3 * Copyright (c) 2007 Brandon L Black
4 * Copyright (c) 2007, 2008 Larry Wall and others
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Artistic License, as specified in the README file.
12 * 'Which order shall we go in?' said Frodo. 'Eldest first, or quickest first?
13 * You'll be last either way, Master Peregrin.'
15 * [p.101 of _The Lord of the Rings_, I/iii: "A Conspiracy Unmasked"]
21 These functions are related to the method resolution order of perl classes
30 static const struct mro_alg dfs_alg =
31 {S_mro_get_linear_isa_dfs, "dfs", 3, 0, 0};
34 Perl_mro_get_private_data(pTHX_ struct mro_meta *const smeta,
35 const struct mro_alg *const which)
38 PERL_ARGS_ASSERT_MRO_GET_PRIVATE_DATA;
40 data = (SV **)Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
41 which->name, which->length, which->kflags,
42 HV_FETCH_JUST_SV, NULL, which->hash);
46 /* If we've been asked to look up the private data for the current MRO, then
48 if (smeta->mro_which == which)
49 smeta->mro_linear_current = *data;
55 Perl_mro_set_private_data(pTHX_ struct mro_meta *const smeta,
56 const struct mro_alg *const which, SV *const data)
58 PERL_ARGS_ASSERT_MRO_SET_PRIVATE_DATA;
60 if (!smeta->mro_linear_all) {
61 if (smeta->mro_which == which) {
62 /* If all we need to store is the current MRO's data, then don't use
63 memory on a hash with 1 element - store it direct, and signal
64 this by leaving the would-be-hash NULL. */
65 smeta->mro_linear_current = data;
68 HV *const hv = newHV();
69 /* Start with 2 buckets. It's unlikely we'll need more. */
71 smeta->mro_linear_all = hv;
73 if (smeta->mro_linear_current) {
74 /* If we were storing something directly, put it in the hash
76 Perl_mro_set_private_data(aTHX_ smeta, smeta->mro_which,
77 smeta->mro_linear_current);
82 /* We get here if we're storing more than one linearisation for this stash,
83 or the linearisation we are storing is not that if its current MRO. */
85 if (smeta->mro_which == which) {
86 /* If we've been asked to store the private data for the current MRO,
88 smeta->mro_linear_current = data;
91 if (!Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
92 which->name, which->length, which->kflags,
93 HV_FETCH_ISSTORE, data, which->hash)) {
94 Perl_croak(aTHX_ "panic: hv_store() failed in set_mro_private_data() "
95 "for '%.*s' %d", (int) which->length, which->name,
102 const struct mro_alg *
103 Perl_mro_get_from_name(pTHX_ SV *name) {
106 PERL_ARGS_ASSERT_MRO_GET_FROM_NAME;
108 data = (SV **)Perl_hv_common(aTHX_ PL_registered_mros, name, NULL, 0, 0,
109 HV_FETCH_JUST_SV, NULL, 0);
112 assert(SvTYPE(*data) == SVt_IV);
113 assert(SvIOK(*data));
114 return INT2PTR(const struct mro_alg *, SvUVX(*data));
118 =for apidoc mro_register
119 Registers a custom mro plugin. See L<perlmroapi> for details.
125 Perl_mro_register(pTHX_ const struct mro_alg *mro) {
126 SV *wrapper = newSVuv(PTR2UV(mro));
128 PERL_ARGS_ASSERT_MRO_REGISTER;
131 if (!Perl_hv_common(aTHX_ PL_registered_mros, NULL,
132 mro->name, mro->length, mro->kflags,
133 HV_FETCH_ISSTORE, wrapper, mro->hash)) {
134 SvREFCNT_dec(wrapper);
135 Perl_croak(aTHX_ "panic: hv_store() failed in mro_register() "
136 "for '%.*s' %d", (int) mro->length, mro->name, mro->kflags);
141 Perl_mro_meta_init(pTHX_ HV* stash)
143 struct mro_meta* newmeta;
145 PERL_ARGS_ASSERT_MRO_META_INIT;
146 assert(HvAUX(stash));
147 assert(!(HvAUX(stash)->xhv_mro_meta));
148 Newxz(newmeta, 1, struct mro_meta);
149 HvAUX(stash)->xhv_mro_meta = newmeta;
150 newmeta->cache_gen = 1;
151 newmeta->pkg_gen = 1;
152 newmeta->mro_which = &dfs_alg;
157 #if defined(USE_ITHREADS)
159 /* for sv_dup on new threads */
161 Perl_mro_meta_dup(pTHX_ struct mro_meta* smeta, CLONE_PARAMS* param)
163 struct mro_meta* newmeta;
165 PERL_ARGS_ASSERT_MRO_META_DUP;
167 Newx(newmeta, 1, struct mro_meta);
168 Copy(smeta, newmeta, 1, struct mro_meta);
170 if (newmeta->mro_linear_all) {
171 newmeta->mro_linear_all
172 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_linear_all, param));
173 /* This is just acting as a shortcut pointer, and will be automatically
174 updated on the first get. */
175 newmeta->mro_linear_current = NULL;
176 } else if (newmeta->mro_linear_current) {
177 /* Only the current MRO is stored, so this owns the data. */
178 newmeta->mro_linear_current
179 = sv_dup_inc((const SV *)newmeta->mro_linear_current, param);
182 if (newmeta->mro_nextmethod)
183 newmeta->mro_nextmethod
184 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_nextmethod, param));
187 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->isa, param));
192 #endif /* USE_ITHREADS */
195 =for apidoc mro_get_linear_isa_dfs
197 Returns the Depth-First Search linearization of @ISA
198 the given stash. The return value is a read-only AV*.
