1 /* 2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/CountFunction.java,v 1.11 2005/06/26 16:07:22 elharo Exp $ 3 * $Revision: 1.11 $ 4 * $Date: 2005/06/26 16:07:22 $ 5 * 6 * ==================================================================== 7 * 8 * Copyright (C) 2000-2002 bob mcwhirter & James Strachan. 9 * All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions, and the following disclaimer. 17 * 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions, and the disclaimer that follows 20 * these conditions in the documentation and/or other materials 21 * provided with the distribution. 22 * 23 * 3. The name "Jaxen" must not be used to endorse or promote products 24 * derived from this software without prior written permission. For 25 * written permission, please contact license@jaxen.org. 26 * 27 * 4. Products derived from this software may not be called "Jaxen", nor 28 * may "Jaxen" appear in their name, without prior written permission 29 * from the Jaxen Project Management (pm@jaxen.org). 30 * 31 * In addition, we request (but do not require) that you include in the 32 * end-user documentation provided with the redistribution and/or in the 33 * software itself an acknowledgement equivalent to the following: 34 * "This product includes software developed by the 35 * Jaxen Project (http://www.jaxen.org/)." 36 * Alternatively, the acknowledgment may be graphical using the logos 37 * available at http://www.jaxen.org/ 38 * 39 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 40 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 41 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 42 * DISCLAIMED. IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT 43 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 45 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 46 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 47 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 48 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 49 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 50 * SUCH DAMAGE. 51 * 52 * ==================================================================== 53 * This software consists of voluntary contributions made by many 54 * individuals on behalf of the Jaxen Project and was originally 55 * created by bob mcwhirter <bob@werken.com> and 56 * James Strachan <jstrachan@apache.org>. For more information on the 57 * Jaxen Project, please see <http://www.jaxen.org/>. 58 * 59 * $Id: CountFunction.java,v 1.11 2005/06/26 16:07:22 elharo Exp $ 60 */ 61 62 package org.jaxen.function; 63 64 import java.util.List; 65 66 import org.jaxen.Context; 67 import org.jaxen.Function; 68 import org.jaxen.FunctionCallException; 69 70 /*** 71 * <p><b>4.1</b> <code><i>number</i> count(<i>node-set</i>)</code> 72 * 73 * <blockquote src="http://www.w3.org/TR/xpath#function-count"> 74 * The <b>count</b> function returns the number of nodes in the argument node-set. 75 * </blockquote> 76 * @author bob mcwhirter (bob @ werken.com) 77 * @see <a href="http://www.w3.org/TR/xpath#function-count">Section 4.1 of the XPath Specification</a> 78 */ 79 public class CountFunction implements Function 80 { 81 82 /*** 83 * Create a new <code>CountFunction</code> object. 84 */ 85 public CountFunction() {} 86 87 /*** 88 * <p> 89 * Returns the number of nodes in the specified node-set. 90 * </p> 91 * @param context ignored 92 * @param args the function arguments 93 * 94 * @return a <code>Double</code> giving the integral number of items in the first argument 95 * 96 * @throws FunctionCallException if args does not have exactly one 97 * item; or that item is not a <code>List</code> 98 */ 99 public Object call(Context context, 100 List args) throws FunctionCallException 101 { 102 if (args.size() == 1) 103 { 104 return evaluate( args.get(0) ); 105 } 106 107 throw new FunctionCallException( "count() requires one argument." ); 108 } 109 110 /*** 111 * <p> 112 * Returns the number of nodes in the specified node-set. 113 * </p> 114 * 115 * @param obj a <code>List</code> of nodes 116 * @return the integral number of items in the list 117 * @throws FunctionCallException if obj is not a <code>List</code> 118 */ 119 public static Double evaluate(Object obj) throws FunctionCallException 120 { 121 122 if (obj instanceof List) 123 { 124 return new Double( ((List) obj).size() ); 125 } 126 127 throw new FunctionCallException("count() function can only be used for node-sets"); 128 129 } 130 131 }