├── test.lua
└── syncobj.lua


/test.lua:
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 1 | local syncobj = require "syncobj"
 2 | 
 3 | local source = syncobj.source()
 4 | local clone = syncobj.clone()
 5 | 
 6 | local obj = source:new { x = 1, y = 2 }
 7 | 
 8 | local function print_table(obj, prefix)
 9 | 	print(prefix)
10 | 	if obj then
11 | 		for k,v in pairs(obj) do
12 | 			print("",k,v)
13 | 		end
14 | 	end
15 | end
16 | 
17 | print_table(obj, "obj")
18 | 
19 | local diff = source:diff(obj)
20 | 
21 | local cobj = clone:patch(diff)
22 | 
23 | print_table(cobj, "clone")
24 | 
25 | obj.x = 3
26 | obj.y = nil
27 | 
28 | print_table(obj, "obj")
29 | 
30 | local diff = source:diff(obj)
31 | 
32 | local cobj = clone:patch(diff)
33 | 
34 | print_table(cobj, "clone")
35 | 
36 | local diff = source:reset(obj)
37 | 
38 | local cobj = clone:patch(diff)
39 | 
40 | print_table(cobj, "clone")
41 | 
42 | local rlist = source:collect()
43 | print_table(rlist, "remove")
44 | clone:collect(rlist)
45 | 
46 | 
47 | 
48 | 


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/syncobj.lua:
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  1 | local tinsert = table.insert
  2 | local pairs = pairs
  3 | local setmetatable = setmetatable
  4 | local next = next
  5 | 
  6 | local syncobj = {}
  7 | local weak_meta = { __mode = "kv" }
  8 | 
  9 | local source = {} ; source.__index = source
 10 | 
 11 | local function object_newindex(self, key, value)
 12 | 	self.__real[key] = value
 13 | 	self.__change[key] = value
 14 | end
 15 | 
 16 | local function object_pairs(self)
 17 | 	return next, self.__real, nil
 18 | end
 19 | 
 20 | function source:new(init)
 21 | 	local obj = {
 22 | 		__real = {},
 23 | 		__last = {},
 24 | 		__change = {},
 25 | 		__changeset = { self.id },
 26 | 	}
 27 | 	self.id_list[self.id] = self.id_mark
 28 | 	self.cache[self.id] = obj
 29 | 	self.id = self.id + 1
 30 | 	setmetatable(obj, {
 31 | 		__index = obj.__real,
 32 | 		__pairs = object_pairs,
 33 | 		__newindex = object_newindex,
 34 | 	})
 35 | 	if init then
 36 | 		for k,v in pairs(init) do
 37 | 			obj[k] = v
 38 | 		end
 39 | 	end
 40 | 	return obj
 41 | end
 42 | 
 43 | function source:diff(obj)
 44 | 	local i = 2
 45 | 	local last = obj.__last
 46 | 	local changeset = obj.__changeset
 47 | 	local change = obj.__change
 48 | 	for k,v in pairs(change) do
 49 | 		if last[k] ~= v then
 50 | 			changeset[i] = k
 51 | 			changeset[i+1] = v
 52 | 			i = i + 2
 53 | 		end
 54 | 		change[k] = nil
 55 | 	end
 56 | 	local real = obj.__real
 57 | 	local remove
 58 | 	for k,v in pairs(last) do
 59 | 		if real[k] == nil then
 60 | 			remove = remove or {}
 61 | 			tinsert(remove, k)
 62 | 		end
 63 | 		last[k] = nil
 64 | 	end
 65 | 	for k,v in pairs(real) do
 66 | 		last[k] = real[k]
 67 | 	end
 68 | 	changeset[i] = remove
 69 | 	for j = i+1, #changeset do
 70 | 		changeset[j] = nil
 71 | 	end
 72 | 	return changeset
 73 | end
 74 | 
 75 | function source:reset(obj)
 76 | 	obj.__last = {}
 77 | 	obj.__change = {}
 78 | 	local lastid = obj.__changeset[1]
 79 | 	local changeset = { self.id }
 80 | 	self.cache[lastid] = nil
 81 | 	self.cache[self.id] = obj
 82 | 	self.id = self.id + 1
 83 | 	obj.__changeset = changeset
 84 | 	for k,v in pairs(obj.__real) do
 85 | 		tinsert(changeset, k)
 86 | 		tinsert(changeset, v)
 87 | 	end
 88 | 	return changeset
 89 | end
 90 | 
 91 | function source:collect()
 92 | 	local mark = not self.id_mark
 93 | 	self.id_mark = mark
 94 | 	local id_list = self.id_list
 95 | 	for id in pairs(self.cache) do
 96 | 		id_list[id] = mark
 97 | 	end
 98 | 	local remove_list
 99 | 	for k,v in pairs(id_list) do
100 | 		if v ~= mark then
101 | 			remove_list = remove_list or {}
102 | 			tinsert(remove_list, k)
103 | 			id_list[k] = nil
104 | 		end
105 | 	end
106 | 	return remove_list
107 | end
108 | 
109 | function syncobj.source()
110 | 	local channel = {
111 | 		id = 1,
112 | 		id_mark = true,
113 | 		id_list = {},
114 | 		cache = setmetatable({}, weak_meta),
115 | 	}
116 | 	return setmetatable(channel, source)
117 | end
118 | 
119 | local clone = {} ; clone.__index = clone
120 | 
121 | function clone:patch(diff)
122 | 	local id = diff[1]
123 | 	local obj = self[id]
124 | 	if obj == nil then
125 | 		obj = {}
126 | 		self[id] = obj
127 | 	end
128 | 	local n = #diff
129 | 	for i = 2, n, 2 do
130 | 		obj[diff[i]] = diff[i+1]
131 | 	end
132 | 	if n % 2 == 0 then
133 | 		-- remove keys
134 | 		for _, v in ipairs(diff[n]) do
135 | 			obj[v] = nil
136 | 		end
137 | 	end
138 | 	return obj
139 | end
140 | 
141 | function clone:collect(remove_set)
142 | 	if remove_set then
143 | 		for _, id in ipairs(remove_set) do
144 | 			self[id] = nil
145 | 		end
146 | 	end
147 | end
148 | 
149 | function syncobj.clone()
150 | 	local channel = {}
151 | 	return setmetatable(channel, clone)
152 | end
153 | 
154 | return syncobj
155 | 


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