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comparison graal/GraalCompiler/src/com/sun/c1x/util/ArrayMap.java @ 2509:16b9a8b5ad39

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Renamings Runtime=>GraalRuntime and Compiler=>GraalCompiler
author Thomas Wuerthinger <thomas@wuerthinger.net>
date Wed, 27 Apr 2011 11:50:44 +0200
parents graal/Compiler/src/com/sun/c1x/util/ArrayMap.java@9ec15d6914ca
children
comparison
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2508:fea94949e0a2 2509:16b9a8b5ad39
1 /*
2 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23 package com.sun.c1x.util;
24
25 /**
26 * The {@code ArrayMap} class implements an efficient one-level map which is implemented
27 * as an array. Note that because of the one-level array inside, this data structure performs best
28 * when the range of integer keys is small and densely used. Note that the implementation can
29 * handle arbitrary intervals, including negative numbers, up to intervals of size 2^31 - 1.
30 *
31 * @author Ben L. Titzer
32 */
33 public class ArrayMap<T> {
34
35 private static final int INITIAL_SIZE = 5; // how big the initial array should be
36 private static final int EXTRA = 2; // how far on the left or right of a new element to grow
37
38 Object[] map;
39 int low;
40
41 /**
42 * Constructs a new {@code ArrayMap} with no initial assumptions.
43 */
44 public ArrayMap() {
45 }
46
47 /**
48 * Constructs a new {@code ArrayMap} that initially covers the specified interval.
49 * Note that this map will automatically expand if necessary later.
50 * @param low the low index, inclusive
51 * @param high the high index, exclusive
52 */
53 public ArrayMap(int low, int high) {
54 this.low = low;
55 this.map = new Object[high - low + 1];
56 }
57
58 /**
59 * Puts a new value in the map at the specified index.
60 * @param i the index at which to store the value
61 * @param value the value to store at the specified index
62 */
63 public void put(int i, T value) {
64 int index = i - low;
65 if (map == null) {
66 // no map yet
67 map = new Object[INITIAL_SIZE];
68 low = index - 2;
69 map[INITIAL_SIZE / 2] = value;
70 } else if (index < 0) {
71 // grow backwards
72 growBackward(i, value);
73 } else if (index >= map.length) {
74 // grow forwards
75 growForward(i, value);
76 } else {
77 // no growth necessary
78 map[index] = value;
79 }
80 }
81
82 /**
83 * Gets the value at the specified index in the map.
84 * @param i the index
85 * @return the value at the specified index; {@code null} if there is no value at the specified index,
86 * or if the index is out of the currently stored range
87 */
88 public T get(int i) {
89 int index = i - low;
90 if (map == null || index < 0 || index >= map.length) {
91 return null;
92 }
93 Class<T> type = null;
94 return Util.uncheckedCast(type, map[index]);
95 }
96
97 public int length() {
98 return map.length;
99 }
100
101 private void growBackward(int i, T value) {
102 int nlow = i - EXTRA;
103 Object[] nmap = new Object[low - nlow + map.length];
104 System.arraycopy(map, 0, nmap, low - nlow, map.length);
105 map = nmap;
106 low = nlow;
107 map[i - low] = value;
108 }
109
110 private void growForward(int i, T value) {
111 int nlen = i - low + 1 + EXTRA;
112 Object[] nmap = new Object[nlen];
113 System.arraycopy(map, 0, nmap, 0, map.length);
114 map = nmap;
115 map[i - low] = value;
116 }
117 }