Tweaks to StepRange: Take 2

[quinnj]

The issorted and in changes are pretty straightforward, using the step for comparison. sort and sortperm remove the T<:Real restriction to apply to StepRange as well. All test/ranges.jl tests still pass with these changes, though I can add some more and try to break things if needed.

The introduction of steprem is annoying, but surprisingly minimal to allow full support for different step types than the difference between start and stop. The reasoning is that most Ordinal types shouldn't have to worry because the fallback to (stop-start) % step should work, but it allows for overloading (similar to how I'm overloading length).

Fixes #6638

cc: @JeffBezanson

Support methods I'm using to get range functionality for dates: https://github.com/karbarcca/Dates.jl/blob/master/src/ranges.jl
Relevant tests the date ranges are passing with these changes: https://github.com/karbarcca/Dates.jl/blob/master/test/test_ranges.jl

[quinnj]

Bump. Thoughts on this? Too hackish? I'd really like to have this for 0.3 release.

[kmsquire]

Why not just override %?

[kmsquire]

Nevermind. I just looked a little closer at your implementation in Dates.

[JeffBezanson]

I don't understand the implementation of steprem in Dates.jl. It seems to compute the last value, not a remainder. I might be missing something.

[quinnj]

Drat, somehow my updated version got lost in some branch shuffling. I just pushed the version that works.

Base.steprem(a::Date,b::Date,c::Day) = (b-a) % c
Base.steprem(a::DateTime,b::DateTime,c::Millisecond) = (b-a) % c

function Base.steprem(start::TimeType,stop::TimeType,step::Period)
    start,stop = start > stop ? (stop,start) : (start,stop)
    step = step < zero(step) ? -step : step
    t = start
    while (t+step) <= stop
        t += step
    end
    return stop - t
end

[quinnj]

I thought about having that manual definition of steprem in Base, and defining the version that uses % for all Reals, but then we'd be excluding other Ordinals that are non-Real, but implement % (somehow...); or at least making them define their own steprem. I don't know if there's a better way to work through all of this, but I keep coming back to the fact that this little patch allows for (seemingly) full functionality.

[quinnj]

Ok, I've updated the Dates.jl range code and added a bunch more tests (based on this patch). Feel free to take a look and let me know if this is good to go or if we should try something else.

Dates.jl range code: https://github.com/karbarcca/Dates.jl/blob/master/src/ranges.jl
Dates.jl range tests: https://github.com/karbarcca/Dates.jl/blob/master/test/test_ranges.jl

[quinnj]

Ok, added another round of testing/tweaks to the range code in Dates.jl (I updated all above links to relevant code and tests). I'm pretty satisfied with test coverage and that all the functionality is there. I think this should be merged. @JeffBezanson?

[quinnj]

Ok, updated the issorted and in definitions.