Re: [PATCH 1/2] [GSOC] ref-filter: add %(raw) atom

[ZheNing Hu <adlternative@gmail.com>]

Felipe Contreras <felipe.contreras@gmail.com> 于2021年5月28日周五 上午12:36写道：
>
> ZheNing Hu via GitGitGadget wrote:
>
> > +static int raw_atom_parser(const struct ref_format *format, struct used_atom *atom,
> > +                             const char *arg, struct strbuf *err)
> > +{
> > +     if (!arg) {
> > +             atom->u.raw_data.option = RAW_BARE;
> > +     } else if (!strcmp(arg, "size"))
>
> No need for braces.
>
>   if (!arg)
>     ...
>   else
>

I sometimes forget this detail, I will pay attention.

> > @@ -1307,10 +1349,22 @@ static void grab_sub_body_contents(struct atom_value *val, int deref, void *buf)
> >                       continue;
> >               if (deref)
> >                       name++;
> > -             if (strcmp(name, "body") &&
> > -                 !starts_with(name, "subject") &&
> > -                 !starts_with(name, "trailers") &&
> > -                 !starts_with(name, "contents"))
> > +
> > +             if (starts_with(name, "raw")) {
> > +                     if (atom->u.raw_data.option == RAW_BARE) {
> > +                             v->s = xmemdupz(buf, buf_size);
> > +                             v->s_size = buf_size;
> > +                     } else if (atom->u.raw_data.option == RAW_LENGTH)
> > +                             v->s = xstrfmt("%"PRIuMAX, (uintmax_t)buf_size);
>
> I think it's better to be consistent: if you used braces in the if, uses
> braces in else.
>

OK.

> > +                     continue;
> > +             }
>
> > +static int memcasecmp(const void *vs1, const void *vs2, size_t n)
>
> Why void *? We can delcare as char *.
>
> > +{
> > +     size_t i;
> > +     const char *s1 = (const char *)vs1;
> > +     const char *s2 = (const char *)vs2;
>
> Then we avoid this extra step.
>
> > +     for (i = 0; i < n; i++) {
> > +             unsigned char u1 = s1[i];
> > +             unsigned char u2 = s2[i];
>
> There's no need for two entirely new variables...
>
> > +             int U1 = toupper (u1);
> > +             int U2 = toupper (u2);
>
> You can do toupper(s1[i]) directly (BTW, there's an extra space: `foo(x)`,
> not `foo (x)`).
>
> While we are at it, why keep an extra index from s1, when s1 is never
> used again?
>
> We can simply advance both s1 and s2:
>
>   s1++, s2++
>
> > +             int diff = (UCHAR_MAX <= INT_MAX ? U1 - U2
> > +                     : U1 < U2 ? -1 : U2 < U1);
>
> I don't understand what this is supposed to achieve. Both U1 and U2 are
> integers, pretty low integers actually.
>
> If we get rid if that complexity we don't even need U1 or U2, just do:
>
>   diff = toupper(u1) - toupper(u2);
>
> > +             if (diff)
> > +                     return diff;
> > +     }
> > +     return 0;
> > +}
>
> All we have to do is define the end point, and then we don't need i:
>
>         static int memcasecmp(const char *s1, const char *s2, size_t n)
>         {
>                 const char *end = s1 + n;
>                 for (; s1 < end; s1++, s2++) {
>                         int diff = tolower(*s1) - tolower(*s2);
>                         if (diff)
>                                 return diff;
>                 }
>                 return 0;
>         }
>
> (and I personally prefer lower to upper)
>

Sorry for the weird, unclean `memcasecmp()`, I referred to memcmp()
in glibc before, and then I was afraid that my writing was not standard
enough like "UCHAR_MAX <= INT_MAX", I can't consider such an
extreme situation. So I copied it directly from gnulib:
https://github.com/gagern/gnulib/blob/master/lib/memcasecmp.c

> Check the following resource for a detailed explanation of why my
> modified version is considered good taste:
>
> https://github.com/felipec/linked-list-good-taste
>

OK. I will gradually standardize my code style.

> >  static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, struct ref_array_item *b)
> >  {
> >       struct atom_value *va, *vb;
> > @@ -2304,6 +2382,7 @@ static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, stru
> >       int cmp_detached_head = 0;
> >       cmp_type cmp_type = used_atom[s->atom].type;
> >       struct strbuf err = STRBUF_INIT;
> > +     size_t slen = 0;
> >
> >       if (get_ref_atom_value(a, s->atom, &va, &err))
> >               die("%s", err.buf);
> > @@ -2317,10 +2396,32 @@ static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, stru
> >       } else if (s->sort_flags & REF_SORTING_VERSION) {
> >               cmp = versioncmp(va->s, vb->s);
> >       } else if (cmp_type == FIELD_STR) {
> > -             int (*cmp_fn)(const char *, const char *);
> > -             cmp_fn = s->sort_flags & REF_SORTING_ICASE
> > -                     ? strcasecmp : strcmp;
> > -             cmp = cmp_fn(va->s, vb->s);
> > +             if (va->s_size == ATOM_VALUE_S_SIZE_INIT &&
> > +                 vb->s_size == ATOM_VALUE_S_SIZE_INIT) {
> > +                     int (*cmp_fn)(const char *, const char *);
> > +                     cmp_fn = s->sort_flags & REF_SORTING_ICASE
> > +                             ? strcasecmp : strcmp;
> > +                     cmp = cmp_fn(va->s, vb->s);
> > +             } else {
> > +                     int (*cmp_fn)(const void *, const void *, size_t);
> > +                     cmp_fn = s->sort_flags & REF_SORTING_ICASE
> > +                             ? memcasecmp : memcmp;
> > +
> > +                     if (va->s_size != ATOM_VALUE_S_SIZE_INIT &&
> > +                         vb->s_size != ATOM_VALUE_S_SIZE_INIT) {
> > +                             cmp = cmp_fn(va->s, vb->s, va->s_size > vb->s_size ?
> > +                                    vb->s_size : va->s_size);
> > +                     } else if (va->s_size == ATOM_VALUE_S_SIZE_INIT) {
> > +                             slen = strlen(va->s);
> > +                             cmp = cmp_fn(va->s, vb->s, slen > vb->s_size ?
> > +                                          vb->s_size : slen);
> > +                     } else {
> > +                             slen = strlen(vb->s);
> > +                             cmp = cmp_fn(va->s, vb->s, slen > va->s_size ?
> > +                                          slen : va->s_size);
> > +                     }
> > +                     cmp = cmp ? cmp : va->s_size - vb->s_size;
> > +             }
>
> This hurts my eyes. I think the complexity of this chunk warrants a
> separate function. Then the logic would be easer to see.
>

Fine. This piece of the situation is a bit complicated...

> Cheers.
>
> --
> Felipe Contreras

Thanks.
--
ZheNing Hu