javax.xml.xpath.XPathFunctionResolver Maven / Gradle / Ivy

/*
 * The contents of this file are subject to the terms
 * of the Common Development and Distribution License
 * (the "License").  You may not use this file except
 * in compliance with the License.
 *
 * You can obtain a copy of the license at
 * https://jaxp.dev.java.net/CDDLv1.0.html.
 * See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL
 * HEADER in each file and include the License file at
 * https://jaxp.dev.java.net/CDDLv1.0.html
 * If applicable add the following below this CDDL HEADER
 * with the fields enclosed by brackets "[]" replaced with
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/*
 * $Id: XPathFunctionResolver.java,v 1.3 2005/11/03 19:34:17 jeffsuttor Exp $
 * %W% %E%
 *
 * Copyright 2005 Sun Microsystems, Inc. All Rights Reserved.
 */

package javax.xml.xpath;

import javax.xml.namespace.QName;

/**
 * XPathFunctionResolver provides access to the set of user defined XPathFunctions.
 *
 * XPath functions are resolved by name and arity.
 * The resolver is not needed for XPath built-in functions and the resolver
 * cannot be used to override those functions.
 *
 * In particular, the resolver is only called for functions in an another
 * namespace (functions with an explicit prefix). This means that you cannot
 * use the XPathFunctionResolver to implement specifications
 * like XML-Signature Syntax
 * and Processing which extend the function library of XPath 1.0 in the
 * same namespace. This is a consequence of the design of the resolver.
 *
 * If you wish to implement additional built-in functions, you will have to
 * extend the underlying implementation directly.
 *
 * @author  Norman Walsh
 * @author  Jeff Suttor
 * @version $Revision: 1.3 $, $Date: 2005/11/03 19:34:17 $
 * @see XML Path Language (XPath) Version 1.0, Core Function Library
 * @since 1.5
 */
public interface XPathFunctionResolver {
  /** 
   * Find a function in the set of available functions.
   * 
   * If functionName or arity is null, then a NullPointerException is thrown.
   *
   * @param functionName The function name.
   * @param arity The number of arguments that the returned function must accept.
   * 
   * @return The function or null if no function named functionName with arity arguments exists.
   * 
   * @throws NullPointerException If functionName or arity is null.
   */
  public XPathFunction resolveFunction(QName functionName, int arity);
}