add sharemap , an example of stm

lualib/sharemap.lua

@@ -0,0 +1,69 @@
+local stm = require "stm"
+local sprotoloader = require "sprotoloader"
+local sproto = require "sproto"
+local setmetatable = setmetatable
+
+local sharemap = {}
+
+function sharemap.register(protofile)
+	-- use global slot 0 for type define
+	sprotoloader.register(protofile, 0)
+end
+
+local sprotoobj
+local function loadsp()
+	if sprotoobj == nil then
+		sprotoobj = sprotoloader.load(0)
+	end
+	return sprotoobj
+end
+
+function sharemap:commit()
+	self.__obj(sprotoobj:encode(self.__typename, self.__data))
+end
+
+function sharemap:copy()
+	return stm.copy(self.__obj)
+end
+
+function sharemap.writer(typename, obj)
+	local sp = loadsp()
+	obj = obj or {}
+	local stmobj = stm.new(sp:encode(typename,obj))
+	obj.__typename = typename
+	obj.__obj = stmobj
+	obj.__data = obj
+	obj.commit = sharemap.commit
+	obj.copy = sharemap.copy
+	return setmetatable(obj, { __index = obj.__data, __newindex = obj.__data })
+end
+
+local function decode(msg, sz, self)
+	local data = self.__data
+	for k in pairs(data) do
+		data[k] = nil
+	end
+	return sprotoobj:decode(self.__typename, msg, sz, data)
+end
+
+function sharemap:update()
+	return self.__obj(decode, self)
+end
+
+function sharemap.reader(typename, stmcpy)
+	local sp = loadsp()
+	local stmobj = stm.newcopy(stmcpy)
+	local _, data = stmobj(function(msg, sz)
+		return sp:decode(typename, msg, sz)
+	end)
+
+	local obj = {
+		__typename = typename,
+		__obj = stmobj,
+		__data = data,
+		update = sharemap.update,
+	}
+	return setmetatable(obj, { __index = obj.__data, __newindex = error })
+end
+
+return sharemap