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 // $Id: XPathFunctionResolver.java 446598 2006-09-15 12:55:40Z jeremias $ 18 19 package javax.xml.xpath; 20 21 import javax.xml.namespace.QName; 22 23 /** 24 * <p><code>XPathFunctionResolver</code> provides access to the set of user defined <code>XPathFunction</code>s.</p> 25 * 26 * <p>XPath functions are resolved by name and arity. 27 * The resolver is not needed for XPath built-in functions and the resolver 28 * <strong><em>cannot</em></strong> be used to override those functions.</p> 29 * 30 * <p>In particular, the resolver is only called for functions in an another 31 * namespace (functions with an explicit prefix). This means that you cannot 32 * use the <code>XPathFunctionResolver</code> to implement specifications 33 * like <a href="http://www.w3.org/TR/xmldsig-core/">XML-Signature Syntax 34 * and Processing</a> which extend the function library of XPath 1.0 in the 35 * same namespace. This is a consequence of the design of the resolver.</p> 36 * 37 * <p>If you wish to implement additional built-in functions, you will have to 38 * extend the underlying implementation directly.</p> 39 * 40 * @author <a href="mailto:Norman.Walsh (at) Sun.com">Norman Walsh</a> 41 * @author <a href="mailto:Jeff.Suttor (at) Sun.com">Jeff Suttor</a> 42 * @version $Revision: 446598 $, $Date: 2006-09-15 05:55:40 -0700 (Fri, 15 Sep 2006) $ 43 * @see <a href="http://www.w3.org/TR/xpath#corelib">XML Path Language (XPath) Version 1.0, Core Function Library</a> 44 * @since 1.5 45 */ 46 public interface XPathFunctionResolver { 47 /** 48 * <p>Find a function in the set of available functions.</p> 49 * 50 * <p>If <code>functionName</code> or <code>arity</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p> 51 * 52 * @param functionName The function name. 53 * @param arity The number of arguments that the returned function must accept. 54 * 55 * @return The function or <code>null</code> if no function named <code>functionName</code> with <code>arity</code> arguments exists. 56 * 57 * @throws NullPointerException If <code>functionName</code> or <code>arity</code> is <code>null</code>. 58 */ 59 public XPathFunction resolveFunction(QName functionName, int arity); 60 } 61
