1 -*- buffer-read-only: t -*-
3 !!!!!!! DO NOT EDIT THIS FILE !!!!!!!
4 This file is built by autodoc.pl extracting documentation from the C source
9 perlintern - autogenerated documentation of purely B<internal>
13 X<internal Perl functions> X<interpreter functions>
15 This file is the autogenerated documentation of functions in the
16 Perl interpreter that are documented using Perl's internal documentation
17 format but are not marked as part of the Perl API. In other words,
18 B<they are not for use in extensions>!
21 =head1 CV reference counts and CvOUTSIDE
28 Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
29 CV (if any). Because pointers to anonymous sub prototypes are
30 stored in C<&> pad slots, it is a possible to get a circular reference,
31 with the parent pointing to the child and vice-versa. To avoid the
32 ensuing memory leak, we do not increment the reference count of the CV
33 pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
34 has a C<&> pad slot pointing back to us. In this case, we set the
35 C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
36 circumstances we should decrement the refcount of the parent when freeing
39 There is a further complication with non-closure anonymous subs (i.e. those
40 that do not refer to any lexicals outside that sub). In this case, the
41 anonymous prototype is shared rather than being cloned. This has the
42 consequence that the parent may be freed while there are still active
45 BEGIN { $a = sub { eval '$x' } }
47 In this case, the BEGIN is freed immediately after execution since there
48 are no active references to it: the anon sub prototype has
49 C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
50 CV, so it doesn't contribute to BEGIN's refcount either. When $a is
51 executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
52 and the freed BEGIN is accessed.
54 To avoid this, whenever a CV and its associated pad is freed, any
55 C<&> entries in the pad are explicitly removed from the pad, and if the
56 refcount of the pointed-to anon sub is still positive, then that
57 child's C<CvOUTSIDE> is set to point to its grandparent. This will only
58 occur in the single specific case of a non-closure anon prototype
59 having one or more active references (such as C<$a> above).
61 One other thing to consider is that a CV may be merely undefined
62 rather than freed, eg C<undef &foo>. In this case, its refcount may
63 not have reached zero, but we still delete its pad and its C<CvROOT> etc.
64 Since various children may still have their C<CvOUTSIDE> pointing at this
65 undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
66 the chain of lexical scopes is unbroken. For example, the following
70 sub tmp { sub { eval '$x' } }
75 bool CvWEAKOUTSIDE(CV *cv)
83 =head1 Functions in file pad.h
91 Save the current pad in the given context block structure.
93 void CX_CURPAD_SAVE(struct context)
101 Access the SV at offset po in the saved current pad in the given
102 context block structure (can be used as an lvalue).
104 SV * CX_CURPAD_SV(struct context, PADOFFSET po)
112 Get the value from slot C<po> in the base (DEPTH=1) pad of a padlist
114 SV * PAD_BASE_SV(PADLIST padlist, PADOFFSET po)
123 Clone the state variables associated with running and compiling pads.
125 void PAD_CLONE_VARS(PerlInterpreter *proto_perl \)
130 =item PAD_COMPNAME_FLAGS
131 X<PAD_COMPNAME_FLAGS>
133 Return the flags for the current compiling pad name
134 at offset C<po>. Assumes a valid slot entry.
136 U32 PAD_COMPNAME_FLAGS(PADOFFSET po)
141 =item PAD_COMPNAME_GEN
144 The generation number of the name at offset C<po> in the current
145 compiling pad (lvalue). Note that C<SvUVX> is hijacked for this purpose.
147 STRLEN PAD_COMPNAME_GEN(PADOFFSET po)
152 =item PAD_COMPNAME_GEN_set
153 X<PAD_COMPNAME_GEN_set>
155 Sets the generation number of the name at offset C<po> in the current
156 ling pad (lvalue) to C<gen>. Note that C<SvUV_set> is hijacked for this purpose.
158 STRLEN PAD_COMPNAME_GEN_set(PADOFFSET po, int gen)
163 =item PAD_COMPNAME_OURSTASH
164 X<PAD_COMPNAME_OURSTASH>
166 Return the stash associated with an C<our> variable.
167 Assumes the slot entry is a valid C<our> lexical.
169 HV * PAD_COMPNAME_OURSTASH(PADOFFSET po)
174 =item PAD_COMPNAME_PV
177 Return the name of the current compiling pad name
178 at offset C<po>. Assumes a valid slot entry.
