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local DeltaTable ={
--[[
This module is for getting the difference between a table and then
being able to merge it back in.
-- Specifically great for networking as it allows us only to send what has changed
This is an independant Module because it has enough parts to it, that it should be
seperated from ADTs and or some sort of "Table" lib. This is abstractly a table differ.
--]]
_VERSION = 2.0
--> Enhanced with better detection of tables, nils, nested tables, and protections
-- so that new tables can be added after the fact
}
------------------------------------------------------------------------------------------------
-- Helpers
local function recursiveCall(old, new, var, count, res)
--its a table, recurse
-- predicate
if type(old[var]) ~= "table" then
count = count + 1
res[var] = new[var]
return res, count
end
local newtable, num = DeltaTable.DiffTable(old[var],new[var])
if (num > 0) then
count = count + 1
res[var] = newtable
end
return res, count
end
local function ifChangedSetCall(old, new, var, count, res)
local a = new[var]
local b = old[var]
if (a ~= b) then
count = count + 1
res[var] = a
end
return res, count
end
local function DeepCopy(original)
local copy = {}
for k, v in pairs(original) do
if type(v) == "table" then
v = DeepCopy(v)
end
copy[k] = v
end
return copy
end
local function nilSanatize(old, new)
for var, data in pairs(old) do
-- "_" is our signal to delete
if new[var] == nil then new[var] = "_" continue end
end
end
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
--[[
This will return the:
Result, and count tuple
]]
DeltaTable.DiffTable = function(old, new)
local res = {}
local count = 0
nilSanatize(old, new)
for var,data in pairs(new) do
-- Sanatize
if (old[var] == nil) then res[var] = "nil" end
if (type(new[var])=="table") then
res, count = recursiveCall(
old,
new,
var,
count,
res
)
else
res, count = ifChangedSetCall(
old,
new,
var,
count,
res
)
end
end
return res,count
end
--[[
Merge Table will then take the an old table and overwrite it with the new table
]]
DeltaTable.MergeTable = function(old, diffTable)
local newTable = DeepCopy(old)
for var,data in pairs(diffTable) do
-- If we signal a deletion then here we go
if diffTable[var] == "_" then
newTable[var] = nil
continue
end
if (type(diffTable[var])=="table") then
if type(old[var]) ~= "table" then
newTable[var] = diffTable[var]
else
newTable[var] = DeltaTable.MergeTable(old[var], diffTable[var])
end
else
newTable[var] = diffTable[var]
end
end
return newTable
end
return DeltaTable
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