Enum


1   /*
2    * Copyright 2006 Google Inc.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License"); you may not
5    * use this file except in compliance with the License. You may obtain a copy of
6    * 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, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations under
14   * the License.
15   */
16  package com.google.gwt.user.rebind;
17  
18  import java.util.Map  ;
19  
20  /**
21   * Common base class for Enum-like 1.4 classes, often needed for generator-like
22   * functionality.
23   */
24  class Enum {
25    /**
26     * Requires the specified object from the pool.
27     * 
28     * @param key the key associated with the <code>Enum</code>
29     * @param pool pool to draw key from
30     * @return associated <code>Enum</code>
31     */
32    public static Enum   require(String   key, Map   pool) {
33      Enum   t = (Enum  ) pool.get(key);
34      if (t == null) {
35        throw new IllegalArgumentException  (key
36            + " is not a valid Enum type. Current options are " + pool.keySet());
37      }
38      return t;
39    }
40  
41    /**
42     * Associated key.
43     */
44    final String   key;
45  
46    /**
47     * Creates a new <code>Enum</code> in a given pool.
48     * 
49     * @param key associated key
50     * @param pool associated pool
51     */
52    protected Enum(String   key, Map   pool) {
53      this.key = key;
54      pool.put(key, this);
55    }
56  
57    /**
58     * @see java.lang.Object#toString()
59     */
60    public String   toString() {
61      return key;
62    }
63  }
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