01: package org.apache.lucene.util;
02:
03: /**
04: * Licensed to the Apache Software Foundation (ASF) under one or more
05: * contributor license agreements. See the NOTICE file distributed with
06: * this work for additional information regarding copyright ownership.
07: * The ASF licenses this file to You under the Apache License, Version 2.0
08: * (the "License"); you may not use this file except in compliance with
09: * the License. You may obtain a copy of the License at
10: *
11: * http://www.apache.org/licenses/LICENSE-2.0
12: *
13: * Unless required by applicable law or agreed to in writing, software
14: * distributed under the License is distributed on an "AS IS" BASIS,
15: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16: * See the License for the specific language governing permissions and
17: * limitations under the License.
18: */
19:
20: import java.io.ObjectStreamException;
21: import java.io.Serializable;
22: import java.io.StreamCorruptedException;
23: import java.util.HashMap;
24: import java.util.Map;
25:
26: /**
27: * A serializable Enum class.
28: */
29: public abstract class Parameter implements Serializable {
30: static Map allParameters = new HashMap();
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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