lua string splitting by delimiter, with limiting the result

split.lua

function string:split(delimiter, max_matches)
	-- Split a string by delimiter. The resulting table will be of size #max_matches.
	max_matches = max_matches or #self
	assert(max_matches > 0, "max_matches must be more than 0!")
	local result = {}
	local pos = 0
	for vstart, vend in function() return string.find(self, delimiter, pos, true) end do
		table.insert(result, string.sub(self, pos, vstart - 1)) 
		pos = vend + 1
		if #result >= max_matches - 1 then 
			table.insert(result, string.sub(self, pos))
			return result
		end
	end
	table.insert(result, string.sub(self, pos))
	return result
end