Pointer wrapper for insertion

Question

Can someone tell me if there is a datatype in C++/STL that allows me to solve the following problem comfortably:

• I have a preallocated contiguous area of memory representing an array of objects of type T.
• I have a raw pointer ptrEnd to this area which points right after the last object of the area.
• I have a pointer ptrCurrent that points to some position inside this area.

Now what I want is some kind of wrapper class that helps me insert new elements into this area. It should have some kind of "append" function which basically does the following things

• Assign *ptrCurrent the value of object to insert
• Increment ptrCurrent by one.
• Omit the aforementioned steps if ptrCurrent >= ptrEnd. Return an error instead (or a false to indicate failure).

I could write something like this myself, but I wanted to ask first if there is a class in C++ STL that allows me to solve this problem more elegantly.

Thanks for your help.

Answer 1

There is a convenient feature for exactly this in C++17, polymorphic allocators. More specifically, this is what you want:

std::pmr::monotonic_buffer_resource buffer(sizeof(T) * 256);
    // Buffer that can hold 256 objects of type `T`.

std::pmr::vector<T> vec(&buffer);
    // The vector will use `buffer` as the backing storage.

live godbolt.org example