中華民國身分證字號驗證器

## bm.rb
require 'benchmark'
require 'id_check'
require 'taiwanese_id_builder'
require 'TaiwanUserID'

n = 100000
Benchmark.bmbm do |x|
  x.report('wayne5540  '){ n.times{ TaiwaneseIdBuilder.valid?('A123456789') } }
  dummy = Object.new.extend(TaiwanUserID)
  x.report('kaochenlong'){ n.times{ dummy.is_valid?('A123456789') } }
  x.report('tonytonyjan'){ n.times{ id_check('A123456789') } }
end

# wayne5540     1.080000   0.230000   1.310000 (  1.319509)
# kaochenlong   1.860000   0.010000   1.870000 (  1.879476)
# tonytonyjan   0.550000   0.000000   0.550000 (  0.557314)

## id_check.rb
MAP = {
  'A' => [1, 0], 'B' => [1, 1], 'C' => [1, 2], 'D' => [1, 3], 'E' => [1, 4], 'F' => [1, 5], 'G' => [1, 6], 'H' => [1, 7], 'I' => [3, 4],
  'J' => [1, 8], 'K' => [1, 9], 'L' => [2, 0], 'M' => [2, 1], 'N' => [2, 2], 'O' => [3, 5], 'P' => [2, 3], 'Q' => [2, 4], 'R' => [2, 5],
  'S' => [2, 6], 'T' => [2, 7], 'U' => [2, 8], 'V' => [2, 9], 'W' => [3, 2], 'X' => [3, 0], 'Y' => [3, 1], 'Z' => [3, 3]
}

MULTIPLIER = [1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 1]

def id_check id
  return false unless id =~ /\A[A-Z]\d{9}\z/
  chars = id.chars
  numbers = MAP[chars.shift] + chars.map!(&:to_i)

  sum, i = 0, 0
  while i < 11
    sum += numbers[i] * MULTIPLIER[i]
    i += 1
  end
  sum % 10 == 0
end