gvp = (GV**)hv_fetch(stash, "ISA", 3, FALSE);
isa = (gvp && (gv = *gvp) && gv != (GV*)&PL_sv_undef) ? GvAV(gv) : NULL;
-
if(isa && AvFILLp(isa) >= 0) {
SV** seqs_ptr;
I32 seqs_items;
AV* const seqs = (AV*)sv_2mortal((SV*)newAV());
I32* heads;
+ /* This builds @seqs, which is an array of arrays.
+ The members of @seqs are the MROs of
+ the members of @ISA, followed by @ISA itself.
+ */
I32 items = AvFILLp(isa) + 1;
SV** isa_ptr = AvARRAY(isa);
while(items--) {
SV* const isa_item = *isa_ptr++;
HV* const isa_item_stash = gv_stashsv(isa_item, 0);
if(!isa_item_stash) {
+ /* if no stash, make a temporary fake MRO
+ containing just itself */
AV* const isa_lin = newAV();
av_push(isa_lin, newSVsv(isa_item));
av_push(seqs, (SV*)isa_lin);
}
else {
- AV* const isa_lin = __mro_linear_isa_c3(aTHX_ isa_item_stash, cache, level + 1); /* recursion */
+ /* recursion */
+ AV* const isa_lin = __mro_linear_isa_c3(aTHX_ isa_item_stash, cache, level + 1);
av_push(seqs, (SV*)isa_lin);
}
}
/* This builds "heads", which as an array of integer array
indices, one per seq, which point at the virtual "head"
of the seq (initially zero) */
-
Newz(0xdead, heads, AvFILLp(seqs)+1, I32);
/* This builds %tails, which has one key for every class
retval = newAV();
av_push(retval, newSVpvn(stashname, stashname_len)); /* us first */
+ /* This loop won't terminate until we either finish building
+ the MRO, or get an exception. */
while(1) {
SV* cand = NULL;
SV* winner = NULL;
int s;
+ /* "foreach $seq (@seqs)" */
SV** const avptr = AvARRAY(seqs);
for(s = 0; s <= AvFILLp(seqs); s++) {
SV** svp;
AV * const seq = (AV*)(avptr[s]);
SV* seqhead;
- if(!seq) continue;
+ if(!seq) continue; /* skip empty seqs */
svp = av_fetch(seq, heads[s], 0);
- seqhead = *svp;
+ seqhead = *svp; /* seqhead = head of this seq */
if(!winner) {
HE* tail_entry;
SV* val;
+ /* if we haven't found a winner for this round yet,
+ and this seqhead is not in tails (or the count
+ for it in tails has dropped to zero), then this
+ seqhead is our new winner, and is added to the
+ final MRO immediately */
cand = seqhead;
if((tail_entry = hv_fetch_ent(tails, cand, 0, 0))
&& (val = HeVAL(tail_entry))
- && (SvIVx(val) > 0))
+ && (SvIVX(val) > 0))
continue;
winner = newSVsv(cand);
av_push(retval, winner);
+ /* note however that even when we find a winner,
+ we continue looping over @seqs to do housekeeping */
}
if(!sv_cmp(seqhead, winner)) {
+ /* Once we have a winner (including the iteration
+ where we first found him), inc the head ptr
+ for any seq which had the winner as a head,
+ NULL out any seq which is now empty,
+ and adjust tails for consistency */
+
const int new_head = ++heads[s];
if(new_head > AvFILLp(seq)) {
SvREFCNT_dec(avptr[s]);
}
}
}
+
+ /* if we found no candidates, we are done building the MRO.
+ !cand means no seqs have any entries left to check */
if(!cand) {
Safefree(heads);
break;
}
+
+ /* If we had candidates, but nobody won, then the @ISA
+ hierarchy is not C3-incompatible */
if(!winner) {
+ /* we have to do some cleanup before we croak */
+
SvREFCNT_dec(retval);
Safefree(heads);
+
Perl_croak(aTHX_ "Inconsistent hierarchy during C3 merge of class '%s': "
"merging failed on parent '%s'", stashname, SvPV_nolen(cand));
}
}
}
- else { /* @ISA does not exist, or was empty */
+ else { /* @ISA was undefined or empty */
+ /* build a retval containing only ourselves */
retval = newAV();
- av_push(retval, newSVpvn(stashname, stashname_len)); /* us first */
+ av_push(retval, newSVpvn(stashname, stashname_len));
}
+ /* we don't want anyone modifying the cache entry but us,
+ and we do so by replacing it completely */
SvREADONLY_on(retval);
if(!made_mortal_cache) {
GV** gvp;
AV* linear_av;
SV** linear_svp;
- SV* linear_sv;
HV* cstash;
GV* candidate = NULL;
CV* cand_cv = NULL;
items = AvFILLp(linear_av) + 1;
while (items--) {
- linear_sv = *linear_svp++;
+ SV* const linear_sv = *linear_svp++;
assert(linear_sv);
if(sv_eq(linear_sv, stashname))
break;
HV* cc3_mro = get_hv("Class::C3::MRO", 0);
while (items--) {
- linear_sv = *linear_svp++;
+ SV* const linear_sv = *linear_svp++;
assert(linear_sv);
if(cc3_mro) {
projects / gitmo/Class-C3-XS.git / blobdiff