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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/PositionFunction.java,v 1.10 2005/09/22 12:55:24 elharo Exp $
    3    * $Revision: 1.10 $
    4    * $Date: 2005/09/22 12:55:24 $
    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: PositionFunction.java,v 1.10 2005/09/22 12:55:24 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
    71  /***
    72   * <p><b>4.1</b> <code><i>number</i> position()</code></p>
    73   *
    74   *
    75   * <blockquote src="http://www.w3.org/TR/xpath">
    76   * The position function returns a number equal to the context position from the expression evaluation context.
    77   * </blockquote>
    78   *
    79   * @author bob mcwhirter (bob @ werken.com)
    80   * @see <a href="http://www.w3.org/TR/xpath#function-position" target="_top">Section 4.1 of the XPath Specification</a>
    81   */
    82  public class PositionFunction implements Function
    83  {
    84
    85      /***
    86       * Create a new <code>PositionFunction</code> object.
    87       */
    88      public PositionFunction() {}
    89
    90      /***
    91       * Returns the position of the context node in the context node-set.
    92       *
    93       * @param context the context at the point in the
    94       *         expression where the function is called
    95       * @param args an empty list
    96       *
    97       * @return a <code>Double</code> containing the context position
    98       *
    99       * @throws FunctionCallException if <code>args</code> is not empty
    100      *
    101      * @see Context#getSize()
    102      */
    103     public Object call(Context context, List args) throws FunctionCallException
    104     {
    105         if ( args.size() == 0 )
    106         {
    107             return evaluate( context );
    108         }
    109
    110         throw new FunctionCallException( "position() does not take any arguments." );
    111     }
    112
    113     /***
    114      *
    115      * Returns the position of the context node in the context node-set.
    116      *
    117      * @param context the context at the point in the
    118      *         expression where the function is called
    119      *
    120      * @return a <code>Double</code> containing the context position
    121      *
    122      * @see Context#getPosition()
    123      */
    124     public static Double evaluate(Context context)
    125     {
    126         return new Double( context.getPosition() );
    127     }
    128
    129 }