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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/NormalizeSpaceFunction.java,v 1.16 2005/06/28 13:44:45 elharo Exp $
    3    * $Revision: 1.16 $
    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: NormalizeSpaceFunction.java,v 1.16 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>
    74   * <b>4.2</b> <code><i>string</i> normalize-space(<i>string</i>)</code>
    75   * </p>
    76   *
    77   * <blockquote src="http://www.w3.org/TR/xpath#function-normalize-space">
    78   * The <b>normalize-space</b> function
    79   * returns the argument string with whitespace normalized by stripping
    80   * leading and trailing whitespace and replacing sequences of whitespace
    81   * characters by a single space. Whitespace characters are the same as
    82   * those allowed by the <a href="http://www.w3.org/TR/REC-xml#NT-S" target="_top">S</a>
    83   * production in XML. If the argument is omitted, it defaults to the
    84   * context node converted to a string, in other words the <a
    85   * href="http://www.w3.org/TR/xpath#dt-string-value"
    86   * target="_top">string-value</a> of the context node.
    87   * </blockquote>
    88   *
    89   * @author James Strachan (james@metastuff.com)
    90   * @see <a href="http://www.w3.org/TR/xpath#function-normalize-space"
    91   *      target="_top">Section 4.2 of the XPath Specification</a>
    92   */
    93  public class NormalizeSpaceFunction implements Function
    94  {
    95
    96
    97      /***
    98       * Create a new <code>NormalizeSpaceFunction</code> object.
    99       */
    100     public NormalizeSpaceFunction() {}
    101
    102     /***
    103      * Returns the string-value of the first item in <code>args</code>
    104      * after removing all leading and trailing white space, and
    105      * replacing each other sequence of whitespace by a single space.
    106      * Whitespace consists of the characters space (0x32), carriage return (0x0D),
    107      * linefeed (0x0A), and tab (0x09).
    108      *
    109      * @param context the context at the point in the
    110      *         expression when the function is called
    111      * @param args a list that contains exactly one item
    112      *
    113      * @return a normalized <code>String</code>
    114      *
    115      * @throws FunctionCallException if <code>args</code> does not have length one
    116      */
    117     public Object call(Context context,
    118                        List args) throws FunctionCallException
    119     {
    120
    121         if (args.size() == 0) {
    122             return evaluate( context.getNodeSet(),
    123                              context.getNavigator() );
    124         }
    125         else if (args.size() == 1)
    126         {
    127             return evaluate( args.get(0),
    128                              context.getNavigator() );
    129         }
    130
    131         throw new FunctionCallException( "normalize-space() cannot have more than one argument" );
    132     }
    133
    134     /***
    135      * Returns the string-value of <code>strArg</code> after removing
    136      * all leading and trailing white space, and
    137      * replacing each other sequence of whitespace by a single space.
    138      * Whitespace consists of the characters space (0x32), carriage return (0x0D),
    139      * linefeed (0x0A), and tab (0x09).
    140      *
    141      * @param strArg the object whose string-value is normalized
    142      * @param nav the context at the point in the
    143      *         expression when the function is called
    144      *
    145      * @return the normalized string-value
    146      */
    147     public static String evaluate(Object strArg,
    148                                   Navigator nav)
    149     {
    150         String str = StringFunction.evaluate( strArg,
    151                                               nav );
    152
    153         char[] buffer = str.toCharArray();
    154         int write = 0;
    155         int lastWrite = 0;
    156         boolean wroteOne = false;
    157         int read = 0;
    158         while (read < buffer.length)
    159         {
    160             if (isXMLSpace(buffer[read]))
    161             {
    162                 if (wroteOne)
    163                 {
    164                     buffer[write++] = ' ';
    165                 }
    166                 do
    167                 {
    168                     read++;
    169                 }
    170                 while(read < buffer.length && isXMLSpace(buffer[read]));
    171             }
    172             else
    173             {
    174                 buffer[write++] = buffer[read++];
    175                 wroteOne = true;
    176                 lastWrite = write;
    177             }
    178         }
    179
    180         return new String(buffer, 0, lastWrite);
    181     }
    182
    183
    184     private static boolean isXMLSpace(char c) {
    185         return c == ' ' || c == '\n' || c == '\r' || c == '\t';
    186     }
    187
    188 }