lib/mongo/auth/stringprep/unicode_normalize/normalize.rb
# frozen_string_literal: true
# rubocop:todo all
# Copyright Ayumu Nojima (野島 歩) and Martin J. Dürst (duerst@it.aoyama.ac.jp)
# This file, the companion file tables.rb (autogenerated), and the module,
# constants, and method defined herein are part of the implementation of the
# built-in String class, not part of the standard library. They should
# therefore never be gemified. They implement the methods
# String#unicode_normalize, String#unicode_normalize!, and String#unicode_normalized?.
#
# They are placed here because they are written in Ruby. They are loaded on
# demand when any of the three methods mentioned above is executed for the
# first time. This reduces the memory footprint and startup time for scripts
# and applications that do not use those methods.
#
# The name and even the existence of the module UnicodeNormalize and all of its
# content are purely an implementation detail, and should not be exposed in
# any test or spec or otherwise.
require 'mongo/auth/stringprep/unicode_normalize/tables'
# @api private
module UnicodeNormalize # :nodoc:
## Constant for max hash capacity to avoid DoS attack
MAX_HASH_LENGTH = 18000 # enough for all test cases, otherwise tests get slow
## Regular Expressions and Hash Constants
REGEXP_D = Regexp.compile(REGEXP_D_STRING, Regexp::EXTENDED)
REGEXP_C = Regexp.compile(REGEXP_C_STRING, Regexp::EXTENDED)
REGEXP_K = Regexp.compile(REGEXP_K_STRING, Regexp::EXTENDED)
NF_HASH_D = Hash.new do |hash, key|
hash.shift if hash.length>MAX_HASH_LENGTH # prevent DoS attack
hash[key] = nfd_one(key)
end
NF_HASH_C = Hash.new do |hash, key|
hash.shift if hash.length>MAX_HASH_LENGTH # prevent DoS attack
hash[key] = nfc_one(key)
end
## Constants For Hangul
# for details such as the meaning of the identifiers below, please see
# http://www.unicode.org/versions/Unicode7.0.0/ch03.pdf, pp. 144/145
SBASE = 0xAC00
LBASE = 0x1100
VBASE = 0x1161
TBASE = 0x11A7
LCOUNT = 19
VCOUNT = 21
TCOUNT = 28
NCOUNT = VCOUNT * TCOUNT
SCOUNT = LCOUNT * NCOUNT
# Unicode-based encodings (except UTF-8)
UNICODE_ENCODINGS = [Encoding::UTF_16BE, Encoding::UTF_16LE, Encoding::UTF_32BE, Encoding::UTF_32LE,
Encoding::GB18030, Encoding::UCS_2BE, Encoding::UCS_4BE]
## Hangul Algorithm
def self.hangul_decomp_one(target)
syllable_index = target.ord - SBASE
return target if syllable_index < 0 || syllable_index >= SCOUNT
l = LBASE + syllable_index / NCOUNT
v = VBASE + (syllable_index % NCOUNT) / TCOUNT
t = TBASE + syllable_index % TCOUNT
(t==TBASE ? [l, v] : [l, v, t]).pack('U*') + target[1..-1]
end
def self.hangul_comp_one(string)
length = string.length
if length>1 and 0 <= (lead =string[0].ord-LBASE) and lead < LCOUNT and
0 <= (vowel=string[1].ord-VBASE) and vowel < VCOUNT
lead_vowel = SBASE + (lead * VCOUNT + vowel) * TCOUNT
if length>2 and 0 <= (trail=string[2].ord-TBASE) and trail < TCOUNT
(lead_vowel + trail).chr(Encoding::UTF_8) + string[3..-1]
else
lead_vowel.chr(Encoding::UTF_8) + string[2..-1]
end
else
string
end
end
## Canonical Ordering
def self.canonical_ordering_one(string)
sorting = string.each_char.collect { |c| [c, CLASS_TABLE[c]] }
(sorting.length-2).downto(0) do |i| # almost, but not exactly bubble sort
(0..i).each do |j|
later_class = sorting[j+1].last
if 0<later_class and later_class<sorting[j].last
sorting[j], sorting[j+1] = sorting[j+1], sorting[j]
end
end
end
return sorting.collect(&:first).join('')
end
## Normalization Forms for Patterns (not whole Strings)
def self.nfd_one(string)
string = string.chars.map {|c| DECOMPOSITION_TABLE[c] || c}.join('')
canonical_ordering_one(hangul_decomp_one(string))
end
def self.nfc_one(string)
nfd_string = nfd_one string
start = nfd_string[0]
last_class = CLASS_TABLE[start]-1
accents = ''
nfd_string[1..-1].each_char do |accent|
accent_class = CLASS_TABLE[accent]
if last_class<accent_class and composite = COMPOSITION_TABLE[start+accent]
start = composite
else
accents << accent
last_class = accent_class
end
end
hangul_comp_one(start+accents)
end
def self.normalize(string, form = :nfc)
encoding = string.encoding
case encoding
when Encoding::UTF_8
case form
when :nfc then
string.gsub REGEXP_C, NF_HASH_C
when :nfd then
string.gsub REGEXP_D, NF_HASH_D
when :nfkc then
string.gsub(REGEXP_K, KOMPATIBLE_TABLE).gsub(REGEXP_C, NF_HASH_C)
when :nfkd then
string.gsub(REGEXP_K, KOMPATIBLE_TABLE).gsub(REGEXP_D, NF_HASH_D)
else
raise ArgumentError, "Invalid normalization form #{form}."
end
when Encoding::US_ASCII
string
when *UNICODE_ENCODINGS
normalize(string.encode(Encoding::UTF_8), form).encode(encoding)
else
raise Encoding::CompatibilityError, "Unicode Normalization not appropriate for #{encoding}"
end
end
def self.normalized?(string, form = :nfc)
encoding = string.encoding
case encoding
when Encoding::UTF_8
case form
when :nfc then
string.scan REGEXP_C do |match|
return false if NF_HASH_C[match] != match
end
true
when :nfd then
string.scan REGEXP_D do |match|
return false if NF_HASH_D[match] != match
end
true
when :nfkc then
normalized?(string, :nfc) and string !~ REGEXP_K
when :nfkd then
normalized?(string, :nfd) and string !~ REGEXP_K
else
raise ArgumentError, "Invalid normalization form #{form}."
end
when Encoding::US_ASCII
true
when *UNICODE_ENCODINGS
normalized? string.encode(Encoding::UTF_8), form
else
raise Encoding::CompatibilityError, "Unicode Normalization not appropriate for #{encoding}"
end
end
end # module