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1   /*
2    * Copyright 1999-2004 The Apache Software Foundation
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package net.sf.morph.context.support;
17  
18  
19  import java.util.Map;
20  
21  
22  /**
23   * <p>Map.Entry implementation that can be constructed to either be read-only
24   * or not.</p>
25   * 
26   * <p>This class was copied from Jakarta Commons Chain.</p>
27   *
28   * @version $Revision: 1.1 $ $Date: 2005/01/10 05:28:48 $
29   */
30  public class MapEntry implements Map.Entry {
31  
32  
33      /**
34       * <p>The entry key.</p>
35       */
36      private Object key;
37  
38      /**
39       * <p>The entry value.</p>
40       */
41      private Object value;
42  
43      /**
44       * <p>Whether the entry can be modified.</p>
45       */
46      private boolean modifiable = false;
47  
48  
49      /**
50       * <p>Creates a map entry that can either allow modifications or not.</p>
51       * 
52       * @param key The entry key
53       * @param value The entry value
54       * @param modifiable Whether the entry should allow modification or not
55       */
56      public MapEntry(Object key, Object value, boolean modifiable) {
57          this.key = key;
58          this.value = value;
59          this.modifiable = modifiable;
60      }
61  
62  
63      /**
64       * <p>Gets the entry key.</p>
65       * 
66       * @return The entry key
67       */
68      public Object getKey() {
69          return key;
70      }
71  
72  
73      /**
74       * <p>Gets the entry value.</p>
75       * 
76       * @return The entry key
77       */
78      public Object getValue() {
79          return value;
80      }
81  
82  
83      /**
84       * <p>Sets the entry value if the entry can be modified.</p>
85       * 
86       * @param val The new value
87       * @return The old entry value
88       * @throws UnsupportedOperationException If the entry cannot be modified
89       */
90      public Object setValue(Object val) {
91          if (modifiable) {
92              Object oldVal = this.value;
93              this.value = val;
94              return oldVal;
95          }
96          throw new UnsupportedOperationException();
97      }
98  
99  
100     /**
101      * <p>Determines if this entry is equal to the passed object.</p>
102      * 
103      * @param o The object to test
104      * @return True if equal, else false
105      */
106     public boolean equals(Object o) {
107         if (o != null && o instanceof Map.Entry) {
108             Map.Entry entry = (Map.Entry)o; 
109             return (this.getKey()==null ?
110                     entry.getKey()==null : this.getKey().equals(entry.getKey()))  &&
111                    (this.getValue()==null ?
112                     entry.getValue()==null : this.getValue().equals(entry.getValue()));
113         }
114         return false;
115     }    
116 
117 
118     /**
119      * <p>Returns the hashcode for this entry.</p>
120      * 
121      * @return The and'ed hashcode of the key and value
122      */
123     public int hashCode() {
124         return (this.getKey()==null   ? 0 : this.getKey().hashCode()) ^
125                (this.getValue()==null ? 0 : this.getValue().hashCode());
126     }
127 }