1 /* 2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/SubstringFunction.java,v 1.7 2005/01/14 02:22:00 elharo Exp $ 3 * $Revision: 1.7 $ 4 * $Date: 2005/01/14 02:22:00 $ 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 */ 60 package org.jaxen.function; 61 62 import java.util.List; 63 64 import org.jaxen.Context; 65 import org.jaxen.Function; 66 import org.jaxen.FunctionCallException; 67 import org.jaxen.Navigator; 68 /*** 69 * <p><b>4.2</b> <code><i>string</i> substring(<i>string</i>,<i>number</i>,<i>number?</i>)</code> 70 * 71 * @author bob mcwhirter (bob @ werken.com) 72 * @see "http://www.w3.org/TR/xpath#function-substring" 73 */ 74 public class SubstringFunction implements Function 75 { 76 public Object call(Context context, 77 List args) throws FunctionCallException 78 { 79 final int argc = args.size(); 80 if (argc < 2 || argc > 3){ 81 throw new FunctionCallException( "substring() requires two or three arguments." ); 82 } 83 84 final Navigator nav = context.getNavigator(); 85 86 final String str = StringFunction.evaluate(args.get(0), nav ); 87 // The spec doesn't really address this case 88 if (str == null){ 89 return ""; 90 } 91 92 final int strlen = str.length(); 93 94 if (strlen == 0){ 95 return ""; 96 } 97 98 Double d1 = NumberFunction.evaluate(args.get(1), nav); 99 100 if (d1.isNaN()){ 101 return ""; 102 } 103 // Round the value and subtract 1 as Java strings are zero based 104 int start = RoundFunction.evaluate(d1, nav).intValue() - 1; 105 106 int len = strlen; 107 if (argc == 3){ 108 Double d2 = NumberFunction.evaluate(args.get(2), nav); 109 110 if (!d2.isNaN()){ 111 len = RoundFunction.evaluate(d2, nav ).intValue(); 112 } 113 else { 114 len = 0; 115 } 116 } 117 118 int end = start + len; 119 120 // negative start is treated as 0 121 if ( start < 0){ 122 start = 0; 123 }else if (start > strlen){ 124 return ""; 125 } 126 127 if (end > strlen){ 128 end = strlen; 129 } 130 return str.substring(start, end); 131 } 132 }