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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/RoundFunction.java,v 1.11 2005/06/28 13:44:45 elharo Exp $
    3    * $Revision: 1.11 $
    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: RoundFunction.java,v 1.11 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>4.4</b> <code><i>number</i> round(<i>number</i>)</code> </p>
    74   *
    75   *
    76   * <blockquote src="http://www.w3.org/TR/xpath">
    77   * The <b>round</b> function returns the number that is closest to the argument and that is an integer.
    78   * If there are two such numbers, then the one that is closest to positive infinity is returned.
    79   * If the argument is NaN, then NaN is returned. If the argument is positive infinity, then positive infinity is returned.
    80   * If the argument is negative infinity, then negative infinity is returned.
    81   * If the argument is positive zero, then positive zero is returned.
    82   * If the argument is negative zero, then negative zero is returned.
    83   * If the argument is less than zero, but greater than or equal to -0.5, then negative zero is returned.
    84   * </blockquote>
    85   *
    86   * @author bob mcwhirter (bob @ werken.com)
    87   *
    88   * @see <a href="http://www.w3.org/TR/xpath#function-round" target="_top">Section 4.4 of the XPath Specification</a>
    89   */
    90  public class RoundFunction implements Function
    91  {
    92
    93      /***
    94       * Create a new <code>RoundFunction</code> object.
    95       */
    96      public RoundFunction() {}
    97
    98
    99      /*** Returns the nearest integer to the number.
    100      *
    101      * @param context the context at the point in the
    102      *         expression when the function is called
    103      * @param args a list with exactly one item which will be converted to a
    104      *     <code>Double</code> as if by the XPath <code>number()</code> function
    105      *
    106      * @return a <code>Double</code> containing the integer nearest to
    107      *     <code>args.get(0)</code>
    108      *
    109      * @throws FunctionCallException if <code>args</code> has more or less than one item
    110      */
    111     public Object call(Context context,
    112                        List args) throws FunctionCallException
    113     {
    114         if (args.size() == 1)
    115         {
    116             return evaluate( args.get(0),
    117                              context.getNavigator() );
    118         }
    119
    120         throw new FunctionCallException( "round() requires one argument." );
    121     }
    122
    123     /***
    124      * Returns the integer nearest to the argument.
    125      * If necessary, the argument is first converted to a <code>Double</code>
    126      * as if by the XPath <code>number()</code> function.
    127      *
    128      * @param obj the object to be rounded
    129      * @param nav ignored
    130      *
    131      * @return the integer nearest to <code>obj</code>
    132      */
    133     public static Double evaluate(Object obj,
    134                                   Navigator nav)
    135     {
    136         Double d  = NumberFunction.evaluate( obj,
    137                                             nav );
    138
    139         if (d.isNaN() || d.isInfinite())
    140         {
    141             return d;
    142         }
    143
    144         double value = d.doubleValue();
    145         return new Double( Math.round( value ) );
    146     }
    147 }