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Diffstat (limited to 'lib/random/formatter.rb')
-rw-r--r-- | lib/random/formatter.rb | 373 |
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 |