Function `convert_while_ascii`

pub unsafe fn convert_while_ascii(s: &str, convert: fn(&u8) -> u8) -> (String, &str)

Converts leading ascii bytes in s by calling the convert function.

For better average performance, this happens in chunks of 2*size_of::<usize>().

Returns a tuple of the converted prefix and the remainder starting from the first non-ascii character.

This function is only public so that it can be verified in a codegen test, see issue-123712-str-to-lower-autovectorization.rs.

Safety

convert must return an ASCII byte for every ASCII input byte.