summaryrefslogtreecommitdiff
path: root/lib/random/formatter.rb
diff options
context:
space:
mode:
Diffstat (limited to 'lib/random/formatter.rb')
-rw-r--r--lib/random/formatter.rb373
1 files changed, 373 insertions, 0 deletions
diff --git a/lib/random/formatter.rb b/lib/random/formatter.rb
new file mode 100644
index 0000000000..037f9d8748
--- /dev/null
+++ b/lib/random/formatter.rb
@@ -0,0 +1,373 @@
+# -*- coding: us-ascii -*-
+# frozen_string_literal: true
+
+# == \Random number formatter.
+#
+# Formats generated random numbers in many manners. When <tt>'random/formatter'</tt>
+# is required, several methods are added to empty core module <tt>Random::Formatter</tt>,
+# making them available as Random's instance and module methods.
+#
+# Standard library SecureRandom is also extended with the module, and the methods
+# described below are available as a module methods in it.
+#
+# === Examples
+#
+# Generate random hexadecimal strings:
+#
+# require 'random/formatter'
+#
+# prng = Random.new
+# prng.hex(10) #=> "52750b30ffbc7de3b362"
+# prng.hex(10) #=> "92b15d6c8dc4beb5f559"
+# prng.hex(13) #=> "39b290146bea6ce975c37cfc23"
+# # or just
+# Random.hex #=> "1aed0c631e41be7f77365415541052ee"
+#
+# Generate random base64 strings:
+#
+# prng.base64(10) #=> "EcmTPZwWRAozdA=="
+# prng.base64(10) #=> "KO1nIU+p9DKxGg=="
+# prng.base64(12) #=> "7kJSM/MzBJI+75j8"
+# Random.base64(4) #=> "bsQ3fQ=="
+#
+# Generate random binary strings:
+#
+# prng.random_bytes(10) #=> "\016\t{\370g\310pbr\301"
+# prng.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337"
+# Random.random_bytes(6) #=> "\xA1\xE6Lr\xC43"
+#
+# Generate alphanumeric strings:
+#
+# prng.alphanumeric(10) #=> "S8baxMJnPl"
+# prng.alphanumeric(10) #=> "aOxAg8BAJe"
+# Random.alphanumeric #=> "TmP9OsJHJLtaZYhP"
+#
+# Generate UUIDs:
+#
+# prng.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
+# prng.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
+# Random.uuid #=> "f14e0271-de96-45cc-8911-8910292a42cd"
+#
+# All methods are available in the standard library SecureRandom, too:
+#
+# SecureRandom.hex #=> "05b45376a30c67238eb93b16499e50cf"
+
+module Random::Formatter
+
+ # Generate 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'
+ #
+ # Random.random_bytes #=> "\xD8\\\xE0\xF4\r\xB2\xFC*WM\xFF\x83\x18\xF45\xB6"
+ # # or
+ # prng = Random.new
+ # 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
+
+ # Generate 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'
+ #
+ # Random.hex #=> "eb693ec8252cd630102fd0d0fb7c3485"
+ # # or
+ # prng = Random.new
+ # prng.hex #=> "91dc3bfb4de5b11d029d376634589b61"
+ def hex(n=nil)
+ random_bytes(n).unpack1("H*")
+ end
+
+ # Generate 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'
+ #
+ # Random.base64 #=> "/2BuBuLf3+WfSKyQbRcc/A=="
+ # # or
+ # prng = Random.new
+ # prng.base64 #=> "6BbW0pxO0YENxn38HMUbcQ=="
+ #
+ # See RFC 3548 for the definition of base64.
+ def base64(n=nil)
+ [random_bytes(n)].pack("m0")
+ end
+
+ # Generate 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'
+ #
+ # Random.urlsafe_base64 #=> "b4GOKm4pOYU_-BOXcrUGDg"
+ # # or
+ # prng = Random.new
+ # 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
+
+ # Generate a random v4 UUID (Universally Unique IDentifier).
