1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one
3  * or more contributor license agreements. See the NOTICE file
4  * distributed with this work for additional information
5  * regarding copyright ownership. The ASF licenses this file
6  * to you under the Apache License, Version 2.0 (the  "License");
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  *     http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18 /*
19  * $Id: FuncSubstring.java 468655 2006-10-28 07:12:06Z minchau $
20  */
21 package org.apache.xpath.functions;
22 
23 import org.apache.xalan.res.XSLMessages;
24 import org.apache.xml.utils.XMLString;
25 import org.apache.xpath.XPathContext;
26 import org.apache.xpath.objects.XObject;
27 import org.apache.xpath.objects.XString;
28 import org.apache.xpath.res.XPATHErrorResources;
29 
30 /**
31  * Execute the Substring() function.
32  * @xsl.usage advanced
33  */
34 public class FuncSubstring extends Function3Args
35 {
36     static final long serialVersionUID = -5996676095024715502L;
37 
38   /**
39    * Execute the function.  The function must return
40    * a valid object.
41    * @param xctxt The current execution context.
42    * @return A valid XObject.
43    *
44    * @throws javax.xml.transform.TransformerException
45    */
execute(XPathContext xctxt)46   public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
47   {
48 
49     XMLString s1 = m_arg0.execute(xctxt).xstr();
50     double start = m_arg1.execute(xctxt).num();
51     int lenOfS1 = s1.length();
52     XMLString substr;
53 
54     if (lenOfS1 <= 0)
55       return XString.EMPTYSTRING;
56     else
57     {
58       int startIndex;
59 
60       if (Double.isNaN(start))
61       {
62 
63         // Double.MIN_VALUE doesn't work with math below
64         // so just use a big number and hope I never get caught.
65         start = -1000000;
66         startIndex = 0;
67       }
68       else
69       {
70         start = Math.round(start);
71         startIndex = (start > 0) ? (int) start - 1 : 0;
72       }
73 
74       if (null != m_arg2)
75       {
76         double len = m_arg2.num(xctxt);
77         int end = (int) (Math.round(len) + start) - 1;
78 
79         // Normalize end index.
80         if (end < 0)
81           end = 0;
82         else if (end > lenOfS1)
83           end = lenOfS1;
84 
85         if (startIndex > lenOfS1)
86           startIndex = lenOfS1;
87 
88         substr = s1.substring(startIndex, end);
89       }
90       else
91       {
92         if (startIndex > lenOfS1)
93           startIndex = lenOfS1;
94         substr = s1.substring(startIndex);
95       }
96     }
97 
98     return (XString)substr; // cast semi-safe
99   }
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    */
checkNumberArgs(int argNum)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    */
reportWrongNumberArgs()121   protected void reportWrongNumberArgs() throws WrongNumberArgsException {
122       throw new WrongNumberArgsException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_TWO_OR_THREE, null)); //"2 or 3");
123   }
124 }
125