-*- buffer-read-only: t -*- !!!!!!! DO NOT EDIT THIS FILE !!!!!!! This file is built by autodoc.pl extracting documentation from the C source files. Any changes made here will be lost! =head1 NAME perlintern - autogenerated documentation of purely B Perl functions =head1 DESCRIPTION X X This file is the autogenerated documentation of functions in the Perl interpreter that are documented using Perl's internal documentation format but are not marked as part of the Perl API. In other words, B! =head1 Compile-time scope hooks =over 8 =item BhkENTRY X NOTE: this function is experimental and may change or be removed without notice. Return an entry from the BHK structure. C is a preprocessor token indicating which entry to return. If the appropriate flag is not set this will return C. The type of the return value depends on which entry you ask for. void * BhkENTRY(BHK *hk, which) =for hackers Found in file op.h =item BhkFLAGS X NOTE: this function is experimental and may change or be removed without notice. Return the BHK's flags. U32 BhkFLAGS(BHK *hk) =for hackers Found in file op.h =item CALL_BLOCK_HOOKS X NOTE: this function is experimental and may change or be removed without notice. Call all the registered block hooks for type C. C is a preprocessing token; the type of C depends on C. void CALL_BLOCK_HOOKS(which, arg) =for hackers Found in file op.h =back =head1 Custom Operators =over 8 =item core_prototype X This function assigns the prototype of the named core function to C, or to a new mortal SV if C is C. It returns the modified C, or C if the core function has no prototype. C is a code as returned by C. It must not be equal to 0. SV * core_prototype(SV *sv, const char *name, const int code, int * const opnum) =for hackers Found in file op.c =back =head1 CV Manipulation Functions =over 8 =item docatch X Check for the cases 0 or 3 of cur_env.je_ret, only used inside an eval context. 0 is used as continue inside eval, 3 is used for a die caught by an inner eval - continue inner loop See F: je_mustcatch, when set at any runlevel to TRUE, means eval ops must establish a local jmpenv to handle exception traps. OP* docatch(OP *o) =for hackers Found in file pp_ctl.c =back =head1 CV reference counts and CvOUTSIDE =over 8 =item CvWEAKOUTSIDE X Each CV has a pointer, C, to its lexically enclosing CV (if any). Because pointers to anonymous sub prototypes are stored in C pad slots, it is a possible to get a circular reference, with the parent pointing to the child and vice-versa. To avoid the ensuing memory leak, we do not increment the reference count of the CV pointed to by C in the I that the parent has a C pad slot pointing back to us. In this case, we set the C flag in the child. This allows us to determine under what circumstances we should decrement the refcount of the parent when freeing the child. There is a further complication with non-closure anonymous subs (i.e. those that do not refer to any lexicals outside that sub). In this case, the anonymous prototype is shared rather than being cloned. This has the consequence that the parent may be freed while there are still active children, I, BEGIN { $a = sub { eval '$x' } } In this case, the BEGIN is freed immediately after execution since there are no active references to it: the anon sub prototype has C set since it's not a closure, and $a points to the same CV, so it doesn't contribute to BEGIN's refcount either. When $a is executed, the C causes the chain of Cs to be followed, and the freed BEGIN is accessed. To avoid this, whenever a CV and its associated pad is freed, any C entries in the pad are explicitly removed from the pad, and if the refcount of the pointed-to anon sub is still positive, then that child's C is set to point to its grandparent. This will only occur in the single specific case of a non-closure anon prototype having one or more active references (such as C above). One other thing to consider is that a CV may be merely undefined rather than freed, eg C. In this case, its refcount may not have reached zero, but we still delete its pad and its C etc. Since various children may still have their C pointing at this undefined CV, we keep its own C for the time being, so that the chain of lexical scopes is unbroken. For example, the following should print 123: my $x = 123; sub tmp { sub { eval '$x' } } my $a = tmp(); undef &tmp; print $a->(); bool CvWEAKOUTSIDE(CV *cv) =for hackers Found in file cv.h =back =head1 Embedding Functions =over 8 =item cv_dump X dump the contents of a CV void cv_dump(CV *cv, const char *title) =for hackers Found in file