Eric Wong <e@xxxxxxxxx> wrote:
> Eric Sunshine <sunshine@xxxxxxxxxxxxxx> wrote:
> > On Tue, May 31, 2016 at 3:45 AM, Eric Wong <e@xxxxxxxxx> wrote:
> > > Eric Sunshine <sunshine@xxxxxxxxxxxxxx> wrote:
> > >> I wonder if hand-coding, rather than using a regex, could be an improvement:
> > >>
> > >> static int is_mboxrd_from(const char *s, size_t n)
> > >> {
> > >> size_t f = strlen("From ");
> > >> const char *t = s + n;
> > >>
> > >> while (s < t && *s == '>')
> > >> s++;
> > >> return t - s >= f && !memcmp(s, "From ", f);
> > >> }
> > >>
> > >> or something.
> > >
> > > Yikes. I mostly work in high-level languages and do my best to
> > > avoid string parsing in C; so that scares me. A lot.
> >
> > The hand-coded is_mboxrd_from() above is pretty much idiomatic C and
> > (I think) typical of how such a function would be coded in Git itself,
> > so it looks normal and easy to grok to me (but, of course, I'm
> > probably biased since I wrote it).
For reference, here is the gfrom function from qmail (gfrom.c,
source package netqmail-1.06 in Debian, reformatted git style)
int gfrom(char *s, int len)
{
while ((len > 0) && (*s == '>')) {
++s;
--len;
}
return (len >= 5) && !str_diffn(s, "From ", 5);
}
Similar to yours, but a several small things improves
readability for me:
* the avoidance of subtraction from the "return" conditional
* s/n/len/ variable name
* extra parentheses
* removal of "t" variable (t for "terminal/termination"?)
str_diffn is memcmp-like, I assume. My eyes glazed over
when I saw that function implemented in str_diffn.c, too.
Just thinking out loud, with sufficient tests I could go with
either. Will reroll when/if I get the chance tomorrow.
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