perlapi

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• NAME
• DESCRIPTION
• "Gimme" Values
• Array Manipulation Functions
• Callback Functions
• Character classes
• Cloning an interpreter
• CV Manipulation Functions
• Embedding Functions
• Functions in file dump.c
• Functions in file mathoms.c
• Functions in file pp_ctl.c
• Functions in file pp_pack.c
• GV Functions
• Handy Values
• Hash Manipulation Functions
• Magical Functions
• Memory Management
• Miscellaneous Functions
• MRO Functions
• Multicall Functions
• Numeric functions
• Optree Manipulation Functions
• Pad Data Structures
• Per-Interpreter Variables
• REGEXP Functions
• Simple Exception Handling Macros
• Stack Manipulation Macros
• SV Flags
• SV Manipulation Functions
• SV-Body Allocation
• Unicode Support
• Variables created by xsubpp and xsubpp internal functions
• Warning and Dieing
• AUTHORS
• SEE ALSO

NAME

perlapi - autogenerated documentation for the perl public API

DESCRIPTION

This file contains the documentation of the perl public API generated by embed.pl, specifically a listing of functions, macros, flags, and variables that may be used by extension writers. The interfaces of any functions that are not listed here are subject to change without notice. For this reason, blindly using functions listed in proto.h is to be avoided when writing extensions.

Note that all Perl API global variables must be referenced with the PL_ prefix. Some macros are provided for compatibility with the older, unadorned names, but this support may be disabled in a future release.

The listing is alphabetical, case insensitive.

"Gimme" Values

• GIMME

  A backward-compatible version of GIMME_V which can only return G_SCALAR or G_ARRAY ; in a void context, it returns G_SCALAR . Deprecated. Use GIMME_V instead.

  	U32	GIMME

• GIMME_V

  The XSUB-writer's equivalent to Perl's wantarray. Returns G_VOID , G_SCALAR or G_ARRAY for void, scalar or list context, respectively.

  	U32	GIMME_V

• G_ARRAY

  Used to indicate list context. See GIMME_V , GIMME and perlcall.

• G_DISCARD

  Indicates that arguments returned from a callback should be discarded. See perlcall.

• G_EVAL

  Used to force a Perl eval wrapper around a callback. See perlcall.

• G_NOARGS

  Indicates that no arguments are being sent to a callback. See perlcall.

• G_SCALAR

  Used to indicate scalar context. See GIMME_V , GIMME , and perlcall.

• G_VOID

  Used to indicate void context. See GIMME_V and perlcall.

Array Manipulation Functions

• AvFILL

  Same as av_len() . Deprecated, use av_len() instead.

  	int	AvFILL(AV* av)

• av_clear

  Clears an array, making it empty. Does not free the memory used by the array itself.

  	void	av_clear(AV* ar)

• av_create_and_push

  Push an SV onto the end of the array, creating the array if necessary. A small internal helper function to remove a commonly duplicated idiom.

  NOTE: this function is experimental and may change or be removed without notice.

  	void	av_create_and_push(AV **const avp, SV *const val)

• av_create_and_unshift_one

  Unshifts an SV onto the beginning of the array, creating the array if necessary. A small internal helper function to remove a commonly duplicated idiom.

  NOTE: this function is experimental and may change or be removed without notice.

  	SV**	av_create_and_unshift_one(AV **const avp, SV *const val)

• av_delete

  Deletes the element indexed by key from the array. Returns the deleted element. If flags equals G_DISCARD , the element is freed and null is returned.

  	SV*	av_delete(AV* ar, I32 key, I32 flags)

• av_exists

  Returns true if the element indexed by key has been initialized.

  This relies on the fact that uninitialized array elements are set to &PL_sv_undef .

  	bool	av_exists(AV* ar, I32 key)

• av_extend

  Pre-extend an array. The key is the index to which the array should be extended.

  	void	av_extend(AV* ar, I32 key)

• av_fetch

  Returns the SV at the specified index in the array. The key is the index. If lval is set then the fetch will be part of a store. Check that the return value is non-null before dereferencing it to a SV* .

  See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.

  	SV**	av_fetch(AV* ar, I32 key, I32 lval)

• av_fill

  Set the highest index in the array to the given number, equivalent to Perl's $#array = $fill; .

  The number of elements in the an array will be fill + 1 after av_fill() returns. If the array was previously shorter then the additional elements appended are set to PL_sv_undef . If the array was longer, then the excess elements are freed. av_fill(av, -1) is the same as av_clear(av) .

  	void	av_fill(AV* ar, I32 fill)

• av_len

  Returns the highest index in the array. The number of elements in the array is av_len(av) + 1 . Returns -1 if the array is empty.

  	I32	av_len(const AV* ar)

• av_make

  Creates a new AV and populates it with a list of SVs. The SVs are copied into the array, so they may be freed after the call to av_make. The new AV will have a reference count of 1.

  	AV*	av_make(I32 size, SV** svp)

• av_pop

  Pops an SV off the end of the array. Returns &PL_sv_undef if the array is empty.

  	SV*	av_pop(AV* ar)

• av_push

  Pushes an SV onto the end of the array. The array will grow automatically to accommodate the addition.

  	void	av_push(AV* ar, SV* val)

• av_shift

  Shifts an SV off the beginning of the array.

  	SV*	av_shift(AV* ar)

• av_store

  Stores an SV in an array. The array index is specified as key . The return value will be NULL if the operation failed or if the value did not need to be actually stored within the array (as in the case of tied arrays). Otherwise it can be dereferenced to get the original SV* . Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL.

  See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.

  	SV**	av_store(AV* ar, I32 key, SV* val)

• av_undef

  Undefines the array. Frees the memory used by the array itself.

  	void	av_undef(AV* ar)

• av_unshift

  Unshift the given number of undef values onto the beginning of the array. The array will grow automatically to accommodate the addition. You must then use av_store to assign values to these new elements.

  	void	av_unshift(AV* ar, I32 num)

• get_av

  Returns the AV of the specified Perl array. If create is set and the Perl variable does not exist then it will be created. If create is not set and the variable does not exist then NULL is returned.

