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 018package org.apache.commons.jxpath; 019 020import java.util.List; 021 022/** 023 * If an extenstion function has an argument of type ExpressionContext, it can gain access to the current node of an XPath expression context. 024 * <p> 025 * Example: <blockquote> 026 * 027 * <pre> 028 * public class MyExtenstionFunctions { 029 * 030 * public static String objectType(ExpressionContext context) { 031 * Object value = context.getContextNodePointer().getValue(); 032 * if (value == null) { 033 * return "null"; 034 * } 035 * return value.getClass().getName(); 036 * } 037 * } 038 * </pre> 039 * 040 * </blockquote> 041 * 042 * You can then register this extension function using a {@link ClassFunctions ClassFunctions} object and call it like this: <blockquote> 043 * 044 * <pre> 045 * "/descendent-or-self::node()[ns:objectType() = 'java.util.Date']" 046 * </pre> 047 * 048 * </blockquote> This expression will find all nodes of the graph that are dates. 049 */ 050public interface ExpressionContext { 051 052 /** 053 * Gets the current context node list. Each element of the list is a Pointer. 054 * 055 * @return A list representing the current context nodes. 056 */ 057 List<Pointer> getContextNodeList(); 058 059 /** 060 * Gets the current context node. 061 * 062 * @return The current context node pointer. 063 */ 064 Pointer getContextNodePointer(); 065 066 /** 067 * Gets the JXPathContext in which this function is being evaluated. 068 * 069 * @return A list representing the current context nodes. 070 */ 071 JXPathContext getJXPathContext(); 072 073 /** 074 * Returns the current context position. 075 * 076 * @return int 077 */ 078 int getPosition(); 079}