1 /* 2 * Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package javax.xml.xpath; 27 28 import javax.xml.namespace.QName; 29 30 /** 31 * <p><code>XPathFunctionResolver</code> provides access to the set of user defined <code>XPathFunction</code>s.</p> 32 * 33 * <p>XPath functions are resolved by name and arity. 34 * The resolver is not needed for XPath built-in functions and the resolver 35 * <strong><em>cannot</em></strong> be used to override those functions.</p> 36 * 37 * <p>In particular, the resolver is only called for functions in an another 38 * namespace (functions with an explicit prefix). This means that you cannot 39 * use the <code>XPathFunctionResolver</code> to implement specifications 40 * like <a href="http://www.w3.org/TR/xmldsig-core/">XML-Signature Syntax 41 * and Processing</a> which extend the function library of XPath 1.0 in the 42 * same namespace. This is a consequence of the design of the resolver.</p> 43 * 44 * <p>If you wish to implement additional built-in functions, you will have to 45 * extend the underlying implementation directly.</p> 46 * 47 * @author Norman Walsh 48 * @author Jeff Suttor 49 * @see <a href="http://www.w3.org/TR/xpath#corelib">XML Path Language (XPath) Version 1.0, Core Function Library</a> 50 * @since 1.5 51 */ 52 public interface XPathFunctionResolver { 53 /** 54 * <p>Find a function in the set of available functions.</p> 55 * 56 * <p>If <code>functionName</code> or <code>arity</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p> 57 * 58 * @param functionName The function name. 59 * @param arity The number of arguments that the returned function must accept. 60 * 61 * @return The function or <code>null</code> if no function named <code>functionName</code> with <code>arity</code> arguments exists. 62 * 63 * @throws NullPointerException If <code>functionName</code> or <code>arity</code> is <code>null</code>. 64 */ resolveFunction(QName functionName, int arity)65 public XPathFunction resolveFunction(QName functionName, int arity); 66 } 67