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