Rust regex crate author here.
fancy-regex is built on top of the regex crate and supports look-around.
The regex crate doesn't support arbitrary look-around because it isn't known how to implement efficiently.
fancy-regex is built on top of the regex crate and supports look-around.
The regex crate doesn't support arbitrary look-around because it isn't known how to implement efficiently.
A bit of a philosophical question:
If how to write an efficient implementation is yet not known to man, ie. not a matter of the library's author time or skills, but literally a limit on human knowledge: why not at least provide the functionality with a good enough implementation? (with caveats just possibly mentioned in documentation)
IMHO that'd be arguably a good thing for everybody, at a minimum better than just not offering the possibility at all. Which drives users to frustration, or leaves them having to discover a more pragmatic alternative lib that opted to add it.
This is no complaint or feature request... I just want to learn from some insight behind the thought process of "if it's not efficient, better not have it at all"
PS. Thanks for the link. Now I have a good read for the weekend, for sure!
One of the key advantages of a regex engine based on finite automata is that it lets you make guarantees about the runtime performance of a search.
You don't need to be all things to all people. Embrace the fact that there are other choices!