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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/StartsWithFunction.java,v 1.10 2005/06/28 13:44:45 elharo Exp $
    3    * $Revision: 1.10 $
    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: StartsWithFunction.java,v 1.10 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>boolean</i> starts-with(<i>string</i>,<i>string</i>)</code></p>
    74   *
    75   *
    76   * <blockquote src="http://www.w3.org/TR/xpath">
    77   * The <b>starts-with</b> function returns true if the first argument string starts
    78   * with the second argument string, and otherwise returns false.
    79   * </blockquote>
    80   *
    81   * @author bob mcwhirter (bob @ werken.com)
    82   * @see <a href="http://www.w3.org/TR/xpath#function-starts-with" target="_top">Section 4.2 of the XPath Specification</a>
    83   */
    84  public class StartsWithFunction implements Function
    85  {
    86
    87      /***
    88       * Create a new <code>StartsWithFunction</code> object.
    89       */
    90      public StartsWithFunction() {}
    91
    92      /***
    93       * Returns true if the string-value of the first item in <code>args</code>
    94       * starts with the string-value of the second item in <code>args</code>.
    95       * Otherwise it returns false.
    96       *
    97       * @param context the context at the point in the
    98       *         expression when the function is called
    99       * @param args a list that contains two items
    100      *
    101      * @return <code>Boolean.TRUE</code> if the first item in <code>args</code>
    102      *     starts with the string-value of the second item in <code>args</code>;
    103      *     otherwise <code>Boolean.FALSE</code>
    104      *
    105      * @throws FunctionCallException if <code>args</code> does not have length two
    106      */
    107     public Object call(Context context,
    108                        List args) throws FunctionCallException
    109     {
    110         if (args.size() == 2)
    111         {
    112             return evaluate( args.get(0),
    113                              args.get(1),
    114                              context.getNavigator() );
    115         }
    116
    117         throw new FunctionCallException( "starts-with() requires two arguments." );
    118     }
    119
    120     /***
    121      * Returns true if the string-value of <code>strArg</code>
    122      * starts with the string-value of <code>matchArg</code>.
    123      * Otherwise it returns false.
    124      *
    125      * @param strArg the object whose string-value searched for the prefix
    126      * @param matchArg the object whose string-value becomes the prefix string to compare against
    127      * @param nav the navigator used to calculate the string-values of the arguments
    128      *
    129      * @return <code>Boolean.TRUE</code> if the string-value of <code>strArg</code>
    130      *     starts with the string-value of <code>matchArg</code>;
    131      *     otherwise <code>Boolean.FALSE</code>
    132      *
    133      */
    134     public static Boolean evaluate(Object strArg,
    135                                    Object matchArg,
    136                                    Navigator nav)
    137     {
    138         String str   = StringFunction.evaluate( strArg,
    139                                                 nav );
    140
    141         String match = StringFunction.evaluate( matchArg,
    142                                                 nav );
    143
    144         return ( str.startsWith(match)
    145                  ? Boolean.TRUE
    146                  : Boolean.FALSE
    147                  );
    148     }
    149
    150 }