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
18 package org.apache.commons.jxpath;
19
20 import java.util.List;
21
22 /**
23 * If an extenstion function has an argument of type ExpressionContext, it can gain access to the current node of an XPath expression context.
24 * <p>
25 * Example: <blockquote>
26 *
27 * <pre>
28 * public class MyExtenstionFunctions {
29 *
30 * public static String objectType(ExpressionContext context) {
31 * Object value = context.getContextNodePointer().getValue();
32 * if (value == null) {
33 * return "null";
34 * }
35 * return value.getClass().getName();
36 * }
37 * }
38 * </pre>
39 *
40 * </blockquote>
41 *
42 * You can then register this extension function using a {@link ClassFunctions ClassFunctions} object and call it like this: <blockquote>
43 *
44 * <pre>
45 * "/descendent-or-self::node()[ns:objectType() = 'java.util.Date']"
46 * </pre>
47 *
48 * </blockquote> This expression will find all nodes of the graph that are dates.
49 */
50 public interface ExpressionContext {
51
52 /**
53 * Gets the current context node list. Each element of the list is a Pointer.
54 *
55 * @return A list representing the current context nodes.
56 */
57 List<Pointer> getContextNodeList();
58
59 /**
60 * Gets the current context node.
61 *
62 * @return The current context node pointer.
63 */
64 Pointer getContextNodePointer();
65
66 /**
67 * Gets the JXPathContext in which this function is being evaluated.
68 *
69 * @return A list representing the current context nodes.
70 */
71 JXPathContext getJXPathContext();
72
73 /**
74 * Returns the current context position.
75 *
76 * @return int
77 */
78 int getPosition();
79 }