author | xdono |
Wed, 02 Jul 2008 12:55:45 -0700 | |
changeset 715 | f16baef3a20e |
parent 468 | 642c8c0be52e |
child 5506 | 202f599c92aa |
permissions | -rw-r--r-- |
2 | 1 |
/* |
715 | 2 |
* Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved. |
2 | 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. Sun designates this |
|
8 |
* particular file as subject to the "Classpath" exception as provided |
|
9 |
* by Sun in the LICENSE file that accompanied this code. |
|
10 |
* |
|
11 |
* This code is distributed in the hope that it will be useful, but WITHOUT |
|
12 |
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
|
13 |
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
|
14 |
* version 2 for more details (a copy is included in the LICENSE file that |
|
15 |
* accompanied this code). |
|
16 |
* |
|
17 |
* You should have received a copy of the GNU General Public License version |
|
18 |
* 2 along with this work; if not, write to the Free Software Foundation, |
|
19 |
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
|
20 |
* |
|
21 |
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
|
22 |
* CA 95054 USA or visit www.sun.com if you need additional information or |
|
23 |
* have any questions. |
|
24 |
*/ |
|
25 |
||
26 |
||
468
642c8c0be52e
6695553: Cleanup GPLv2+SPL legal notices in hat sources
ohair
parents:
2
diff
changeset
|
27 |
/* |
2 | 28 |
* The Original Code is HAT. The Initial Developer of the |
29 |
* Original Code is Bill Foote, with contributions from others |
|
468
642c8c0be52e
6695553: Cleanup GPLv2+SPL legal notices in hat sources
ohair
parents:
2
diff
changeset
|
30 |
* at JavaSoft/Sun. |
2 | 31 |
*/ |
32 |
||
33 |
package com.sun.tools.hat.internal.util; |
|
34 |
import java.util.*; |
|
35 |
||
36 |
/** |
|
37 |
* A singleton utility class that sorts an array of objects. |
|
38 |
* <p> |
|
39 |
* Use: |
|
40 |
* <pre> |
|
41 |
* |
|
42 |
* Stuff[] arr = ...; |
|
43 |
* ArraySorter.sort(arr, new Comparer() { |
|
44 |
* public int compare(Object lhs, Object rhs) { |
|
45 |
* return ((String) lhs).compareTo((String) rhs); |
|
46 |
* } |
|
47 |
* }); |
|
48 |
* </pre> |
|
49 |
* |
|
50 |
* @author Bill Foote |
|
51 |
*/ |
|
52 |
||
53 |
public class ArraySorter { |
|
54 |
||
55 |
/** |
|
56 |
* Sort the given array, using c for comparison |
|
57 |
**/ |
|
58 |
static public void sort(Object[] arr, Comparer c) { |
|
59 |
quickSort(arr, c, 0, arr.length-1); |
|
60 |
} |
|
61 |
||
62 |
||
63 |
/** |
|
64 |
* Sort an array of strings, using String.compareTo() |
|
65 |
**/ |
|
66 |
static public void sortArrayOfStrings(Object[] arr) { |
|
67 |
sort(arr, new Comparer() { |
|
68 |
public int compare(Object lhs, Object rhs) { |
|
69 |
return ((String) lhs).compareTo((String) rhs); |
|
70 |
} |
|
71 |
}); |
|
72 |
} |
|
73 |
||
74 |
||
75 |
static private void swap(Object[] arr, int a, int b) { |
|
76 |
Object tmp = arr[a]; |
|
77 |
arr[a] = arr[b]; |
|
78 |
arr[b] = tmp; |
|
79 |
} |
|
80 |
||
81 |
// |
|
82 |
// Sorts arr between from and to, inclusive. This is a quick, off-the-top- |
|
83 |
// of-my-head quicksort: I haven't put any thought into optimizing it. |
|
84 |
// I _did_ put thought into making sure it's safe (it will always |
|
85 |
// terminate). Worst-case it's O(n^2), but it will usually run in |
|
86 |
// in O(n log n). It's well-behaved if the list is already sorted, |
|
87 |
// or nearly so. |
|
88 |
// |
|
89 |
static private void quickSort(Object[] arr, Comparer c, int from, int to) { |
|
90 |
if (to <= from) |
|
91 |
return; |
|
92 |
int mid = (from + to) / 2; |
|
93 |
if (mid != from) |
|
94 |
swap(arr, mid, from); |
|
95 |
Object pivot = arr[from]; // Simple-minded, but reasonable |
|
96 |
int highestBelowPivot = from - 1; |
|
97 |
int low = from+1; |
|
98 |
int high = to; |
|
99 |
// We now move low and high toward each other, maintaining the |
|
100 |
// invariants: |
|
101 |
// arr[i] <= pivot for all i < low |
|
102 |
// arr[i] > pivot for all i > high |
|
103 |
// As long as these invariants hold, and every iteration makes |
|
104 |
// progress, we are safe. |
|
105 |
while (low <= high) { |
|
106 |
int cmp = c.compare(arr[low], pivot); |
|
107 |
if (cmp <= 0) { // arr[low] <= pivot |
|
108 |
if (cmp < 0) { |
|
109 |
highestBelowPivot = low; |
|
110 |
} |
|
111 |
low++; |
|
112 |
} else { |
|
113 |
int c2; |
|
114 |
for (;;) { |
|
115 |
// arr[high] > pivot: |
|
116 |
c2 = c.compare(arr[high], pivot); |
|
117 |
if (c2 > 0) { |
|
118 |
high--; |
|
119 |
if (low > high) { |
|
120 |
break; |
|
121 |
} |
|
122 |
} else { |
|
123 |
break; |
|
124 |
} |
|
125 |
} |
|
126 |
// At this point, low is never == high, BTW |
|
127 |
if (low <= high) { |
|
128 |
swap(arr, low, high); |
|
129 |
if (c2 < 0) { |
|
130 |
highestBelowPivot = low; |
|
131 |
} |
|
132 |
low++; |
|
133 |
high--; |
|
134 |
} |
|
135 |
} |
|
136 |
} |
|
137 |
// At this point, low == high+1 |
|
138 |
// Now we just need to sort from from..highestBelowPivot |
|
139 |
// and from high+1..to |
|
140 |
if (highestBelowPivot > from) { |
|
141 |
// pivot == pivot, so ensure algorithm terminates |
|
142 |
swap(arr, from, highestBelowPivot); |
|
143 |
quickSort(arr, c, from, highestBelowPivot-1); |
|
144 |
} |
|
145 |
quickSort(arr, c, high+1, to); |
|
146 |
} |
|
147 |
} |