loot / libloot / 16580222127

push

github

Switch to the regress crate for regex

It uses about 56 MB less memory when LOOT launches into my Skyrim SE
large test load order with the latest masterlist and prelude, and
explicitly targets ECMAScript-like syntax like C++ std::regex does.

Compared to fancy-regex's syntax support, regress adds support for the
\0 nul character escape and removes support for:

- modifiers (e.g. `(?i)`)
- some Unicode character classes (e.g. used with `\p{}` and `\P{}`)
- the ASCII/POSIX character classes (e.g. `[:alpha:]`)

Another difference is that fancy-regex's u flag is a combination of
JavaScript's (and regress's) u and v flags.

The nul character escape is irrelevant for filename matching as it's not
allowed in Windows or Linux filenames.

Compared to C++ std::regex, the new restrictions are:

- the lack of support for ASCII/POSIX character classes
- the lack of support for control character escapes (e.g. `\cX`)

The lack of support for control character escapes is irrelevant as
control characters aren't allowed in Windows filenames.

A search of the masterlists doesn't find any use of the ASCII character
classes, and it's very unlikely that any user metadata would use them.
If such syntax is in use, it'll cause an error.

35 of 37 new or added lines in 3 files covered. (94.59%)

10655 of 11470 relevant lines covered (92.89%)

217.08 hits per line