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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/NamespaceUriFunction.java,v 1.12 2005/06/28 13:44:45 elharo Exp $
    3    * $Revision: 1.12 $
    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: NamespaceUriFunction.java,v 1.12 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>4.1</b>
    75   * <code><i>string</i> namespace-uri(<i>node-set?</i>)</code>
    76   * </p>
    77   *
    78   * <blockquote src="http://www.w3.org/TR/xpath">
    79   * <p>
    80   * The <b>namespace-uri</b>
    81   * function returns the namespace URI of the <a
    82   * href="http://www.w3.org/TR/xpath#dt-expanded-name" target="_top">expanded-name</a> of the node in the
    83   * argument node-set that is first in <a
    84   * href="http://www.w3.org/TR/xpath#dt-document-order" target="_top">document order</a>. If the argument
    85   * node-set is empty, the first node has no <a
    86   * href="http://www.w3.org/TR/xpath#dt-expanded-name" target="_top">expanded-name</a>, or the namespace URI of
    87   * the <a href="http://www.w3.org/TR/xpath#dt-expanded-name" target="_top">expanded-name</a> is null, an empty
    88   * string is returned. If the argument is omitted, it defaults to a
    89   * node-set with the context node as its only member.
    90   * </p>
    91   *
    92   * <blockquote> <b>NOTE: </b>The string returned by the <b>namespace-uri</b> function will
    93   * be empty except for element nodes and attribute nodes.</blockquote>
    94   *
    95   * </blockquote>
    96   *
    97   * @author bob mcwhirter (bob @ werken.com)
    98   * @see <a href="http://www.w3.org/TR/xpath#function-namespace-uri"
    99   *      target="_top">Section 4.1 of the XPath Specification</a>
    100  */
    101 public class NamespaceUriFunction implements Function
    102 {
    103
    104     /***
    105      * Create a new <code>NamespaceUriFunction</code> object.
    106      */
    107     public NamespaceUriFunction() {}
    108
    109     /***
    110      * Returns the namespace URI of the specified node or the namespace URI of the context node if
    111      * no arguments are provided.
    112      *
    113      * @param context the context at the point in the
    114      *         expression where the function is called
    115      * @param args a <code>List</code> containing zero or one items
    116      *
    117      * @return a <code>String</code> containing the namespace URI
    118      *
    119      * @throws FunctionCallException if <code>args</code> has more than one item
    120      */
    121     public Object call(Context context,
    122                        List args) throws FunctionCallException
    123     {
    124         if (args.size() == 0)
    125         {
    126             return evaluate( context.getNodeSet(),
    127                              context.getNavigator() );
    128         }
    129
    130         if ( args.size() == 1 )
    131         {
    132             return evaluate( args,
    133                              context.getNavigator() );
    134         }
    135
    136         throw new FunctionCallException( "namespace-uri() requires zero or one argument." );
    137     }
    138
    139     /***
    140      * Returns the namespace URI of <code>list.get(0)</code>
    141      *
    142      * @param list a list of nodes
    143      * @param nav the <code>Navigator</code> used to retrieve the namespace
    144      *
    145      * @return the namespace URI of <code>list.get(0)</code>
    146      *
    147      * @throws FunctionCallException if <code>list.get(0)</code> is not a node
    148      */
    149     public static String evaluate(List list,
    150                                   Navigator nav) throws FunctionCallException
    151     {
    152         if ( ! list.isEmpty() )
    153         {
    154             Object first = list.get(0);
    155
    156             if ( first instanceof List )
    157             {
    158                 return evaluate( (List) first,
    159                                  nav );
    160             }
    161             else if ( nav.isElement( first ) )
    162             {
    163                 return nav.getElementNamespaceUri( first );
    164             }
    165             else if ( nav.isAttribute( first ) )
    166             {
    167                 String uri = nav.getAttributeNamespaceUri( first );
    168                 if (uri == null) return "";
    169                 return uri;
    170             }
    171             else if ( nav.isProcessingInstruction( first ) )
    172             {
    173                 return "";
    174             }
    175             else if ( nav.isNamespace( first ) )
    176             {
    177                 return "";
    178             }
    179             else if ( nav.isDocument( first ) )
    180             {
    181                 return "";
    182             }
    183             else if ( nav.isComment( first ) )
    184             {
    185                 return "";
    186             }
    187             else if ( nav.isText( first ) )
    188             {
    189                 return "";
    190             }
    191             else {
    192                 throw new FunctionCallException(
    193                   "The argument to the namespace-uri function must be a node-set");
    194             }
    195
    196         }
    197
    198         return "";
    199
    200     }
    201 }
    202