content: /*
   * $Header$
   * $Revision$
   * $Date$
   *
   * ====================================================================
   *
   * Copyright 2000-2002 bob mcwhirter & James Strachan.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   * 
   *   * Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   * 
   *   * Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   * 
   *   * Neither the name of the Jaxen Project nor the names of its
   *     contributors may be used to endorse or promote products derived 
   *     from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * ====================================================================
   * This software consists of voluntary contributions made by many 
   * individuals on behalf of the Jaxen Project and was originally 
   * created by bob mcwhirter <bob@werken.com> and 
   * James Strachan <jstrachan@apache.org>.  For more information on the 
   * Jaxen Project, please see <http://www.jaxen.org/>.
   * 
   * $Id$
   */
  
  
  package org.jaxen;
  
  /** Resolves namespace prefixes to namespace URIs.
   *
   *  <p>
   *  The prefixes used within an XPath expression are
   *  independent of those used within any target document.
   *  When evaluating an XPath against a document, only
   *  the resolved namespace URIs are compared, not their
   *  prefixes.
   *  </p>
   *
   *  <p>
   *  A <code>NamespaceContext</code> is responsible for
   *  translating prefixes as they appear in XPath expressions
   *  into URIs for comparison.  A document's prefixes are
   *  resolved internal to the document based upon its own
   *  namespace nodes.
   *  </p>
   *  
   *  <p>
   *  Implementations of this interface should implement <code>Serializable</code>.
   *  </p>
   *
   *  @see BaseXPath
   *  @see Navigator#getElementNamespaceUri
   *  @see Navigator#getAttributeNamespaceUri
   *
   *  @author <a href="mailto:bob@werken.com">bob mcwhirter</a>
   */
  public interface NamespaceContext
  {
      /** Translate the provided namespace prefix into 
       *  the matching bound namespace URI.
       *
       *  <p>
       *  In XPath, there is no such thing as a 'default namespace'.
       *  The empty prefix <strong>always</strong> resolves to the empty
       *  namespace URI. This method should return null for the
       *  empty prefix.
       *  Similarly, the prefix "xml" always resolves to
       *  the URI "http://www.w3.org/XML/1998/namespace".
       *  </p>
       *
       *  @param prefix the namespace prefix to resolve
       *
       *  @return the namespace URI bound to the prefix; or null if there
       *     is no such namespace 
       */
      String translateNamespacePrefixToUri(String prefix);
  }
  