IRC 発言内容構文解析

irc_msg_parser.rb

# vim: fileencoding=utf-8

require 'strscan'

module Converter
  AVAILABLE_TAGS = {
    /\u0002/ => {
      start_tag: '<b>',
      end_tag: '</b>'
    },
    /\u001f/ => {
      start_tag: '<u>',
      end_tag: '</u>'
    }
  }
  STOP_TAG = /\u000f/

  def convert(source)
    scanner = StringScanner.new(source)
    opened_tags = []
    result = ''

    until scanner.eos?
      if scanner.scan(STOP_TAG)
        until opened_tags.empty?
          tag = opened_tags.pop
          result << tag[:end_tag]
        end

        next
      end

      AVAILABLE_TAGS.each do |pattern, tag|
        if scanner.scan(pattern)
          result << tag[:start_tag]
          opened_tags.push(tag)

          next
        end
      end

      result << scanner.getch
    end

    raise 'opened tags remain' until opened_tags.empty?

    result
  end
  module_function :convert
end