A couple of POD fixes by Steven Schubiger

[perl5.git] / pod / perlapi.pod

-*- buffer-read-only: t -*-

!!!!!!!   DO NOT EDIT THIS FILE   !!!!!!!
This file is built by autodoc.pl extracting documentation from the C source
files.

=head1 NAME

perlapi - autogenerated documentation for the perl public API

=head1 DESCRIPTION
X<Perl API> X<API> X<api>

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 C<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.


=head1 "Gimme" Values

=over 8

=item GIMME
X<GIMME>

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

	U32	GIMME

=for hackers
Found in file op.h

=item GIMME_V
X<GIMME_V>

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

	U32	GIMME_V

=for hackers
Found in file op.h

=item G_ARRAY
X<G_ARRAY>

Used to indicate list context.  See C<GIMME_V>, C<GIMME> and
L<perlcall>.

=for hackers
Found in file cop.h

=item G_DISCARD
X<G_DISCARD>

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

=for hackers
Found in file cop.h

=item G_EVAL
X<G_EVAL>

Used to force a Perl C<eval> wrapper around a callback.  See
L<perlcall>.

=for hackers
Found in file cop.h

=item G_NOARGS
X<G_NOARGS>

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

=for hackers
Found in file cop.h

=item G_SCALAR
X<G_SCALAR>

Used to indicate scalar context.  See C<GIMME_V>, C<GIMME>, and
L<perlcall>.

=for hackers
Found in file cop.h

=item G_VOID
X<G_VOID>

Used to indicate void context.  See C<GIMME_V> and L<perlcall>.

=for hackers
Found in file cop.h


=back

=head1 Array Manipulation Functions

=over 8

=item AvFILL
X<AvFILL>

Same as C<av_len()>.  Deprecated, use C<av_len()> instead.

	int	AvFILL(AV* av)

=for hackers
Found in file av.h

=item av_clear
X<av_clear>

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

	void	av_clear(AV* ar)

=for hackers
Found in file av.c

=item av_create_and_push
X<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)

=for hackers
Found in file av.c

=item av_create_and_unshift_one
X<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)

=for hackers
Found in file av.c

=item av_delete
X<av_delete>

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

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

=for hackers
Found in file av.c

=item av_exists
X<av_exists>

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

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

	bool	av_exists(AV* ar, I32 key)

=for hackers
Found in file av.c

=item av_extend
X<av_extend>

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

	void	av_extend(AV* ar, I32 key)

=for hackers
Found in file av.c

=item av_fetch
X<av_fetch>

Returns the SV at the specified index in the array.  The C<key> is the
index.  If C<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 C<SV*>.

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

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

=for hackers
Found in file av.c

=item av_fill
X<av_fill>

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

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

	void	av_fill(AV* ar, I32 fill)

=for hackers
Found in file av.c

=item av_len
X<av_len>

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

	I32	av_len(const AV* ar)

=for hackers
Found in file av.c

=item av_make
X<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)

=for hackers
Found in file av.c

=item av_pop
X<av_pop>

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

	SV*	av_pop(AV* ar)

=for hackers
Found in file av.c

=item av_push
X<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)

=for hackers
Found in file av.c

=item av_shift
X<av_shift>

Shifts an SV off the beginning of the array.

	SV*	av_shift(AV* ar)

=for hackers
Found in file av.c

=item av_store
X<av_store>

Stores an SV in an array.  The array index is specified as C<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 C<SV*>.  Note
that the caller is responsible for suitably incrementing the reference
count of C<val> before the call, and decrementing it if the function
returned NULL.

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

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

=for hackers
Found in file av.c

=item av_undef
X<av_undef>

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

	void	av_undef(AV* ar)

=for hackers
Found in file av.c

=item av_unshift
X<av_unshift>

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

	void	av_unshift(AV* ar, I32 num)

=for hackers
Found in file av.c

=item get_av
X<get_av>

Returns the AV of the specified Perl array.  If C<create> is set and the
Perl variable does not exist then it will be created.  If C<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)

=for hackers
Found in file perl.c

=item newAV
X<newAV>

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

	AV*	newAV()

=for hackers
Found in file av.h

=item sortsv
X<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)

=for hackers
Found in file pp_sort.c

=item sortsv_flags
X<sortsv_flags>

Sort an array, with various options.

