition = getCurrentPosition();
97 super.setPosition(position);
98 if (oldPosition == 0) {
99 prepare();
100 }
101 return iterator == null ? false : iterator.setPosition(position);
102 }
103
104 /**
105 * Allocates a PropertyIterator.
106 */
107 private void prepare() {
108 NodePointer parent = parentContext.getCurrentNodePointer();
109 if (parent == null) {
110 return;
111 }
112 NodePointer useParent = startFromParentLocation ? parent.getParent() : parent;
113 iterator = useParent.childIterator(nodeTest, reverse,
114 startFromParentLocation ? parent : null);
115 }
116 }