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Java > Open Source Codes > org > apache > hivemind > schema > rules > EnumerationTranslator


1 // Copyright 2004, 2005 The Apache Software Foundation
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 package org.apache.hivemind.schema.rules;
16
17 import java.lang.reflect.Field JavaDoc;
18 import java.util.Map JavaDoc;
19
20 import org.apache.hivemind.ApplicationRuntimeException;
21 import org.apache.hivemind.HiveMind;
22 import org.apache.hivemind.Location;
23 import org.apache.hivemind.internal.Module;
24 import org.apache.hivemind.schema.Translator;
25
26 /**
27  * Used to translate a set of strings to one of a number of constant values.
28  * Each input string is matched against the name of a public static field
29  * of a class. The name of the class, and the mappings, are provided
30  * in the initializer.
31  *
32  * @author Howard Lewis Ship
33  */
34 public class EnumerationTranslator implements Translator
35 {
36     private Map JavaDoc _mappings;
37     private String JavaDoc _className;
38     private Class JavaDoc _class;
39
40     /**
41      * Initialized the translator; the intitializer is the name of the class, a comma,
42      * and a series of key=value mappings from the input values to the names
43      * of the public static fields of the class.
44      */
45     public EnumerationTranslator(String JavaDoc initializer)
46     {
47         int commax = initializer.indexOf(',');
48
49         _className = initializer.substring(0, commax);
50
51         _mappings = RuleUtils.convertInitializer(initializer.substring(commax + 1));
52     }
53
54     private synchronized Class JavaDoc getClass(Module contributingModule)
55     {
56         if (_class == null)
57             _class = contributingModule.resolveType(_className);
58
59         return _class;
60     }
61
62     public Object JavaDoc translate(
63         Module contributingModule,
64         Class JavaDoc propertyType,
65         String JavaDoc inputValue,
66         Location location)
67     {
68         if (HiveMind.isBlank(inputValue))
69             return null;
70
71         Class JavaDoc c = getClass(contributingModule);
72
73         String JavaDoc fieldName = (String JavaDoc) _mappings.get(inputValue);
74
75         if (fieldName == null)
76             throw new ApplicationRuntimeException(
77                 RulesMessages.enumNotRecognized(inputValue),
78                 location,
79                 null);
80
81         try
82         {
83             Field JavaDoc f = c.getField(fieldName);
84
85             return f.get(null);
86         }
87         catch (Exception JavaDoc ex)
88         {
89             throw new ApplicationRuntimeException(
90                 RulesMessages.enumError(c, fieldName, ex),
91                 location,
92                 ex);
93         }
94     }
95
96 }
97
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