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

=for hackers
Found in file pp_sort.c


=back

=head1 Callback Functions

=over 8

=item call_argv
X<call_argv>

Performs a callback to the specified Perl sub.  See L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

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

=for hackers
Found in file perl.c

=item call_method
X<call_method>

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

NOTE: the perl_ form of this function is deprecated.

	I32	call_method(const char* methname, I32 flags)

=for hackers
Found in file perl.c

=item call_pv
X<call_pv>

Performs a callback to the specified Perl sub.  See L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

	I32	call_pv(const char* sub_name, I32 flags)

=for hackers
Found in file perl.c

=item call_sv
X<call_sv>

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

NOTE: the perl_ form of this function is deprecated.

	I32	call_sv(SV* sv, I32 flags)

=for hackers
Found in file perl.c

=item ENTER
X<ENTER>

Opening bracket on a callback.  See C<LEAVE> and L<perlcall>.

		ENTER;

=for hackers
Found in file scope.h

=item eval_pv
X<eval_pv>

Tells Perl to C<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)

=for hackers
Found in file perl.c

=item eval_sv
X<eval_sv>

Tells Perl to C<eval> the string in the SV.

NOTE: the perl_ form of this function is deprecated.

	I32	eval_sv(SV* sv, I32 flags)

=for hackers
Found in file perl.c

=item FREETMPS
X<FREETMPS>

Closing bracket for temporaries on a callback.  See C<SAVETMPS> and
L<perlcall>.

		FREETMPS;

=for hackers
Found in file scope.h

=item LEAVE
X<LEAVE>

Closing bracket on a callback.  See C<ENTER> and L<perlcall>.

		LEAVE;

=for hackers
Found in file scope.h

=item SAVETMPS
X<SAVETMPS>

Opening bracket for temporaries on a callback.  See C<FREETMPS> and
L<perlcall>.

		SAVETMPS;

=for hackers
Found in file scope.h


=back

=head1 Character classes

=over 8

=item isALNUM
X<isALNUM>

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

	bool	isALNUM(char ch)

=for hackers
Found in file handy.h

=item isALPHA
X<isALPHA>

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

	bool	isALPHA(char ch)

=for hackers
Found in file handy.h

=item isDIGIT
X<isDIGIT>

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

	bool	isDIGIT(char ch)

=for hackers
Found in file handy.h

=item isLOWER
X<isLOWER>

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

	bool	isLOWER(char ch)

=for hackers
Found in file handy.h

=item isSPACE
X<isSPACE>

Returns a boolean indicating whether the C C<char> is whitespace.

	bool	isSPACE(char ch)

=for hackers
Found in file handy.h

=item isUPPER
X<isUPPER>

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

	bool	isUPPER(char ch)

=for hackers
Found in file handy.h

=item toLOWER
X<toLOWER>

Converts the specified character to lowercase.

	char	toLOWER(char ch)

=for hackers
Found in file handy.h

=item toUPPER
X<toUPPER>

Converts the specified character to uppercase.

	char	toUPPER(char ch)

=for hackers
Found in file handy.h


=back

=head1 Cloning an interpreter

=over 8

=item perl_clone
X<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
C<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)

=for hackers
Found in file sv.c


=back

=head1 CV Manipulation Functions

=over 8

=item CvSTASH
X<CvSTASH>

Returns the stash of the CV.

	HV*	CvSTASH(CV* cv)

=for hackers
Found in file cv.h

=item get_cv
X<get_cv>

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

NOTE: the perl_ form of this function is deprecated.

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

=for hackers
Found in file perl.c

=item get_cvn_flags
X<get_cvn_flags>

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

=for hackers
Found in file perl.c


=back

=head1 Embedding Functions

=over 8

=item cv_undef
X<cv_undef>

Clear out all the active components of a CV. This can happen either
by an explicit C<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)

=for hackers
Found in file op.c

=item load_module
X<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 C<use Foo::Bar VERSION>.  The optional trailing SV*
arguments can be used to specify arguments to the module's import()
method, similar to C<use Foo::Bar VERSION LIST>.

