From: eregontp@...
Date: 2020-08-28T15:30:28+00:00
Subject: [ruby-core:99752] [Ruby master Bug#17030] Enumerable#grep{_v} should be optimized for Regexp

Issue #17030 has been updated by Eregon (Benoit Daloze).


I'm surprised at the performance difference on MRI though. Just allocating the MatchData shouldn't be so expensive. Maybe `Regexp#match?` has additional optimizations?

----------------------------------------
Bug #17030: Enumerable#grep{_v} should be optimized for Regexp
https://bugs.ruby-lang.org/issues/17030#change-87252

* 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) }
```

is about three times faster and six times more memory efficient than

```ruby
array.grep(REGEXP)
```

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



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