+ #
+ # require 'random/formatter'
+ #
+ # Random.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
+ # Random.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
+ # # or
+ # prng = Random.new
+ # 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 RFC4122[https://www.rfc-editor.org/rfc/rfc4122] for details of UUID.
+ #
+ def uuid
+ ary = random_bytes(16)
+ ary.setbyte(6, (ary.getbyte(6) & 0x0f) | 0x40)
+ ary.setbyte(8, (ary.getbyte(8) & 0x3f) | 0x80)
+ ary.unpack("H8H4H4H4H12").join(?-)
+ end
+
+ alias uuid_v4 uuid
+
+ # Generate a random v7 UUID (Universally Unique IDentifier).
+ #
+ # require 'random/formatter'
+ #
+ # Random.uuid_v7 # => "0188d4c3-1311-7f96-85c7-242a7aa58f1e"
+ # Random.uuid_v7 # => "0188d4c3-16fe-744f-86af-38fa04c62bb5"
+ # Random.uuid_v7 # => "0188d4c3-1af8-764f-b049-c204ce0afa23"
+ # Random.uuid_v7 # => "0188d4c3-1e74-7085-b14f-ef6415dc6f31"
+ # # |<--sorted-->| |<----- random ---->|
+ #
+ # # or
+ # prng = Random.new
+ # prng.uuid_v7 # => "0188ca51-5e72-7950-a11d-def7ff977c98"
+ #
+ # The version 7 UUID starts with the least significant 48 bits of a 64 bit
+ # Unix timestamp (milliseconds since the epoch) and fills the remaining bits
+ # with random data, excluding the version and variant bits.
+ #
+ # This allows version 7 UUIDs to be sorted by creation time. Time ordered
+ # UUIDs can be used for better database index locality of newly inserted
+ # records, which may have a significant performance benefit compared to random
+ # data inserts.
+ #
+ # The result contains 74 random bits (9.25 random bytes).
+ #
+ # Note that this method cannot be made reproducible because its output
+ # includes not only random bits but also timestamp.
+ #
+ # See draft-ietf-uuidrev-rfc4122bis[https://datatracker.ietf.org/doc/draft-ietf-uuidrev-rfc4122bis/]
+ # for details of UUIDv7.
+ #
+ # ==== Monotonicity
+ #
+ # UUIDv7 has millisecond precision by default, so multiple UUIDs created
+ # within the same millisecond are not issued in monotonically increasing
+ # order. To create UUIDs that are time-ordered with sub-millisecond
+ # precision, up to 12 bits of additional timestamp may added with
+ # +extra_timestamp_bits+. The extra timestamp precision comes at the expense
+ # of random bits. Setting <tt>extra_timestamp_bits: 12</tt> provides ~244ns
+ # of precision, but only 62 random bits (7.75 random bytes).
+ #
+ # prng = Random.new
+ # Array.new(4) { prng.uuid_v7(extra_timestamp_bits: 12) }
+ # # =>
+ # ["0188d4c7-13da-74f9-8b53-22a786ffdd5a",
+ # "0188d4c7-13da-753b-83a5-7fb9b2afaeea",
+ # "0188d4c7-13da-754a-88ea-ac0baeedd8db",
+ # "0188d4c7-13da-7557-83e1-7cad9cda0d8d"]
+ # # |<--- sorted --->| |<-- random --->|
+ #
+ # Array.new(4) { prng.uuid_v7(extra_timestamp_bits: 8) }
+ # # =>
+ # ["0188d4c7-3333-7a95-850a-de6edb858f7e",
+ # "0188d4c7-3333-7ae8-842e-bc3a8b7d0cf9", # <- out of order
+ # "0188d4c7-3333-7ae2-995a-9f135dc44ead", # <- out of order
+ # "0188d4c7-3333-7af9-87c3-8f612edac82e"]
+ # # |<--- sorted -->||<---- random --->|
+ #
+ # Any rollbacks of the system clock will break monotonicity. UUIDv7 is based
+ # on UTC, which excludes leap seconds and can rollback the clock. To avoid
+ # this, the system clock can synchronize with an NTP server configured to use
+ # a "leap smear" approach. NTP or PTP will also be needed to synchronize
+ # across distributed nodes.
