code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the  "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id$
   */
  package org.apache.xml.utils;
  
  /**
   * The class that implements this interface can resolve prefixes to
   * namespaces. Examples would include resolving the meaning of a
   * prefix at a particular point in a document, or mapping the prefixes
   * used in an XPath expression.
   * @xsl.usage advanced
   */
  public interface PrefixResolver
  {
  
    /**
     * Given a namespace, get the corrisponding prefix.  This assumes that
     * the PrefixResolver holds its own namespace context, or is a namespace
     * context itself.
     *
     * @param prefix The prefix to look up, which may be an empty string ("") for the default Namespace.
     *
     * @return The associated Namespace URI, or null if the prefix
     *         is undeclared in this context.
     */
    String getNamespaceForPrefix(String prefix);
  
    /**
     * Given a namespace, get the corresponding prefix, based on the context node.
     *
     * @param prefix The prefix to look up, which may be an empty string ("") for the default Namespace.
     * @param context The node context from which to look up the URI.
     *
     * @return The associated Namespace URI as a string, or null if the prefix
     *         is undeclared in this context.
     */
    String getNamespaceForPrefix(String prefix, org.w3c.dom.Node context);
  
    /**
     * Return the base identifier.
     *
     * @return The base identifier from where relative URIs should be absolutized, or null 
     * if the base ID is unknown.
     * <p>
     * CAVEAT: Note that the base URI in an XML document may vary with where
     * you are in the document, if part of the doc's contents were brought in
     * via an external entity reference or if mechanisms such as xml:base have
     * been used. Unless this PrefixResolver is bound to a specific portion of
     * the document, or has been kept up to date via some other mechanism, it
     * may not accurately reflect that context information.
     */
    public String getBaseIdentifier();
    
    public boolean handlesNullPrefixes();
  }
  