199 C<level> should be 0 (it is used internally in this
200 function's recursion).
202 You are responsible for C<SvREFCNT_inc()> on the
203 return value if you plan to store it anywhere
204 semi-permanently (otherwise it might be deleted
205 out from under you the next time the cache is
211 S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
218 struct mro_meta* meta;
222 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA_DFS;
223 assert(HvAUX(stash));
226 = HvAUX(stash)->xhv_name_u.xhvnameu_name && HvENAME_HEK_NN(stash)
227 ? HvENAME_HEK_NN(stash)
231 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
235 "Recursive inheritance detected in package '%"HEKf"'",
238 meta = HvMROMETA(stash);
240 /* return cache if valid */
241 if((retval = MUTABLE_AV(MRO_GET_PRIVATE_DATA(meta, &dfs_alg)))) {
245 /* not in cache, make a new one */
247 retval = MUTABLE_AV(sv_2mortal(MUTABLE_SV(newAV())));
248 /* We use this later in this function, but don't need a reference to it
249 beyond the end of this function, so reference count is fine. */
250 our_name = newSVhek(stashhek);
251 av_push(retval, our_name); /* add ourselves at the top */
254 gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
255 av = (gvp && (gv = *gvp) && isGV_with_GP(gv)) ? GvAV(gv) : NULL;
257 /* "stored" is used to keep track of all of the classnames we have added to
258 the MRO so far, so we can do a quick exists check and avoid adding
259 duplicate classnames to the MRO as we go.
260 It's then retained to be re-used as a fast lookup for ->isa(), by adding
261 our own name and "UNIVERSAL" to it. */
263 if(av && AvFILLp(av) >= 0) {
265 SV **svp = AvARRAY(av);
266 I32 items = AvFILLp(av) + 1;
270 SV* const sv = *svp++;
271 HV* const basestash = gv_stashsv(sv, 0);
276 /* if no stash exists for this @ISA member,
277 simply add it to the MRO and move on */
282 /* otherwise, recurse into ourselves for the MRO
283 of this @ISA member, and append their MRO to ours.
284 The recursive call could throw an exception, which
285 has memory management implications here, hence the use of
287 const AV *const subrv
288 = mro_get_linear_isa_dfs(basestash, level + 1);
290 subrv_p = AvARRAY(subrv);
291 subrv_items = AvFILLp(subrv) + 1;
294 while(subrv_items--) {
295 SV *const subsv = *subrv_p++;
296 /* LVALUE fetch will create a new undefined SV if necessary
298 HE *const he = hv_fetch_ent(stored, subsv, 1, 0);
300 if(HeVAL(he) != &PL_sv_undef) {
301 /* It was newly created. Steal it for our new SV, and
302 replace it in the hash with the "real" thing. */
303 SV *const val = HeVAL(he);
304 HEK *const key = HeKEY_hek(he);
306 HeVAL(he) = &PL_sv_undef;
307 /* Save copying by making a shared hash key scalar. We
308 inline this here rather than calling
309 Perl_newSVpvn_share because we already have the
310 scalar, and we already have the hash key. */
311 assert(SvTYPE(val) == SVt_NULL);
312 sv_upgrade(val, SVt_PV);
313 SvPV_set(val, HEK_KEY(share_hek_hek(key)));
314 SvCUR_set(val, HEK_LEN(key));
321 av_push(retval, val);
325 /* We are the first (or only) parent. We can short cut the
326 complexity above, because our @ISA is simply us prepended
327 to our parent's @ISA, and our ->isa cache is simply our
328 parent's, with our name added. */
329 /* newSVsv() is slow. This code is only faster if we can avoid
330 it by ensuring that SVs in the arrays are shared hash key
331 scalar SVs, because we can "copy" them very efficiently.