pad.c =item cv_forget_slab X When a CV has a reference count on its slab (C), it is responsible for making sure it is freed. (Hence, no two CVs should ever have a reference count on the same slab.) The CV only needs to reference the slab during compilation. Once it is compiled and C attached, it has finished its job, so it can forget the slab. void cv_forget_slab(CV *cv) =for hackers Found in file pad.c =item do_dump_pad X Dump the contents of a padlist void do_dump_pad(I32 level, PerlIO *file, PADLIST *padlist, int full) =for hackers Found in file pad.c =item pad_alloc_name X Allocates a place in the currently-compiling pad (via L) and then stores a name for that entry. C is adopted and becomes the name entry; it must already contain the name string. C and C and the C flag get added to C. None of the other processing of L is done. Returns the offset of the allocated pad slot. PADOFFSET pad_alloc_name(PADNAME *name, U32 flags, HV *typestash, HV *ourstash) =for hackers Found in file pad.c =item pad_block_start X Update the pad compilation state variables on entry to a new block. void pad_block_start(int full) =for hackers Found in file pad.c =item pad_check_dup X Check for duplicate declarations: report any of: * a 'my' in the current scope with the same name; * an 'our' (anywhere in the pad) with the same name and the same stash as 'ourstash' C indicates that the name to check is an C declaration. void pad_check_dup(PADNAME *name, U32 flags, const HV *ourstash) =for hackers Found in file pad.c =item pad_findlex X Find a named lexical anywhere in a chain of nested pads. Add fake entries in the inner pads if it's found in an outer one. Returns the offset in the bottom pad of the lex or the fake lex. C is the CV in which to start the search, and seq is the current C to match against. If C is true, print appropriate warnings. The C* vars return values, and so are pointers to where the returned values should be stored. C, if non-null, requests that the innermost instance of the lexical is captured; C is set to the innermost matched pad name or fake pad name; C returns the flags normally associated with the C field of a fake pad name. Note that C is recursive; it recurses up the chain of CVs, then comes back down, adding fake entries as it goes. It has to be this way because fake names in anon protoypes have to store in C the index into the parent pad. PADOFFSET pad_findlex(const char *namepv, STRLEN namelen, U32 flags, const CV* cv, U32 seq, int warn, SV** out_capture, PADNAME** out_name, int *out_flags) =for hackers Found in file pad.c =item pad_fixup_inner_anons X For any anon CVs in the pad, change C of that CV from C to C if necessary. Needed when a newly-compiled CV has to be moved to a pre-existing CV struct. void pad_fixup_inner_anons(PADLIST *padlist, CV *old_cv, CV *new_cv) =for hackers Found in file pad.c =item pad_free X Free the SV at offset po in the current pad. void pad_free(PADOFFSET po) =for hackers Found in file pad.c =item pad_leavemy X Cleanup at end of scope during compilation: set the max seq number for lexicals in this scope and warn of any lexicals that never got introduced. void pad_leavemy() =for hackers Found in file pad.c =item padlist_dup X Duplicates a pad. PADLIST * padlist_dup(PADLIST *srcpad, CLONE_PARAMS *param) =for hackers Found in file pad.c =item padname_dup X Duplicates a pad name. PADNAME * padname_dup(PADNAME *src, CLONE_PARAMS *param) =for hackers Found in file pad.c =item padnamelist_dup X Duplicates a pad name list. PADNAMELIST * padnamelist_dup(PADNAMELIST *srcpad, CLONE_PARAMS *param) =for hackers Found in file pad.c =item pad_push X Push a new pad frame onto the padlist, unless there's already a pad at this depth, in which case don't bother creating a new one. Then give the new pad an C in slot zero. void pad_push(PADLIST *padlist, int depth) =for hackers Found in file pad.c =item pad_reset X Mark all the current temporaries for reuse void pad_reset() =for hackers Found in file pad.c =item pad_swipe X Abandon the tmp in the current pad at offset C and replace with a new one. void pad_swipe(PADOFFSET po, bool refadjust) =for hackers Found in file pad.c =back =head1 GV Functions =over 8 =item gv_try_downgrade X NOTE: this function is experimental and may change or be removed without notice. If the typeglob C can be expressed more succinctly, by having something other than a real GV in its place in the stash, replace it with the optimised form. Basic requirements for this are that C is a real typeglob, is sufficiently ordinary, and is only referenced from its package. This