On the source code interpretation of the clone function in Cocos2dx Lua

COCOS2DX's clone function, is a deep copy, a complete copy, this code content is not much, but the first time to see or a little dizzy, I read down to share. Source code Interpretation:

function Clone (object)--clone functions    Local lookup_table = {}--New table is used to record    local function _copy (object)--_copy ( Object) function is used to implement the copy if        type (object) ~= "table" then return             object   ---If the content is not directly returned by the Table object (for example, if it is a number \ String directly returns the number \ The string)        ElseIf Lookup_table[object] then            return lookup_table[object]--here is used for recursion drop time, If the table has already been copied, return to        end        local new_table = {}        lookup_table[object] = new_table--The two-level child table that the new new_table record needs to replicate , and put it in lookup_table[object].        For key, value in pairs (object) do            new_table[_copy (key)] = _copy (value)--traverse object and recursive _copy (value) to copy the data from each table        End        return setmetatable (new_table, Getmetatable (object))--Sets the MetaTable key value end for the specified table after each traversal        

Example Demonstration:

function Clone (object)    local lookup_table = {}    local function _copy (object)        if Type (object) ~= "table" then< C3/>return object         ElseIf Lookup_table[object] then            return lookup_table[object]        End        Local new_table = {}        Lookup_table[object] = new_table        for key, value in pairs (object) do            new_table[_copy (key)] = _copy (value            Print (key,value)-This sentence adds the print function to demonstrate the process of output replication        end        return setmetatable (new_table, Getmetatable (object))    End    return _copy (object)--return clone out of Object table pointer/Address End local A = {[{], +}] = {+, +}, c = "abc"}local MyPolygon = {color= "blue", thickness=2, Npoints=4,{x=0, y=0}, {x=-10, y=0}, {x=-5, y=4}, {x=0, y=4}}loca L newtable = Clone (a) Local newtable2 = Clone (MyPolygon)

-----------Output Content 1200
1 300
2 500
2 table:0x7ffa43d06930
1 100
2 200
1 300
2 400
table:0x7ffa43d06610 Table:0x7ffa43d068f0
Abc ABC---above is the output content of table MyPolygon after copying the output of table A
X 0
Y 0
1 Table:0x7ffa43d064f0
X -10
Y 0
2 Table:0x7ffa43d06a60
X -5
Y 4
3 Table:0x7ffa43d06af0
X 0
Y 4
4 Table:0x7ffa43d06b80
Npoints 4
Thickness 2
Color Blue

On the source code interpretation of the clone function in Cocos2dx Lua