332 Although to be fair, we can't *ensure* this, as a reference
333 to the internal array is returned by mro::get_linear_isa(),
334 so we'll have to be defensive just in case someone faffed
338 stored = MUTABLE_HV(sv_2mortal((SV*)newHVhv(HvMROMETA(basestash)->isa)));
339 av_extend(retval, subrv_items);
340 AvFILLp(retval) = subrv_items;
341 svp = AvARRAY(retval);
342 while(subrv_items--) {
343 SV *const val = *subrv_p++;
344 *++svp = SvIsCOW_shared_hash(val)
345 ? newSVhek(SvSHARED_HEK_FROM_PV(SvPVX(val)))
349 /* They have no stash. So create ourselves an ->isa cache
350 as if we'd copied it from what theirs should be. */
351 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
352 (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
354 newSVhek(HeKEY_hek(hv_store_ent(stored, sv,
360 /* We have no parents. */
361 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
362 (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
365 (void) hv_store_ent(stored, our_name, &PL_sv_undef, 0);
367 SvREFCNT_inc_simple_void_NN(stored);
369 SvREADONLY_on(stored);
373 /* now that we're past the exception dangers, grab our own reference to
374 the AV we're about to use for the result. The reference owned by the
375 mortals' stack will be released soon, so everything will balance. */
376 SvREFCNT_inc_simple_void_NN(retval);
379 /* we don't want anyone modifying the cache entry but us,
380 and we do so by replacing it completely */
381 SvREADONLY_on(retval);
383 return MUTABLE_AV(Perl_mro_set_private_data(aTHX_ meta, &dfs_alg,
384 MUTABLE_SV(retval)));
388 =for apidoc mro_get_linear_isa
390 Returns the mro linearisation for the given stash. By default, this
391 will be whatever C<mro_get_linear_isa_dfs> returns unless some
392 other MRO is in effect for the stash. The return value is a
395 You are responsible for C<SvREFCNT_inc()> on the
396 return value if you plan to store it anywhere
397 semi-permanently (otherwise it might be deleted
398 out from under you the next time the cache is
404 Perl_mro_get_linear_isa(pTHX_ HV *stash)
406 struct mro_meta* meta;
409 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA;
411 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
413 meta = HvMROMETA(stash);
414 if (!meta->mro_which)
415 Perl_croak(aTHX_ "panic: invalid MRO!");
416 isa = meta->mro_which->resolve(aTHX_ stash, 0);
418 if (meta->mro_which != &dfs_alg) { /* skip for dfs, for speed */
420 (HvENAME(stash)||HvNAME(stash))
421 ? newSVhek(HvENAME_HEK(stash)
426 if(namesv && (AvFILLp(isa) == -1 || !sv_eq(*AvARRAY(isa), namesv)))
428 AV * const old = isa;
430 SV **ovp = AvARRAY(old);
431 SV * const * const oend = ovp + AvFILLp(old) + 1;
432 isa = (AV *)sv_2mortal((SV *)newAV());
433 av_extend(isa, AvFILLp(isa) = AvFILLp(old)+1);
434 *AvARRAY(isa) = namesv;
435 svp = AvARRAY(isa)+1;
436 while (ovp < oend) *svp++ = SvREFCNT_inc(*ovp++);
438 else SvREFCNT_dec(namesv);
442 HV *const isa_hash = newHV();
443 /* Linearisation didn't build it for us, so do it here. */
444 SV *const *svp = AvARRAY(isa);
445 SV *const *const svp_end = svp + AvFILLp(isa) + 1;
446 const HEK *canon_name = HvENAME_HEK(stash);
447 if (!canon_name) canon_name = HvNAME_HEK(stash);
449 while (svp < svp_end) {
450 (void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
453 (void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
454 HEK_LEN(canon_name), HEK_FLAGS(canon_name),
455 HV_FETCH_ISSTORE, &PL_sv_undef,
456 HEK_HASH(canon_name));
457 (void) hv_store(isa_hash, "UNIVERSAL", 9, &PL_sv_undef, 0);
459 SvREADONLY_on(isa_hash);
461 meta->isa = isa_hash;
468 =for apidoc mro_isa_changed_in
470 Takes the necessary steps (cache invalidations, mostly)
471 when the @ISA of the given package has changed. Invoked
472 by the C<setisa> magic, should not need to invoke directly.
