Re: delete text block with regexp

[Edi Weitz]

On Sun, 16 Nov 2003 23:42:37 GMT, Stefan Monnier <monnier@iro.umontreal.ca> 
wrote:

>> The critical part is that "." matches anything but a newline.
>> Therefore use "\(.\|\n\)" for any character or a newline.
>
> Beware: such a regexp tends to suffer from the "regexp stack
> overflow" problem.  Better use \(.*\n\)*.* which is equivalent but
> uses a lot less stack space.
>
> Sadly, to understand why you need to understand details of how the
> regexp matching happens to be implemented in Emacs.

Shouldn't a good regex implementation be able to optimize the problem
away in simple cases like this? I've written a regex engine for Common
Lisp which does transformations like (Perl syntax)

  <regex>*   ->   (?:<regex'>*<regex>)?
  <regex>+   ->   <regex'>*<regex>

if <regex> includes register groups and is of fixed length. <regex'>
is an equivalent regular expression but without the register
groups. I'm pretty sure Perl does something similar.

Edi.