A dynamic array or vector supporting small buffer optimization.
SmallVec<T, N> is, in essence, just an enum with two variants:
LocalBuf: a buffer allocated locally inside theSmallVecitself.RemoteBuf: aVec<T>, i.e., a remote buffer allocated on the heap.
The capacity of the local buffer is specified at compile time as a constant generic argument to SmallVec thanks to const generics.