477 /* Macro to avoid repeating the code five times. */
478 #define CLEAR_LINEAR(mEta) \
479 if (mEta->mro_linear_all) { \
480 SvREFCNT_dec(MUTABLE_SV(mEta->mro_linear_all)); \
481 mEta->mro_linear_all = NULL; \
482 /* This is just acting as a shortcut pointer. */ \
483 mEta->mro_linear_current = NULL; \
484 } else if (mEta->mro_linear_current) { \
485 /* Only the current MRO is stored, so this owns the data. */ \
486 SvREFCNT_dec(mEta->mro_linear_current); \
487 mEta->mro_linear_current = NULL; \
491 Perl_mro_isa_changed_in(pTHX_ HV* stash)
500 struct mro_meta * meta;
503 const char * const stashname = HvENAME_get(stash);
504 const STRLEN stashname_len = HvENAMELEN_get(stash);
505 const bool stashname_utf8 = HvENAMEUTF8(stash) ? 1 : 0;
507 PERL_ARGS_ASSERT_MRO_ISA_CHANGED_IN;
510 Perl_croak(aTHX_ "Can't call mro_isa_changed_in() on anonymous symbol table");
513 /* wipe out the cached linearizations for this stash */
514 meta = HvMROMETA(stash);
517 /* Steal it for our own purposes. */
518 isa = (HV *)sv_2mortal((SV *)meta->isa);
522 /* Inc the package generation, since our @ISA changed */
525 /* Wipe the global method cache if this package
526 is UNIVERSAL or one of its parents */
528 svp = hv_fetch(PL_isarev, stashname,
529 stashname_utf8 ? -(I32)stashname_len : (I32)stashname_len, 0);
530 isarev = svp ? MUTABLE_HV(*svp) : NULL;
532 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
533 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
537 else { /* Wipe the local method cache otherwise */
539 is_universal = FALSE;
542 /* wipe next::method cache too */
543 if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
545 /* Iterate the isarev (classes that are our children),
546 wiping out their linearization, method and isa caches
547 and upating PL_isarev. */
549 HV *isa_hashes = NULL;
551 /* We have to iterate through isarev twice to avoid a chicken and
552 * egg problem: if A inherits from B and both are in isarev, A might
553 * be processed before B and use B's previous linearisation.
556 /* First iteration: Wipe everything, but stash away the isa hashes
557 * since we still need them for updating PL_isarev.
560 if(hv_iterinit(isarev)) {
561 /* Only create the hash if we need it; i.e., if isarev has
563 isa_hashes = (HV *)sv_2mortal((SV *)newHV());
565 while((iter = hv_iternext(isarev))) {
566 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
567 struct mro_meta* revmeta;
569 if(!revstash) continue;
570 revmeta = HvMROMETA(revstash);
571 CLEAR_LINEAR(revmeta);
573 revmeta->cache_gen++;
574 if(revmeta->mro_nextmethod)
575 hv_clear(revmeta->mro_nextmethod);
579 isa_hashes, (const char*)&revstash, sizeof(HV *),
580 revmeta->isa ? (SV *)revmeta->isa : &PL_sv_undef, 0
585 /* Second pass: Update PL_isarev. We can just use isa_hashes to
586 * avoid another round of stash lookups. */
588 /* isarev might be deleted from PL_isarev during this loop, so hang
590 SvREFCNT_inc_simple_void_NN(sv_2mortal((SV *)isarev));
593 hv_iterinit(isa_hashes);
594 while((iter = hv_iternext(isa_hashes))) {
595 HV* const revstash = *(HV **)HEK_KEY(HeKEY_hek(iter));
596 HV * const isa = (HV *)HeVAL(iter);
599 /* We're starting at the 2nd element, skipping revstash */
600 linear_mro = mro_get_linear_isa(revstash);
601 svp = AvARRAY(linear_mro) + 1;
602 items = AvFILLp(linear_mro);
604 namehek = HvENAME_HEK(revstash);
605 if (!namehek) namehek = HvNAME_HEK(revstash);
608 SV* const sv = *svp++;
611 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
613 /* That fetch should not fail. But if it had to create
614 a new SV for us, then will need to upgrade it to an
615 HV (which sv_upgrade() can now do for us). */
617 mroisarev = MUTABLE_HV(HeVAL(he));
619 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
621 /* This hash only ever contains PL_sv_yes. Storing it
622 over itself is almost as cheap as calling hv_exists,
623 so on aggregate we expect to save time by not making
624 two calls to the common HV code for the case where
629 mroisarev, HEK_KEY(namehek),
630 HEK_UTF8(namehek) ? -HEK_LEN(namehek) : HEK_LEN(namehek),
635 if((SV *)isa != &PL_sv_undef)
637 isa, HEK_KEY(namehek), HEK_LEN(namehek),
638 HvMROMETA(revstash)->isa, (HEK_UTF8(namehek) ? SVf_UTF8 : 0)
644 /* Now iterate our MRO (parents), adding ourselves and everything from
645 our isarev to their isarev.