180 char * PAD_COMPNAME_PV(PADOFFSET po)
185 =item PAD_COMPNAME_TYPE
188 Return the type (stash) of the current compiling pad name at offset
189 C<po>. Must be a valid name. Returns null if not typed.
191 HV * PAD_COMPNAME_TYPE(PADOFFSET po)
201 void PAD_DUP(PADLIST dstpad, PADLIST srcpad, CLONE_PARAMS* param)
206 =item PAD_RESTORE_LOCAL
209 Restore the old pad saved into the local variable opad by PAD_SAVE_LOCAL()
211 void PAD_RESTORE_LOCAL(PAD *opad)
219 Save the current pad to the local variable opad, then make the
220 current pad equal to npad
222 void PAD_SAVE_LOCAL(PAD *opad, PAD *npad)
227 =item PAD_SAVE_SETNULLPAD
228 X<PAD_SAVE_SETNULLPAD>
230 Save the current pad then set it to null.
232 void PAD_SAVE_SETNULLPAD()
240 Set the slot at offset C<po> in the current pad to C<sv>
242 SV * PAD_SETSV(PADOFFSET po, SV* sv)
250 Set the current pad to be pad C<n> in the padlist, saving
251 the previous current pad. NB currently this macro expands to a string too
252 long for some compilers, so it's best to replace it with
255 PAD_SET_CUR_NOSAVE(padlist,n);
258 void PAD_SET_CUR(PADLIST padlist, I32 n)
263 =item PAD_SET_CUR_NOSAVE
264 X<PAD_SET_CUR_NOSAVE>
266 like PAD_SET_CUR, but without the save
268 void PAD_SET_CUR_NOSAVE(PADLIST padlist, I32 n)
276 Get the value at offset C<po> in the current pad
278 void PAD_SV(PADOFFSET po)
286 Lightweight and lvalue version of C<PAD_SV>.
287 Get or set the value at offset C<po> in the current pad.
288 Unlike C<PAD_SV>, does not print diagnostics with -DX.
289 For internal use only.
291 SV * PAD_SVl(PADOFFSET po)
299 Clear the pointed to pad value on scope exit. (i.e. the runtime action of 'my')
301 void SAVECLEARSV(SV **svp)
309 save PL_comppad and PL_curpad
323 Save a pad slot (used to restore after an iteration)
325 XXX DAPM it would make more sense to make the arg a PADOFFSET
326 void SAVEPADSV(PADOFFSET po)
341 Returns C<TRUE> if given the name of a magical GV.
343 Currently only useful internally when determining if a GV should be
344 created even in rvalue contexts.
346 C<flags> is not used at present but available for future extension to
347 allow selecting particular classes of magical variable.
349 Currently assumes that C<name> is NUL terminated (as well as len being valid).
350 This assumption is met by all callers within the perl core, which all pass
351 pointers returned by SvPV.
353 bool is_gv_magical(const char *name, STRLEN len, U32 flags)
358 =item is_gv_magical_sv
361 Returns C<TRUE> if given the name of a magical GV. Calls is_gv_magical.
363 bool is_gv_magical_sv(SV *name, U32 flags)
371 =head1 Hash Manipulation Functions
375 =item refcounted_he_chain_2hv
376 X<refcounted_he_chain_2hv>
378 Generates and returns a C<HV *> by walking up the tree starting at the passed
379 in C<struct refcounted_he *>.
381 HV * refcounted_he_chain_2hv(const struct refcounted_he *c)
386 =item refcounted_he_free
387 X<refcounted_he_free>
389 Decrements the reference count of the passed in C<struct refcounted_he *>
390 by one. If the reference count reaches zero the structure's memory is freed,
391 and C<refcounted_he_free> iterates onto the parent node.
393 void refcounted_he_free(struct refcounted_he *he)
398 =item refcounted_he_new
401 Creates a new C<struct refcounted_he>. As S<key> is copied, and value is
402 stored in a compact form, all references remain the property of the caller.
403 The C<struct refcounted_he> is returned with a reference count of 1.
405 struct refcounted_he * refcounted_he_new(struct refcounted_he *const parent, SV *const key, SV *const value)
420 Function called by C<do_readline> to spawn a glob (or do the glob inside
421 perl on VMS). This code used to be inline, but now perl uses C<File::Glob>
422 this glob starter is only used by miniperl during the build process.
423 Moving it away shrinks pp_hot.c; shrinking pp_hot.c helps speed perl up.
425 PerlIO* start_glob(SV* pattern, IO *io)
433 =head1 Magical Functions
440 Triggered by a delete from %^H, records the key to
441 C<PL_compiling.cop_hints_hash>.
443 int magic_sethint(SV* sv, MAGIC* mg)
451 Copy some of the magic from an existing SV to new localized version of
452 that SV. Container magic (eg %ENV, $1, tie) gets copied, value magic
453 doesn't (eg taint, pos).
