# Fenced code blocks parser factory
class MdFencedCodeBlockParserFactory
	super MdBlockQuoteParserFactory

	redef fun try_start(state, matched_block_parser) do
		var next_non_space = state.next_non_space_index
		var line = state.line_string

		if state.indent >= 4 then return null

		var match = line.substring(next_non_space, line.length - next_non_space).search(re_opening_fence)
		if match == null then return null

		var fence_length
		var fence_char
		var sub0 = match.subs[0]
		if sub0 != null then
			fence_length = sub0.length
			fence_char = sub0.to_s.chars.first
		else
			fence_length = match.subs[2].as(not null).length
			fence_char = match.subs[2].as(not null).to_s.chars.first
		end
		if fence_char == '`' and match.to_s.has("[^`]+`".to_re) then
			return null
		else if match.to_s.has("[^~]+~".to_re) then
			return null
		end
		return (new MdBlockStart(
			[new MdFencedCodeBlockParser(
				state.line,
				state.column + 1,
				state.column,
				fence_char,
				fence_length,
				state.indent)]
			)).at_index(next_non_space + fence_length)
	end
end