648 /* We're starting at the 2nd element, skipping ourselves here */
649 linear_mro = mro_get_linear_isa(stash);
650 svp = AvARRAY(linear_mro) + 1;
651 items = AvFILLp(linear_mro);
654 SV* const sv = *svp++;
657 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
659 /* That fetch should not fail. But if it had to create a new SV for
660 us, then will need to upgrade it to an HV (which sv_upgrade() can
663 mroisarev = MUTABLE_HV(HeVAL(he));
665 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
667 /* This hash only ever contains PL_sv_yes. Storing it over itself is
668 almost as cheap as calling hv_exists, so on aggregate we expect to
669 save time by not making two calls to the common HV code for the
670 case where it doesn't exist. */
672 (void)hv_store(mroisarev, stashname,
673 stashname_utf8 ? -(I32)stashname_len : (I32)stashname_len, &PL_sv_yes, 0);
676 /* Delete our name from our former parents' isarevs. */
677 if(isa && HvARRAY(isa))
678 mro_clean_isarev(isa, stashname, stashname_len, meta->isa,
679 (stashname_utf8 ? SVf_UTF8 : 0) );
682 /* Deletes name from all the isarev entries listed in isa */
684 S_mro_clean_isarev(pTHX_ HV * const isa, const char * const name,
685 const STRLEN len, HV * const exceptions, U32 flags)
689 PERL_ARGS_ASSERT_MRO_CLEAN_ISAREV;
691 /* Delete our name from our former parents' isarevs. */
692 if(isa && HvARRAY(isa) && hv_iterinit(isa)) {
694 while((iter = hv_iternext(isa))) {
696 const char * const key = hv_iterkey(iter, &klen);
697 if(exceptions && hv_exists(exceptions, key, HeKUTF8(iter) ? -klen : klen))
699 svp = hv_fetch(PL_isarev, key, HeKUTF8(iter) ? -klen : klen, 0);
701 HV * const isarev = (HV *)*svp;
702 (void)hv_delete(isarev, name, (flags & SVf_UTF8) ? -(I32)len : (I32)len, G_DISCARD);
703 if(!HvARRAY(isarev) || !HvUSEDKEYS(isarev))
704 (void)hv_delete(PL_isarev, key,
705 HeKUTF8(iter) ? -klen : klen, G_DISCARD);
712 =for apidoc mro_package_moved
714 Call this function to signal to a stash that it has been assigned to
715 another spot in the stash hierarchy. C<stash> is the stash that has been
716 assigned. C<oldstash> is the stash it replaces, if any. C<gv> is the glob
717 that is actually being assigned to.
719 This can also be called with a null first argument to
720 indicate that C<oldstash> has been deleted.
722 This function invalidates isa caches on the old stash, on all subpackages
723 nested inside it, and on the subclasses of all those, including
724 non-existent packages that have corresponding entries in C<stash>.
726 It also sets the effective names (C<HvENAME>) on all the stashes as
729 If the C<gv> is present and is not in the symbol table, then this function
730 simply returns. This checked will be skipped if C<flags & 1>.
735 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
736 const GV * const gv, U32 flags)
744 PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
745 assert(stash || oldstash);
747 /* Determine the name(s) of the location that stash was assigned to
748 * or from which oldstash was removed.
750 * We cannot reliably use the name in oldstash, because it may have
751 * been deleted from the location in the symbol table that its name
752 * suggests, as in this case:
754 * $globref = \*foo::bar::;
755 * Symbol::delete_package("foo");
756 * *$globref = \%baz::;
757 * *$globref = *frelp::;
758 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
760 * So we get it from the gv. But, since the gv may no longer be in the
761 * symbol table, we check that first. The only reliable way to tell is
762 * to see whether its stash has an effective name and whether the gv
763 * resides in that stash under its name. That effective name may be
764 * different from what gv_fullname4 would use.
765 * If flags & 1, the caller has asked us to skip the check.
770 !GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
771 !(svp = hv_fetch(GvSTASH(gv), GvNAME(gv),
772 GvNAMEUTF8(gv) ? -GvNAMELEN(gv) : GvNAMELEN(gv), 0)) ||
776 assert(SvOOK(GvSTASH(gv)));
777 assert(GvNAMELEN(gv));
778 assert(GvNAME(gv)[GvNAMELEN(gv) - 1] == ':');
779 assert(GvNAMELEN(gv) == 1 || GvNAME(gv)[GvNAMELEN(gv) - 2] == ':');
780 name_count = HvAUX(GvSTASH(gv))->xhv_name_count;
783 namep = &HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_name;
786 namep = HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_names;
787 if (name_count < 0) ++namep, name_count = -name_count - 1;
789 if (name_count == 1) {
790 if (HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)) {
791 namesv = GvNAMELEN(gv) == 1
792 ? newSVpvs_flags(":", SVs_TEMP)
793 : newSVpvs_flags("", SVs_TEMP);
796 namesv = sv_2mortal(newSVhek(*namep));
797 if (GvNAMELEN(gv) == 1) sv_catpvs(namesv, ":");
798 else sv_catpvs(namesv, "::");
800 if (GvNAMELEN(gv) != 1) {
802 namesv, GvNAME(gv), GvNAMELEN(gv) - 2,
803 /* skip trailing :: */
804 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
810 namesv = sv_2mortal((SV *)newAV());
811 while (name_count--) {
812 if(HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)){
813 aname = GvNAMELEN(gv) == 1
819 aname = newSVhek(*namep++);
820 if (GvNAMELEN(gv) == 1) sv_catpvs(aname, ":");
821 else sv_catpvs(aname, "::");
823 if (GvNAMELEN(gv) != 1) {
825 aname, GvNAME(gv), GvNAMELEN(gv) - 2,
826 /* skip trailing :: */
827 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
830 av_push((AV *)namesv, aname);
834 /* Get a list of all the affected classes. */
835 /* We cannot simply pass them all to mro_isa_changed_in to avoid
836 the list, as that function assumes that only one package has
837 changed. It does not work with:
839 @foo::ISA = qw( B B::B );
840 *B:: = delete $::{"A::"};
842 as neither B nor B::B can be updated before the other, since they
843 will reset caches on foo, which will see either B or B::B with the
844 wrong name. The names must be set on *all* affected stashes before
845 we do anything else. (And linearisations must be cleared, too.)
