Remove valindex

[nalimilan]

This used to make getindex faster, but it's no longer the case on Julia 1.6, and since it triggers one allocation for each level it makes getindex with slices slower with large pools.

master, Julia 1.6:

using CategoricalArrays, BenchmarkTools
function sumequals(A::AbstractArray, v::CategoricalValue)
    n = 0
    @inbounds for x in A
        n += isequal(x, v)
    end
    n
end

ca = CategoricalArray(repeat(string.('A':'J'), outer=1000));
mca = CategoricalArray(repeat([missing; string.('A':'J')], outer=1000));


julia> @btime sumequals(ca, ca[1]);
  30.187 μs (1 allocation: 16 bytes)

julia> @btime sumequals(mca, $(first(skipmissing(mca))));
  42.165 μs (1 allocation: 16 bytes)

PR, Julia 1.6

julia> @btime sumequals(ca, ca[1]);
  30.175 μs (1 allocation: 16 bytes)

julia> @btime sumequals(mca, $(first(skipmissing(mca))));
  28.608 μs (1 allocation: 16 bytes)

PR, Julia 1.5.3:

julia> @btime sumequals(ca, ca[1]);
  20.152 μs (2 allocations: 48 bytes)

julia> @btime sumequals(mca, $(first(skipmissing(mca))));
  82.890 μs (10001 allocations: 312.52 KiB)

[bkamins]

If compiler is able to handle this it is great. I also understand that it should speed things up when creating or slicing CategoricalArray as it reduces its memory footprint. Right?

[nalimilan]

Yes -- but mainly with large pools.