std.SegmentedList
This is a stack data structure where pointers to indexes have the same lifetime as the data structure
itself, unlike ArrayList where append() invalidates all existing element pointers.
The tradeoff is that elements are not guaranteed to be contiguous. For that, use ArrayList.
Note however that most elements are contiguous, making this data structure cache-friendly.Because it never has to copy elements from an old location to a new location, it does not require
its elements to be copyable, and it avoids wasting memory when backed by an ArenaAllocator.
Note that the append() and pop() convenience methods perform a copy, but you can instead use
addOne(), at(), setCapacity(), and shrinkCapacity() to avoid copying items.This data structure has O(1) append and O(1) pop.
It supports preallocated elements, making it especially well suited when the expected maximum
size is small.prealloc_item_countmust be 0, or a power of 2.