847 stashes = (HV *) sv_2mortal((SV *)newHV());
848 mro_gather_and_rename(
849 stashes, (HV *) sv_2mortal((SV *)newHV()),
850 stash, oldstash, namesv
853 /* Once the caches have been wiped on all the classes, call
854 mro_isa_changed_in on each. */
855 hv_iterinit(stashes);
856 while((iter = hv_iternext(stashes))) {
857 HV * const stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
859 /* We have to restore the original meta->isa (that
860 mro_gather_and_rename set aside for us) this way, in case
861 one class in this list is a superclass of a another class
862 that we have already encountered. In such a case, meta->isa
863 will have been overwritten without old entries being deleted
865 struct mro_meta * const meta = HvMROMETA(stash);
866 if(meta->isa != (HV *)HeVAL(iter)){
867 SvREFCNT_dec(meta->isa);
869 = HeVAL(iter) == &PL_sv_yes
872 HeVAL(iter) = NULL; /* We donated our reference count. */
874 mro_isa_changed_in(stash);
880 S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
881 HV *stash, HV *oldstash, SV *namesv)
887 const bool stash_had_name = stash && HvENAME(stash);
888 bool fetched_isarev = FALSE;
893 PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
895 /* We use the seen_stashes hash to keep track of which packages have
896 been encountered so far. This must be separate from the main list of
897 stashes, as we need to distinguish between stashes being assigned
898 and stashes being replaced/deleted. (A nested stash can be on both
899 sides of an assignment. We cannot simply skip iterating through a
900 stash on the right if we have seen it on the left, as it will not
901 get its ename assigned to it.)
903 To avoid allocating extra SVs, instead of a bitfield we can make
904 bizarre use of immortals:
906 &PL_sv_undef: seen on the left (oldstash)
907 &PL_sv_no : seen on the right (stash)
908 &PL_sv_yes : seen on both sides
913 /* Add to the big list. */
914 struct mro_meta * meta;
918 seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
919 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
921 if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
926 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
927 meta = HvMROMETA(oldstash);
930 stashes, (const char *)&oldstash, sizeof(HV *),
932 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
938 /* Update the effective name. */
939 if(HvENAME_get(oldstash)) {
940 const HEK * const enamehek = HvENAME_HEK(oldstash);
941 if(SvTYPE(namesv) == SVt_PVAV) {
942 items = AvFILLp((AV *)namesv) + 1;
943 svp = AvARRAY((AV *)namesv);
950 const U32 name_utf8 = SvUTF8(*svp);
952 const char *name = SvPVx_const(*svp++, len);
954 (void)hv_delete(PL_stashcache, name, name_utf8 ? -(I32)len : (I32)len, G_DISCARD);
955 hv_ename_delete(oldstash, name, len, name_utf8);
957 if (!fetched_isarev) {
958 /* If the name deletion caused a name change, then we
959 * are not going to call mro_isa_changed_in with this
960 * name (and not at all if it has become anonymous) so
961 * we need to delete old isarev entries here, both
962 * those in the superclasses and this class's own list
963 * of subclasses. We simply delete the latter from
964 * PL_isarev, since we still need it. hv_delete morti-
965 * fies it for us, so sv_2mortal is not necessary. */
966 if(HvENAME_HEK(oldstash) != enamehek) {
967 if(meta->isa && HvARRAY(meta->isa))
968 mro_clean_isarev(meta->isa, name, len, 0, name_utf8);
969 isarev = (HV *)hv_delete(PL_isarev, name,
970 name_utf8 ? -(I32)len : (I32)len, 0);
979 if(SvTYPE(namesv) == SVt_PVAV) {
980 items = AvFILLp((AV *)namesv) + 1;
981 svp = AvARRAY((AV *)namesv);
988 const U32 name_utf8 = SvUTF8(*svp);
990 const char *name = SvPVx_const(*svp++, len);
991 hv_ename_add(stash, name, len, name_utf8);
994 /* Add it to the big list if it needs
995 * mro_isa_changed_in called on it. That happens if it was
996 * detached from the symbol table (so it had no HvENAME) before
997 * being assigned to the spot named by the 'name' variable, because
998 * its cached isa linearisation is now stale (the effective name
999 * having changed), and subclasses will then use that cache when
1000 * mro_package_moved calls mro_isa_changed_in. (See
1003 * If it did have a name, then its previous name is still
1004 * used in isa caches, and there is no need for
1005 * mro_package_moved to call mro_isa_changed_in.
