001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 /*
019 * $Id: FuncSubstring.java 468655 2006-10-28 07:12:06Z minchau $
020 */
021 package org.apache.xpath.functions;
022
023 import org.apache.xalan.res.XSLMessages;
024 import org.apache.xml.utils.XMLString;
025 import org.apache.xpath.XPathContext;
026 import org.apache.xpath.objects.XObject;
027 import org.apache.xpath.objects.XString;
028 import org.apache.xpath.res.XPATHErrorResources;
029
030 /**
031 * Execute the Substring() function.
032 * @xsl.usage advanced
033 */
034 public class FuncSubstring extends Function3Args
035 {
036 static final long serialVersionUID = -5996676095024715502L;
037
038 /**
039 * Execute the function. The function must return
040 * a valid object.
041 * @param xctxt The current execution context.
042 * @return A valid XObject.
043 *
044 * @throws javax.xml.transform.TransformerException
045 */
046 public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
047 {
048
049 XMLString s1 = m_arg0.execute(xctxt).xstr();
050 double start = m_arg1.execute(xctxt).num();
051 int lenOfS1 = s1.length();
052 XMLString substr;
053
054 if (lenOfS1 <= 0)
055 return XString.EMPTYSTRING;
056 else
057 {
058 int startIndex;
059
060 if (Double.isNaN(start))
061 {
062
063 // Double.MIN_VALUE doesn't work with math below
064 // so just use a big number and hope I never get caught.
065 start = -1000000;
066 startIndex = 0;
067 }
068 else
069 {
070 start = Math.round(start);
071 startIndex = (start > 0) ? (int) start - 1 : 0;
072 }
073
074 if (null != m_arg2)
075 {
076 double len = m_arg2.num(xctxt);
077 int end = (int) (Math.round(len) + start) - 1;
078
079 // Normalize end index.
080 if (end < 0)
081 end = 0;
082 else if (end > lenOfS1)
083 end = lenOfS1;
084
085 if (startIndex > lenOfS1)
086 startIndex = lenOfS1;
087
088 substr = s1.substring(startIndex, end);
089 }
090 else
091 {
092 if (startIndex > lenOfS1)
093 startIndex = lenOfS1;
094 substr = s1.substring(startIndex);
095 }
096 }
097
098 return (XString)substr; // cast semi-safe
099 }
100
101 /**
102 * Check that the number of arguments passed to this function is correct.
103 *
104 *
105 * @param argNum The number of arguments that is being passed to the function.
106 *
107 * @throws WrongNumberArgsException
108 */
109 public void checkNumberArgs(int argNum) throws WrongNumberArgsException
110 {
111 if (argNum < 2)
112 reportWrongNumberArgs();
113 }
114
115 /**
116 * Constructs and throws a WrongNumberArgException with the appropriate
117 * message for this function object.
118 *
119 * @throws WrongNumberArgsException
120 */
121 protected void reportWrongNumberArgs() throws WrongNumberArgsException {
122 throw new WrongNumberArgsException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_TWO_OR_THREE, null)); //"2 or 3");
123 }
124 }