[ruby-core:99706] [Ruby master Bug#17030] Enumerable#grep{_v} should be optimized for Regexp

Issue #17030 has been updated by fatkodima (Dima Fatko).


marcandre (Marc-Andre Lafortune) wrote in #note-12:
> Maybe it would be best to start a different thread as none of these proposals have a relation to `grep{_v}` without block not being optimized.

I have already implemented a patch to make `grep{_v}` faster and right before submitting the `Create Pull Request` button, I realized (with the help of scivola20's comment), that this case can be generalized. Because we already have, at least, `Enumerable#{all?,any?,none?}` and many future methods to be added (like `grep`), which can benefit from this generalized solution. 


> This is Ruby, so I can think of some corner cases where things like `const_get(:Regexp).last_match` would be impacted (in theory), what other limitations would this have?
> 

`case-when`? 

> Couldn't static analysis of the code determine in most cases if match data need be generated or not?
> 

In many cases, probably yes, but again, `case-when`.

----------------------------------------
Bug #17030: Enumerable#grep{_v} should be optimized for Regexp
https://bugs.ruby-lang.org/issues/17030#change-87197

* Author: marcandre (Marc-Andre Lafortune)
* Status: Open
* Priority: Normal
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
Currently:

```ruby
array.select { |e| e.match?(REGEXP) }

# about 3x faster and 6x more memory efficient than
array.grep(REGEXP)
```

This is because `grep` calls `Regexp#===` which creates useless `MatchData`



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