class Treetop::Runtime::CompiledParser

def has_terminal?(terminal, mode, index)
  case mode
  when :regexp    # A Regexp has been passed in, either a character class or a literel regex 'foo'r
    (terminal =~ input[index..-1]) == 0 && $&.length
  when false      # The terminal is a string which must match exactly
    input[index, terminal.size] == terminal && terminal.size
  when :insens    # The terminal is a downcased string which must match input downcased
    input[index, terminal.size].downcase == terminal && terminal.size
  when true       # Only occurs with old compiled grammars, for character classes
    rx = @regexps[terminal] ||= Regexp.new(terminal)
    input.index(rx, index) == index && $&.length
  end
end