  NOTE: the perl_ form of this function is deprecated.

  	AV*	get_av(const char* name, I32 create)

• newAV

  Creates a new AV. The reference count is set to 1.

  	AV*	newAV()

• sortsv

  Sort an array. Here is an example:

      sortsv(AvARRAY(av), av_len(av)+1, Perl_sv_cmp_locale);

  Currently this always uses mergesort. See sortsv_flags for a more flexible routine.

  	void	sortsv(SV** array, size_t num_elts, SVCOMPARE_t cmp)

• sortsv_flags

  Sort an array, with various options.

  	void	sortsv_flags(SV** array, size_t num_elts, SVCOMPARE_t cmp, U32 flags)

Callback Functions

• call_argv

  Performs a callback to the specified Perl sub. See perlcall.

  NOTE: the perl_ form of this function is deprecated.

  	I32	call_argv(const char* sub_name, I32 flags, char** argv)

• call_method

  Performs a callback to the specified Perl method. The blessed object must be on the stack. See perlcall.

  NOTE: the perl_ form of this function is deprecated.

  	I32	call_method(const char* methname, I32 flags)

• call_pv

  Performs a callback to the specified Perl sub. See perlcall.

  NOTE: the perl_ form of this function is deprecated.

  	I32	call_pv(const char* sub_name, I32 flags)

• call_sv

  Performs a callback to the Perl sub whose name is in the SV. See perlcall.

  NOTE: the perl_ form of this function is deprecated.

  	I32	call_sv(SV* sv, I32 flags)

• ENTER

  Opening bracket on a callback. See LEAVE and perlcall.

  		ENTER;

• eval_pv

  Tells Perl to eval the given string and return an SV* result.

  NOTE: the perl_ form of this function is deprecated.

  	SV*	eval_pv(const char* p, I32 croak_on_error)

• eval_sv

  Tells Perl to eval the string in the SV.

  NOTE: the perl_ form of this function is deprecated.

  	I32	eval_sv(SV* sv, I32 flags)

• FREETMPS

  Closing bracket for temporaries on a callback. See SAVETMPS and perlcall.

  		FREETMPS;

• LEAVE

  Closing bracket on a callback. See ENTER and perlcall.

  		LEAVE;

• SAVETMPS

  Opening bracket for temporaries on a callback. See FREETMPS and perlcall.

  		SAVETMPS;

Character classes

• isALNUM

  Returns a boolean indicating whether the C char is an ASCII alphanumeric character (including underscore) or digit.

  	bool	isALNUM(char ch)

• isALPHA

  Returns a boolean indicating whether the C char is an ASCII alphabetic character.

  	bool	isALPHA(char ch)

• isDIGIT

  Returns a boolean indicating whether the C char is an ASCII digit.

  	bool	isDIGIT(char ch)

• isLOWER

  Returns a boolean indicating whether the C char is a lowercase character.

  	bool	isLOWER(char ch)

• isSPACE

  Returns a boolean indicating whether the C char is whitespace.

  	bool	isSPACE(char ch)

• isUPPER

  Returns a boolean indicating whether the C char is an uppercase character.

  	bool	isUPPER(char ch)

• toLOWER

  Converts the specified character to lowercase.

  	char	toLOWER(char ch)

• toUPPER

  Converts the specified character to uppercase.

  	char	toUPPER(char ch)

Cloning an interpreter

• perl_clone

  Create and return a new interpreter by cloning the current one.

  perl_clone takes these flags as parameters:

  CLONEf_COPY_STACKS - is used to, well, copy the stacks also, without it we only clone the data and zero the stacks, with it we copy the stacks and the new perl interpreter is ready to run at the exact same point as the previous one. The pseudo-fork code uses COPY_STACKS while the threads->create doesn't.

  CLONEf_KEEP_PTR_TABLE perl_clone keeps a ptr_table with the pointer of the old variable as a key and the new variable as a value, this allows it to check if something has been cloned and not clone it again but rather just use the value and increase the refcount. If KEEP_PTR_TABLE is not set then perl_clone will kill the ptr_table using the function ptr_table_free(PL_ptr_table); PL_ptr_table = NULL; , reason to keep it around is if you want to dup some of your own variable who are outside the graph perl scans, example of this code is in threads.xs create

  CLONEf_CLONE_HOST This is a win32 thing, it is ignored on unix, it tells perls win32host code (which is c++) to clone itself, this is needed on win32 if you want to run two threads at the same time, if you just want to do some stuff in a separate perl interpreter and then throw it away and return to the original one, you don't need to do anything.

  	PerlInterpreter*	perl_clone(PerlInterpreter* interp, UV flags)

CV Manipulation Functions

• CvSTASH

  Returns the stash of the CV.

  	HV*	CvSTASH(CV* cv)

• get_cv

  Uses strlen to get the length of name , then calls get_cvn_flags .

  NOTE: the perl_ form of this function is deprecated.

  	CV*	get_cv(const char* name, I32 flags)

• get_cvn_flags

  Returns the CV of the specified Perl subroutine. flags are passed to gv_fetchpvn_flags . If GV_ADD is set and the Perl subroutine does not exist then it will be declared (which has the same effect as saying sub name; ). If GV_ADD is not set and the subroutine does not exist then NULL is returned.

  NOTE: the perl_ form of this function is deprecated.

  	CV*	get_cvn_flags(const char* name, STRLEN len, I32 flags)

Embedding Functions

• cv_undef

  Clear out all the active components of a CV. This can happen either by an explicit undef &foo , or by the reference count going to zero. In the former case, we keep the CvOUTSIDE pointer, so that any anonymous children can still follow the full lexical scope chain.

  	void	cv_undef(CV* cv)

• load_module

  Loads the module whose name is pointed to by the string part of name. Note that the actual module name, not its filename, should be given. Eg, "Foo::Bar" instead of "Foo/Bar.pm". flags can be any of PERL_LOADMOD_DENY, PERL_LOADMOD_NOIMPORT, or PERL_LOADMOD_IMPORT_OPS (or 0 for no flags). ver, if specified, provides version semantics similar to use Foo::Bar VERSION . The optional trailing SV* arguments can be used to specify arguments to the module's import() method, similar to use Foo::Bar VERSION LIST .

  	void	load_module(U32 flags, SV* name, SV* ver, ...)

