Re: Emulating advanced regex features using Lua patterns and pure Lua code

[Lorenzo Donati <lorenzodonatibz@...>]

On 20/06/2011 13.13, steve donovan wrote:
> On Mon, Jun 20, 2011 at 12:12 PM, Lorenzo Donati
> <lorenzodonatibz@interfree.it>  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.

I had that feeling, unfortunately :-(

> 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 ;)
>
> steve d.