function is meant to be used when a GV has been looked up in part to see what was there, causing upgrading, but based on what was found it turns out that the real GV isn't required after all. If C is a completely empty typeglob, it is deleted from the stash. If C is a typeglob containing only a sufficiently-ordinary constant sub, the typeglob is replaced with a scalar-reference placeholder that more compactly represents the same thing. void gv_try_downgrade(GV* gv) =for hackers Found in file gv.c =back =head1 Hash Manipulation Functions =over 8 =item hv_ename_add X Adds a name to a stash's internal list of effective names. See C>. This is called when a stash is assigned to a new location in the symbol table. void hv_ename_add(HV *hv, const char *name, U32 len, U32 flags) =for hackers Found in file hv.c =item hv_ename_delete X Removes a name from a stash's internal list of effective names. If this is the name returned by C, then another name in the list will take its place (C will use it). This is called when a stash is deleted from the symbol table. void hv_ename_delete(HV *hv, const char *name, U32 len, U32 flags) =for hackers Found in file hv.c =item refcounted_he_chain_2hv X Generates and returns a C representing the content of a C chain. C is currently unused and must be zero. HV * refcounted_he_chain_2hv( const struct refcounted_he *c, U32 flags ) =for hackers Found in file hv.c =item refcounted_he_fetch_pv X Like L, but takes a nul-terminated string instead of a string/length pair. SV * refcounted_he_fetch_pv( const struct refcounted_he *chain, const char *key, U32 hash, U32 flags ) =for hackers Found in file hv.c =item refcounted_he_fetch_pvn X Search along a C chain for an entry with the key specified by C and C. If C has the C bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. C is a precomputed hash of the key string, or zero if it has not been precomputed. Returns a mortal scalar representing the value associated with the key, or C if there is no value associated with the key. SV * refcounted_he_fetch_pvn( const struct refcounted_he *chain, const char *keypv, STRLEN keylen, U32 hash, U32 flags ) =for hackers Found in file hv.c =item refcounted_he_fetch_pvs X Like L, but takes a C-terminated literal string instead of a string/length pair, and no precomputed hash. SV * refcounted_he_fetch_pvs( const struct refcounted_he *chain, const char *key, U32 flags ) =for hackers Found in file hv.h =item refcounted_he_fetch_sv X Like L, but takes a Perl scalar instead of a string/length pair. SV * refcounted_he_fetch_sv( const struct refcounted_he *chain, SV *key, U32 hash, U32 flags ) =for hackers Found in file hv.c =item refcounted_he_free X Decrements the reference count of a C by one. If the reference count reaches zero the structure's memory is freed, which (recursively) causes a reduction of its parent C's reference count. It is safe to pass a null pointer to this function: no action occurs in this case. void refcounted_he_free(struct refcounted_he *he) =for hackers Found in file hv.c =item refcounted_he_inc X Increment the reference count of a C. The pointer to the C is also returned. It is safe to pass a null pointer to this function: no action occurs and a null pointer is returned. struct refcounted_he * refcounted_he_inc( struct refcounted_he *he ) =for hackers Found in file hv.c =item refcounted_he_new_pv X Like L, but takes a nul-terminated string instead of a string/length pair. struct refcounted_he * refcounted_he_new_pv( struct refcounted_he *parent, const char *key, U32 hash, SV *value, U32 flags ) =for hackers Found in file hv.c =item refcounted_he_new_pvn X Creates a new C. This consists of a single key/value pair and a reference to an existing C chain (which may be empty), and thus forms a longer chain. When using the longer chain, the new key/value pair takes precedence over any entry for the same key further along the chain. The new key is specified by C and C. If C has the C bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. C is a precomputed hash of the key string, or zero if it has not been precomputed. C is the scalar value to store for this key. C is copied by this function, which thus does not take ownership of any reference to it, and later changes to the scalar will not be reflected in the value visible in the C. Complex types of scalar will not be stored with referential integrity, but will be coerced to strings. C may be either null or C to indicate that no value is to be associated with the key; this, as with any non-null value, takes precedence over the existence of a value