Also, the search documentation is spread out and seems to be missing guidance on features that are crucial. For example, AND works as you would expect (like: hello AND world), but it isn't mentioned anywhere.
Anyway, thanks for posting it!
No online service in the world does not index things.
If you need full access to everything, why not just clone the repo and do these things in the comfort of your command line?
foo AND bar NOT baz OR fizz
So, it supports AND, NOT, and OR. Nowhere, though, does it say that. I don't know if I can group these to get around precedence either. Parenthesis are ignored. It does mention NOT somewhere. And, there's no navigation to search help by the search button. I had to google to find out any help was available.
Also, it ignores some characters for unknown reasons. Like $, for example. That's a meaningful sigil in Perl, PHP, and so on...it's quite frustrating that it's ignored.
`AND` being implicit in `bar NOT baz`, and in `foo bar`. Also AND/OR is per file, rather than line which I wondered after reading this comment.
There's some information here [0] that's mainly centred on issues/PRs, but some transferable (this might be what you referred to that does mention NOT). There's also a bit more information here [1]; it does at least acknowledge that `$` will be swallowed.
The link below shows timings for various regex on a 20MiB text file for several different regex softwares. The best code never exceeds half a second for even the worst expressions. Most are much faster.
When you add to this the fact that it's possible to deliberately construct regexes that are much more complicated to evaluate (particularly if you allow extensions beyond a true regular language) - potentially being a DoS target - and many repos won't be cached when the search comes in (or caching them would also be very expensive), the costs just get higher.
In contrast, a simple keyword search can be performed with a predictable, low cost, so it's no wonder that they'd prefer to implement this instead.
Only if you allow extensions, but then they aren't regular expressions.
Re2 excludes them specifically .
They still use Perl-like syntax, and might still be able to parse non-regular languages, but you don't need to worry about users deliberately crafting regexes to eat up CPU time like PCRE.