class Regexp::Parser

def escape(token)
  case token.token
  when :backspace;      node << EscapeSequence::Backspace.new(token, active_opts)
  when :escape;         node << EscapeSequence::AsciiEscape.new(token, active_opts)
  when :bell;           node << EscapeSequence::Bell.new(token, active_opts)
  when :form_feed;      node << EscapeSequence::FormFeed.new(token, active_opts)
  when :newline;        node << EscapeSequence::Newline.new(token, active_opts)
  when :carriage;       node << EscapeSequence::Return.new(token, active_opts)
  when :tab;            node << EscapeSequence::Tab.new(token, active_opts)
  when :vertical_tab;   node << EscapeSequence::VerticalTab.new(token, active_opts)
  when :codepoint;      node << EscapeSequence::Codepoint.new(token, active_opts)
  when :codepoint_list; node << EscapeSequence::CodepointList.new(token, active_opts)
  when :hex;            node << EscapeSequence::Hex.new(token, active_opts)
  when :octal;          node << EscapeSequence::Octal.new(token, active_opts)
  when :control
    if token.text =~ /\A(?:\\C-\\M|\\c\\M)/
      # TODO: emit :meta_control_sequence token in v3.0.0
      node << EscapeSequence::MetaControl.new(token, active_opts)
    else
      node << EscapeSequence::Control.new(token, active_opts)
    end
  when :meta_sequence
    if token.text =~ /\A\\M-\\[Cc]/
      # TODO: emit :meta_control_sequence token in v3.0.0:
      node << EscapeSequence::MetaControl.new(token, active_opts)
    else
      node << EscapeSequence::Meta.new(token, active_opts)
    end
  else
    # treating everything else as a literal
    # TODO: maybe split this up a bit more in v3.0.0?
    # E.g. escaped quantifiers or set meta chars are not the same
    # as stuff that would be a literal even without the backslash.
    # Right now, they all end up here.
    node << EscapeSequence::Literal.new(token, active_opts)
  end
end