• nothreadhook

  Stub that provides thread hook for perl_destruct when there are no threads.

  	int	nothreadhook()

• perl_alloc

  Allocates a new Perl interpreter. See perlembed.

  	PerlInterpreter*	perl_alloc()

• perl_construct

  Initializes a new Perl interpreter. See perlembed.

  	void	perl_construct(PerlInterpreter* interp)

• perl_destruct

  Shuts down a Perl interpreter. See perlembed.

  	int	perl_destruct(PerlInterpreter* interp)

• perl_free

  Releases a Perl interpreter. See perlembed.

  	void	perl_free(PerlInterpreter* interp)

• perl_parse

  Tells a Perl interpreter to parse a Perl script. See perlembed.

  	int	perl_parse(PerlInterpreter* interp, XSINIT_t xsinit, int argc, char** argv, char** env)

• perl_run

  Tells a Perl interpreter to run. See perlembed.

  	int	perl_run(PerlInterpreter* interp)

• require_pv

  Tells Perl to require the file named by the string argument. It is analogous to the Perl code eval "require '$file'" . It's even implemented that way; consider using load_module instead.

  NOTE: the perl_ form of this function is deprecated.

  	void	require_pv(const char* pv)

Functions in file dump.c

• pv_display

    char *pv_display(SV *dsv, const char *pv, STRLEN cur, STRLEN len,
                     STRLEN pvlim, U32 flags)

  Similar to

    pv_escape(dsv,pv,cur,pvlim,PERL_PV_ESCAPE_QUOTE);

  except that an additional "\0" will be appended to the string when len > cur and pv[cur] is "\0".

  Note that the final string may be up to 7 chars longer than pvlim.

  	char*	pv_display(SV *dsv, const char *pv, STRLEN cur, STRLEN len, STRLEN pvlim)

• pv_escape

                 |const STRLEN count|const STRLEN max
                 |STRLEN const *escaped, const U32 flags

  Escapes at most the first "count" chars of pv and puts the results into dsv such that the size of the escaped string will not exceed "max" chars and will not contain any incomplete escape sequences.

  If flags contains PERL_PV_ESCAPE_QUOTE then any double quotes in the string will also be escaped.

  Normally the SV will be cleared before the escaped string is prepared, but when PERL_PV_ESCAPE_NOCLEAR is set this will not occur.

  If PERL_PV_ESCAPE_UNI is set then the input string is treated as Unicode, if PERL_PV_ESCAPE_UNI_DETECT is set then the input string is scanned using is_utf8_string() to determine if it is Unicode.

  If PERL_PV_ESCAPE_ALL is set then all input chars will be output using \x01F1 style escapes, otherwise only chars above 255 will be escaped using this style, other non printable chars will use octal or common escaped patterns like \n . If PERL_PV_ESCAPE_NOBACKSLASH then all chars below 255 will be treated as printable and will be output as literals.

  If PERL_PV_ESCAPE_FIRSTCHAR is set then only the first char of the string will be escaped, regardles of max. If the string is utf8 and the chars value is >255 then it will be returned as a plain hex sequence. Thus the output will either be a single char, an octal escape sequence, a special escape like \n or a 3 or more digit hex value.

  If PERL_PV_ESCAPE_RE is set then the escape char used will be a '%' and not a '\\'. This is because regexes very often contain backslashed sequences, whereas '%' is not a particularly common character in patterns.

  Returns a pointer to the escaped text as held by dsv.

  NOTE: the perl_ form of this function is deprecated.

  	char*	pv_escape(SV *dsv, char const * const str, const STRLEN count, const STRLEN max, STRLEN * const escaped, const U32 flags)

• pv_pretty

             |const STRLEN count|const STRLEN max\
             |const char const *start_color| const char const *end_color\
             |const U32 flags

  Converts a string into something presentable, handling escaping via pv_escape() and supporting quoting and ellipses.

  If the PERL_PV_PRETTY_QUOTE flag is set then the result will be double quoted with any double quotes in the string escaped. Otherwise if the PERL_PV_PRETTY_LTGT flag is set then the result be wrapped in angle brackets.

  If the PERL_PV_PRETTY_ELLIPSES flag is set and not all characters in string were output then an ellipsis ... will be appended to the string. Note that this happens AFTER it has been quoted.

  If start_color is non-null then it will be inserted after the opening quote (if there is one) but before the escaped text. If end_color is non-null then it will be inserted after the escaped text but before any quotes or ellipses.

  Returns a pointer to the prettified text as held by dsv.

  NOTE: the perl_ form of this function is deprecated.

  	char*	pv_pretty(SV *dsv, char const * const str, const STRLEN count, const STRLEN max, char const * const start_color, char const * const end_color, const U32 flags)

Functions in file mathoms.c

• gv_fetchmethod

  See gv_fetchmethod_autoload.

  	GV*	gv_fetchmethod(HV* stash, const char* name)

• pack_cat

  The engine implementing pack() Perl function. Note: parameters next_in_list and flags are not used. This call should not be used; use packlist instead.

  	void	pack_cat(SV *cat, const char *pat, const char *patend, SV **beglist, SV **endlist, SV ***next_in_list, U32 flags)

• sv_2pvbyte_nolen

  Return a pointer to the byte-encoded representation of the SV. May cause the SV to be downgraded from UTF-8 as a side-effect.

  Usually accessed via the SvPVbyte_nolen macro.

  	char*	sv_2pvbyte_nolen(SV* sv)

• sv_2pvutf8_nolen

  Return a pointer to the UTF-8-encoded representation of the SV. May cause the SV to be upgraded to UTF-8 as a side-effect.

