class Regexp::Parser

def anchor(token)
  case token.token
  when :bol;              node << Anchor::BeginningOfLine.new(token, active_opts)
  when :bos;              node << Anchor::BOS.new(token, active_opts)
  when :eol;              node << Anchor::EndOfLine.new(token, active_opts)
  when :eos;              node << Anchor::EOS.new(token, active_opts)
  when :eos_ob_eol;       node << Anchor::EOSobEOL.new(token, active_opts)
  when :match_start;      node << Anchor::MatchStart.new(token, active_opts)
  when :nonword_boundary; node << Anchor::NonWordBoundary.new(token, active_opts)
  when :word_boundary;    node << Anchor::WordBoundary.new(token, active_opts)
  else
    raise UnknownTokenError.new('Anchor', token)
  end
end