add `sliding_window_maxima`

[nsajko]

Feature addition: add iterator whose elements are maxima of a sliding window over an original iterator.

[codecov[bot]]

Codecov Report

:x: Patch coverage is 98.64865% with 1 line in your changes missing coverage. Please review. :white_check_mark: Project coverage is 91.96%. Comparing base (568d12c) to head (b589762).

Files with missing lines	Patch %	Lines
src/IterTools.jl	98.64%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #126      +/-   ##
==========================================
+ Coverage   90.72%   91.96%   +1.23%     
==========================================
  Files           1        1              
  Lines         399      473      +74     
==========================================
+ Hits          362      435      +73     
- Misses         37       38       +1     

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[oxinabox]

why does this have some very aggressive compiler directives thoughout it?

these are going to require careful hand checking. The compiler can normally work things out.

[nsajko]

why does this have some very aggressive compiler directives

• ~~The @assume_effects :terminates_locally is for the loops. The compiler currently does not attempt to prove termination of any loop, see Julia issue https://github.com/JuliaLang/julia/issues/57097. The terminates effect is necessary for both dead code elimination and for constant folding, see the @assume_effects doc string. The :terminates_locally, as opposed to :terminates_globally, only applies to the local loops, so I'd say the directives are correct.~~ EDIT: the PR doesn't do assume_effects any more.

• The @constprop :aggressive directives were necessary (some of them, at least) to make the test suite (the @inferred, to be specific) pass on some versions of Julia (v1.8, at least). We definitely want constant propagation to happen, and these directives are not dangerous (in contrast to @assume_effects), so applying them seems like a no-brainer. The worst these can cause is excessive compilation latency, so I think excessive scrutiny of @constprop :aggressive might just be premature (compile-time) optimization.

[nsajko]

bump

[nsajko]

bump

[oxinabox]

sorry, its just i am not sure if this belongs in this package or not. It's a very intricate function.