455 void mg_localize(SV* sv, SV* nsv)
467 =item mro_get_linear_isa_c3
468 X<mro_get_linear_isa_c3>
470 Returns the C3 linearization of @ISA
471 the given stash. The return value is a read-only AV*.
472 C<level> should be 0 (it is used internally in this
473 function's recursion).
475 You are responsible for C<SvREFCNT_inc()> on the
476 return value if you plan to store it anywhere
477 semi-permanently (otherwise it might be deleted
478 out from under you the next time the cache is
481 AV* mro_get_linear_isa_c3(HV* stash, I32 level)
486 =item mro_get_linear_isa_dfs
487 X<mro_get_linear_isa_dfs>
489 Returns the Depth-First Search linearization of @ISA
490 the given stash. The return value is a read-only AV*.
491 C<level> should be 0 (it is used internally in this
492 function's recursion).
494 You are responsible for C<SvREFCNT_inc()> on the
495 return value if you plan to store it anywhere
496 semi-permanently (otherwise it might be deleted
497 out from under you the next time the cache is
500 AV* mro_get_linear_isa_dfs(HV* stash, I32 level)
505 =item mro_isa_changed_in
506 X<mro_isa_changed_in>
508 Takes the necessary steps (cache invalidations, mostly)
509 when the @ISA of the given package has changed. Invoked
510 by the C<setisa> magic, should not need to invoke directly.
512 void mro_isa_changed_in(HV* stash)
520 =head1 Pad Data Structures
527 CV's can have CvPADLIST(cv) set to point to an AV.
529 For these purposes "forms" are a kind-of CV, eval""s are too (except they're
530 not callable at will and are always thrown away after the eval"" is done
531 executing). Require'd files are simply evals without any outer lexical
534 XSUBs don't have CvPADLIST set - dXSTARG fetches values from PL_curpad,
535 but that is really the callers pad (a slot of which is allocated by
538 The CvPADLIST AV has does not have AvREAL set, so REFCNT of component items
539 is managed "manual" (mostly in pad.c) rather than normal av.c rules.
540 The items in the AV are not SVs as for a normal AV, but other AVs:
542 0'th Entry of the CvPADLIST is an AV which represents the "names" or rather
543 the "static type information" for lexicals.
545 The CvDEPTH'th entry of CvPADLIST AV is an AV which is the stack frame at that
546 depth of recursion into the CV.
547 The 0'th slot of a frame AV is an AV which is @_.
548 other entries are storage for variables and op targets.
551 C<PL_comppad_name> is set to the names AV.
552 C<PL_comppad> is set to the frame AV for the frame CvDEPTH == 1.
553 C<PL_curpad> is set to the body of the frame AV (i.e. AvARRAY(PL_comppad)).
555 During execution, C<PL_comppad> and C<PL_curpad> refer to the live
556 frame of the currently executing sub.
558 Iterating over the names AV iterates over all possible pad
559 items. Pad slots that are SVs_PADTMP (targets/GVs/constants) end up having
560 &PL_sv_undef "names" (see pad_alloc()).
562 Only my/our variable (SVs_PADMY/SVs_PADOUR) slots get valid names.
563 The rest are op targets/GVs/constants which are statically allocated
564 or resolved at compile time. These don't have names by which they
565 can be looked up from Perl code at run time through eval"" like
566 my/our variables can be. Since they can't be looked up by "name"
567 but only by their index allocated at compile time (which is usually
568 in PL_op->op_targ), wasting a name SV for them doesn't make sense.
570 The SVs in the names AV have their PV being the name of the variable.
571 xlow+1..xhigh inclusive in the NV union is a range of cop_seq numbers for
572 which the name is valid. For typed lexicals name SV is SVt_PVMG and SvSTASH
573 points at the type. For C<our> lexicals, the type is also SVt_PVMG, with the
574 SvOURSTASH slot pointing at the stash of the associated global (so that
575 duplicate C<our> declarations in the same package can be detected). SvUVX is
576 sometimes hijacked to store the generation number during compilation.
578 If SvFAKE is set on the name SV, then that slot in the frame AV is
579 a REFCNT'ed reference to a lexical from "outside". In this case,
580 the name SV does not use xlow and xhigh to store a cop_seq range, since it is
581 in scope throughout. Instead xhigh stores some flags containing info about
582 the real lexical (is it declared in an anon, and is it capable of being
583 instantiated multiple times?), and for fake ANONs, xlow contains the index
584 within the parent's pad where the lexical's value is stored, to make
587 If the 'name' is '&' the corresponding entry in frame AV
588 is a CV representing a possible closure.
