blob: 23ea0efbdc558fcd2f2c6a8600cceab9e642744b (
plain)
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
175
176
177
178
179
|
// Copyright 2011 The Closure Library Authors. All Rights Reserved.
//
// 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.
/**
* @fileoverview PseudoRandom provides a mechanism for generating deterministic
* psuedo random numbers based on a seed. Based on the Park-Miller algorithm.
* See http://dx.doi.org/10.1145%2F63039.63042 for details.
*
*/
goog.provide('goog.testing.PseudoRandom');
goog.require('goog.Disposable');
/**
* Class for unit testing code that uses Math.random. Generates deterministic
* random numbers.
*
* @param {number=} opt_seed The seed to use.
* @param {boolean=} opt_install Whether to install the PseudoRandom at
* construction time.
* @extends {goog.Disposable}
* @constructor
*/
goog.testing.PseudoRandom = function(opt_seed, opt_install) {
goog.Disposable.call(this);
if (!goog.isDef(opt_seed)) {
opt_seed = goog.testing.PseudoRandom.seedUniquifier_++ + goog.now();
}
this.seed(opt_seed);
if (opt_install) {
this.install();
}
};
goog.inherits(goog.testing.PseudoRandom, goog.Disposable);
/**
* Helps create a unique seed.
* @type {number}
* @private
*/
goog.testing.PseudoRandom.seedUniquifier_ = 0;
/**
* Constant used as part of the algorithm.
* @type {number}
*/
goog.testing.PseudoRandom.A = 48271;
/**
* Constant used as part of the algorithm. 2^31 - 1.
* @type {number}
*/
goog.testing.PseudoRandom.M = 2147483647;
/**
* Constant used as part of the algorithm. It is equal to M / A.
* @type {number}
*/
goog.testing.PseudoRandom.Q = 44488;
/**
* Constant used as part of the algorithm. It is equal to M % A.
* @type {number}
*/
goog.testing.PseudoRandom.R = 3399;
/**
* Constant used as part of the algorithm to get values from range [0, 1).
* @type {number}
*/
goog.testing.PseudoRandom.ONE_OVER_M_MINUS_ONE =
1.0 / (goog.testing.PseudoRandom.M - 1);
/**
* The seed of the random sequence and also the next returned value (before
* normalization). Must be between 1 and M - 1 (inclusive).
* @type {number}
* @private
*/
goog.testing.PseudoRandom.prototype.seed_ = 1;
/**
* Whether this PseudoRandom has been installed.
* @type {boolean}
* @private
*/
goog.testing.PseudoRandom.prototype.installed_;
/**
* The original Math.random function.
* @type {function(): number}
* @private
*/
goog.testing.PseudoRandom.prototype.mathRandom_;
/**
* Installs this PseudoRandom as the system number generator.
*/
goog.testing.PseudoRandom.prototype.install = function() {
if (!this.installed_) {
this.mathRandom_ = Math.random;
Math.random = goog.bind(this.random, this);
this.installed_ = true;
}
};
/** @override */
goog.testing.PseudoRandom.prototype.disposeInternal = function() {
goog.testing.PseudoRandom.superClass_.disposeInternal.call(this);
this.uninstall();
};
/**
* Uninstalls the PseudoRandom.
*/
goog.testing.PseudoRandom.prototype.uninstall = function() {
if (this.installed_) {
Math.random = this.mathRandom_;
this.installed_ = false;
}
};
/**
* Seed the generator.
*
* @param {number=} seed The seed to use.
*/
goog.testing.PseudoRandom.prototype.seed = function(seed) {
this.seed_ = seed % (goog.testing.PseudoRandom.M - 1);
if (this.seed_ <= 0) {
this.seed_ += goog.testing.PseudoRandom.M - 1;
}
};
/**
* @return {number} The next number in the sequence.
*/
goog.testing.PseudoRandom.prototype.random = function() {
var hi = Math.floor(this.seed_ / goog.testing.PseudoRandom.Q);
var lo = this.seed_ % goog.testing.PseudoRandom.Q;
var test = goog.testing.PseudoRandom.A * lo -
goog.testing.PseudoRandom.R * hi;
if (test > 0) {
this.seed_ = test;
} else {
this.seed_ = test + goog.testing.PseudoRandom.M;
}
return (this.seed_ - 1) * goog.testing.PseudoRandom.ONE_OVER_M_MINUS_ONE;
};
|
