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
|
require "backports/tools/arguments"
require "backports/random/MT19937"
require "backports/random/bits_and_bytes"
module Backports
class Random
# Implementation corresponding to the actual Random class of Ruby
# The actual random generator (mersenne twister) is in MT19937.
# Ruby specific conversions are handled in bits_and_bytes.
# The high level stuff (argument checking) is done here.
#
module Implementation
attr_reader :seed
def initialize(seed = 0)
super()
srand(seed)
end
def srand(new_seed = 0)
new_seed = Backports.coerce_to_int(new_seed)
old, @seed = @seed, new_seed.nonzero? || Random.new_seed
@mt = MT19937[ @seed ]
old
end
def rand(limit = Backports::Undefined)
case limit
when Backports::Undefined
@mt.random_float
when Float
limit * @mt.random_float unless limit <= 0
when Range
_rand_range(limit)
else
limit = Backports.coerce_to_int(limit)
@mt.random_integer(limit) unless limit <= 0
end || raise(ArgumentError, "invalid argument #{limit}")
end
def bytes(nb)
nb = Backports.coerce_to_int(nb)
raise ArgumentError, "negative size" if nb < 0
@mt.random_bytes(nb)
end
def ==(other)
other.is_a?(Random) &&
seed == other.seed &&
left == other.send(:left) &&
state == other.send(:state)
end
def marshal_dump
@mt.marshal_dump << @seed
end
def marshal_load(ary)
@seed = ary.pop
@mt = MT19937.allocate
@mt.marshal_load(ary)
end
private
def state
@mt.state_as_bignum
end
def left
@mt.left
end
def _rand_range(limit)
range = limit.end - limit.begin
if (!range.is_a?(Float)) && range.respond_to?(:to_int) && range = Backports.coerce_to_int(range)
range += 1 unless limit.exclude_end?
limit.begin + @mt.random_integer(range) unless range <= 0
elsif range = Backports.coerce_to(range, Float, :to_f)
if range < 0
nil
elsif limit.exclude_end?
limit.begin + @mt.random_float * range unless range <= 0
else
# cheat a bit... this will reduce the nb of random bits
loop do
r = @mt.random_float * range * 1.0001
break limit.begin + r unless r > range
end
end
end
end
end
end
end
|
