01: /*
02: * Copyright 2004-2006 the original author or authors.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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:
17: package org.compass.core.util;
18:
19: import java.io.ObjectStreamException;
20: import java.io.Serializable;
21: import java.io.StreamCorruptedException;
22: import java.util.HashMap;
23: import java.util.Map;
24:
25: /**
26: * A serializable Enum class. (Taken from lucene).
27: */
28: public abstract class Parameter implements Serializable {
29:
30: static Map<String, Parameter> allParameters = new HashMap<String, Parameter>();
31:
32: private String name;
33:
34: private Parameter() {
35: // typesafe enum pattern, no public constructor
36: }
37:
38: protected Parameter(String name) {
39: // typesafe enum pattern, no public constructor
40: this .name = name;
41: String key = makeKey(name);
42:
43: if (allParameters.containsKey(key))
44: throw new IllegalArgumentException("Parameter name " + key
45: + " already used!");
46:
47: allParameters.put(key, this );
48: }
49:
50: private String makeKey(String name) {
51: return getClass() + " " + name;
52: }
53:
54: public String toString() {
55: return name;
56: }
57:
58: /**
59: * Resolves the deserialized instance to the local reference for accurate
60: * equals() and == comparisons.
61: *
62: * @return a reference to Parameter as resolved in the local VM
63: * @throws ObjectStreamException
64: */
65: protected Object readResolve() throws ObjectStreamException {
66: Object par = allParameters.get(makeKey(name));
67:
68: if (par == null)
69: throw new StreamCorruptedException(
70: "Unknown parameter value: " + name);
71:
72: return par;
73: }
74:
75: }
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