# Check if the link is a valid link.
	private fun check_link(v: MarkdownProcessor, out: FlatBuffer, start: Int, token: Token): Int do
		var md = v.current_text
		if md == null then return -1
		var pos
		if token isa TokenLink then
			pos = start + 1
		else
			pos = start + 2
		end
		var tmp = new FlatBuffer
		pos = md.read_md_link_id(tmp, pos)
		if pos < start then return -1
		name = tmp
		var old_pos = pos
		pos += 1
		pos = md.skip_spaces(pos)
		if pos < start then
			var tid = name.as(not null).write_to_string.to_lower
			if v.link_refs.has_key(tid) then
				var lr = v.link_refs[tid]
				is_abbrev = lr.is_abbrev
				link = lr.link
				comment = lr.title
				pos = old_pos
			else
				return -1
			end
		else if md[pos] == '(' then
			pos += 1
			pos = md.skip_spaces(pos)
			if pos < start then return -1
			tmp = new FlatBuffer
			var use_lt = md[pos] == '<'
			if use_lt then
				pos = md.read_until(tmp, pos + 1, '>')
			else
				pos = md.read_md_link(tmp, pos)
			end
			if pos < start then return -1
			if use_lt then pos += 1
			link = tmp.write_to_string
			if md[pos] == ' ' then
				pos = md.skip_spaces(pos)
				if pos > start and md[pos] == '"' then
					pos += 1
					tmp = new FlatBuffer
					pos = md.read_until(tmp, pos, '"')
					if pos < start then return -1
					comment = tmp.write_to_string
					pos += 1
					pos = md.skip_spaces(pos)
					if pos == -1 then return -1
				end
			end
			if pos < start then return -1
			if md[pos] != ')' then return -1
		else if md[pos] == '[' then
			pos += 1
			tmp = new FlatBuffer
			pos = md.read_raw_until(tmp, pos, ']')
			if pos < start then return -1
			var id
			if tmp.length > 0 then
				id = tmp
			else
				id = name
			end
			var tid = id.as(not null).write_to_string.to_lower
			if v.link_refs.has_key(tid) then
				var lr = v.link_refs[tid]
				link = lr.link
				comment = lr.title
			end
		else
			var tid = name.as(not null).write_to_string.replace("\n", " ").to_lower
			if v.link_refs.has_key(tid) then
				var lr = v.link_refs[tid]
				link = lr.link
				comment = lr.title
				pos = old_pos
			else
				return -1
			end
		end
		if link == null then return -1
		return pos
	end