1011 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
1012 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
1014 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
1018 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
1021 struct mro_meta * const meta = HvMROMETA(stash);
1024 stashes, (const char *)&stash, sizeof(HV *),
1026 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1035 if(!stash && !oldstash)
1036 /* Both stashes have been encountered already. */
1039 /* Add all the subclasses to the big list. */
1040 if(!fetched_isarev) {
1041 /* If oldstash is not null, then we can use its HvENAME to look up
1042 the isarev hash, since all its subclasses will be listed there.
1043 It will always have an HvENAME. It the HvENAME was removed
1044 above, then fetch_isarev will be true, and this code will not be
1047 If oldstash is null, then this is an empty spot with no stash in
1048 it, so subclasses could be listed in isarev hashes belonging to
1049 any of the names, so we have to check all of them.
1051 assert(!oldstash || HvENAME(oldstash));
1053 /* Extra variable to avoid a compiler warning */
1054 char * const hvename = HvENAME(oldstash);
1055 fetched_isarev = TRUE;
1056 svp = hv_fetch(PL_isarev, hvename,
1057 HvENAMEUTF8(oldstash)
1058 ? -HvENAMELEN_get(oldstash)
1059 : HvENAMELEN_get(oldstash), 0);
1060 if (svp) isarev = MUTABLE_HV(*svp);
1062 else if(SvTYPE(namesv) == SVt_PVAV) {
1063 items = AvFILLp((AV *)namesv) + 1;
1064 svp = AvARRAY((AV *)namesv);
1072 isarev || !fetched_isarev
1074 while (fetched_isarev || items--) {
1077 if (!fetched_isarev) {
1078 HE * const he = hv_fetch_ent(PL_isarev, *svp++, 0, 0);
1079 if (!he || !(isarev = MUTABLE_HV(HeVAL(he)))) continue;
1082 hv_iterinit(isarev);
1083 while((iter = hv_iternext(isarev))) {
1084 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1085 struct mro_meta * meta;
1087 if(!revstash) continue;
1088 meta = HvMROMETA(revstash);
1091 stashes, (const char *)&revstash, sizeof(HV *),
1093 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1100 if (fetched_isarev) break;
1104 /* This is partly based on code in hv_iternext_flags. We are not call-
1105 ing that here, as we want to avoid resetting the hash iterator. */
1107 /* Skip the entire loop if the hash is empty. */
1108 if(oldstash && HvUSEDKEYS(oldstash)) {
1109 xhv = (XPVHV*)SvANY(oldstash);
1110 seen = (HV *) sv_2mortal((SV *)newHV());
1112 /* Iterate through entries in the oldstash, adding them to the
1113 list, meanwhile doing the equivalent of $seen{$key} = 1.
1116 while (++riter <= (I32)xhv->xhv_max) {
1117 entry = (HvARRAY(oldstash))[riter];
1119 /* Iterate through the entries in this list */
1120 for(; entry; entry = HeNEXT(entry)) {
1124 /* If this entry is not a glob, ignore it.
1126 if (!isGV(HeVAL(entry))) continue;
1128 key = hv_iterkey(entry, &len);
1129 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1130 || (len == 1 && key[0] == ':')) {
1131 HV * const oldsubstash = GvHV(HeVAL(entry));
1132 SV ** const stashentry
1133 = stash ? hv_fetch(stash, key, HeUTF8(entry) ? -(I32)len : (I32)len, 0) : NULL;
1134 HV *substash = NULL;
1136 /* Avoid main::main::main::... */
1137 if(oldsubstash == oldstash) continue;
1141 stashentry && *stashentry
1142 && (substash = GvHV(*stashentry))
1144 || (oldsubstash && HvENAME_get(oldsubstash))
1147 /* Add :: and the key (minus the trailing ::)
1150 if(SvTYPE(namesv) == SVt_PVAV) {
1152 items = AvFILLp((AV *)namesv) + 1;
1153 svp = AvARRAY((AV *)namesv);
1154 subname = sv_2mortal((SV *)newAV());
1156 aname = newSVsv(*svp++);
1158 sv_catpvs(aname, ":");
1160 sv_catpvs(aname, "::");
1164 ? SV_CATUTF8 : SV_CATBYTES
1167 av_push((AV *)subname, aname);
1171 subname = sv_2mortal(newSVsv(namesv));
1172 if (len == 1) sv_catpvs(subname, ":");
1174 sv_catpvs(subname, "::");
1176 subname, key, len-2,
1177 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1181 mro_gather_and_rename(
1182 stashes, seen_stashes,
1183 substash, oldsubstash, subname
1187 (void)hv_store(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len, &PL_sv_yes, 0);
1193 /* Skip the entire loop if the hash is empty. */
1194 if (stash && HvUSEDKEYS(stash)) {
1195 xhv = (XPVHV*)SvANY(stash);
1198 /* Iterate through the new stash, skipping $seen{$key} items,
1199 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1200 while (++riter <= (I32)xhv->xhv_max) {
1201 entry = (HvARRAY(stash))[riter];
1203 /* Iterate through the entries in this list */
1204 for(; entry; entry = HeNEXT(entry)) {
1208 /* If this entry is not a glob, ignore it.
