# Builds a location instance from its string representation.
	#
	# Examples:
	#
	# ~~~
	# var loc = new Location.from_string("location.nit:82,2--105,8")
	# assert loc.to_s == "location.nit:82,2--105,8"
	#
	# loc = new Location.from_string("location.nit")
	# assert loc.to_s == "location.nit"
	#
	# loc = new Location.from_string("location.nit:82,2")
	# assert loc.to_s == "location.nit:82,2--0,0"
	#
	# loc = new Location.from_string("location.nit:82--105")
	# assert loc.to_s == "location.nit:82,0--105,0"
	#
	# loc = new Location.from_string("location.nit:82,2--105")
	# assert loc.to_s == "location.nit:82,2--105,0"
	#
	# loc = new Location.from_string("location.nit:82--105,8")
	# assert loc.to_s == "location.nit:82,0--105,8"
	# ~~~
	init from_string(string: String) is
		nosuper
	do
		self.line_start = 0
		self.line_end = 0
		self.column_start = 0
		self.column_end = 0
		# parses the location string and init position vars
		var parts = string.split_with(":")
		var filename = parts.shift
		self.file = new SourceFile(filename, new FileReader.open(filename))
		# split position
		if parts.is_empty then return
		var pos = parts.first.split_with("--")
		# split start position
		if pos.first.has(",") then
			var pos1 = pos.first.split_with(",")
			self.line_start = pos1[0].to_i
			if pos1.length > 1 then
				self.column_start = pos1[1].to_i
			end
		else
			self.line_start = pos.first.to_i
		end
		# split end position
		if pos.length <= 1 then return
		if pos[1].has(",") then
			var pos2 = pos[1].split_with(",")
			if pos2.length > 1 then
				self.line_end = pos2[0].to_i
				self.column_end = pos2[1].to_i
			else
				self.line_end = self.line_start
				self.column_end = pos2[0].to_i
			end
		else
			self.line_end = pos[1].to_i
		end
	end