001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.jxpath;
018
019 import java.util.List;
020
021 /**
022 * If an extenstion function has an argument of type ExpressionContext,
023 * it can gain access to the current node of an XPath expression context.
024 * <p>
025 * Example:
026 * <blockquote><pre>
027 * public class MyExtenstionFunctions {
028 * public static String objectType(ExpressionContext context){
029 * Object value = context.getContextNodePointer().getValue();
030 * if (value == null){
031 * return "null";
032 * }
033 * return value.getClass().getName();
034 * }
035 * }
036 * </pre></blockquote>
037 *
038 * You can then register this extension function using a {@link ClassFunctions
039 * ClassFunctions} object and call it like this:
040 * <blockquote><pre>
041 * "/descendent-or-self::node()[ns:objectType() = 'java.util.Date']"
042 * </pre></blockquote>
043 * This expression will find all nodes of the graph that are dates.
044 */
045 public interface ExpressionContext {
046
047 /**
048 * Get the JXPathContext in which this function is being evaluated.
049 *
050 * @return A list representing the current context nodes.
051 */
052 JXPathContext getJXPathContext();
053
054 /**
055 * Get the current context node.
056 *
057 * @return The current context node pointer.
058 */
059 Pointer getContextNodePointer();
060
061 /**
062 * Get the current context node list. Each element of the list is
063 * a Pointer.
064 *
065 * @return A list representing the current context nodes.
066 */
067 List getContextNodeList();
068
069 /**
070 * Returns the current context position.
071 * @return int
072 */
073 int getPosition();
074 }