  Usually accessed via the SvPVutf8_nolen macro.

  	char*	sv_2pvutf8_nolen(SV* sv)

• sv_2pv_nolen

  Like sv_2pv() , but doesn't return the length too. You should usually use the macro wrapper SvPV_nolen(sv) instead. char* sv_2pv_nolen(SV* sv)

• sv_catpvn_mg

  Like sv_catpvn , but also handles 'set' magic.

  	void	sv_catpvn_mg(SV *sv, const char *ptr, STRLEN len)

• sv_catsv_mg

  Like sv_catsv , but also handles 'set' magic.

  	void	sv_catsv_mg(SV *dstr, SV *sstr)

• sv_force_normal

  Undo various types of fakery on an SV: if the PV is a shared string, make a private copy; if we're a ref, stop refing; if we're a glob, downgrade to an xpvmg. See also sv_force_normal_flags .

  	void	sv_force_normal(SV *sv)

• sv_iv

  A private implementation of the SvIVx macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

  	IV	sv_iv(SV* sv)

• sv_nolocking

  Dummy routine which "locks" an SV when there is no locking module present. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

  "Superseded" by sv_nosharing().

  	void	sv_nolocking(SV *sv)

• sv_nounlocking

  Dummy routine which "unlocks" an SV when there is no locking module present. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

  "Superseded" by sv_nosharing().

  	void	sv_nounlocking(SV *sv)

• sv_nv

  A private implementation of the SvNVx macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

  	NV	sv_nv(SV* sv)

• sv_pv

  Use the SvPV_nolen macro instead

  	char*	sv_pv(SV *sv)

• sv_pvbyte

  Use SvPVbyte_nolen instead.

  	char*	sv_pvbyte(SV *sv)

• sv_pvbyten

  A private implementation of the SvPVbyte macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

  	char*	sv_pvbyten(SV *sv, STRLEN *len)

• sv_pvn

  A private implementation of the SvPV macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

  	char*	sv_pvn(SV *sv, STRLEN *len)

• sv_pvutf8

  Use the SvPVutf8_nolen macro instead

  	char*	sv_pvutf8(SV *sv)

• sv_pvutf8n

  A private implementation of the SvPVutf8 macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

  	char*	sv_pvutf8n(SV *sv, STRLEN *len)

• sv_taint

  Taint an SV. Use SvTAINTED_on instead. void sv_taint(SV* sv)

• sv_unref

  Unsets the RV status of the SV, and decrements the reference count of whatever was being referenced by the RV. This can almost be thought of as a reversal of newSVrv . This is sv_unref_flags with the flag being zero. See SvROK_off .

  	void	sv_unref(SV* sv)

• sv_usepvn

  Tells an SV to use ptr to find its string value. Implemented by calling sv_usepvn_flags with flags of 0, hence does not handle 'set' magic. See sv_usepvn_flags .

  	void	sv_usepvn(SV* sv, char* ptr, STRLEN len)

• sv_usepvn_mg

  Like sv_usepvn , but also handles 'set' magic.

  	void	sv_usepvn_mg(SV *sv, char *ptr, STRLEN len)

• sv_uv

  A private implementation of the SvUVx macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

  	UV	sv_uv(SV* sv)

• unpack_str

  The engine implementing unpack() Perl function. Note: parameters strbeg, new_s and ocnt are not used. This call should not be used, use unpackstring instead.

  	I32	unpack_str(const char *pat, const char *patend, const char *s, const char *strbeg, const char *strend, char **new_s, I32 ocnt, U32 flags)

Functions in file pp_ctl.c

• find_runcv

  Locate the CV corresponding to the currently executing sub or eval. If db_seqp is non_null, skip CVs that are in the DB package and populate *db_seqp with the cop sequence number at the point that the DB:: code was entered. (allows debuggers to eval in the scope of the breakpoint rather than in the scope of the debugger itself).

  	CV*	find_runcv(U32 *db_seqp)

Functions in file pp_pack.c

• packlist

  The engine implementing pack() Perl function.

  	void	packlist(SV *cat, const char *pat, const char *patend, SV **beglist, SV **endlist)

• unpackstring

  The engine implementing unpack() Perl function. unpackstring puts the extracted list items on the stack and returns the number of elements. Issue PUTBACK before and SPAGAIN after the call to this function.

  	I32	unpackstring(const char *pat, const char *patend, const char *s, const char *strend, U32 flags)

GV Functions

• GvSV

  Return the SV from the GV.

  	SV*	GvSV(GV* gv)

• gv_const_sv

  If gv is a typeglob whose subroutine entry is a constant sub eligible for inlining, or gv is a placeholder reference that would be promoted to such a typeglob, then returns the value returned by the sub. Otherwise, returns NULL.

  	SV*	gv_const_sv(GV* gv)

• gv_fetchmeth

  Returns the glob with the given name and a defined subroutine or NULL . The glob lives in the given stash , or in the stashes accessible via @ISA and UNIVERSAL::.

  The argument level should be either 0 or -1. If level==0 , as a side-effect creates a glob with the given name in the given stash which in the case of success contains an alias for the subroutine, and sets up caching info for this glob.

  This function grants "SUPER" token as a postfix of the stash name. The GV returned from gv_fetchmeth may be a method cache entry, which is not visible to Perl code. So when calling call_sv , you should not use the GV directly; instead, you should use the method's CV, which can be obtained from the GV with the GvCV macro.

  	GV*	gv_fetchmeth(HV* stash, const char* name, STRLEN len, I32 level)

• gv_fetchmethod_autoload

  Returns the glob which contains the subroutine to call to invoke the method on the stash . In fact in the presence of autoloading this may be the glob for "AUTOLOAD". In this case the corresponding variable $AUTOLOAD is already setup.

