1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
package com.jclark.xml.tok;
/**
* Caches conversion of byte subarrays into Strings.
* @version $Revision: 1.3 $ $Date: 1998/02/17 04:24:24 $
*/
public class StringConversionCache {
private static final int DEFAULT_CACHE_SIZE = 1009;
private static final int CONVERSION_BUF_SIZE = 64;
private static class Bucket {
/* JDK 1.1 javac incorrectly fails to allows access to private members
of inner class from enclosing class. */
/* private */ byte[] bytes;
/* private */ String string;
/* private */ Bucket nextMru;
/* private */ Bucket prevMru;
/* private */ Bucket nextBucket;
/* private */ Bucket prevBucket;
/* private */ final boolean matches(byte[] buf, int start, int end) {
if (end - start != bytes.length)
return false;
for (int i = 0; i < bytes.length; i++)
if (bytes[i] != buf[start++])
return false;
return true;
}
}
/* JDK 1.1 javac can't handle blank finals correcltly when there are
inner classes. */
private /* final */ Bucket[] table;
private /* final */ Bucket mru = new Bucket();
private char[] conversionBuf = new char[CONVERSION_BUF_SIZE];
private Encoding enc;
private /* final */ int minBPC;
private int cacheFree;
private static final double LOAD_FACTOR = 0.7;
/**
* Create a cache of the specified size
* for converting byte subarrays in the specified encoding
* into Strings.
*/
public StringConversionCache(Encoding enc, int cacheSize) {
this.enc = enc;
minBPC = enc.getMinBytesPerChar();
table = new Bucket[cacheSize];
cacheFree = (int)(table.length * LOAD_FACTOR);
mru.nextMru = mru;
mru.prevMru = mru;
}
/**
* Create a cache of the default size for converting byte subarrays
* in the specified encoding into Strings.
*/
public StringConversionCache(Encoding enc) {
this(enc, DEFAULT_CACHE_SIZE);
}
/**
* Changes the encoding for the cache.
* This cannot be called after any calls to <code>convert</code>
* have been made.
*/
public void setEncoding(Encoding enc) {
if (cacheFree != (int)(table.length * LOAD_FACTOR))
throw new IllegalStateException("cache already used");
this.enc = enc;
if (minBPC != enc.getMinBytesPerChar())
throw new IllegalStateException("change to incompatible encoding");
}
/**
* Convert a byte subarray into a String.
* If <code>permanent</code> is true, then this conversion will
* be kept in the cache in preference to any non-permanent conversions.
*/
public String convert(byte[] buf, int start, int end, boolean permanent) {
int i = hash(buf, start, end) % table.length;
Bucket bucket = table[i];
if (bucket != null) {
for (Bucket p = bucket.nextBucket;
p != bucket;
p = p.nextBucket) {
if (p.matches(buf, start, end)) {
if (p.nextMru != null) {
unlinkMru(p);
if (permanent)
p.nextMru = null;
else
linkMru(mru, p);
}
return p.string;
}
}
}
else {
bucket = new Bucket();
bucket.nextBucket = bucket.prevBucket = bucket;
table[i] = bucket;
}
Bucket tem;
if (cacheFree <= 0) {
if (mru.nextMru == mru) {
for (int j = 0; j < table.length; j++) {
Bucket h = table[j];
if (h != null) {
for (Bucket p = h.nextBucket;
p != h;
p = p.nextBucket) {
linkMru(mru, p);
}
h.nextBucket = h.prevBucket = h;
}
}
}
tem = mru.prevMru;
unlinkMru(tem);
tem.prevBucket.nextBucket = tem.nextBucket;
tem.nextBucket.prevBucket = tem.prevBucket;
if (permanent)
tem.nextMru = null;
else
linkMru(mru, tem);
}
else {
--cacheFree;
tem = new Bucket();
if (!permanent)
linkMru(mru, tem);
}
if (end - start > conversionBuf.length * minBPC)
conversionBuf = new char[(end - start)/minBPC];
tem.string = new String(conversionBuf,
0,
enc.convert(buf, start, end, conversionBuf, 0));
byte[] bytes = new byte[end - start];
System.arraycopy(buf, start, bytes, 0, bytes.length);
tem.bytes = bytes;
tem.nextBucket = bucket.nextBucket;
tem.nextBucket.prevBucket = tem;
tem.prevBucket = bucket;
bucket.nextBucket = tem;
return tem.string;
}
private static final int hash(byte buf[], int start, int end) {
int h = 0;
while (start != end)
h += (h << 5) + (buf[start++] & 0xFF);
return h & 0x7FFFFFFF;
}
static private final void linkMru(Bucket after, Bucket s) {
s.nextMru = after.nextMru;
s.nextMru.prevMru = s;
s.prevMru = after;
after.nextMru = s;
}
static private final void unlinkMru(Bucket s) {
s.prevMru.nextMru = s.nextMru;
s.nextMru.prevMru = s.prevMru;
}
}
|
