A collection of utility methods for Japanese chars.

japanese_chars.rb

# -*- coding: utf-8 -*-

require 'nkf'

def full2half(str)
  NKF.nkf('-wxZ4Z1', str).gsub('-', 'ｰ')
end

def is_half?(str)
  !!(/^[ -~｡-ﾟ]*$/.match str)
end

def is_full?(str)
  !!(/^[^ -~｡-ﾟ]*$/.match str)
end

def is_full_katakana?(str)
  !!(/^[ァ-ヺ　ー]*$/.match str)
end

def is_full_hiragana?(str)
  !!(/^[ぁ-ゖ　ー]*$/.match str)
end

def is_half_katakana?(str)
  !!(/^[ｦ-ﾝ　]*$/.match str)
end

cc/ @amiruci

awesome. thanks @kn

their cool emoticons don't work in gist comments