/*
    * $Id: VelocityScopeExtractor.java 1066512 2011-02-02 16:13:31Z apetrelli $
    *
    * 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.tiles.request.velocity.extractor;
  
  import java.util.Enumeration;
  
  import org.apache.tiles.request.attribute.AttributeExtractor;
  import org.apache.velocity.context.Context;
  
  /**
   * Extracts attributes from Velocity context..
   *
   * @version $Rev: 1066512 $ $Date: 2011-02-03 03:13:31 +1100 (Thu, 03 Feb 2011) $
   */
  public class VelocityScopeExtractor implements AttributeExtractor {
  
      /**
       * The Velocity context.
       */
      private Context context;
  
      /**
       * Constructor.
       *
       * @param context The Velocity context.
       */
      public VelocityScopeExtractor(Context context) {
          this.context = context;
      }
  
      @Override
      public void removeValue(String name) {
          context.remove(name);
      }
  
      @Override
      public Enumeration<String> getKeys() {
          return new KeyEnumeration(context.getKeys());
      }
  
      @Override
      public Object getValue(String key) {
          return context.get(key);
      }
  
      @Override
      public void setValue(String key, Object value) {
          context.put(key, value);
      }
  
      /**
       * Enumerates an array.
       */
      private static class KeyEnumeration implements Enumeration<String> {
  
          /**
           * The current index.
           */
          private int index = 0;
  
          /**
           * The array to enumerate.
           */
          private Object[] keys;
  
          /**
           * Constructor.
           *
           * @param keys The array to enumerate.
           */
          public KeyEnumeration(Object[] keys) {
              this.keys = keys;
          }
  
          @Override
          public boolean hasMoreElements() {
              return index < keys.length;
          }
  
          @Override
          public String nextElement() {
             return (String) keys[index++];
         }
     }
 }