Generate random Japanese characters naively

random_japanese.rb

module RandomJapanese
  KANJI_LOWER_RANGE = 0x4E00
  KANJI_UPPER_RANGE = 0x9FBF
  HIRAGANA_LOWER_RANGE = 0x3040
  HIRAGANA_UPPER_RANGE = 0x309F
  KATAKANA_LOWER_RANGE = 0x30A0
  KATAKANA_UPPER_RANGE = 0x30FF

  class << self
    def kanji(length = 1)
      length.times.map {
        random_unicode(KANJI_LOWER_RANGE, KANJI_UPPER_RANGE)
      }.join
    end

    def hiragana(length = 1)
      length.times.map {
        random_unicode(HIRAGANA_LOWER_RANGE, HIRAGANA_UPPER_RANGE)
      }.join
    end

    def katakana(length = 1)
      length.times.map {
        random_unicode(KATAKANA_LOWER_RANGE, KATAKANA_UPPER_RANGE)
      }.join
    end

    private

    def random_unicode(lower, upper)
      codepoint = lower + rand(upper - lower)
      [codepoint].pack('U')
    end
  end
end