keylog.rb

require 'strscan'

class Keylog
  def convert(input)
    output = ""
    scan(input) {|s| output << s }
    output
  end
  def count_keys(input)
    keys = 0
    scan(input) {|s| keys += 1 }
    keys
  end
  def scan(input)
    scanner = StringScanner.new(input)
    output = ""

    until scanner.eos?
      c = scanner.get_byte
      n = c.unpack('C').first

      out_char = \
        case n

        # Special platform-independent encoding stuff
        when 0x80
          code = scanner.get_byte + scanner.get_byte

          # This list has been populated by experimentation so far,
          # because I haven't bothered looking for a more authoritative
          # source.
          case code
          when "k1"; "<F1>"
          when "k2"; "<F2>"
          when "k3"; "<F3>"
          when "k4"; "<F4>"
          when "k5"; "<F5>"
          when "k6"; "<F6>"
          when "k7"; "<F7>"
          when "k8"; "<F8>"
          when "k9"; "<F9>"
          when "k;"; "<F10>"
          when "F1"; "<F11>"
          when "F2"; "<F12>"

          when "kP"; "<PageUp>"
          when "kN"; "<PageDown>"
          when "kh"; "<Home>"
          when "@7"; "<End>"
          when "kI"; "<Insert>"
          when "kD"; "<Del>"
          when "kb"; "<BS>"

          when "ku"; "<Up>"
          when "kd"; "<Down>"
          when "kl"; "<Left>"
          when "kr"; "<Right>"
          when "#4"; "<S-Left>"
          when "%i"; "<S-Right>"

          when "kB"; "<S-Tab>"
          when "\xffX"; "<C-Space>"

          else
            #puts "Unknown Vim code: #{code.inspect}"
            '<%02x-%02x>' % code.unpack('CC')
          end

        # Control characters with special names
        when 0; "<Nul>"
        when 9; "<Tab>"
        when 10; "<NL>"
        when 13; "<CR>"
        when 27; "<Esc>"

        when 127; "<Del>"

        # Otherwise, use <C-x> format
        when 0..31; "<C-#{(n + 64).chr}>"

        # The rest of ANSI is printable
        when 32..126; c

        else
          #puts "Unexpected extended ASCII: #{'%#04x' % n}"
          '<%#04x>' % n

        end

      yield out_char
    end
  end
end