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.
   */
  
  package org.apache.xalan.extensions;
  
  import java.util.Iterator;
  import javax.xml.XMLConstants;
  import javax.xml.namespace.NamespaceContext;
  import org.apache.xalan.res.XSLMessages;
  import org.apache.xalan.res.XSLTErrorResources;
  
  /**
   * A sample implementation of NamespaceContext, with support for 
   * EXSLT extension functions and Java extension functions.
   */
  public class ExtensionNamespaceContext implements NamespaceContext
  {
      public static final String EXSLT_PREFIX = "exslt";
      public static final String EXSLT_URI = "http://exslt.org/common";
      public static final String EXSLT_MATH_PREFIX = "math";
      public static final String EXSLT_MATH_URI = "http://exslt.org/math";
      public static final String EXSLT_SET_PREFIX = "set";
      public static final String EXSLT_SET_URI = "http://exslt.org/sets";
      public static final String EXSLT_STRING_PREFIX = "str";
      public static final String EXSLT_STRING_URI = "http://exslt.org/strings";
      public static final String EXSLT_DATETIME_PREFIX = "datetime";
      public static final String EXSLT_DATETIME_URI = "http://exslt.org/dates-and-times";
      public static final String EXSLT_DYNAMIC_PREFIX = "dyn";
      public static final String EXSLT_DYNAMIC_URI = "http://exslt.org/dynamic";    
      public static final String JAVA_EXT_PREFIX = "java";
      public static final String JAVA_EXT_URI = "http://xml.apache.org/xalan/java";
      
      /**
       * Return the namespace uri for a given prefix
       */
      public String getNamespaceURI(String prefix)
      {
          if (prefix == null)
              throw new IllegalArgumentException(
                  XSLMessages.createMessage(
                      XSLTErrorResources.ER_NAMESPACE_CONTEXT_NULL_PREFIX, null));
          
          if (prefix.equals(XMLConstants.DEFAULT_NS_PREFIX))
              return XMLConstants.NULL_NS_URI;
          else if (prefix.equals(XMLConstants.XML_NS_PREFIX))
              return XMLConstants.XML_NS_URI;
          else if (prefix.equals(XMLConstants.XMLNS_ATTRIBUTE))
              return XMLConstants.XMLNS_ATTRIBUTE_NS_URI;
          else if (prefix.equals(EXSLT_PREFIX))
              return EXSLT_URI;
          else if (prefix.equals(EXSLT_MATH_PREFIX))
              return EXSLT_MATH_URI;
          else if (prefix.equals(EXSLT_SET_PREFIX))
              return EXSLT_SET_URI;
          else if (prefix.equals(EXSLT_STRING_PREFIX))
              return EXSLT_STRING_URI;
          else if (prefix.equals(EXSLT_DATETIME_PREFIX))
              return EXSLT_DATETIME_URI;
          else if (prefix.equals(EXSLT_DYNAMIC_PREFIX))
              return EXSLT_DYNAMIC_URI;        
          else if (prefix.equals(JAVA_EXT_PREFIX))
              return JAVA_EXT_URI;
          else
              return XMLConstants.NULL_NS_URI;        
      }
      
      /**
       * Return the prefix for a given namespace uri.
       */
      public String getPrefix(String namespace)
      {
          if (namespace == null)
              throw new IllegalArgumentException(
                  XSLMessages.createMessage(
                      XSLTErrorResources.ER_NAMESPACE_CONTEXT_NULL_NAMESPACE, null));
          
          if (namespace.equals(XMLConstants.XML_NS_URI))
              return XMLConstants.XML_NS_PREFIX;
          else if (namespace.equals(XMLConstants.XMLNS_ATTRIBUTE_NS_URI))
              return XMLConstants.XMLNS_ATTRIBUTE;
          else if (namespace.equals(EXSLT_URI))
              return EXSLT_PREFIX;
          else if (namespace.equals(EXSLT_MATH_URI))
              return EXSLT_MATH_PREFIX;
          else if (namespace.equals(EXSLT_SET_URI))
              return EXSLT_SET_PREFIX;
          else if (namespace.equals(EXSLT_STRING_URI))
              return EXSLT_STRING_PREFIX;
          else if (namespace.equals(EXSLT_DATETIME_URI))
              return EXSLT_DATETIME_PREFIX;
          else if (namespace.equals(EXSLT_DYNAMIC_URI))
              return EXSLT_DYNAMIC_PREFIX;
          else if (namespace.equals(JAVA_EXT_URI))
              return JAVA_EXT_PREFIX;
          else
              return null;        
      }
      
      public Iterator getPrefixes(String namespace)
      {
      	final String result = getPrefix(namespace);
      	
          return new Iterator () {
          	
          	private boolean isFirstIteration = (result != null);
          	
          	public boolean hasNext() {
          		return isFirstIteration;
          	}
          	
          	public Object next() {
          		if (isFirstIteration) {
          			isFirstIteration = false;
          			return result;
          		}
          		else
          			return null;
          	}
          	
          	public void remove() {
          		throw new UnsupportedOperationException();
          	}
          };
      }
  }
  