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# -*- coding: us-ascii -*-
# frozen_string_literal: true
# == Random number formatter.
#
# Formats generated random numbers in many manners.
#
# === Examples
#
# Generate random hexadecimal strings:
#
# require 'random/formatter'
#
# prng.hex(10) #=> "52750b30ffbc7de3b362"
# prng.hex(10) #=> "92b15d6c8dc4beb5f559"
# prng.hex(13) #=> "39b290146bea6ce975c37cfc23"
#
# Generate random base64 strings:
#
# prng.base64(10) #=> "EcmTPZwWRAozdA=="
# prng.base64(10) #=> "KO1nIU+p9DKxGg=="
# prng.base64(12) #=> "7kJSM/MzBJI+75j8"
#
# Generate random binary strings:
#
# prng.random_bytes(10) #=> "\016\t{\370g\310pbr\301"
# prng.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337"
#
# Generate alphanumeric strings:
#
# prng.alphanumeric(10) #=> "S8baxMJnPl"
# prng.alphanumeric(10) #=> "aOxAg8BAJe"
#
# Generate UUIDs:
#
# prng.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
# prng.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
module Random::Formatter
# Random::Formatter#random_bytes generates a random binary string.
#
# The argument _n_ specifies the length of the result string.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in future.
#
# The result may contain any byte: "\x00" - "\xff".
#
# require 'random/formatter'
#
# prng.random_bytes #=> "\xD8\\\xE0\xF4\r\xB2\xFC*WM\xFF\x83\x18\xF45\xB6"
# prng.random_bytes #=> "m\xDC\xFC/\a\x00Uf\xB2\xB2P\xBD\xFF6S\x97"
def random_bytes(n=nil)
n = n ? n.to_int : 16
gen_random(n)
end
# Random::Formatter#hex generates a random hexadecimal string.
#
# The argument _n_ specifies the length, in bytes, of the random number to be generated.
# The length of the resulting hexadecimal string is twice of _n_.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in the future.
#
# The result may contain 0-9 and a-f.
#
# require 'random/formatter'
#
# prng.hex #=> "eb693ec8252cd630102fd0d0fb7c3485"
# prng.hex #=> "91dc3bfb4de5b11d029d376634589b61"
def hex(n=nil)
random_bytes(n).unpack1("H*")
end
# Random::Formatter#base64 generates a random base64 string.
#
# The argument _n_ specifies the length, in bytes, of the random number
# to be generated. The length of the result string is about 4/3 of _n_.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in the future.
#
# The result may contain A-Z, a-z, 0-9, "+", "/" and "=".
#
# require 'random/formatter'
#
# prng.base64 #=> "/2BuBuLf3+WfSKyQbRcc/A=="
# prng.base64 #=> "6BbW0pxO0YENxn38HMUbcQ=="
#
# See RFC 3548 for the definition of base64.
def base64(n=nil)
[random_bytes(n)].pack("m0")
end
# Random::Formatter#urlsafe_base64 generates a random URL-safe base64 string.
#
# The argument _n_ specifies the length, in bytes, of the random number
# to be generated. The length of the result string is about 4/3 of _n_.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in the future.
#
# The boolean argument _padding_ specifies the padding.
# If it is false or nil, padding is not generated.
# Otherwise padding is generated.
# By default, padding is not generated because "=" may be used as a URL delimiter.
#
# The result may contain A-Z, a-z, 0-9, "-" and "_".
# "=" is also used if _padding_ is true.
#
# require 'random/formatter'
#
# prng.urlsafe_base64 #=> "b4GOKm4pOYU_-BOXcrUGDg"
# prng.urlsafe_base64 #=> "UZLdOkzop70Ddx-IJR0ABg"
#
# prng.urlsafe_base64(nil, true) #=> "i0XQ-7gglIsHGV2_BNPrdQ=="
# prng.urlsafe_base64(nil, true) #=> "-M8rLhr7JEpJlqFGUMmOxg=="
#
# See RFC 3548 for the definition of URL-safe base64.
def urlsafe_base64(n=nil, padding=false)
s = [random_bytes(n)].pack("m0")
s.tr!("+/", "-_")
s.delete!("=") unless padding
s
end
# Random::Formatter#uuid generates a random v4 UUID (Universally Unique IDentifier).
#
# require 'random/formatter'
#
# prng.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
# prng.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
# prng.uuid #=> "62936e70-1815-439b-bf89-8492855a7e6b"
#
# The version 4 UUID is purely random (except the version).
# It doesn't contain meaningful information such as MAC addresses, timestamps, etc.
#
# The result contains 122 random bits (15.25 random bytes).
#
# See RFC 4122 for details of UUID.
#
def uuid
ary = random_bytes(16).unpack("NnnnnN")
ary[2] = (ary[2] & 0x0fff) | 0x4000
ary[3] = (ary[3] & 0x3fff) | 0x8000
"%08x-%04x-%04x-%04x-%04x%08x" % ary
end
private def gen_random(n)
self.bytes(n)
end
# Random::Formatter#choose generates a string that randomly draws from a
# source array of characters.
#
# The argument _source_ specifies the array of characters from which
# to generate the string.
# The argument _n_ specifies the length, in characters, of the string to be
# generated.
#
# The result may contain whatever characters are in the source array.
#
# require 'random/formatter'
#
# prng.choose([*'l'..'r'], 16) #=> "lmrqpoonmmlqlron"
# prng.choose([*'0'..'9'], 5) #=> "27309"
private def choose(source, n)
size = source.size
m = 1
limit = size
while limit * size <= 0x100000000
limit *= size
m += 1
end
result = ''.dup
while m <= n
rs = random_number(limit)
is = rs.digits(size)
(m-is.length).times { is << 0 }
result << source.values_at(*is).join('')
n -= m
end
if 0 < n
rs = random_number(limit)
is = rs.digits(size)
if is.length < n
(n-is.length).times { is << 0 }
else
is.pop while n < is.length
end
result.concat source.values_at(*is).join('')
end
result
end
ALPHANUMERIC = [*'A'..'Z', *'a'..'z', *'0'..'9']
# Random::Formatter#alphanumeric generates a random alphanumeric string.
#
# The argument _n_ specifies the length, in characters, of the alphanumeric
# string to be generated.
#
# If _n_ is not specified or is nil, 16 is assumed.
# It may be larger in the future.
#
# The result may contain A-Z, a-z and 0-9.
#
# require 'random/formatter'
#
# prng.alphanumeric #=> "2BuBuLf3WfSKyQbR"
# prng.alphanumeric(10) #=> "i6K93NdqiH"
def alphanumeric(n=nil)
n = 16 if n.nil?
choose(ALPHANUMERIC, n)
end
end
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