  The third parameter of gv_fetchmethod_autoload determines whether AUTOLOAD lookup is performed if the given method is not present: non-zero means yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD. Calling gv_fetchmethod is equivalent to calling gv_fetchmethod_autoload with a non-zero autoload parameter.

  These functions grant "SUPER" token as a prefix of the method name. Note that if you want to keep the returned glob for a long time, you need to check for it being "AUTOLOAD", since at the later time the call may load a different subroutine due to $AUTOLOAD changing its value. Use the glob created via a side effect to do this.

  These functions have the same side-effects and as gv_fetchmeth with level==0 . name should be writable if contains ':' or ' ''. The warning against passing the GV returned by gv_fetchmeth to call_sv apply equally to these functions.

  	GV*	gv_fetchmethod_autoload(HV* stash, const char* name, I32 autoload)

• gv_fetchmeth_autoload

  Same as gv_fetchmeth(), but looks for autoloaded subroutines too. Returns a glob for the subroutine.

  For an autoloaded subroutine without a GV, will create a GV even if level < 0 . For an autoloaded subroutine without a stub, GvCV() of the result may be zero.

  	GV*	gv_fetchmeth_autoload(HV* stash, const char* name, STRLEN len, I32 level)

• gv_stashpv

  Returns a pointer to the stash for a specified package. Uses strlen to determine the length of name , then calls gv_stashpvn() .

  	HV*	gv_stashpv(const char* name, I32 flags)

• gv_stashpvn

  Returns a pointer to the stash for a specified package. The namelen parameter indicates the length of the name , in bytes. flags is passed to gv_fetchpvn_flags() , so if set to GV_ADD then the package will be created if it does not already exist. If the package does not exist and flags is 0 (or any other setting that does not create packages) then NULL is returned.

  	HV*	gv_stashpvn(const char* name, U32 namelen, I32 flags)

• gv_stashpvs

  Like gv_stashpvn , but takes a literal string instead of a string/length pair.

  	HV*	gv_stashpvs(const char* name, I32 create)

• gv_stashsv

  Returns a pointer to the stash for a specified package. See gv_stashpvn .

  	HV*	gv_stashsv(SV* sv, I32 flags)

Handy Values

• Nullav

  Null AV pointer.

• Nullch

  Null character pointer.

• Nullcv

  Null CV pointer.

• Nullhv

  Null HV pointer.

• Nullsv

  Null SV pointer.

Hash Manipulation Functions

• get_hv

  Returns the HV of the specified Perl hash. If create is set and the Perl variable does not exist then it will be created. If create is not set and the variable does not exist then NULL is returned.

  NOTE: the perl_ form of this function is deprecated.

  	HV*	get_hv(const char* name, I32 create)

• HEf_SVKEY

  This flag, used in the length slot of hash entries and magic structures, specifies the structure contains an SV* pointer where a char* pointer is to be expected. (For information only--not to be used).

• HeHASH

  Returns the computed hash stored in the hash entry.

  	U32	HeHASH(HE* he)

• HeKEY

  Returns the actual pointer stored in the key slot of the hash entry. The pointer may be either char* or SV* , depending on the value of HeKLEN() . Can be assigned to. The HePV() or HeSVKEY() macros are usually preferable for finding the value of a key.

  	void*	HeKEY(HE* he)

• HeKLEN

  If this is negative, and amounts to HEf_SVKEY , it indicates the entry holds an SV* key. Otherwise, holds the actual length of the key. Can be assigned to. The HePV() macro is usually preferable for finding key lengths.

  	STRLEN	HeKLEN(HE* he)

• HePV

  Returns the key slot of the hash entry as a char* value, doing any necessary dereferencing of possibly SV* keys. The length of the string is placed in len (this is a macro, so do not use &len ). If you do not care about what the length of the key is, you may use the global variable PL_na , though this is rather less efficient than using a local variable. Remember though, that hash keys in perl are free to contain embedded nulls, so using strlen() or similar is not a good way to find the length of hash keys. This is very similar to the SvPV() macro described elsewhere in this document.

  	char*	HePV(HE* he, STRLEN len)

• HeSVKEY

  Returns the key as an SV* , or NULL if the hash entry does not contain an SV* key.

  	SV*	HeSVKEY(HE* he)

• HeSVKEY_force

  Returns the key as an SV* . Will create and return a temporary mortal SV* if the hash entry contains only a char* key.

  	SV*	HeSVKEY_force(HE* he)

• HeSVKEY_set

  Sets the key to a given SV* , taking care to set the appropriate flags to indicate the presence of an SV* key, and returns the same SV* .

  	SV*	HeSVKEY_set(HE* he, SV* sv)

• HeVAL

  Returns the value slot (type SV* ) stored in the hash entry.

  	SV*	HeVAL(HE* he)

• HvNAME

  Returns the package name of a stash, or NULL if stash isn't a stash. See SvSTASH , CvSTASH .

  	char*	HvNAME(HV* stash)

• hv_assert

  Check that a hash is in an internally consistent state.

  	void	hv_assert(HV* tb)

• hv_clear

  Clears a hash, making it empty.

  	void	hv_clear(HV* tb)

• hv_clear_placeholders

  Clears any placeholders from a hash. If a restricted hash has any of its keys marked as readonly and the key is subsequently deleted, the key is not actually deleted but is marked by assigning it a value of &PL_sv_placeholder. This tags it so it will be ignored by future operations such as iterating over the hash, but will still allow the hash to have a value reassigned to the key at some future point. This function clears any such placeholder keys from the hash. See Hash::Util::lock_keys() for an example of its use.

  	void	hv_clear_placeholders(HV* hb)

• hv_delete

  Deletes a key/value pair in the hash. The value SV is removed from the hash and returned to the caller. The klen is the length of the key. The flags value will normally be zero; if set to G_DISCARD then NULL will be returned.

  	SV*	hv_delete(HV* tb, const char* key, I32 klen, I32 flags)

• hv_delete_ent

  Deletes a key/value pair in the hash. The value SV is removed from the hash and returned to the caller. The flags value will normally be zero; if set to G_DISCARD then NULL will be returned. hash can be a valid precomputed hash value, or 0 to ask for it to be computed.