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

=for hackers
Found in file op.c

=item nothreadhook
X<nothreadhook>

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

	int	nothreadhook()

=for hackers
Found in file perl.c

=item perl_alloc
X<perl_alloc>

Allocates a new Perl interpreter.  See L<perlembed>.

	PerlInterpreter*	perl_alloc()

=for hackers
Found in file perl.c

=item perl_construct
X<perl_construct>

Initializes a new Perl interpreter.  See L<perlembed>.

	void	perl_construct(PerlInterpreter* interp)

=for hackers
Found in file perl.c

=item perl_destruct
X<perl_destruct>

Shuts down a Perl interpreter.  See L<perlembed>.

	int	perl_destruct(PerlInterpreter* interp)

=for hackers
Found in file perl.c

=item perl_free
X<perl_free>

Releases a Perl interpreter.  See L<perlembed>.

	void	perl_free(PerlInterpreter* interp)

=for hackers
Found in file perl.c

=item perl_parse
X<perl_parse>

Tells a Perl interpreter to parse a Perl script.  See L<perlembed>.

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

=for hackers
Found in file perl.c

=item perl_run
X<perl_run>

Tells a Perl interpreter to run.  See L<perlembed>.

	int	perl_run(PerlInterpreter* interp)

=for hackers
Found in file perl.c

=item require_pv
X<require_pv>

Tells Perl to C<require> the file named by the string argument.  It is
analogous to the Perl code C<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)

=for hackers
Found in file perl.c


=back

=head1 Functions in file dump.c


=over 8

=item pv_display
X<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)

=for hackers
Found in file dump.c

=item pv_escape
X<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 C<is_utf8_string()> to determine if it is Unicode.

If PERL_PV_ESCAPE_ALL is set then all input chars will be output
using C<\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 C<\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 C<\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)

=for hackers
Found in file dump.c

=item pv_pretty
X<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 C<...> 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)

=for hackers
Found in file dump.c


=back

=head1 Functions in file mathoms.c


=over 8

=item gv_fetchmethod
X<gv_fetchmethod>

See L<gv_fetchmethod_autoload>.

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

=for hackers
Found in file mathoms.c

=item pack_cat
X<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)

=for hackers
Found in file mathoms.c

=item sv_2pvbyte_nolen
X<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 C<SvPVbyte_nolen> macro.

	char*	sv_2pvbyte_nolen(SV* sv)

=for hackers
Found in file mathoms.c

=item sv_2pvutf8_nolen
X<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 C<SvPVutf8_nolen> macro.

	char*	sv_2pvutf8_nolen(SV* sv)

=for hackers
Found in file mathoms.c

=item sv_2pv_nolen
X<sv_2pv_nolen>

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

=for hackers
Found in file mathoms.c

=item sv_catpvn_mg
X<sv_catpvn_mg>

Like C<sv_catpvn>, but also handles 'set' magic.

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

=for hackers
Found in file mathoms.c

=item sv_catsv_mg
X<sv_catsv_mg>

Like C<sv_catsv>, but also handles 'set' magic.

	void	sv_catsv_mg(SV *dstr, SV *sstr)

=for hackers
Found in file mathoms.c

=item sv_force_normal
X<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 C<sv_force_normal_flags>.

	void	sv_force_normal(SV *sv)

=for hackers
Found in file mathoms.c

=item sv_iv
X<sv_iv>

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

	IV	sv_iv(SV* sv)

=for hackers
Found in file mathoms.c

=item sv_nolocking
X<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)

=for hackers
Found in file mathoms.c

=item sv_nounlocking
X<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)

=for hackers
Found in file mathoms.c

=item sv_nv
X<sv_nv>

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

	NV	sv_nv(SV* sv)

=for hackers
Found in file mathoms.c

=item sv_pv
X<sv_pv>

Use the C<SvPV_nolen> macro instead

	char*	sv_pv(SV *sv)

=for hackers
Found in file mathoms.c

=item sv_pvbyte
X<sv_pvbyte>

Use C<SvPVbyte_nolen> instead.

	char*	sv_pvbyte(SV *sv)

