DataStructures.SparseIntSet

Implementation of a Sparse Integer Set, for background see Sparse Sets. Only positive non-zero Ints are allowed inside the set. The idea is to have one packed Vector storing all the Ints contained in the set as to allow for fast iteration, and a sparse, paged reverse Vector with the position of a particular Int inside the packed Vector. This allows for very fast iteration, insertion and deletion of indices. Most behavior is similar to a normal IntSet, however collect, first and last are with respected to the packed vector, in which the ordering is not guaranteed. The reverse Vector is paged, meaning that it is a Vector{Vector{Int}} where each of the Vector{Int}s has the length of one memory page of Ints. Every time an index that was not yet in the range of the already present pages, a new one will be created and added to the reverse, allowing for dynamical growth. Popping the last Int of a particular page will automatically clean up the memory of that page.