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- Subject: Re: Emulating advanced regex features using Lua patterns and pure Lua code
- From: David Kastrup <dak@<a href="/cgi-bin/echo.cgi?gnu.org">...</a>>
- Date: Mon, 20 Jun 2011 14:13:52 +0200
steve donovan <firstname.lastname@example.org> writes:
> On Mon, Jun 20, 2011 at 12:12 PM, Lorenzo Donati
> <email@example.com> wrote:
>> if pcre.match( haystack, "^foo|bar$" ) then ...
>> may be rewritten in pure Lua as:
>> if haystack:match "^foo$" or haystack:match "^bar$" then ...
> Ah, but soon as you get multiple alternation, especially nested, then
> the resulting code is not so obvious. And obviously it is going to be
> slower than any regexp implementation. OK, that may be acceptable for
> the application, but the code generation could get hairy fast.
> Another idea is to use LPeg to implement a regexp subset - that should
> be fast. But it does require non-triivial knowledge of LPeg which I
> understand is not on your immediate to-do list ;)