=for hackers
Found in file mathoms.c

=item sv_pvbyten
X<sv_pvbyten>

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

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

=for hackers
Found in file mathoms.c

=item sv_pvn
X<sv_pvn>

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

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

=for hackers
Found in file mathoms.c

=item sv_pvutf8
X<sv_pvutf8>

Use the C<SvPVutf8_nolen> macro instead

	char*	sv_pvutf8(SV *sv)

=for hackers
Found in file mathoms.c

=item sv_pvutf8n
X<sv_pvutf8n>

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

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

=for hackers
Found in file mathoms.c

=item sv_taint
X<sv_taint>

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

=for hackers
Found in file mathoms.c

=item sv_unref
X<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 C<newSVrv>.  This is C<sv_unref_flags> with the C<flag>
being zero.  See C<SvROK_off>.

	void	sv_unref(SV* sv)

=for hackers
Found in file mathoms.c

=item sv_usepvn
X<sv_usepvn>

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

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

=for hackers
Found in file mathoms.c

=item sv_usepvn_mg
X<sv_usepvn_mg>

Like C<sv_usepvn>, but also handles 'set' magic.

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

=for hackers
Found in file mathoms.c

=item sv_uv
X<sv_uv>

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

	UV	sv_uv(SV* sv)

=for hackers
Found in file mathoms.c

=item unpack_str
X<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)

=for hackers
Found in file mathoms.c


=back

=head1 Functions in file pp_ctl.c


=over 8

=item find_runcv
X<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)

=for hackers
Found in file pp_ctl.c


=back

=head1 Functions in file pp_pack.c


=over 8

=item packlist
X<packlist>

The engine implementing pack() Perl function.

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

=for hackers
Found in file pp_pack.c

=item unpackstring
X<unpackstring>

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

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

=for hackers
Found in file pp_pack.c


=back

=head1 GV Functions

=over 8

=item GvSV
X<GvSV>

Return the SV from the GV.

	SV*	GvSV(GV* gv)

=for hackers
Found in file gv.h

=item gv_const_sv
X<gv_const_sv>

If C<gv> is a typeglob whose subroutine entry is a constant sub eligible for
inlining, or C<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)

=for hackers
Found in file gv.c

=item gv_fetchmeth
X<gv_fetchmeth>

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

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

This function grants C<"SUPER"> token as a postfix of the stash name. The
GV returned from C<gv_fetchmeth> may be a method cache entry, which is not
visible to Perl code.  So when calling C<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 C<GvCV> macro.

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

=for hackers
Found in file gv.c

=item gv_fetchmethod_autoload
X<gv_fetchmethod_autoload>

Returns the glob which contains the subroutine to call to invoke the method
on the C<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 C<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 C<gv_fetchmethod> is equivalent to calling C<gv_fetchmethod_autoload>
with a non-zero C<autoload> parameter.

These functions grant C<"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 C<gv_fetchmeth> with
C<level==0>.  C<name> should be writable if contains C<':'> or C<'
''>. The warning against passing the GV returned by C<gv_fetchmeth> to
C<call_sv> apply equally to these functions.

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

=for hackers
Found in file gv.c

=item gv_fetchmeth_autoload
X<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 C<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)

=for hackers
Found in file gv.c

=item gv_stashpv
X<gv_stashpv>

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

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

=for hackers
Found in file gv.c

=item gv_stashpvn
X<gv_stashpvn>

Returns a pointer to the stash for a specified package.  The C<namelen>
parameter indicates the length of the C<name>, in bytes.  C<flags> is passed
to C<gv_fetchpvn_flags()>, so if set to C<GV_ADD> then the package will be
created if it does not already exist.  If the package does not exist and
C<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)

=for hackers
Found in file gv.c

=item gv_stashpvs
X<gv_stashpvs>

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

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

=for hackers
Found in file handy.h

=item gv_stashsv
X<gv_stashsv>

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

	HV*	gv_stashsv(SV* sv, I32 flags)

=for hackers
Found in file gv.c


=back

=head1 Handy Values

=over 8

=item Nullav
X<Nullav>

Null AV pointer.

=for hackers
Found in file av.h

=item Nullch
X<Nullch>

Null character pointer. (No longer available when C<PERL_CORE> is defined.)