for the key further along the chain. C points to the rest of the C chain to be attached to the new C. This function takes ownership of one reference to C, and returns one reference to the new C. struct refcounted_he * refcounted_he_new_pvn( struct refcounted_he *parent, const char *keypv, STRLEN keylen, U32 hash, SV *value, U32 flags ) =for hackers Found in file hv.c =item refcounted_he_new_pvs X Like L, but takes a C-terminated literal string instead of a string/length pair, and no precomputed hash. struct refcounted_he * refcounted_he_new_pvs( struct refcounted_he *parent, const char *key, SV *value, U32 flags ) =for hackers Found in file hv.h =item refcounted_he_new_sv X Like L, but takes a Perl scalar instead of a string/length pair. struct refcounted_he * refcounted_he_new_sv( struct refcounted_he *parent, SV *key, U32 hash, SV *value, U32 flags ) =for hackers Found in file hv.c =back =head1 IO Functions =over 8 =item start_glob X NOTE: this function is experimental and may change or be removed without notice. Function called by C to spawn a glob (or do the glob inside perl on VMS). This code used to be inline, but now perl uses C<:glob> this glob starter is only used by miniperl during the build process, or when PERL_EXTERNAL_GLOB is defined. Moving it away shrinks F; shrinking F helps speed perl up. PerlIO* start_glob(SV *tmpglob, IO *io) =for hackers Found in file doio.c =back =head1 Lexer interface =over 8 =item validate_proto X NOTE: this function is experimental and may change or be removed without notice. This function performs syntax checking on a prototype, C. If C is true, any illegal characters or mismatched brackets will trigger illegalproto warnings, declaring that they were detected in the prototype for C. The return value is C if this is a valid prototype, and C if it is not, regardless of whether C was C or C. Note that C is a valid C and will always return C. NOTE: the perl_ form of this function is deprecated. bool validate_proto(SV *name, SV *proto, bool warn) =for hackers Found in file toke.c =back =head1 Magical Functions =over 8 =item magic_clearhint X Triggered by a delete from C, records the key to C. int magic_clearhint(SV* sv, MAGIC* mg) =for hackers Found in file mg.c =item magic_clearhints X Triggered by clearing C, resets C. int magic_clearhints(SV* sv, MAGIC* mg) =for hackers Found in file mg.c =item magic_methcall X Invoke a magic method (like FETCH). C and C are the tied thingy and the tie magic. C is the name of the method to call. C is the number of args (in addition to $self) to pass to the method. The C can be: G_DISCARD invoke method with G_DISCARD flag and don't return a value G_UNDEF_FILL fill the stack with argc pointers to PL_sv_undef The arguments themselves are any values following the C argument. Returns the SV (if any) returned by the method, or C on failure. SV* magic_methcall(SV *sv, const MAGIC *mg, SV *meth, U32 flags, U32 argc, ...) =for hackers Found in file mg.c =item magic_sethint X Triggered by a store to C, records the key/value pair to C. It is assumed that hints aren't storing anything that would need a deep copy. Maybe we should warn if we find a reference. int magic_sethint(SV* sv, MAGIC* mg) =for hackers Found in file mg.c =item mg_localize X Copy some of the magic from an existing SV to new localized version of that SV. Container magic (I, C, C, C) gets copied, value magic doesn't (I, C, C). If C is false then no set magic will be called on the new (empty) SV. This typically means that assignment will soon follow (e.g. S>), and that will handle the magic. void mg_localize(SV* sv, SV* nsv, bool setmagic) =for hackers Found in file mg.c =back =head1 Miscellaneous Functions =over 8 =item free_c_backtrace X Deallocates a backtrace received from get_c_bracktrace. void free_c_backtrace(Perl_c_backtrace* bt) =for hackers Found in file util.c =item get_c_backtrace X Collects the backtrace (aka "stacktrace") into a single linear malloced buffer, which the caller B C. Scans the frames back by S>, then drops the C innermost, returning at most C frames. Perl_c_backtrace* get_c_backtrace(int max_depth, int skip) =for hackers Found in file util.c =back =head1 MRO Functions =over 8 =item mro_get_linear_isa_dfs X Returns the Depth-First Search linearization of C the given stash. The return value is a read-only AV*. C should be 0 (it is used internally in this function's recursion). You are responsible for C on the return value if you plan to store it anywhere semi-permanently (otherwise it might be deleted out from under you the next time the cache is