readuntil.lua

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----------------------------------------------------------------------------
-- Reads an input until a given character.
--
-- @release $Id: readuntil.lua,v 1.5 2007/04/16 14:01:32 tomas Exp $
----------------------------------------------------------------------------

local strsub, strfind, strlen = string.sub, string.find, string.len

module ("cgilua.readuntil")

----------------------------------------------------------------------------
-- Creates a function which reads an input until a given character.
-- @param inp Function which reads the input.
-- @return Function which receives a delimiter character and an output
--	function.
----------------------------------------------------------------------------
function iterate (inp)
	local current = ""
	return function (del, out)
		local dellen = strlen(del) 
		local i, e
		while true do
			i, e = strfind(current, del, 1, 1)
			if i then break end
			local new = inp()
			if not new then break end
			do	 -- handle borders
				local endcurrent = strsub(current, -dellen+1)
				local border = endcurrent .. strsub(new, 1, dellen-1)
				if strlen(current) < dellen or strlen(new) < dellen or
					 strfind(border, del, 1, 1) then
					-- move last part of `current' to new block
					current = strsub(current, 1, -dellen)
					new = endcurrent .. new
				end
			end
			out(current)
			current = new
		end
		out(strsub(current, 1, (i or 0) - 1))
		current = strsub(current, (e or strlen(current)) + 1)
		return (i ~= nil)
	end
end