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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/SubstringBeforeFunction.java,v 1.9 2005/06/28 13:44:45 elharo Exp $
    3    * $Revision: 1.9 $
    4    * $Date: 2005/06/28 13:44:45 $
    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   * $Id: SubstringBeforeFunction.java,v 1.9 2005/06/28 13:44:45 elharo Exp $
    60   */
    61
    62
    63  package org.jaxen.function;
    64
    65  import java.util.List;
    66
    67  import org.jaxen.Context;
    68  import org.jaxen.Function;
    69  import org.jaxen.FunctionCallException;
    70  import org.jaxen.Navigator;
    71
    72  /***
    73   * <p><b>4.2</b> <code><i>string</i> substring-before(<i>string</i>,<i>string</i>)</code></p>
    74   *
    75   *
    76   * <blockquote src="http://www.w3.org/TR/xpath#function-substring-before">
    77   * The substring-before function returns the substring of the first argument
    78   * string that precedes the first occurrence of the second argument string
    79   * in the first argument string, or the empty string if the
    80   * first argument string does not contain the second argument string.
    81   * For example, substring-before("1999/04/01","/") returns 1999.
    82   * </blockquote>
    83   *
    84   * @author bob mcwhirter (bob @ werken.com)
    85   *
    86   * @see <a href="http://www.w3.org/TR/xpath#function-substring-before" target="_top">Section 4.2 of the XPath Specification</a>
    87   */
    88  public class SubstringBeforeFunction implements Function
    89  {
    90
    91
    92      /***
    93       * Create a new <code>SubstringBeforeFunction</code> object.
    94       */
    95      public SubstringBeforeFunction() {}
    96
    97
    98      /***
    99       * Returns the part of the string-value of the first item in <code>args</code>
    100      * that comes before the string-value of the second item in <code>args</code>;
    101      * or the empty string if the second string is not a substring of the first string.
    102      *
    103      * @param context the context at the point in the
    104      *         expression when the function is called
    105      * @param args a list that contains two items
    106      *
    107      * @return a <code>String</code> containing that
    108      *     part of the string-value of the first item in <code>args</code>
    109      *     that comes before the string-value of the second item in <code>args</code>
    110      *
    111      * @throws FunctionCallException if <code>args</code> does not have length two
    112      */
    113     public Object call(Context context,
    114                        List args) throws FunctionCallException
    115     {
    116         if (args.size() == 2)
    117         {
    118             return evaluate( args.get(0),
    119                              args.get(1),
    120                              context.getNavigator() );
    121         }
    122
    123         throw new FunctionCallException( "substring-before() requires two arguments." );
    124     }
    125
    126     /***
    127      * Returns the part of <code>strArg</code> that precedes the first occurence
    128      * of <code>matchArg</code>; or the empty string if the
    129      * <code>strArg</code> does not contain <code>matchArg</code>
    130      *
    131      * @param strArg the string from which the substring is extracted
    132      * @param matchArg the string that marks the boundary of the substring
    133      * @param nav the <code>Navigator</code> used to calculate the string-values of
    134      *     the first two arguments
    135      *
    136      * @return a <code>String</code> containing the part of <code>strArg</code> that precedes the first occurence
    137      * of <code>matchArg</code>
    138      *
    139      */
    140     public static String evaluate(Object strArg,
    141                                   Object matchArg,
    142                                   Navigator nav)
    143     {
    144         String str   = StringFunction.evaluate( strArg,
    145                                                 nav );
    146
    147         String match = StringFunction.evaluate( matchArg,
    148                                                 nav );
    149
    150         int loc = str.indexOf(match);
    151
    152         if ( loc < 0 )
    153         {
    154             return "";
    155         }
    156
    157         return str.substring(0, loc);
    158
    159     }
    160 }