Optimized Minimal Custom Vector Container
A minimal approach to create optimized Custom Vector Container in C++, covering ‘Rule of Five’ & implementing the concept of ‘Mapping Objects on Dynamically Allocated Buffer’.
Hey lads, so I’ve been working on custom approach for improving & optimizing the STL::Vector class as contiguous container. In this regard, I also recently shared two posts on our Facebook Group for improving Vector class by implementing Rule of Three (covering copy-semantics) & further Rule of Five (covering move-semantics).
Now, after implementing both of these Rules, I realized that still my Vector class was inefficient to carry out larger operations. So, I did my further research & found out that these Vectors basically work by separate Allocation & Construction. Yes, you heard it right. Allocation & Construction are two separate concepts which you normally implement both at same time by declaring object or array of objects with ‘new/malloc’ keyword.
So, STL::Vector initially only allocates & reserves the space for your objects & holds the construction part (i.e. by using reserve modifier), and when user decides to use this space (i.e. by using push_back, emplace_back or resize modifier), the Vector constructs the objects on that dynamically allocated space (called Buffer on Heap).
Now, here comes the role of placement new operator which basically takes the address of buffer & constructs the object of given structure or class on that position of buffer (i.e. we usually take array of char type to create buffer).
After allocation & construction of these objects, comes the accessing part. Well, It was kind of tricky for me but I managed to find out (thanks to stackoverflow) that the objects created by placement new operator maintains like void type status. Means you can access them by type-casting the buffer-pointer to the type of objects & voila, you are ready to use the optimized Vector class.
P.S: For better understanding, I have provided a lot of test-cases seperately in below attached source code folder link (which are also well-commented) & they almost cover all of the use-cases of my custom Vector class. Also, I have used an Instance-Counter class in some test-cases to keep the track of Constructions & Destructions of objects in Vector class. If there is anything ambiguous, feel free to reach out. Peace!!!
