cache the Range for gen_ascii_chars

[TheIronBorn]

could even use unsafe fn get_unchecked.

• passes all tests

[dhardy]

Just an optimisation? This may get removed anyway (check my branch/PR).

[TheIronBorn]

Will this function/feature be moved elsewhere? If not, I think archiving a more optimal version somewhere is still a good idea.

[dhardy]

Sorry, @TheIronBorn. I'm not quite sure what will happen; I have an experimental refactor of quite a lot of rand, but obviously can't promise it will get merged.

You might be able to apply the same optimisation here. Note that TODO comment and the note in the refactor RFC; some more tweaks to this (e.g. other character classes) are possible (please open a PR or comment on the RFC if you have suggestions):

AsciiWordChar is currently an oddity, used in many tests but with no hard requirements on form or function. This could be renamed and augmented in line with Regex character classes.

[pitdicker]

In dhardy#69 I have an other solution that does not need caching, and is about 4,5 times faster than the current version. And no unsafe indexing necessary: the range check needed to ensure a uniform range doubles as a bounds check.

@TheIronBorn Sorry for working on the same thing.

[dhardy]

Great, lets go for the second version then.