Lua php serialize port

serialize.lua

--[[
	LUA variant of the php serialize function 
	Port of http://phpjs.org/functions/unserialize
]]--
function serialize (mixed_value)
	-- body
	local val, key, okey,
		  ktype, vals, count, _type;
		  
		  ktype = ''; vals = ''; count = 0;
	
	-- https://gist.github.com/978154
	_round = function(num) return math.floor(num + .5) end	
	  
	_utf8Size = function (str)
		local size, i, l, code, val;
		size = 0; i = 0; 
		l = string.len(str); code = '';
	
		for i = 1, l, 1 do
			code = str:byte(i)
	        if code < 0x0080 then
	            val = 1
	        elseif code < 0x0800 then
	            val = 2
	        else
	            val = 3
			end
			size = size + val
		end
		
		return size
	end
	
	
	_type = type(mixed_value)
	
	if _type == 'function' then
		val = ''
		
	elseif _type == 'boolean' then
		val = 'b:' .. (mixed_value and '1' or '0')
		
	elseif _type == 'number' then
		val = (_round(mixed_value) == mixed_value and 'i' or 'd') .. ':' .. tostring(mixed_value)
		
	elseif _type == 'string' then
		val = 's:' .. _utf8Size(mixed_value) .. ':"' .. mixed_value .. '"'
		
	elseif _type == 'table' then
		val = 'a'
		
		for k,v in pairs(mixed_value) do
			ktype = type(v)
			if ktype ~= 'function' then
				
				vals = vals .. serialize(k) .. serialize(v)
				count = count + 1
			end
		end
		val = val .. ':' .. count .. ':{' .. vals .. '}'
	else
		--- if the object has a property which contains a null value, the string cannot be unserialized by PHP
		val = 'N'
	end
	
	if _type ~= 'table' then
		val = val ..';'
	end
	
	return val	
end