=for hackers
Found in file handy.h

=item Nullcv
X<Nullcv>

Null CV pointer.

=for hackers
Found in file cv.h

=item Nullhv
X<Nullhv>

Null HV pointer.

=for hackers
Found in file hv.h

=item Nullsv
X<Nullsv>

Null SV pointer. (No longer available when C<PERL_CORE> is defined.)

=for hackers
Found in file handy.h


=back

=head1 Hash Manipulation Functions

=over 8

=item get_hv
X<get_hv>

Returns the HV of the specified Perl hash.  If C<create> is set and the
Perl variable does not exist then it will be created.  If C<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)

=for hackers
Found in file perl.c

=item HEf_SVKEY
X<HEf_SVKEY>

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

=for hackers
Found in file hv.h

=item HeHASH
X<HeHASH>

Returns the computed hash stored in the hash entry.

	U32	HeHASH(HE* he)

=for hackers
Found in file hv.h

=item HeKEY
X<HeKEY>

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

	void*	HeKEY(HE* he)

=for hackers
Found in file hv.h

=item HeKLEN
X<HeKLEN>

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

	STRLEN	HeKLEN(HE* he)

=for hackers
Found in file hv.h

=item HePV
X<HePV>

Returns the key slot of the hash entry as a C<char*> value, doing any
necessary dereferencing of possibly C<SV*> keys.  The length of the string
is placed in C<len> (this is a macro, so do I<not> use C<&len>).  If you do
not care about what the length of the key is, you may use the global
variable C<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 C<strlen()> or similar is not a good way to find
the length of hash keys. This is very similar to the C<SvPV()> macro
described elsewhere in this document. See also C<HeUTF8>.

If you are using C<HePV> to get values to pass to C<newSVpvn()> to create a
new SV, you should consider using C<newSVhek(HeKEY_hek(he))> as it is more
efficient.

	char*	HePV(HE* he, STRLEN len)

=for hackers
Found in file hv.h

=item HeSVKEY
X<HeSVKEY>

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

	SV*	HeSVKEY(HE* he)

=for hackers
Found in file hv.h

=item HeSVKEY_force
X<HeSVKEY_force>

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

	SV*	HeSVKEY_force(HE* he)

=for hackers
Found in file hv.h

=item HeSVKEY_set
X<HeSVKEY_set>

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

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

=for hackers
Found in file hv.h

=item HeUTF8
X<HeUTF8>

Returns whether the C<char *> value returned by C<HePV> is encoded in UTF-8,
doing any necessary dereferencing of possibly C<SV*> keys.  The value returned
will be 0 or non-0, not necessarily 1 (or even a value with any low bits set),
so B<do not> blindly assign this to a C<bool> variable, as C<bool> may be a
typedef for C<char>.

	char*	HeUTF8(HE* he, STRLEN len)

=for hackers
Found in file hv.h

=item HeVAL
X<HeVAL>

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

	SV*	HeVAL(HE* he)

=for hackers
Found in file hv.h

=item HvNAME
X<HvNAME>

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

	char*	HvNAME(HV* stash)

=for hackers
Found in file hv.h

=item hv_assert
X<hv_assert>

Check that a hash is in an internally consistent state.

	void	hv_assert(HV* tb)

=for hackers
Found in file hv.c

=item hv_clear
X<hv_clear>

Clears a hash, making it empty.

	void	hv_clear(HV* tb)

=for hackers
Found in file hv.c

=item hv_clear_placeholders
X<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)

=for hackers
Found in file hv.c

=item hv_delete
X<hv_delete>

Deletes a key/value pair in the hash.  The value SV is removed from the
hash and returned to the caller.  The C<klen> is the length of the key.
The C<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)

=for hackers
Found in file hv.c

=item hv_delete_ent
X<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 C<flags> value will normally be zero;
if set to G_DISCARD then NULL will be returned.  C<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)

=for hackers
Found in file hv.c

=item hv_exists
X<hv_exists>

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

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

=for hackers
Found in file hv.c

=item hv_exists_ent
X<hv_exists_ent>

Returns a boolean indicating whether the specified hash key exists. C<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)

=for hackers
Found in file hv.c

=item hv_fetch
X<hv_fetch>

Returns the SV which corresponds to the specified key in the hash.  The
C<klen> is the length of the key.  If C<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 C<SV*>.

