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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.configuration;
19  
20  import java.util.AbstractMap;
21  import java.util.AbstractSet;
22  import java.util.Iterator;
23  import java.util.Map;
24  import java.util.Set;
25  
26  /**
27   * <p>The {@code ConfigurationMap} wraps a
28   * configuration-collection
29   * {@link org.apache.commons.configuration.Configuration}
30   * instance to provide a {@code Map} interface.</p>
31   *
32   * <p><em>Note:</em> This implementation is incomplete.</p>
33   *
34   * @author <a href="mailto:ricardo.gladwell@btinternet.com">Ricardo Gladwell</a>
35   * @version $Id: ConfigurationMap.java 1301959 2012-03-17 16:43:18Z oheger $
36   * @since 1.0
37   */
38  public class ConfigurationMap extends AbstractMap<Object, Object>
39  {
40      /**
41       * The {@code Configuration} wrapped by this class.
42       */
43      private final Configuration configuration;
44  
45      /**
46       * Creates a new instance of a {@code ConfigurationMap}
47       * that wraps the specified {@code Configuration}
48       * instance.
49       * @param configuration {@code Configuration}
50       * instance.
51       */
52      public ConfigurationMap(Configuration configuration)
53      {
54          this.configuration = configuration;
55      }
56  
57      /**
58       * Returns the wrapped {@code Configuration} object.
59       *
60       * @return the wrapped configuration
61       * @since 1.2
62       */
63      public Configuration getConfiguration()
64      {
65          return configuration;
66      }
67  
68      /**
69       * Returns a set with the entries contained in this configuration-based map.
70       *
71       * @return a set with the contained entries
72       * @see java.util.Map#entrySet()
73       */
74      @Override
75      public Set<Map.Entry<Object, Object>> entrySet()
76      {
77          return new ConfigurationSet(configuration);
78      }
79  
80      /**
81       * Stores the value for the specified key. The value is stored in the
82       * underlying configuration.
83       *
84       * @param key the key (will be converted to a string)
85       * @param value the value
86       * @return the old value of this key or <b>null</b> if it is new
87       * @see java.util.Map#put(java.lang.Object, java.lang.Object)
88       */
89      @Override
90      public Object put(Object key, Object value)
91      {
92          String strKey = String.valueOf(key);
93          Object old = configuration.getProperty(strKey);
94          configuration.setProperty(strKey, value);
95          return old;
96      }
97  
98      /**
99       * Returns the value of the specified key. The key is converted to a string
100      * and then passed to the underlying configuration.
101      *
102      * @param key the key
103      * @return the value of this key
104      * @see java.util.Map#get(java.lang.Object)
105      */
106     @Override
107     public Object get(Object key)
108     {
109         return configuration.getProperty(String.valueOf(key));
110     }
111 
112     /**
113      * Set of entries in the map.
114      */
115     static class ConfigurationSet extends AbstractSet<Map.Entry<Object, Object>>
116     {
117         /** The configuration mapped to this entry set. */
118         private final Configuration configuration;
119 
120         /**
121          * A Map entry in the ConfigurationMap.
122          */
123         private final class Entry implements Map.Entry<Object, Object>
124         {
125             /** The key of the map entry. */
126             private Object key;
127 
128             private Entry(Object key)
129             {
130                 this.key = key;
131             }
132 
133             public Object getKey()
134             {
135                 return key;
136             }
137 
138             public Object getValue()
139             {
140                 return configuration.getProperty((String) key);
141             }
142 
143             public Object setValue(Object value)
144             {
145                 Object old = getValue();
146                 configuration.setProperty((String) key, value);
147                 return old;
148             }
149         }
150 
151         /**
152          * Iterator over the entries in the ConfigurationMap.
153          */
154         private final class ConfigurationSetIterator implements Iterator<Map.Entry<Object, Object>>
155         {
156             /** An iterator over the keys in the configuration. */
157             private final Iterator<String> keys;
158 
159             private ConfigurationSetIterator()
160             {
161                 keys = configuration.getKeys();
162             }
163 
164             public boolean hasNext()
165             {
166                 return keys.hasNext();
167             }
168 
169             public Map.Entry<Object, Object> next()
170             {
171                 return new Entry(keys.next());
172             }
173 
174             public void remove()
175             {
176                 keys.remove();
177             }
178         }
179 
180         ConfigurationSet(Configuration configuration)
181         {
182             this.configuration = configuration;
183         }
184 
185         /**
186          * @see java.util.Collection#size()
187          */
188         @Override
189         public int size()
190         {
191             // Ouch. Now _that_ one is expensive...
192             int count = 0;
193             for (Iterator<String> iterator = configuration.getKeys(); iterator.hasNext();)
194             {
195                 iterator.next();
196                 count++;
197             }
198             return count;
199         }
200 
201         /**
202          * @see java.util.Collection#iterator()
203          */
204         @Override
205         public Iterator<Map.Entry<Object, Object>> iterator()
206         {
207             return new ConfigurationSetIterator();
208         }
209     }
210 }