Description
It would be nice to add support for compile-time regular expressions for the following reasons as it would
- Allow for compile-time checking of validation regexes (pretty much impossible to push invalid regexes if the code doesn't compile)
- Quicker runtime validation of fields (since the regex is processed at compile-time)
- Allow for compile-time validation whenever we (eventually) support compile-time parsing of JSON
This last point seems like science-fiction, or like something that wouldn't ever be useful, but with the addition of #embed to C23 and its likely addition to C++ at some point (hopefully by C++26) it wouldn't be crazy to expect users to want to configure programs using inline / embedded JSON or other formats. There are already a few options for compile-time JSON parsing, so it's not unheard of, in which case, validation of JSON fields would be necessary too.
For all this, I propose (and will be working on a PR for) the addition of Hanickadot's CTRE as a dependency, as well as tweaks in the validator code to get rid of the extremely slow std::regex. If you want to see the speed differences, please check P1433R0, which received a very positive reaction from the C++ Standard's committee (hopefully we'll have a constexpr capable option for regex in the standard library soon).