module RuboCop::Cop::RegexpMetacharacter

def literal_at_start_with_backslash_a?(regex_str)
  # is this regexp 'literal' in the sense of only matching literal
  # chars, rather than using metachars like `.` and `*` and so on?
  # also, is it anchored at the start of the string?
  # (tricky: \s, \d, and so on are metacharacters, but other characters
  #  escaped with a slash are just literals. LITERAL_REGEX takes all
  #  that into account.)
  /\A\\A(?:#{Util::LITERAL_REGEX})+\z/o.match?(regex_str)
end