/
AbstractNonStreamingHashFunction.java
134 lines (114 loc) · 3.79 KB
/
AbstractNonStreamingHashFunction.java
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
/*
* Copyright (C) 2011 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.common.hash;
import com.google.common.base.Preconditions;
import com.google.errorprone.annotations.Immutable;
import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.charset.Charset;
import java.util.Arrays;
/**
* Skeleton implementation of {@link HashFunction}, appropriate for non-streaming algorithms. All
* the hash computation done using {@linkplain #newHasher()} are delegated to the {@linkplain
* #hashBytes(byte[], int, int)} method.
*
* @author Dimitris Andreou
*/
@Immutable
@ElementTypesAreNonnullByDefault
abstract class AbstractNonStreamingHashFunction extends AbstractHashFunction {
@Override
public Hasher newHasher() {
return newHasher(32);
}
@Override
public Hasher newHasher(int expectedInputSize) {
Preconditions.checkArgument(expectedInputSize >= 0);
return new BufferingHasher(expectedInputSize);
}
@Override
public HashCode hashInt(int input) {
return hashBytes(ByteBuffer.allocate(4).order(ByteOrder.LITTLE_ENDIAN).putInt(input).array());
}
@Override
public HashCode hashLong(long input) {
return hashBytes(ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).putLong(input).array());
}
@Override
public HashCode hashUnencodedChars(CharSequence input) {
int len = input.length();
ByteBuffer buffer = ByteBuffer.allocate(len * 2).order(ByteOrder.LITTLE_ENDIAN);
for (int i = 0; i < len; i++) {
buffer.putChar(input.charAt(i));
}
return hashBytes(buffer.array());
}
@Override
public HashCode hashString(CharSequence input, Charset charset) {
return hashBytes(input.toString().getBytes(charset));
}
@Override
public abstract HashCode hashBytes(byte[] input, int off, int len);
@Override
public HashCode hashBytes(ByteBuffer input) {
return newHasher(input.remaining()).putBytes(input).hash();
}
/** In-memory stream-based implementation of Hasher. */
private final class BufferingHasher extends AbstractHasher {
final ExposedByteArrayOutputStream stream;
BufferingHasher(int expectedInputSize) {
this.stream = new ExposedByteArrayOutputStream(expectedInputSize);
}
@Override
public Hasher putByte(byte b) {
stream.write(b);
return this;
}
@Override
public Hasher putBytes(byte[] bytes, int off, int len) {
stream.write(bytes, off, len);
return this;
}
@Override
public Hasher putBytes(ByteBuffer bytes) {
stream.write(bytes);
return this;
}
@Override
public HashCode hash() {
return hashBytes(stream.byteArray(), 0, stream.length());
}
}
// Just to access the byte[] without introducing an unnecessary copy
private static final class ExposedByteArrayOutputStream extends ByteArrayOutputStream {
ExposedByteArrayOutputStream(int expectedInputSize) {
super(expectedInputSize);
}
void write(ByteBuffer input) {
int remaining = input.remaining();
if (count + remaining > buf.length) {
buf = Arrays.copyOf(buf, count + remaining);
}
input.get(buf, count, remaining);
count += remaining;
}
byte[] byteArray() {
return buf;
}
int length() {
return count;
}
}
}