AllocVec

A vector where each element pushed is guaranteed to keep its index until it is removed.

Internally, a normal Vec is used along with a linked list for fast allocation and de-allocation.

Example

use allocvec::AllocVec;

let mut vec = AllocVec::new();
let idx1 = vec.alloc(4);
let idx2 = vec.alloc(8);
let idx3 = vec.alloc(15);

vec.dealloc(idx1);
vec.dealloc(idx3);

assert_eq!(Some(8), vec.get(idx2));

Speed

Though I haven't benchmarked the efficiency of the implementation, allocation, deallocation and indexing are O(1) operations, while calculating the length of the vector is O(n).

Iterators need to filter unallocated slots in the vector, so that will most likely be bad for branch prediction.