/*
    * 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.commons.collections.map;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.util.Map;
  
  /**
   * A case-insensitive <code>Map</code>.
   * <p>
   * Before keys are added to the map or compared to other existing keys, they are converted
   * to all lowercase in a locale-independent fashion by using information from the Unicode
   * data file.
   * <p>
   * Null keys are supported.  
   * <p>
   * The <code>keySet()</code> method returns all lowercase keys, or nulls.
   * <p>
   * Example:
   * <pre><code>
   *  Map&lt;String, String&gt; map = new CaseInsensitiveMap&lt;String, String&gt;();
   *  map.put("One", "One");
   *  map.put("Two", "Two");
   *  map.put(null, "Three");
   *  map.put("one", "Four");
   * </code></pre>
   * creates a <code>CaseInsensitiveMap</code> with three entries.<br>
   * <code>map.get(null)</code> returns <code>"Three"</code> and <code>map.get("ONE")</code>
   * returns <code>"Four".</code>  The <code>Set</code> returned by <code>keySet()</code>
   * equals <code>{"one", "two", null}.</code>
   * <p>
   * <strong>This map will violate the detail of various Map and map view contracts.</note>
   * As a general rule, don't compare this map to other maps. In particular, you can't
   * use decorators like {@link ListOrderedMap} on it, which silently assume that these
   * contracts are fulfilled.
   * <p>
   * <strong>Note that CaseInsensitiveMap is not synchronized and is not thread-safe.</strong>
   * If you wish to use this map from multiple threads concurrently, you must use
   * appropriate synchronization. The simplest approach is to wrap this map
   * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw 
   * exceptions when accessed by concurrent threads without synchronization.
   *
   * @since 3.0
   * @version $Id: CaseInsensitiveMap.java 1436463 2013-01-21 16:35:01Z tn $
   */
  public class CaseInsensitiveMap<K, V> extends AbstractHashedMap<K, V> implements Serializable, Cloneable {
  
      /** Serialisation version */
      private static final long serialVersionUID = -7074655917369299456L;
  
      /**
       * Constructs a new empty map with default size and load factor.
       */
      public CaseInsensitiveMap() {
          super(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD);
      }
  
      /**
       * Constructs a new, empty map with the specified initial capacity. 
       *
       * @param initialCapacity  the initial capacity
       * @throws IllegalArgumentException if the initial capacity is negative
       */
      public CaseInsensitiveMap(final int initialCapacity) {
          super(initialCapacity);
      }
  
      /**
       * Constructs a new, empty map with the specified initial capacity and
       * load factor. 
       *
       * @param initialCapacity  the initial capacity
       * @param loadFactor  the load factor
       * @throws IllegalArgumentException if the initial capacity is negative
       * @throws IllegalArgumentException if the load factor is less than zero
       */
      public CaseInsensitiveMap(final int initialCapacity, final float loadFactor) {
          super(initialCapacity, loadFactor);
      }
  
      /**
       * Constructor copying elements from another map.
      * <p>
      * Keys will be converted to lower case strings, which may cause
      * some entries to be removed (if string representation of keys differ
      * only by character case).
      *
      * @param map  the map to copy
      * @throws NullPointerException if the map is null
      */
     public CaseInsensitiveMap(final Map<K, V> map) {
         super(map);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Overrides convertKey() from {@link AbstractHashedMap} to convert keys to 
      * lower case.
      * <p>
      * Returns {@link AbstractHashedMap#NULL} if key is null.
      * 
      * @param key  the key convert
      * @return the converted key
      */
     @Override
     protected Object convertKey(final Object key) {
         if (key != null) {
             final char[] chars = key.toString().toCharArray();
             for (int i = chars.length - 1; i >= 0; i--) {
                 chars[i] = Character.toLowerCase(Character.toUpperCase(chars[i]));
             }
             return new String(chars);
         }
         return AbstractHashedMap.NULL;
     }   
 
     //-----------------------------------------------------------------------
     /**
      * Clones the map without cloning the keys or values.
      *
      * @return a shallow clone
      */
     @Override
     public CaseInsensitiveMap<K, V> clone() {
         return (CaseInsensitiveMap<K, V>) super.clone();
     }
 
     /**
      * Write the map out using a custom routine.
      */
     private void writeObject(final ObjectOutputStream out) throws IOException {
         out.defaultWriteObject();
         doWriteObject(out);
     }
 
     /**
      * Read the map in using a custom routine.
      */
     private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
         doReadObject(in);
     }
  
 }