589 (SvFAKE and name of '&' is not a meaningful combination currently but could
590 become so if C<my sub foo {}> is implemented.)
592 Note that formats are treated as anon subs, and are cloned each time
593 write is called (if necessary).
595 The flag SVf_PADSTALE is cleared on lexicals each time the my() is executed,
596 and set on scope exit. This allows the 'Variable $x is not available' warning
597 to be generated in evals, such as
599 { my $x = 1; sub f { eval '$x'} } f();
601 AV * CvPADLIST(CV *cv)
609 Clone a CV: make a new CV which points to the same code etc, but which
610 has a newly-created pad built by copying the prototype pad and capturing
613 CV* cv_clone(CV* proto)
621 dump the contents of a CV
623 void cv_dump(const CV *cv, const char *title)
631 Dump the contents of a padlist
633 void do_dump_pad(I32 level, PerlIO *file, PADLIST *padlist, int full)
641 "Introduce" my variables to visible status.
651 Add an anon code entry to the current compiling pad
653 PADOFFSET pad_add_anon(SV* sv, OPCODE op_type)
661 Create a new name and associated PADMY SV in the current pad; return the
663 If C<typestash> is valid, the name is for a typed lexical; set the
664 name's stash to that value.
665 If C<ourstash> is valid, it's an our lexical, set the name's
666 SvOURSTASH to that value
668 If fake, it means we're cloning an existing entry
670 PADOFFSET pad_add_name(const char *name, HV* typestash, HV* ourstash, bool clone, bool state)
678 Allocate a new my or tmp pad entry. For a my, simply push a null SV onto
679 the end of PL_comppad, but for a tmp, scan the pad from PL_padix upwards
680 for a slot which has no name and no active value.
682 PADOFFSET pad_alloc(I32 optype, U32 tmptype)
687 =item pad_block_start
690 Update the pad compilation state variables on entry to a new block
692 void pad_block_start(int full)
700 Check for duplicate declarations: report any of:
701 * a my in the current scope with the same name;
702 * an our (anywhere in the pad) with the same name and the same stash
704 C<is_our> indicates that the name to check is an 'our' declaration
706 void pad_check_dup(const char* name, bool is_our, const HV* ourstash)
714 Find a named lexical anywhere in a chain of nested pads. Add fake entries
715 in the inner pads if it's found in an outer one.
717 Returns the offset in the bottom pad of the lex or the fake lex.
718 cv is the CV in which to start the search, and seq is the current cop_seq
719 to match against. If warn is true, print appropriate warnings. The out_*
720 vars return values, and so are pointers to where the returned values
721 should be stored. out_capture, if non-null, requests that the innermost
722 instance of the lexical is captured; out_name_sv is set to the innermost
723 matched namesv or fake namesv; out_flags returns the flags normally
724 associated with the IVX field of a fake namesv.
726 Note that pad_findlex() is recursive; it recurses up the chain of CVs,
727 then comes back down, adding fake entries as it goes. It has to be this way
728 because fake namesvs in anon protoypes have to store in xlow the index into
731 PADOFFSET pad_findlex(const char *name, const CV* cv, U32 seq, int warn, SV** out_capture, SV** out_name_sv, int *out_flags)
739 Given a lexical name, try to find its offset, first in the current pad,
740 or failing that, in the pads of any lexically enclosing subs (including
741 the complications introduced by eval). If the name is found in an outer pad,
742 then a fake entry is added to the current pad.
743 Returns the offset in the current pad, or NOT_IN_PAD on failure.
745 PADOFFSET pad_findmy(const char* name)
750 =item pad_fixup_inner_anons
751 X<pad_fixup_inner_anons>
753 For any anon CVs in the pad, change CvOUTSIDE of that CV from
754 old_cv to new_cv if necessary. Needed when a newly-compiled CV has to be
755 moved to a pre-existing CV struct.
757 void pad_fixup_inner_anons(PADLIST *padlist, CV *old_cv, CV *new_cv)
765 Free the SV at offset po in the current pad.
767 void pad_free(PADOFFSET po)
775 Cleanup at end of scope during compilation: set the max seq number for
776 lexicals in this scope and warn of any lexicals that never got introduced.
786 Create a new compiling padlist, saving and updating the various global
787 vars at the same time as creating the pad itself. The following flags
788 can be OR'ed together:
790 padnew_CLONE this pad is for a cloned CV
791 padnew_SAVE save old globals
792 padnew_SAVESUB also save extra stuff for start of sub
794 PADLIST* pad_new(int flags)
802 Push a new pad frame onto the padlist, unless there's already a pad at
803 this depth, in which case don't bother creating a new one. Then give
804 the new pad an @_ in slot zero.