  	SV*	hv_delete_ent(HV* tb, SV* key, I32 flags, U32 hash)

• hv_exists

  Returns a boolean indicating whether the specified hash key exists. The klen is the length of the key.

  	bool	hv_exists(HV* tb, const char* key, I32 klen)

• hv_exists_ent

  Returns a boolean indicating whether the specified hash key exists. hash can be a valid precomputed hash value, or 0 to ask for it to be computed.

  	bool	hv_exists_ent(HV* tb, SV* key, U32 hash)

• hv_fetch

  Returns the SV which corresponds to the specified key in the hash. The klen is the length of the key. If lval is set then the fetch will be part of a store. Check that the return value is non-null before dereferencing it to an SV* .

  See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

  	SV**	hv_fetch(HV* tb, const char* key, I32 klen, I32 lval)

• hv_fetchs

  Like hv_fetch , but takes a literal string instead of a string/length pair.

  	SV**	hv_fetchs(HV* tb, const char* key, I32 lval)

• hv_fetch_ent

  Returns the hash entry which corresponds to the specified key in the hash. hash must be a valid precomputed hash number for the given key , or 0 if you want the function to compute it. IF lval is set then the fetch will be part of a store. Make sure the return value is non-null before accessing it. The return value when tb is a tied hash is a pointer to a static location, so be sure to make a copy of the structure if you need to store it somewhere.

  See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

  	HE*	hv_fetch_ent(HV* tb, SV* key, I32 lval, U32 hash)

• hv_iterinit

  Prepares a starting point to traverse a hash table. Returns the number of keys in the hash (i.e. the same as HvKEYS(tb) ). The return value is currently only meaningful for hashes without tie magic.

  NOTE: Before version 5.004_65, hv_iterinit used to return the number of hash buckets that happen to be in use. If you still need that esoteric value, you can get it through the macro HvFILL(tb) .

  	I32	hv_iterinit(HV* tb)

• hv_iterkey

  Returns the key from the current position of the hash iterator. See hv_iterinit .

  	char*	hv_iterkey(HE* entry, I32* retlen)

• hv_iterkeysv

  Returns the key as an SV* from the current position of the hash iterator. The return value will always be a mortal copy of the key. Also see hv_iterinit .

  	SV*	hv_iterkeysv(HE* entry)

• hv_iternext

  Returns entries from a hash iterator. See hv_iterinit .

  You may call hv_delete or hv_delete_ent on the hash entry that the iterator currently points to, without losing your place or invalidating your iterator. Note that in this case the current entry is deleted from the hash with your iterator holding the last reference to it. Your iterator is flagged to free the entry on the next call to hv_iternext , so you must not discard your iterator immediately else the entry will leak - call hv_iternext to trigger the resource deallocation.

  	HE*	hv_iternext(HV* tb)

• hv_iternextsv

  Performs an hv_iternext , hv_iterkey , and hv_iterval in one operation.

  	SV*	hv_iternextsv(HV* hv, char** key, I32* retlen)

• hv_iternext_flags

  Returns entries from a hash iterator. See hv_iterinit and hv_iternext . The flags value will normally be zero; if HV_ITERNEXT_WANTPLACEHOLDERS is set the placeholders keys (for restricted hashes) will be returned in addition to normal keys. By default placeholders are automatically skipped over. Currently a placeholder is implemented with a value that is &Perl_sv_placeholder . Note that the implementation of placeholders and restricted hashes may change, and the implementation currently is insufficiently abstracted for any change to be tidy.

  NOTE: this function is experimental and may change or be removed without notice.

  	HE*	hv_iternext_flags(HV* tb, I32 flags)

• hv_iterval

  Returns the value from the current position of the hash iterator. See hv_iterkey .

  	SV*	hv_iterval(HV* tb, HE* entry)

• hv_magic

  Adds magic to a hash. See sv_magic .

  	void	hv_magic(HV* hv, GV* gv, int how)

• hv_scalar

  Evaluates the hash in scalar context and returns the result. Handles magic when the hash is tied.

  	SV*	hv_scalar(HV* hv)

• hv_store

  Stores an SV in a hash. The hash key is specified as key and klen is the length of the key. The hash parameter is the precomputed hash value; if it is zero then Perl will compute it. The return value will be NULL if the operation failed or if the value did not need to be actually stored within the hash (as in the case of tied hashes). Otherwise it can be dereferenced to get the original SV* . Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store takes ownership of one reference to val . This is usually what you want; a newly created SV has a reference count of one, so if all your code does is create SVs then store them in a hash, hv_store will own the only reference to the new SV, and your code doesn't need to do anything further to tidy up. hv_store is not implemented as a call to hv_store_ent, and does not create a temporary SV for the key, so if your key data is not already in SV form then use hv_store in preference to hv_store_ent.

  See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

  	SV**	hv_store(HV* tb, const char* key, I32 klen, SV* val, U32 hash)

• hv_stores

  Like hv_store , but takes a literal string instead of a string/length pair and omits the hash parameter.

  	SV**	hv_stores(HV* tb, const char* key, NULLOK SV* val)

• hv_store_ent

  Stores val in a hash. The hash key is specified as key . The hash parameter is the precomputed hash value; if it is zero then Perl will compute it. The return value is the new hash entry so created. It will be NULL if the operation failed or if the value did not need to be actually stored within the hash (as in the case of tied hashes). Otherwise the contents of the return value can be accessed using the He? macros described here. Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store_ent takes ownership of one reference to val . This is usually what you want; a newly created SV has a reference count of one, so if all your code does is create SVs then store them in a hash, hv_store will own the only reference to the new SV, and your code doesn't need to do anything further to tidy up. Note that hv_store_ent only reads the key ; unlike val it does not take ownership of it, so maintaining the correct reference count on key is entirely the caller's responsibility. hv_store is not implemented as a call to hv_store_ent, and does not create a temporary SV for the key, so if your key data is not already in SV form then use hv_store in preference to hv_store_ent.

