01: /***
02: * Retrotranslator: a Java bytecode transformer that translates Java classes
03: * compiled with JDK 5.0 into classes that can be run on JVM 1.4.
04: *
05: * Copyright (c) 2005 - 2008 Taras Puchko
06: * All rights reserved.
07: *
08: * Redistribution and use in source and binary forms, with or without
09: * modification, are permitted provided that the following conditions
10: * are met:
11: * 1. Redistributions of source code must retain the above copyright
12: * notice, this list of conditions and the following disclaimer.
13: * 2. Redistributions in binary form must reproduce the above copyright
14: * notice, this list of conditions and the following disclaimer in the
15: * documentation and/or other materials provided with the distribution.
16: * 3. Neither the name of the copyright holders nor the names of its
17: * contributors may be used to endorse or promote products derived from
18: * this software without specific prior written permission.
19: *
20: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21: * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23: * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24: * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25: * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26: * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27: * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28: * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29: * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
30: * THE POSSIBILITY OF SUCH DAMAGE.
31: */package net.sf.retrotranslator.runtime.impl;
32:
33: /**
34: * @author Taras Puchko
35: */
36: public abstract class LazyValue<I, R> {
37:
38: private I input;
39: private R result;
40:
41: public LazyValue(I input) {
42: this .input = input;
43: }
44:
45: public final synchronized R get() {
46: return result != null ? result : (result = resolve(input));
47: }
48:
49: public final synchronized void provide(R result) {
50: this .result = result;
51: }
52:
53: protected abstract R resolve(I input);
54:
55: }
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