From: Brandon L Black Date: Mon, 14 May 2007 23:25:43 +0000 (+0000) Subject: more backport work X-Git-Tag: 0.05~1 X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=053556af2954a716218645aff9e07c0f4276d405;p=gitmo%2FClass-C3-XS.git more backport work --- diff --git a/XS.xs b/XS.xs index 20c1ea6..6acd791 100644 --- a/XS.xs +++ b/XS.xs @@ -46,7 +46,6 @@ __mro_linear_isa_c3(pTHX_ HV* stash, HV* cache, I32 level) 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; @@ -54,18 +53,25 @@ __mro_linear_isa_c3(pTHX_ HV* stash, HV* cache, I32 level) 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); } } @@ -74,7 +80,6 @@ __mro_linear_isa_c3(pTHX_ HV* stash, HV* cache, I32 level) /* 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 @@ -107,31 +112,47 @@ __mro_linear_isa_c3(pTHX_ HV* stash, HV* cache, I32 level) 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]); @@ -151,23 +172,35 @@ __mro_linear_isa_c3(pTHX_ HV* stash, HV* cache, I32 level) } } } + + /* 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) { @@ -205,7 +238,6 @@ __nextcan(pTHX_ SV* self, I32 throw_nomethod) GV** gvp; AV* linear_av; SV** linear_svp; - SV* linear_sv; HV* cstash; GV* candidate = NULL; CV* cand_cv = NULL; @@ -314,7 +346,7 @@ __nextcan(pTHX_ SV* self, I32 throw_nomethod) 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; @@ -325,7 +357,7 @@ __nextcan(pTHX_ SV* self, I32 throw_nomethod) 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) {