+ #
+ # Counters and other mechanisms for stronger guarantees of monotonicity are
+ # not implemented. Applications with stricter requirements should follow
+ # {Section 6.2}[https://www.ietf.org/archive/id/draft-ietf-uuidrev-rfc4122bis-07.html#monotonicity_counters]
+ # of the specification.
+ #
+ def uuid_v7(extra_timestamp_bits: 0)
+ case (extra_timestamp_bits = Integer(extra_timestamp_bits))
+ when 0 # min timestamp precision
+ ms = Process.clock_gettime(Process::CLOCK_REALTIME, :millisecond)
+ rand = random_bytes(10)
+ rand.setbyte(0, rand.getbyte(0) & 0x0f | 0x70) # version
+ rand.setbyte(2, rand.getbyte(2) & 0x3f | 0x80) # variant
+ "%08x-%04x-%s" % [
+ (ms & 0x0000_ffff_ffff_0000) >> 16,
+ (ms & 0x0000_0000_0000_ffff),
+ rand.unpack("H4H4H12").join("-")
+ ]
+
+ when 12 # max timestamp precision
+ ms, ns = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond)
+ .divmod(1_000_000)
+ extra_bits = ns * 4096 / 1_000_000
+ rand = random_bytes(8)
+ rand.setbyte(0, rand.getbyte(0) & 0x3f | 0x80) # variant
+ "%08x-%04x-7%03x-%s" % [
+ (ms & 0x0000_ffff_ffff_0000) >> 16,
+ (ms & 0x0000_0000_0000_ffff),
+ extra_bits,
+ rand.unpack("H4H12").join("-")
+ ]
+
+ when (0..12) # the generic version is slower than the special cases above
+ rand_a, rand_b1, rand_b2, rand_b3 = random_bytes(10).unpack("nnnN")
+ rand_mask_bits = 12 - extra_timestamp_bits
+ ms, ns = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond)
+ .divmod(1_000_000)
+ "%08x-%04x-%04x-%04x-%04x%08x" % [
+ (ms & 0x0000_ffff_ffff_0000) >> 16,
+ (ms & 0x0000_0000_0000_ffff),
+ 0x7000 |
+ ((ns * (1 << extra_timestamp_bits) / 1_000_000) << rand_mask_bits) |
+ rand_a & ((1 << rand_mask_bits) - 1),
+ 0x8000 | (rand_b1 & 0x3fff),
+ rand_b2,
+ rand_b3
+ ]
+
+ else
+ raise ArgumentError, "extra_timestamp_bits must be in 0..12"
+ end
+ end
+
+ # Internal interface to Random; Generate random data _n_ bytes.
+ private def gen_random(n)
+ self.bytes(n)
+ end
+
+ # Generate 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
+
+ # The default character list for #alphanumeric.
+ ALPHANUMERIC = [*'A'..'Z', *'a'..'z', *'0'..'9']
+
+ # Generate a random alphanumeric string.
+ #
+ # The argument _n_ specifies the length, in characters, of the alphanumeric
+ # string to be generated.
+ # The argument _chars_ specifies the character list which the result is
+ # consist of.
+ #
+ # 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, unless _chars_ is specified.
+ #
+ # require 'random/formatter'
+ #
+ # Random.alphanumeric #=> "2BuBuLf3WfSKyQbR"
+ # # or
+ # prng = Random.new
+ # prng.alphanumeric(10) #=> "i6K93NdqiH"
+ #
+ # Random.alphanumeric(4, chars: [*"0".."9"]) #=> "2952"
+ # # or
+ # prng = Random.new
+ # prng.alphanumeric(10, chars: [*"!".."/"]) #=> ",.,++%/''."
+ def alphanumeric(n = nil, chars: ALPHANUMERIC)
+ n = 16 if n.nil?
+ choose(chars, n)
+ end
+end