unserialize.lua

--[[
	LUA variant of the php unserialize function 
	Port of http://phpjs.org/functions/unserialize
]]--
local function unserialize (data)

	local function utf8Overhead (chr)
		local code = chr:byte()
		if (code < 0x0080) then
			return 0
		end

		if (code < 0x0800) then
			return 1
		end

		return 2
	end

	local function error (type, msg, filename, line)
		print ("[Error(" .. type .. ", " ..  message ..")]")
	end

	local function read_until (data, offset, stopchr)
		local buf, chr, len;

	    buf = {}; chr = data:sub(offset, offset); 
		len = string.len(data);
	    while (chr ~= stopchr) do
	        if (offset > len) then
	           error('Error', 'Invalid')
		    end
	        table.insert(buf, chr)
			offset = offset + 1

	        chr = data:sub(offset, offset)
		end

	    return {#buf, table.concat(buf,'')};
	end

	local function read_chrs(data, offset, length)
		local i, buf;
		buf = {};
	    for i = 0, length - 1, 1 do
	        chr = data:sub(offset + i, offset + i);
	        table.insert(buf, chr);

	        length = length - utf8Overhead(chr);
		end
	    return {#buf, table.concat(buf,'')};
	end


	local function _unserialize(data, offset)
		local dtype, dataoffset, keyandchrs, keys, 
			  readdata, readData, ccount, stringlength, 
			  i, key, kprops, kchrs, vprops, vchrs, value,
              chrs, typeconvert;
		chrs = 0;
		typeconvert = function(x) return x end;

		if offset == nil then
			offset = 1 -- lua offsets starts at 1
		end

		dtype = string.lower(data:sub(offset, offset))
		-- print ("dtype " .. dtype .. " offset " ..offset)

		dataoffset = offset + 2
		if (dtype == 'i') or (dtype == 'd') or (dtype == 'r') then
			typeconvert = function(x) 
				return tonumber(x) 
			end

			readData = read_until(data, dataoffset, ';');
            chrs     = tonumber(readData[1]);
            readdata = readData[2];
            dataoffset = dataoffset + chrs + 1;

		elseif dtype == 'b' then
			typeconvert = function(x) 
				return tonumber(x) ~= 0 
			end

			readData = read_until(data, dataoffset, ';');
            chrs 	 = tonumber(readData[1]);
            readdata = readData[2];
            dataoffset = dataoffset + chrs + 1;
		elseif dtype == 'n' then
			readData = nil

		elseif dtype == 's' then
			ccount = read_until(data, dataoffset, ':');

			chrs         = tonumber(ccount[1]);
            stringlength = tonumber(ccount[2]);
            dataoffset = dataoffset + chrs + 2;

            readData = read_chrs(data, dataoffset, stringlength);
            chrs     = readData[1];
            readdata = readData[2];
            dataoffset = dataoffset + chrs + 2;

            if ((chrs ~= stringlength) and (chrs ~= string.length(readdata.length))) then
                error('SyntaxError', 'String length mismatch');
			end

		elseif (dtype == 'a') or (dtype == 'o')  then
			readdata = {}

            if dtype == 'o' then
                ccount = read_until(data, dataoffset, ':');

                chrs         = tonumber(ccount[1]);
                stringlength = tonumber(ccount[2]);
                dataoffset = dataoffset + chrs + 2;

                readData = read_chrs(data, dataoffset, stringlength);
                chrs     = readData[1];
                readdata['_silly_serialized_object'] = readData[2];
                dataoffset = dataoffset + chrs + 2;

                if ((chrs ~= stringlength) and (chrs ~= string.length(readdata.length))) then
                    error('SyntaxError', 'String length mismatch');
                end
            end

			keyandchrs = read_until(data, dataoffset, ':');
            chrs = tonumber(keyandchrs[1]);
            keys = tonumber(keyandchrs[2]);

			dataoffset = dataoffset + chrs + 2

			for i = 0, keys - 1, 1 do
				kprops = _unserialize(data, dataoffset);

				kchrs  = tonumber(kprops[2]);
				key    = kprops[3];
				dataoffset = dataoffset + kchrs

				vprops = _unserialize(data, dataoffset)
                vchrs  = tonumber(vprops[2]);
                value  = vprops[3];
				dataoffset = dataoffset + vchrs;

                readdata[key] = value;				
			end

			dataoffset = dataoffset + 1
		else 
            print(dtype)
            print(dataoffset)
			error('SyntaxError', 'Unknown / Unhandled data type(s): ' + dtype);
		end

		return {dtype, dataoffset - offset, typeconvert(readdata)};
	end

	return _unserialize((data .. ''), 1)[3];
end