private class NitunitMdVisitor
	super MdVisitor

	var executor: NitUnitExecutor

	redef fun visit(node) do node.accept_nitunit(self)

	fun parse_code(block: MdCodeBlock) do
		var code = block.literal
		if code == null then return

		var meta = block.info or else "nit"
		# Do not try to test non-nit code.
		if meta != "nit" then return

		# Try to parse code blocks
		var executor = self.executor
		var ast = executor.toolcontext.parse_something(code)

		var mdoc = executor.mdoc
		assert mdoc != null

		# Skip pure comments
		if ast isa TComment then return

		# The location is computed according to the starts of the mdoc and the block
		# Note, the following assumes that all the comments of the mdoc are correctly aligned.
		var loc = block.location
		var line_offset = loc.line_start + mdoc.location.line_start - 2
		var column_offset = loc.column_start + mdoc.location.column_start
		# Hack to handle precise location in blocks
		# TODO remove when markdown is more reliable
		if block isa MdFencedCodeBlock then
			# Skip the starting fence
			line_offset += 1
		else
			# Account a standard 4 space indentation
			column_offset += 4
		end

		# We want executable code
		if not (ast isa AModule or ast isa ABlockExpr or ast isa AExpr) then
			var message
			var l = ast.location
			# Get real location of the node (or error)
			var location = new Location(mdoc.location.file,
				l.line_start + line_offset,
				l.line_end + line_offset,
				l.column_start + column_offset,
				l.column_end + column_offset)
			if ast isa AError then
				message = ast.message
			else
				message = "Error: Invalid Nit code."
			end

			var du = new_docunit
			du.block += code
			du.error_location = location
			du.error = message
			executor.toolcontext.modelbuilder.failed_entities += 1
			return
		end

		# Create a first block
		# Or create a new block for modules that are more than a main part
		var last_docunit = executor.last_docunit
		if last_docunit == null or ast isa AModule then
			last_docunit = new_docunit
			executor.last_docunit = last_docunit
		end

		# Add it to the file
		last_docunit.block += code

		# In order to retrieve precise positions,
		# the real position of each line of the raw_content is stored.
		# See `DocUnit::real_location`
		line_offset -= loc.line_start - 1
		for i in [loc.line_start..loc.line_end] do
			last_docunit.lines.add i + line_offset
			last_docunit.columns.add column_offset
		end
	end

	# Return and register a new empty docunit
	fun new_docunit: DocUnit do
		var mdoc = executor.mdoc
		assert mdoc != null

		var next_number = 1
		var name = executor.xml_name
		if executor.docunits.not_empty and executor.docunits.last.mdoc == mdoc then
			next_number = executor.docunits.last.number + 1
			name += "#" + next_number.to_s
		end

		var res = new DocUnit(mdoc, next_number, "", executor.xml_classname, name)
		executor.docunits.add res
		executor.toolcontext.modelbuilder.unit_entities += 1
		return res
	end
end