FuncSubstring.java revision 9f8118474e9513f7a5b7d2a05e4a0fb15d1a6569 
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 */
21package org.apache.xpath.functions;
22
23import org.apache.xalan.res.XSLMessages;
24import org.apache.xml.utils.XMLString;
25import org.apache.xpath.XPathContext;
26import org.apache.xpath.objects.XObject;
27import org.apache.xpath.objects.XString;
28import org.apache.xpath.res.XPATHErrorResources;
29
30/**
31 * Execute the Substring() function.
32 * @xsl.usage advanced
33 */
34public 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   */
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   */
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}
125