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Re: extended rx.el

From: Dave Love
Subject: Re: extended rx.el
Date: Mon, 26 Apr 2004 15:19:50 +0100
User-agent: Gnus/5.1002 (Gnus v5.10.2) Emacs/21.2 (gnu/linux)

Stefan Monnier <address@hidden> writes:

> Normally no.  A shy-group turns into a nop, so it's very efficient.
> But it can prevent some optimizations that recognize special cases.
> E.g. IIRC \(?:.\)*\n will be (measurably) slower than .*\n because
> the optimizer is too stupid to notice it's the same thing (if the
> optimization was applied after byte-compilation it would work, tho).

I think that info is worth including somewhere -- in the rx.el
commentary if nowhere else, but probably in the doc for shy groups.

I'm glad I guessed correctly that I didn't know enough to make a
useful measurement!

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