  See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

  	HE*	hv_store_ent(HV* tb, SV* key, SV* val, U32 hash)

• hv_undef

  Undefines the hash.

  	void	hv_undef(HV* tb)

• newHV

  Creates a new HV. The reference count is set to 1.

  	HV*	newHV()

Magical Functions

• mg_clear

  Clear something magical that the SV represents. See sv_magic .

  	int	mg_clear(SV* sv)

• mg_copy

  Copies the magic from one SV to another. See sv_magic .

  	int	mg_copy(SV* sv, SV* nsv, const char* key, I32 klen)

• mg_find

  Finds the magic pointer for type matching the SV. See sv_magic .

  	MAGIC*	mg_find(const SV* sv, int type)

• mg_free

  Free any magic storage used by the SV. See sv_magic .

  	int	mg_free(SV* sv)

• mg_get

  Do magic after a value is retrieved from the SV. See sv_magic .

  	int	mg_get(SV* sv)

• mg_length

  Report on the SV's length. See sv_magic .

  	U32	mg_length(SV* sv)

• mg_magical

  Turns on the magical status of an SV. See sv_magic .

  	void	mg_magical(SV* sv)

• mg_set

  Do magic after a value is assigned to the SV. See sv_magic .

  	int	mg_set(SV* sv)

• SvGETMAGIC

  Invokes mg_get on an SV if it has 'get' magic. This macro evaluates its argument more than once.

  	void	SvGETMAGIC(SV* sv)

• SvLOCK

  Arranges for a mutual exclusion lock to be obtained on sv if a suitable module has been loaded.

  	void	SvLOCK(SV* sv)

• SvSETMAGIC

  Invokes mg_set on an SV if it has 'set' magic. This macro evaluates its argument more than once.

  	void	SvSETMAGIC(SV* sv)

• SvSetMagicSV

  Like SvSetSV , but does any set magic required afterwards.

  	void	SvSetMagicSV(SV* dsb, SV* ssv)

• SvSetMagicSV_nosteal

  Like SvSetSV_nosteal , but does any set magic required afterwards.

  	void	SvSetMagicSV_nosteal(SV* dsv, SV* ssv)

• SvSetSV

  Calls sv_setsv if dsv is not the same as ssv. May evaluate arguments more than once.

  	void	SvSetSV(SV* dsb, SV* ssv)

• SvSetSV_nosteal

  Calls a non-destructive version of sv_setsv if dsv is not the same as ssv. May evaluate arguments more than once.

  	void	SvSetSV_nosteal(SV* dsv, SV* ssv)

• SvSHARE

  Arranges for sv to be shared between threads if a suitable module has been loaded.

  	void	SvSHARE(SV* sv)

• SvUNLOCK

  Releases a mutual exclusion lock on sv if a suitable module has been loaded.

  	void	SvUNLOCK(SV* sv)

Memory Management

• Copy

  The XSUB-writer's interface to the C memcpy function. The src is the source, dest is the destination, nitems is the number of items, and type is the type. May fail on overlapping copies. See also Move .

  	void	Copy(void* src, void* dest, int nitems, type)

• CopyD

  Like Copy but returns dest. Useful for encouraging compilers to tail-call optimise.

  	void *	CopyD(void* src, void* dest, int nitems, type)

• Move

  The XSUB-writer's interface to the C memmove function. The src is the source, dest is the destination, nitems is the number of items, and type is the type. Can do overlapping moves. See also Copy .

  	void	Move(void* src, void* dest, int nitems, type)

• MoveD

  Like Move but returns dest. Useful for encouraging compilers to tail-call optimise.

  	void *	MoveD(void* src, void* dest, int nitems, type)

• Newx

  The XSUB-writer's interface to the C malloc function.

  In 5.9.3, Newx() and friends replace the older New() API, and drops the first parameter, x, a debug aid which allowed callers to identify themselves. This aid has been superseded by a new build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in perlhack). The older API is still there for use in XS modules supporting older perls.

  	void	Newx(void* ptr, int nitems, type)

• Newxc

  The XSUB-writer's interface to the C malloc function, with cast. See also Newx .

  	void	Newxc(void* ptr, int nitems, type, cast)

• Newxz

  The XSUB-writer's interface to the C malloc function. The allocated memory is zeroed with memzero . See also Newx .

  	void	Newxz(void* ptr, int nitems, type)

• Poison

  PoisonWith(0xEF) for catching access to freed memory.

  	void	Poison(void* dest, int nitems, type)

• PoisonFree

  PoisonWith(0xEF) for catching access to freed memory.

  	void	PoisonFree(void* dest, int nitems, type)

• PoisonNew

  PoisonWith(0xAB) for catching access to allocated but uninitialized memory.

  	void	PoisonNew(void* dest, int nitems, type)

• PoisonWith

  Fill up memory with a byte pattern (a byte repeated over and over again) that hopefully catches attempts to access uninitialized memory.

  	void	PoisonWith(void* dest, int nitems, type, U8 byte)

• Renew

  The XSUB-writer's interface to the C realloc function.

  	void	Renew(void* ptr, int nitems, type)

• Renewc

  The XSUB-writer's interface to the C realloc function, with cast.

  	void	Renewc(void* ptr, int nitems, type, cast)

• Safefree

  The XSUB-writer's interface to the C free function.

  	void	Safefree(void* ptr)

• savepv

  Perl's version of strdup() . Returns a pointer to a newly allocated string which is a duplicate of pv . The size of the string is determined by strlen() . The memory allocated for the new string can be freed with the Safefree() function.

  	char*	savepv(const char* pv)

• savepvn

  Perl's version of what strndup() would be if it existed. Returns a pointer to a newly allocated string which is a duplicate of the first len bytes from pv , plus a trailing NUL byte. The memory allocated for the new string can be freed with the Safefree() function.

  	char*	savepvn(const char* pv, I32 len)

• savepvs

  Like savepvn , but takes a literal string instead of a string/length pair.

