Lua line iterator

lines.lua

-- Iterate over all lines in `text`, use it like this (handles only
-- plain "\n", not "\r\n"):
--     for line_num, line in Lines(text) do
--         -- line_num - number of the line, starting from 1
--         -- line - contents of the line without "\n"
--     end
local function Lines(text)
	local function next_line(state)
		local text, begin, line_n = state[1], state[2], state[3]
		if begin < 0 then
			return nil
		end
		state[3] = line_n + 1
		local b, e = text:find("\n", begin, true)
		if b then
			state[2] = e+1
			return line_n, text:sub(begin, e-1)
		else
			state[2] = -1
			return line_n, text:sub(begin)
		end
	end
	local state = {text, 1, 1}
	return next_line, state
end