module Backports::Random::Implementation

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.

Attributes

seed[R]

Public Class Methods

new(seed = 0) click to toggle source
Calls superclass method
# File lib/backports/random/implementation.rb, line 15
def initialize(seed = 0)
  super()
  srand(seed)
end

Public Instance Methods

==(other) click to toggle source
# File lib/backports/random/implementation.rb, line 47
def ==(other)
  other.is_a?(::Random) &&
    seed == other.seed &&
    left == other.send(:left) &&
    state == other.send(:state)
end
bytes(nb) click to toggle source
# File lib/backports/random/implementation.rb, line 41
def bytes(nb)
  nb = Backports.coerce_to_int(nb)
  raise ArgumentError, "negative size" if nb < 0
  @mt.random_bytes(nb)
end
marshal_dump() click to toggle source
# File lib/backports/random/implementation.rb, line 54
def marshal_dump
  @mt.marshal_dump << @seed
end
marshal_load(ary) click to toggle source
# File lib/backports/random/implementation.rb, line 58
def marshal_load(ary)
  @seed = ary.pop
  @mt = MT19937.allocate
  @mt.marshal_load(ary)
end
rand(limit = Backports::Undefined) click to toggle source
# File lib/backports/random/implementation.rb, line 27
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
srand(new_seed = 0) click to toggle source
# File lib/backports/random/implementation.rb, line 20
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

Private Instance Methods

_rand_range(limit) click to toggle source
# File lib/backports/random/implementation.rb, line 73
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
left() click to toggle source
# File lib/backports/random/implementation.rb, line 69
def left
  @mt.left
end
state() click to toggle source
# File lib/backports/random/implementation.rb, line 65
def state
  @mt.state_as_bignum
end