  	char*	savepvs(const char* s)

• savesharedpv

  A version of savepv() which allocates the duplicate string in memory which is shared between threads.

  	char*	savesharedpv(const char* pv)

• savesharedpvn

  A version of savepvn() which allocates the duplicate string in memory which is shared between threads. (With the specific difference that a NULL pointer is not acceptable)

  	char*	savesharedpvn(const char *const pv, const STRLEN len)

• savesvpv

  A version of savepv() /savepvn() which gets the string to duplicate from the passed in SV using SvPV()

  	char*	savesvpv(SV* sv)

• StructCopy

  This is an architecture-independent macro to copy one structure to another.

  	void	StructCopy(type src, type dest, type)

• Zero

  The XSUB-writer's interface to the C memzero function. The dest is the destination, nitems is the number of items, and type is the type.

  	void	Zero(void* dest, int nitems, type)

• ZeroD

  Like Zero but returns dest. Useful for encouraging compilers to tail-call optimise.

  	void *	ZeroD(void* dest, int nitems, type)

Miscellaneous Functions

• fbm_compile

  Analyses the string in order to make fast searches on it using fbm_instr() -- the Boyer-Moore algorithm.

  	void	fbm_compile(SV* sv, U32 flags)

• fbm_instr

  Returns the location of the SV in the string delimited by str and strend . It returns NULL if the string can't be found. The sv does not have to be fbm_compiled, but the search will not be as fast then.

  	char*	fbm_instr(unsigned char* big, unsigned char* bigend, SV* littlesv, U32 flags)

• form

  Takes a sprintf-style format pattern and conventional (non-SV) arguments and returns the formatted string.

      (char *) Perl_form(pTHX_ const char* pat, ...)

  can be used any place a string (char *) is required:

      char * s = Perl_form("%d.%d",major,minor);

  Uses a single private buffer so if you want to format several strings you must explicitly copy the earlier strings away (and free the copies when you are done).

  	char*	form(const char* pat, ...)

• getcwd_sv

  Fill the sv with current working directory

  	int	getcwd_sv(SV* sv)

• my_snprintf

  The C library snprintf functionality, if available and standards-compliant (uses vsnprintf , actually). However, if the vsnprintf is not available, will unfortunately use the unsafe vsprintf which can overrun the buffer (there is an overrun check, but that may be too late). Consider using sv_vcatpvf instead, or getting vsnprintf .

  	int	my_snprintf(char *buffer, const Size_t len, const char *format, ...)

• my_sprintf

  The C library sprintf, wrapped if necessary, to ensure that it will return the length of the string written to the buffer. Only rare pre-ANSI systems need the wrapper function - usually this is a direct call to sprintf.

  	int	my_sprintf(char *buffer, const char *pat, ...)

• my_vsnprintf

  The C library vsnprintf if available and standards-compliant. However, if if the vsnprintf is not available, will unfortunately use the unsafe vsprintf which can overrun the buffer (there is an overrun check, but that may be too late). Consider using sv_vcatpvf instead, or getting vsnprintf .

  	int	my_vsnprintf(char *buffer, const Size_t len, const char *format, va_list ap)

• new_version

  Returns a new version object based on the passed in SV:

      SV *sv = new_version(SV *ver);

  Does not alter the passed in ver SV. See "upg_version" if you want to upgrade the SV.

  	SV*	new_version(SV *ver)

• scan_version

  Returns a pointer to the next character after the parsed version string, as well as upgrading the passed in SV to an RV.

  Function must be called with an already existing SV like

      sv = newSV(0);
      s = scan_version(s, SV *sv, bool qv);

  Performs some preprocessing to the string to ensure that it has the correct characteristics of a version. Flags the object if it contains an underscore (which denotes this is an alpha version). The boolean qv denotes that the version should be interpreted as if it had multiple decimals, even if it doesn't.

  	const char*	scan_version(const char *vstr, SV *sv, bool qv)

• strEQ

  Test two strings to see if they are equal. Returns true or false.

  	bool	strEQ(char* s1, char* s2)

• strGE

  Test two strings to see if the first, s1 , is greater than or equal to the second, s2 . Returns true or false.

  	bool	strGE(char* s1, char* s2)

• strGT

  Test two strings to see if the first, s1 , is greater than the second, s2 . Returns true or false.

  	bool	strGT(char* s1, char* s2)

• strLE

  Test two strings to see if the first, s1 , is less than or equal to the second, s2 . Returns true or false.

  	bool	strLE(char* s1, char* s2)

• strLT

  Test two strings to see if the first, s1 , is less than the second, s2 . Returns true or false.

  	bool	strLT(char* s1, char* s2)

• strNE

  Test two strings to see if they are different. Returns true or false.

  	bool	strNE(char* s1, char* s2)

• strnEQ

  Test two strings to see if they are equal. The len parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for strncmp ).

  	bool	strnEQ(char* s1, char* s2, STRLEN len)

• strnNE

  Test two strings to see if they are different. The len parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for strncmp ).

  	bool	strnNE(char* s1, char* s2, STRLEN len)

• sv_destroyable

  Dummy routine which reports that object can be destroyed when there is no sharing module present. It ignores its single SV argument, and returns 'true'. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

  	bool	sv_destroyable(SV *sv)

• sv_nosharing

  Dummy routine which "shares" an SV when there is no sharing module present. Or "locks" it. Or "unlocks" it. In other words, ignores its single SV argument. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

  	void	sv_nosharing(SV *sv)

• upg_version

  In-place upgrade of the supplied SV to a version object.

      SV *sv = upg_version(SV *sv, bool qv);

  Returns a pointer to the upgraded SV. Set the boolean qv if you want to force this SV to be interpreted as an "extended" version.

  	SV*	upg_version(SV *ver, bool qv)

• vcmp

  Version object aware cmp. Both operands must already have been converted into version objects.

  	int	vcmp(SV *lvs, SV *rvs)

• vnormal

  Accepts a vers