806 void pad_push(PADLIST *padlist, int depth)
814 Mark all the current temporaries for reuse
824 Set the entry at offset po in the current pad to sv.
825 Use the macro PAD_SETSV() rather than calling this function directly.
827 void pad_setsv(PADOFFSET po, SV* sv)
835 Abandon the tmp in the current pad at offset po and replace with a
838 void pad_swipe(PADOFFSET po, bool refadjust)
846 Tidy up a pad after we've finished compiling it:
847 * remove most stuff from the pads of anonsub prototypes;
851 void pad_tidy(padtidy_type type)
859 Free the padlist associated with a CV.
860 If parts of it happen to be current, we null the relevant
861 PL_*pad* global vars so that we don't have any dangling references left.
862 We also repoint the CvOUTSIDE of any about-to-be-orphaned
863 inner subs to the outer of this cv.
865 (This function should really be called pad_free, but the name was already
868 void pad_undef(CV* cv)
876 =head1 Per-Interpreter Variables
883 When Perl is run in debugging mode, with the B<-d> switch, this SV is a
884 boolean which indicates whether subs are being single-stepped.
885 Single-stepping is automatically turned on after every step. This is the C
886 variable which corresponds to Perl's $DB::single variable. See
892 Found in file intrpvar.h
897 When Perl is run in debugging mode, with the B<-d> switch, this GV contains
898 the SV which holds the name of the sub being debugged. This is the C
899 variable which corresponds to Perl's $DB::sub variable. See
905 Found in file intrpvar.h
910 Trace variable used when Perl is run in debugging mode, with the B<-d>
911 switch. This is the C variable which corresponds to Perl's $DB::trace
912 variable. See C<PL_DBsingle>.
917 Found in file intrpvar.h
922 The C variable which corresponds to Perl's $^W warning variable.
927 Found in file intrpvar.h
932 The GV which was last used for a filehandle input operation. (C<< <FH> >>)
937 Found in file intrpvar.h
942 The output field separator - C<$,> in Perl space.
947 Found in file intrpvar.h
952 The input record separator - C<$/> in Perl space.
957 Found in file intrpvar.h
962 =head1 Stack Manipulation Macros
969 Declare Just C<SP>. This is actually identical to C<dSP>, and declares
970 a local copy of perl's stack pointer, available via the C<SP> macro.
971 See C<SP>. (Available for backward source code compatibility with the
972 old (Perl 5.005) thread model.)
982 True if this op will be the return value of an lvalue subroutine
990 =head1 SV Manipulation Functions
997 Given a chunk of memory, link it to the head of the list of arenas,
998 and split it into a list of free SVs.
1000 void sv_add_arena(char* ptr, U32 size, U32 flags)
1008 Decrement the refcnt of each remaining SV, possibly triggering a
1009 cleanup. This function may have to be called multiple times to free
1010 SVs which are in complex self-referential hierarchies.
1020 Attempt to destroy all objects not yet freed
1022 void sv_clean_objs()
1027 =item sv_free_arenas
1030 Deallocate the memory used by all arenas. Note that all the individual SV
1031 heads and bodies within the arenas must already have been freed.
1033 void sv_free_arenas()
1041 =head1 Unicode Support
1045 =item find_uninit_var
1048 Find the name of the undefined variable (if any) that caused the operator o
1049 to issue a "Use of uninitialized value" warning.
1050 If match is true, only return a name if it's value matches uninit_sv.
1051 So roughly speaking, if a unary operator (such as OP_COS) generates a
1052 warning, then following the direct child of the op may yield an
1053 OP_PADSV or OP_GV that gives the name of the undefined variable. On the
1054 other hand, with OP_ADD there are two branches to follow, so we only print
1055 the variable name if we get an exact match.
1057 The name is returned as a mortal SV.
1059 Assumes that PL_op is the op that originally triggered the error, and that
1060 PL_comppad/PL_curpad points to the currently executing pad.
1062 SV* find_uninit_var(OP* obase, SV* uninit_sv, bool top)
1070 Print appropriate "Use of uninitialized variable" warning
1072 void report_uninit(SV* uninit_sv)
1082 The autodocumentation system was originally added to the Perl core by
1083 Benjamin Stuhl. Documentation is by whoever was kind enough to
1084 document their functions.
1088 perlguts(1), perlapi(1)
projects / p5sagit/p5-mst-13.2.git / blob