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      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    */
     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