Initial Commit

gxg/standard/unicode_normalize/normalize.rb

@@ -0,0 +1,175 @@
+# coding: utf-8
+# frozen_string_literal: false
+
+# 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 'unicode_normalize/tables.rb'
+
+
+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