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Re: [Emacs-diffs] master 938d252 4/4: Make regex matching reentrant; up

From: Daniel Colascione
Subject: Re: [Emacs-diffs] master 938d252 4/4: Make regex matching reentrant; update syntax during match
Date: Sun, 17 Jun 2018 12:50:38 -0700
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>> Oh, yeah. One more thing. The busy flag isn't *just* to prevent the
>> regex
>> bytecode engine confusing itself with self-modifying bytecode. It also
>> serves to protect the cache slot holding the regex pattern from reuse,
>> which would be disastrous whether or not the bytecode of a particular
>> pattern happens to be mutable.
> It doesn't have to be disastrous *if* we complexify the code such that
> removing a pattern from the cache doesn't inevitably free that pattern ;-)
> [ But, yes, we'd still need to mark the pattern as "busy" in order to
>   know when it can be freed.  ]

Sure. And at that point, we might as well make compiled patterns into
GC-able heap objects. That's probably a good idea, but it's a bigger

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