# Attempt to parse a link destination, returning the string or null if not match
	private fun parse_link_destination: Couple[nullable String, Bool] do
		var buffer = new Buffer

		var c = peek
		var parens = 0

		var has_bracket = c == '<'
		if has_bracket then advance 1

		loop
			c = peek
			if c == '\0' then
				break # end of input
			else if c == ' ' or c == '\t' or c == '\n' or c == '\r' then
				break # no spaces allowed in urls
			else if c == '\\' then
				var next = peek_next
				if escapable.has(next) then
					buffer.add next
					advance 2 # skip over the backslash
					continue
				end
			else if has_bracket and c == '>' then
				advance 1
				break
			else if not has_bracket and c == '(' then
				parens += 1
			else if not has_bracket and c == ')' then
				if parens == 0 then break
				parens -= 1
			else if c == '\0' then
				break
			end
			buffer.add c
			advance 1
		end
		return new Couple[nullable String, Bool](buffer.to_s, has_bracket)
	end