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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/SimpleFunctionContext.java,v 1.12 2005/09/25 11:39:21 elharo Exp $
    3    * $Revision: 1.12 $
    4    * $Date: 2005/09/25 11:39:21 $
    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: SimpleFunctionContext.java,v 1.12 2005/09/25 11:39:21 elharo Exp $
    60   */
    61
    62
    63  package org.jaxen;
    64
    65  import java.util.HashMap;
    66
    67  /*** Simple default implementation of <code>FunctionContext</code>.
    68   *
    69   *  <p>
    70   *  This is a simple table-based key-lookup implementation
    71   *  for <code>FunctionContext</code> which can be programmatically
    72   *  extended by registering additional functions.
    73   *  </p>
    74   *
    75   *  @see XPathFunctionContext
    76   *
    77   *  @author <a href="mailto:bob@werken.com">bob mcwhirter</a>
    78   */
    79  public class SimpleFunctionContext implements FunctionContext
    80  {
    81      /*** Table of functions. */
    82      private HashMap functions;
    83
    84      /***
    85       *  <p>
    86       *  Construct an empty function context.
    87       *  </p>
    88       */
    89      public SimpleFunctionContext()
    90      {
    91          this.functions = new HashMap();
    92      }
    93
    94      /*** Register a new function.
    95       *
    96       *  <p>
    97       *  By registering a new function, any XPath expression
    98       *  that utilizes this <code>FunctionContext</code> may
    99       *  refer to and use the new function.
    100      *  </p>
    101      *
    102      *  <p>
    103      *  Functions may exist either in a namespace or not.
    104      *  Namespace prefix-to-URI resolution is the responsibility
    105      *  of a {@link NamespaceContext}.  Within this <code>FunctionContext</code>
    106      *  functions are only referenced using the URI, <strong>not</strong>
    107      *  the prefix.
    108      *  </p>
    109      *
    110      *  <p>
    111      *  The namespace URI of a function may be <code>null</code>
    112      *  to indicate that it exists without a namespace.
    113      *  </p>
    114      *
    115      *  @param namespaceURI the namespace URI of the function to
    116      *         be registered with this context
    117      *  @param localName the non-prefixed local portion of the
    118      *         function to be registered with this context
    119      *  @param function a {@link Function} implementation object
    120      *         to be used when evaluating the function
    121      */
    122     public void registerFunction(String namespaceURI,
    123                                  String localName,
    124                                  Function function )
    125     {
    126         this.functions.put( new QualifiedName(namespaceURI, null, localName),
    127                             function );
    128     }
    129
    130     public Function getFunction(String namespaceURI,
    131                                 String prefix,
    132                                 String localName )
    133         throws UnresolvableException
    134     {
    135         QualifiedName key = new QualifiedName( namespaceURI, prefix, localName );
    136
    137         if ( this.functions.containsKey(key) ) {
    138             return (Function) this.functions.get( key );
    139         }
    140         else {
    141             throw new UnresolvableException( "No Such Function " + key.getClarkForm() );
    142         }
    143     }
    144 }