kansuji.rb

#!/usr/bin/env ruby

$KCODE = 'utf8'

# 漢数字を数値に変換する
#
# * http://ja.wikipedia.org/wiki/%E6%BC%A2%E6%95%B0%E5%AD%97
# * http://www.akatsukinishisu.net/kanji/kansuji.html
module Kansuji

  module Const
    NUMBERS = {
      '０' => 0, '１' => 1, '２' => 2, '３' => 3, '４' => 4,
      '５' => 5, '６' => 6, '７' => 7, '８' => 8, '９' => 9,
    }
    UNITS = {
      '十' => 10,
      '百' => 10 ** 2,
      '千' => 10 ** 3,
    }
    PLACES = {
      '万' => 10000,
      '億' => 10000 ** 2,
      '兆' => 10000 ** 3,
      '京' => 10000 ** 4,
      '垓' => 10000 ** 5,
    }
    NORMALIZE_TABLE = {
      '零' => '０', '〇' => '０',
      '一' => '１', '壱' => '１', '壹' => '１',
      '二' => '２', '弐' => '２', '貳' => '２', '貮' => '２',
      '三' => '３', '参' => '３', '參' => '３', '弎' => '３',
      '四' => '４', '肆' => '４',
      '五' => '５', '伍' => '５',
      '六' => '６', '陸' => '６',
      '七' => '７', '漆' => '７', '柒' => '７', '質' => '７',
      '八' => '８', '捌' => '８',
      '九' => '９', '玖' => '９',
      '拾' => '十',
      '廿' => '２十',
      '卅' => '３十', '丗' => '３十',
      '卌' => '４十',
      '佰' => '百',
      '仟' => '千', '阡' => '千',
      '萬' => '万',
    }
    CHARACTERS = [
      NUMBERS,
      UNITS,
      PLACES,
      NORMALIZE_TABLE
    ].map { |item| item.keys }.flatten.uniq
    CHARACTERS_RE = /\A[#{CHARACTERS.join}]+\z/
  end

  def kansuji_normalize
    self.split(//).map { |chr| Kansuji::Const::NORMALIZE_TABLE[chr] || chr }.join
  end

  def kansuji_valid?
    (Kansuji::Const::CHARACTERS_RE =~ self) ? true : false
  end

  def kansuji_split_by_place
    source = self
    place_chars = Kansuji::Const::PLACES.keys.join
    place_parts = []
    while /([^#{place_chars}]+)([#{place_chars}])(.*)/ =~ source
      place_parts << { :source => $1, :base => Kansuji::Const::PLACES[$2] }
      source = $3
    end
    place_parts << { :source => source, :base => 1 } unless source.empty?
    place_parts
  end

  def kansuji_split_by_unit
    source = self
    unit_chars = Kansuji::Const::UNITS.keys.join
    unit_parts = []
    while /([^#{unit_chars}]*)([#{unit_chars}])(.*)/ =~ source
      unit_parts << { :source => ($1.empty?) ? '１' : $1, :base => Kansuji::Const::UNITS[$2] }
      source = $3
    end
    unit_parts << { :source => source, :base => 1 } unless source.empty?
    unit_parts
  end

  def kansuji_to_i
    return 0 unless self.kansuji_valid?
    source = self.kansuji_normalize
    result = 0
    source.kansuji_split_by_place.each do |place_part|
      place_result = 0
      place_part[:source].kansuji_split_by_unit.each do |unit_part|
        unit_part[:source].split(//).reverse.each_with_index do |n, i|
          place_result += Kansuji::Const::NUMBERS[n] * unit_part[:base] * (10 ** i)
        end
      end
      result += place_result * place_part[:base]
    end
    result
  end

end


class String

  include Kansuji

  alias_method :original_to_i, :to_i

  def to_i(base = 10)
    self.kansuji_valid? ? self.kansuji_to_i : self.original_to_i(base)
  end

end


if File.basename($0) == File.basename(__FILE__)
  require 'test/unit'

  class TC_Kansuji < Test::Unit::TestCase

    def test_normalize
      testcases = {
        '零〇' => '００',
        '一壱壹' => '１１１',
        '二弐貳貮' => '２２２２',
        '三参參弎' => '３３３３',
        '四肆' => '４４',
        '五伍' => '５５',
        '六陸' => '６６',
        '七漆柒質' => '７７７７',
        '八捌' => '８８',
        '九玖' => '９９',
        '拾' => '十',
        '廿' => '２十',
        '卅丗' => '３十３十',
        '卌' => '４十',
        '佰' => '百',
        '仟阡' => '千千',
        '萬' => '万',
      }
      testcases.each do |str, expected|
        assert_equal(expected, actual = str.kansuji_normalize, actual)
      end
    end

    def test_validation
      testcases = {
        '零〇一壱壹二弐貳貮三参參弎四肆五伍六陸' \
        '七漆柒質八捌九玖拾廿卅丗卌佰仟阡萬' => true,
        '零〇一壱壹二弐貳貮三参參弎四肆五伍六陸' \
        '七漆柒質八捌九玖拾廿卅丗卌佰仟阡萬0' => false,
      }
      testcases.each do |str, expected|
        assert_equal(expected, actual = str.kansuji_valid?)
      end
    end

    def test_kansuji_split_by_place
      testcases = {
        '１２３垓４５６京７８９兆１２３億４５６万７８９０' => [
          { :source => '１２３', :base => Kansuji::Const::PLACES['垓'] },
          { :source => '４５６', :base => Kansuji::Const::PLACES['京'] },
          { :source => '７８９', :base => Kansuji::Const::PLACES['兆'] },
          { :source => '１２３', :base => Kansuji::Const::PLACES['億'] },
          { :source => '４５６', :base => Kansuji::Const::PLACES['万'] },
          { :source => '７８９０', :base => 1 },
        ]
      }
      testcases.each do |source, expected|
        assert_equal(expected, source.kansuji_split_by_place)
      end
    end

    def test_kansuji_split_by_unit
      testcases = {
        '２千３百４十５' => [
          { :source => '２', :base => Kansuji::Const::UNITS['千'] },
          { :source => '３', :base => Kansuji::Const::UNITS['百'] },
          { :source => '４', :base => Kansuji::Const::UNITS['十'] },
          { :source => '５', :base => 1 },
        ]
      }
      testcases.each do |source, expected|
        assert_equal(expected, source.kansuji_split_by_unit)
      end
    end

    def test_to_i
      testcases = {
        '１２３４５６７８９０' => 1234567890,
        '一二三四五六七八九零' => 1234567890,
        '千百十' => 1110,
        '一千一百一十零億三千' => 111000003000,
        '拾' => 10,
        '廿' => 20,
        '卅' => 30,
        '卌' => 40,
        '佰' => 100,
        '仟' => 1000,
        '１萬' => 10000,
        '１２３４５６７８９０千' => 1234567890000,
        '１２３４５６７８９０万' => 12345678900000,
        '１２３４５６７８９０億' => 123456789000000000,
        '１億１千万五十三' => 110000053,
      }
      testcases.each do |str, expected|
        assert_equal(expected, str.kansuji_to_i, str)
        assert_equal(expected, str.to_i, str)
      end
    end

  end

end