std.mem: add namespace for comparing sentinel-terminated pointers
#24683
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probably still gonna change the naming. TODO: more functions, maybe link to `std.mem.len()` from there I am happy to report though, that I tested the speed of these, even if in a very bad way, but still conclusive enough, and the versions I wrote/stole from ifreund are faster :3 note that I didn't test the `allEquals()` function, but I'll just assume it's faster too.. ziglang#7848 (comment)
also i tested the `eql` and `eqlSlice` functions for speed, and.. its all definitely faster than using `span()`, but the unexpected result is that if you have a sentinel-terminated slice, it is faster to compare the pointers, than it is to do the slice (at least for small (`< 32` or so) slice size).
just to ensure i didn't turn the wrong `0` into a `sentinel` in `order()`
closes ziglang#22618 (from where i stole the code) i don't think this syntax will work with pull requests, but i can try at least :3
found some cases where these functions are useful the test finished with some errors on my system, but it always does, even if a commit is confirmed to work, probably just something wrong on my end. the compiler still builds tho and test-std also finishes cleanly, so ill just hope there isn't too much wrong
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This adds a new namespace to
std.memfor comparing sentinel-terminated pointers:std.mem.sentinel_terminated.This includes both a function for comparing two such pointers and a function for comparing one to a slice (latter addresses #7848 (comment)).
Ordering is also provided, which also works if the sentinel is not the minimal possible value in the slice (copied from and closes #22618).
I also included
allEqual(),min()andmax()functions.len()andspan()link to the implementation currently instd.mem, though if this get accepted, moving the implementations and deprecating the original functions might be a possibility.The naming I chose isn't final, if a better one is suggested, I can change it.
Similarly, I am not quite sure on the explicitness of the sentinel value in the function calls, though it does follow a similar pattern as many functions in
std.memdo currently.I tested the speed of
eql()andeqlSlice(). Both are faster than usingstd.mem.eql()with sentinel-terminated pointer to slice conversion, especially at smaller lengths.If operating on sentinel-terminated slices it is actually sometimes faster to use
std.mem.sentinel_terminated.eql()on the pointers than it is to pass the slices tostd.mem.eql(), though more testing should be done before this is used.Lastly, if there are any more functions I should add, or any usecase in the standard library or the compiler where these functions could help, tell me and I will implement them to the best of my ability.