invalidated). AV* mro_get_linear_isa_dfs(HV* stash, U32 level) =for hackers Found in file mro_core.c =item mro_isa_changed_in X Takes the necessary steps (cache invalidations, mostly) when the C of the given package has changed. Invoked by the C magic, should not need to invoke directly. void mro_isa_changed_in(HV* stash) =for hackers Found in file mro_core.c =item mro_package_moved X Call this function to signal to a stash that it has been assigned to another spot in the stash hierarchy. C is the stash that has been assigned. C is the stash it replaces, if any. C is the glob that is actually being assigned to. This can also be called with a null first argument to indicate that C has been deleted. This function invalidates isa caches on the old stash, on all subpackages nested inside it, and on the subclasses of all those, including non-existent packages that have corresponding entries in C. It also sets the effective names (C) on all the stashes as appropriate. If the C is present and is not in the symbol table, then this function simply returns. This checked will be skipped if C. void mro_package_moved(HV * const stash, HV * const oldstash, const GV * const gv, U32 flags) =for hackers Found in file mro_core.c =back =head1 Optree Manipulation Functions =over 8 =item finalize_optree X This function finalizes the optree. Should be called directly after the complete optree is built. It does some additional checking which can't be done in the normal Cxxx functions and makes the tree thread-safe. void finalize_optree(OP* o) =for hackers Found in file op.c =back =head1 Pad Data Structures =over 8 =item CX_CURPAD_SAVE X Save the current pad in the given context block structure. void CX_CURPAD_SAVE(struct context) =for hackers Found in file pad.h =item CX_CURPAD_SV X Access the SV at offset C in the saved current pad in the given context block structure (can be used as an lvalue). SV * CX_CURPAD_SV(struct context, PADOFFSET po) =for hackers Found in file pad.h =item PAD_BASE_SV X Get the value from slot C in the base (DEPTH=1) pad of a padlist SV * PAD_BASE_SV(PADLIST padlist, PADOFFSET po) =for hackers Found in file pad.h =item PAD_CLONE_VARS X Clone the state variables associated with running and compiling pads. void PAD_CLONE_VARS(PerlInterpreter *proto_perl, CLONE_PARAMS* param) =for hackers Found in file pad.h =item PAD_COMPNAME_FLAGS X Return the flags for the current compiling pad name at offset C. Assumes a valid slot entry. U32 PAD_COMPNAME_FLAGS(PADOFFSET po) =for hackers Found in file pad.h =item PAD_COMPNAME_GEN X The generation number of the name at offset C in the current compiling pad (lvalue). STRLEN PAD_COMPNAME_GEN(PADOFFSET po) =for hackers Found in file pad.h =item PAD_COMPNAME_GEN_set X Sets the generation number of the name at offset C in the current ling pad (lvalue) to C. STRLEN PAD_COMPNAME_GEN_set(PADOFFSET po, int gen) =for hackers Found in file pad.h =item PAD_COMPNAME_OURSTASH X Return the stash associated with an C variable. Assumes the slot entry is a valid C lexical. HV * PAD_COMPNAME_OURSTASH(PADOFFSET po) =for hackers Found in file pad.h =item PAD_COMPNAME_PV X Return the name of the current compiling pad name at offset C. Assumes a valid slot entry. char * PAD_COMPNAME_PV(PADOFFSET po) =for hackers Found in file pad.h =item PAD_COMPNAME_TYPE X Return the type (stash) of the current compiling pad name at offset C. Must be a valid name. Returns null if not typed. HV * PAD_COMPNAME_TYPE(PADOFFSET po) =for hackers Found in file pad.h =item PadnameIsOUR X Whether this is an "our" variable. bool PadnameIsOUR(PADNAME pn) =for hackers Found in file pad.h =item PadnameIsSTATE X Whether this is a "state" variable. bool PadnameIsSTATE(PADNAME pn) =for hackers Found in file pad.h =item PadnameOURSTASH X The stash in which this "our" variable was declared. HV * PadnameOURSTASH() =for hackers Found in file pad.h =item PadnameOUTER X Whether this entry belongs to an outer pad. Entries for which this is true are often referred to as 'fake'. bool PadnameOUTER(PADNAME pn) =for hackers Found in file pad.h =item PadnameTYPE X The stash associated with a typed lexical. This returns the C hash for C. HV * PadnameTYPE(PADNAME pn) =for hackers Found in file pad.h =item PAD_RESTORE_LOCAL X Restore the old pad saved into the local variable C by C void PAD_RESTORE_LOCAL(PAD *opad) =for hackers Found in file pad.h =item PAD_SAVE_LOCAL X Save the current pad to the local variable C, then make the current pad equal to C void PAD_SAVE_LOCAL(PAD *opad, PAD *npad) =for hackers Found in file pad.h =item PAD_SAVE_SETNULLPAD X Save