Re: [bug] type -m '^foo'

[Peter Stephenson <pws@csr.com>]

Bart Schaefer wrote:
> On Fri, 1 Oct 2004, Peter Stephenson wrote:
> 
> > > This fixes the crash, but it would be better if pattry() could be 
> > > rewritten so as not to need to modify the string in place.
> > 
> > I think this fixes it, but it's horribly complicated around there.
> 
> Hmm, well, what I meant was that it would be better if it could be re- 
> written so as not to need a null terminator at that point, i.e., to do 
> everything with array indices or starting/ending pointers rather than rely 
> on having a nul-terminated string.  Copying and freeing the string down in 
> the recursive guts of matching is probably more expensive (for certain 
> patterns, although far less expensive for other patterns) than copying the 
> whole string beforehand.
> 
> On the other hand the code is already doing zshcalloc() in that vicinity,
> so perhaps a few more allocs/frees is not enough to worry about.

Yes, I agree with all of that... however, rewriting the whole thing not
to require NULL-terminated strings is quite a big change (there's no
"memncmp" function, for example, and I'm not sure if you can guarantee
memcmp will stop comparing soon enough).  Only a few of the nasty
negative pattern matches need to rejig the string, so it would probably
make the vast majority of matches a bit slower.  I'll put it on the list
to look at.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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