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Java > Open Source Codes > net > sf > retrotranslator > runtime > impl > LazyList


1 /***
2  * Retrotranslator: a Java bytecode transformer that translates Java classes
3  * compiled with JDK 5.0 into classes that can be run on JVM 1.4.
4  *
5  * Copyright (c) 2005 - 2007 Taras Puchko
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * 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  */
32 package net.sf.retrotranslator.runtime.impl;
33
34 import java.util.*;
35
36 /**
37  * @author Taras Puchko
38  */
39 public abstract class LazyList<I, R> {
40
41     private List<I> inputs;
42     private R[] results;
43
44     public void add(I input) {
45         if (inputs == null) inputs = new ArrayList<I>();
46         inputs.add(input);
47     }
48
49     public I getLast() {
50         return inputs.get(inputs.size() - 1);
51     }
52
53     public I get(int index) {
54         return inputs == null || inputs.size() <= index ? null : inputs.get(index);
55     }
56
57     public void set(int index, I element) {
58         if (inputs == null) inputs = new ArrayList<I>();
59         while (inputs.size() <= index) {
60             inputs.add(null);
61         }
62         inputs.set(index, element);
63     }
64
65     public final synchronized R[] getLive() {
66         if (results == null) {
67             if (inputs == null) {
68                 results = newArray(0);
69                 for (int i = 0; i < results.length; i++) {
70                     results[i] = resolve(null);
71                 }
72             } else {
73                 results = newArray(inputs.size());
74                 Iterator<I> iterator = inputs.iterator();
75                 for (int i = 0; i < results.length; i++) {
76                     results[i] = resolve(iterator.hasNext() ? iterator.next() : null);
77                 }
78             }
79         }
80         return results;
81     }
82
83     public final R[] getClone() {
84         R[] live = getLive();
85         return live.length == 0 ? live : live.clone();
86     }
87
88     protected abstract R resolve(I input);
89
90     protected abstract R[] newArray(int size);
91
92 }
93
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