the current pad then set it to null. void PAD_SAVE_SETNULLPAD() =for hackers Found in file pad.h =item PAD_SETSV X Set the slot at offset C in the current pad to C SV * PAD_SETSV(PADOFFSET po, SV* sv) =for hackers Found in file pad.h =item PAD_SET_CUR X Set the current pad to be pad C in the padlist, saving the previous current pad. NB currently this macro expands to a string too long for some compilers, so it's best to replace it with SAVECOMPPAD(); PAD_SET_CUR_NOSAVE(padlist,n); void PAD_SET_CUR(PADLIST padlist, I32 n) =for hackers Found in file pad.h =item PAD_SET_CUR_NOSAVE X like PAD_SET_CUR, but without the save void PAD_SET_CUR_NOSAVE(PADLIST padlist, I32 n) =for hackers Found in file pad.h =item PAD_SV X Get the value at offset C in the current pad SV * PAD_SV(PADOFFSET po) =for hackers Found in file pad.h =item PAD_SVl X Lightweight and lvalue version of C. Get or set the value at offset C in the current pad. Unlike C, does not print diagnostics with -DX. For internal use only. SV * PAD_SVl(PADOFFSET po) =for hackers Found in file pad.h =item SAVECLEARSV X Clear the pointed to pad value on scope exit. (i.e. the runtime action of C) void SAVECLEARSV(SV **svp) =for hackers Found in file pad.h =item SAVECOMPPAD X save C and C void SAVECOMPPAD() =for hackers Found in file pad.h =item SAVEPADSV X Save a pad slot (used to restore after an iteration) XXX DAPM it would make more sense to make the arg a PADOFFSET void SAVEPADSV(PADOFFSET po) =for hackers Found in file pad.h =back =head1 Per-Interpreter Variables =over 8 =item PL_DBsingle X When Perl is run in debugging mode, with the B switch, this SV is a boolean which indicates whether subs are being single-stepped. Single-stepping is automatically turned on after every step. This is the C variable which corresponds to Perl's $DB::single variable. See C>. SV * PL_DBsingle =for hackers Found in file intrpvar.h =item PL_DBsub X When Perl is run in debugging mode, with the B switch, this GV contains the SV which holds the name of the sub being debugged. This is the C variable which corresponds to Perl's $DB::sub variable. See C>. GV * PL_DBsub =for hackers Found in file intrpvar.h =item PL_DBtrace X Trace variable used when Perl is run in debugging mode, with the B switch. This is the C variable which corresponds to Perl's $DB::trace variable. See C>. SV * PL_DBtrace =for hackers Found in file intrpvar.h =item PL_dowarn X The C variable that roughly corresponds to Perl's C warning variable. However, C is treated as a boolean, whereas C is a collection of flag bits. U8 PL_dowarn =for hackers Found in file intrpvar.h =item PL_last_in_gv X The GV which was last used for a filehandle input operation. (C >>) GV* PL_last_in_gv =for hackers Found in file intrpvar.h =item PL_ofsgv X The glob containing the output field separator - C in Perl space. GV* PL_ofsgv =for hackers Found in file intrpvar.h =item PL_rs X The input record separator - C in Perl space. SV* PL_rs =for hackers Found in file intrpvar.h =back =head1 Stack Manipulation Macros =over 8 =item djSP X Declare Just C. This is actually identical to C, and declares a local copy of perl's stack pointer, available via the C macro. See C>. (Available for backward source code compatibility with the old (Perl 5.005) thread model.) djSP; =for hackers Found in file pp.h =item LVRET X True if this op will be the return value of an lvalue subroutine =for hackers Found in file pp.h =back =head1 SV-Body Allocation =over 8 =item sv_2num X NOTE: this function is experimental and may change or be removed without notice. Return an SV with the numeric value of the source SV, doing any necessary reference or overload conversion. The caller is expected to have handled get-magic already. SV* sv_2num(SV *const sv) =for hackers Found in file sv.c =back =head1 SV Manipulation Functions An SV (or AV, HV, etc.) is allocated in two parts: the head (struct sv, av, hv...) contains type and reference count information, and for many types, a pointer to the body (struct xrv, xpv, xpviv...), which contains fields specific to each type. Some types store all they need in the head, so don't have a body. In all but the most memory-paranoid configurations (ex: PURIFY), heads and bodies are allocated out of arenas, which by default are approximately 4K chunks of memory parcelled up into N heads or bodies. Sv-bodies are allocated by their sv-type, guaranteeing size consistency needed to allocate safely from arrays. For SV-heads, the first slot in each arena is reserved, and holds a link to the next arena, some flags, and a note of the number of