class Regexp::Lexer

def break_literal(token)

into two separate tokens when it is followed by a quantifier
called by scan to break a literal run that is longer than one character 
def break_literal(token)
  lead, last, _ = token.text.partition(/.\z/mu)
  return if lead.empty?
  tokens.pop
  tokens << Regexp::Token.new(:literal, :literal, lead,
            token.ts, (token.te - last.length),
            nesting, set_nesting, conditional_nesting)
  tokens << Regexp::Token.new(:literal, :literal, last,
            (token.ts + lead.length), token.te,
            nesting, set_nesting, conditional_nesting)
end