1210 if (!isGV(HeVAL(entry))) continue;
1212 key = hv_iterkey(entry, &len);
1213 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1214 || (len == 1 && key[0] == ':')) {
1217 /* If this entry was seen when we iterated through the
1218 oldstash, skip it. */
1219 if(seen && hv_exists(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len)) continue;
1221 /* We get here only if this stash has no corresponding
1222 entry in the stash being replaced. */
1224 substash = GvHV(HeVAL(entry));
1228 /* Avoid checking main::main::main::... */
1229 if(substash == stash) continue;
1231 /* Add :: and the key (minus the trailing ::)
1233 if(SvTYPE(namesv) == SVt_PVAV) {
1235 items = AvFILLp((AV *)namesv) + 1;
1236 svp = AvARRAY((AV *)namesv);
1237 subname = sv_2mortal((SV *)newAV());
1239 aname = newSVsv(*svp++);
1241 sv_catpvs(aname, ":");
1243 sv_catpvs(aname, "::");
1247 ? SV_CATUTF8 : SV_CATBYTES
1250 av_push((AV *)subname, aname);
1254 subname = sv_2mortal(newSVsv(namesv));
1255 if (len == 1) sv_catpvs(subname, ":");
1257 sv_catpvs(subname, "::");
1259 subname, key, len-2,
1260 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1264 mro_gather_and_rename(
1265 stashes, seen_stashes,
1266 substash, NULL, subname
1276 =for apidoc mro_method_changed_in
1278 Invalidates method caching on any child classes
1279 of the given stash, so that they might notice
1280 the changes in this one.
1282 Ideally, all instances of C<PL_sub_generation++> in
1283 perl source outside of F<mro.c> should be
1284 replaced by calls to this.
1286 Perl automatically handles most of the common
1287 ways a method might be redefined. However, there
1288 are a few ways you could change a method in a stash
1289 without the cache code noticing, in which case you
1290 need to call this method afterwards:
1292 1) Directly manipulating the stash HV entries from
1295 2) Assigning a reference to a readonly scalar
1296 constant into a stash entry in order to create
1297 a constant subroutine (like constant.pm
1300 This same method is available from pure perl
1301 via, C<mro::method_changed_in(classname)>.
1306 Perl_mro_method_changed_in(pTHX_ HV *stash)
1308 const char * const stashname = HvENAME_get(stash);
1309 const STRLEN stashname_len = HvENAMELEN_get(stash);
1310 const bool stashname_utf8 = HvENAMEUTF8(stash) ? 1 : 0;
1312 SV ** const svp = hv_fetch(PL_isarev, stashname,
1313 stashname_utf8 ? -(I32)stashname_len : (I32)stashname_len, 0);
1314 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1316 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1319 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1321 /* Inc the package generation, since a local method changed */
1322 HvMROMETA(stash)->pkg_gen++;
1324 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1325 invalidate all method caches globally */
1326 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
1327 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
1328 PL_sub_generation++;
1332 /* else, invalidate the method caches of all child classes,
1337 hv_iterinit(isarev);
1338 while((iter = hv_iternext(isarev))) {
1339 HV* const revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1340 struct mro_meta* mrometa;
1342 if(!revstash) continue;
1343 mrometa = HvMROMETA(revstash);
1344 mrometa->cache_gen++;
1345 if(mrometa->mro_nextmethod)
1346 hv_clear(mrometa->mro_nextmethod);
1352 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1354 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1356 PERL_ARGS_ASSERT_MRO_SET_MRO;
1359 Perl_croak(aTHX_ "Invalid mro name: '%"SVf"'", name);
1361 if(meta->mro_which != which) {
1362 if (meta->mro_linear_current && !meta->mro_linear_all) {
1363 /* If we were storing something directly, put it in the hash before
1365 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1366 MUTABLE_SV(meta->mro_linear_current));
1368 meta->mro_which = which;
1369 /* Scrub our cached pointer to the private data. */
1370 meta->mro_linear_current = NULL;
1371 /* Only affects local method cache, not
1372 even child classes */
1374 if(meta->mro_nextmethod)
1375 hv_clear(meta->mro_nextmethod);
1381 XS(XS_mro_method_changed_in);
1384 Perl_boot_core_mro(pTHX)
1387 static const char file[] = __FILE__;
1389 Perl_mro_register(aTHX_ &dfs_alg);
1391 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1394 XS(XS_mro_method_changed_in)
1402 croak_xs_usage(cv, "classname");
1406 class_stash = gv_stashsv(classname, 0);
1407 if(!class_stash) Perl_croak(aTHX_ "No such class: '%"SVf"'!", SVfARG(classname));
1409 mro_method_changed_in(class_stash);
1416 * c-indentation-style: bsd
1418 * indent-tabs-mode: t
1421 * ex: set ts=8 sts=4 sw=4 noet: