/*

  * 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.shiro.cache;

 import org.apache.shiro.util.CollectionUtils;

 import java.util.Collection;

 import java.util.Collections;

 import java.util.Map;

 import java.util.Set;

 /**

  * A <code>MapCache</code> is a {@link Cache Cache} implementation that uses a backing {@link Map} instance to store

  * and retrieve cached data.

  *

  * @since 1.0

  */

 public class MapCache<K, V> implements Cache<K, V> {

     /**

      * Backing instance.

      */

     private final Map<K, V> map;

     /**

      * The name of this cache.

      */

     private final String name;

     public MapCache(String name, Map<K, V> backingMap) {

         if (name == null) {

             throw new IllegalArgumentException("Cache name cannot be null.");

         }

         if (backingMap == null) {

             throw new IllegalArgumentException("Backing map cannot be null.");

         }

         this.name = name;

         this.map = backingMap;

     }

     public V get(K key) throws CacheException {

         return map.get(key);

     }

     public V put(K key, V value) throws CacheException {

         return map.put(key, value);

     }

     public V remove(K key) throws CacheException {

         return map.remove(key);

     }

     public void clear() throws CacheException {

         map.clear();

     }

     public int size() {

         return map.size();

     }

     public Set<K> keys() {

         Set<K> keys = map.keySet();

         if (!keys.isEmpty()) {

             return Collections.unmodifiableSet(keys);

         }

         return Collections.emptySet();

     }

     public Collection<V> values() {

         Collection<V> values = map.values();

         if (!CollectionUtils.isEmpty(values)) {

             return Collections.unmodifiableCollection(values);

         }

         return Collections.emptySet();

     }

     public String toString() {

         return new StringBuilder("MapCache '")

                 .append(name).append("' (")

                 .append(map.size())

                 .append(" entries)")

                 .toString();

     }

 }