slots. Snaked through each arena chain is a linked list of free items; when this becomes empty, an extra arena is allocated and divided up into N items which are threaded into the free list. SV-bodies are similar, but they use arena-sets by default, which separate the link and info from the arena itself, and reclaim the 1st slot in the arena. SV-bodies are further described later. The following global variables are associated with arenas: PL_sv_arenaroot pointer to list of SV arenas PL_sv_root pointer to list of free SV structures PL_body_arenas head of linked-list of body arenas PL_body_roots[] array of pointers to list of free bodies of svtype arrays are indexed by the svtype needed A few special SV heads are not allocated from an arena, but are instead directly created in the interpreter structure, eg PL_sv_undef. The size of arenas can be changed from the default by setting PERL_ARENA_SIZE appropriately at compile time. The SV arena serves the secondary purpose of allowing still-live SVs to be located and destroyed during final cleanup. At the lowest level, the macros new_SV() and del_SV() grab and free an SV head. (If debugging with -DD, del_SV() calls the function S_del_sv() to return the SV to the free list with error checking.) new_SV() calls more_sv() / sv_add_arena() to add an extra arena if the free list is empty. SVs in the free list have their SvTYPE field set to all ones. At the time of very final cleanup, sv_free_arenas() is called from perl_destruct() to physically free all the arenas allocated since the start of the interpreter. The function visit() scans the SV arenas list, and calls a specified function for each SV it finds which is still live - ie which has an SvTYPE other than all 1's, and a non-zero SvREFCNT. visit() is used by the following functions (specified as [function that calls visit()] / [function called by visit() for each SV]): sv_report_used() / do_report_used() dump all remaining SVs (debugging aid) sv_clean_objs() / do_clean_objs(),do_clean_named_objs(), do_clean_named_io_objs(),do_curse() Attempt to free all objects pointed to by RVs, try to do the same for all objects indir- ectly referenced by typeglobs too, and then do a final sweep, cursing any objects that remain. Called once from perl_destruct(), prior to calling sv_clean_all() below. sv_clean_all() / do_clean_all() SvREFCNT_dec(sv) each remaining SV, possibly triggering an sv_free(). It also sets the SVf_BREAK flag on the SV to indicate that the refcnt has been artificially lowered, and thus stopping sv_free() from giving spurious warnings about SVs which unexpectedly have a refcnt of zero. called repeatedly from perl_destruct() until there are no SVs left. =over 8 =item sv_add_arena X Given a chunk of memory, link it to the head of the list of arenas, and split it into a list of free SVs. void sv_add_arena(char *const ptr, const U32 size, const U32 flags) =for hackers Found in file sv.c =item sv_clean_all X Decrement the refcnt of each remaining SV, possibly triggering a cleanup. This function may have to be called multiple times to free SVs which are in complex self-referential hierarchies. I32 sv_clean_all() =for hackers Found in file sv.c =item sv_clean_objs X Attempt to destroy all objects not yet freed. void sv_clean_objs() =for hackers Found in file sv.c =item sv_free_arenas X Deallocate the memory used by all arenas. Note that all the individual SV heads and bodies within the arenas must already have been freed. void sv_free_arenas() =for hackers Found in file sv.c =item SvTHINKFIRST X A quick flag check to see whether an C should be passed to C to be "downgraded" before C or C can be modified directly. For example, if your scalar is a reference and you want to modify the C slot, you can't just do C, as that will leak the referent. This is used internally by various sv-modifying functions, such as C, C and C. One case that this does not handle is a gv without SvFAKE set. After if (SvTHINKFIRST(gv)) sv_force_normal(gv); it will still be a gv. C sometimes produces false positives. In those cases C does nothing. U32 SvTHINKFIRST(SV *sv) =for hackers Found in file sv.h =back =head1 Unicode Support =over 8 =item find_uninit_var X NOTE: this function is experimental and may change or be removed without notice. Find the name of the undefined variable (if any) that caused the operator to issue a "Use of uninitialized value" warning. If match is true, only return a name if its value matches C. So roughly speaking, if a unary operator (such as C) generates a warning, then following the direct child of the op may yield an C or C