Copy Table

lua-users home
wiki

This function returns a deep copy of a given table. The function below also copies the metatable to the new table if there is one, so the behaviour of the copied table is the same as the original. But the 2 tables share the same metatable, you can avoid this by changing this 'getmetatable(object)' to '_copy( getmetatable(object) )'.

function deepcopy(object)
    local lookup_table = {}
    local function _copy(object)
        if type(object) ~= "table" then
            return object
        elseif lookup_table[object] then
            return lookup_table[object]
        end
        local new_table = {}
        lookup_table[object] = new_table
        for index, value in pairs(object) do
            new_table[_copy(index)] = _copy(value)
        end
        return setmetatable(new_table, getmetatable(object))
    end
    return _copy(object)
end

FindPage · RecentChanges · preferences
edit · history
Last edited August 26, 2007 4:30 pm GMT (diff)