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

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

=for hackers
Found in file hv.c

=item hv_fetchs
X<hv_fetchs>

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

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

=for hackers
Found in file handy.h

=item hv_fetch_ent
X<hv_fetch_ent>

Returns the hash entry which corresponds to the specified key in the hash.
C<hash> must be a valid precomputed hash number for the given C<key>, or 0
if you want the function to compute it.  IF C<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 C<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 L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for more
information on how to use this function on tied hashes.

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

=for hackers
Found in file hv.c

=item hv_iterinit
X<hv_iterinit>

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

NOTE: Before version 5.004_65, C<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 C<HvFILL(tb)>.


	I32	hv_iterinit(HV* tb)

=for hackers
Found in file hv.c

=item hv_iterkey
X<hv_iterkey>

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

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

=for hackers
Found in file hv.c

=item hv_iterkeysv
X<hv_iterkeysv>

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

	SV*	hv_iterkeysv(HE* entry)

=for hackers
Found in file hv.c

=item hv_iternext
X<hv_iternext>

Returns entries from a hash iterator.  See C<hv_iterinit>.

You may call C<hv_delete> or C<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 C<hv_iternext>, so you must not discard
your iterator immediately else the entry will leak - call C<hv_iternext> to
trigger the resource deallocation.

	HE*	hv_iternext(HV* tb)

=for hackers
Found in file hv.c

=item hv_iternextsv
X<hv_iternextsv>

Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one
operation.

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

=for hackers
Found in file hv.c

=item hv_iternext_flags
X<hv_iternext_flags>

Returns entries from a hash iterator.  See C<hv_iterinit> and C<hv_iternext>.
The C<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
C<&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)

=for hackers
Found in file hv.c

=item hv_iterval
X<hv_iterval>

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

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

=for hackers
Found in file hv.c

=item hv_magic
X<hv_magic>

Adds magic to a hash.  See C<sv_magic>.

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

=for hackers
Found in file hv.c

=item hv_scalar
X<hv_scalar>

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

	SV*	hv_scalar(HV* hv)

=for hackers
Found in file hv.c

=item hv_store
X<hv_store>

Stores an SV in a hash.  The hash key is specified as C<key> and C<klen> is
the length of the key.  The C<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 C<SV*>.  Note that the caller is
responsible for suitably incrementing the reference count of C<val> before
the call, and decrementing it if the function returned NULL.  Effectively
a successful hv_store takes ownership of one reference to C<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 L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> 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)

=for hackers
Found in file hv.c

=item hv_stores
X<hv_stores>

Like C<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)

=for hackers
Found in file handy.h

=item hv_store_ent
X<hv_store_ent>

Stores C<val> in a hash.  The hash key is specified as C<key>.  The C<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 C<He?> macros
described here.  Note that the caller is responsible for suitably
incrementing the reference count of C<val> before the call, and
decrementing it if the function returned NULL.  Effectively a successful
hv_store_ent takes ownership of one reference to C<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 C<key>;
unlike C<val> it does not take ownership of it, so maintaining the correct
reference count on C<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 L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for more
information on how to use this function on tied hashes.

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

=for hackers
Found in file hv.c

=item hv_undef
X<hv_undef>

Undefines the hash.

	void	hv_undef(HV* tb)

=for hackers
Found in file hv.c

=item newHV
X<newHV>

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

	HV*	newHV()

=for hackers
Found in file hv.h


=back

=head1 Magical Functions

=over 8

=item mg_clear
X<mg_clear>

Clear something magical that the SV represents.  See C<sv_magic>.

	int	mg_clear(SV* sv)

=for hackers
Found in file mg.c

=item mg_copy
X<mg_copy>

Copies the magic from one SV to another.  See C<sv_magic>.

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

=for hackers
Found in file mg.c

=item mg_find
X<mg_find>

Finds the magic pointer for type matching the SV.  See C<sv_magic>.

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

=for hackers
Found in file mg.c

=item mg_free
X<mg_free>

Free any magic storage used by the SV.  See C<sv_magic>.

	int	mg_free(SV* sv)

=for hackers
Found in file mg.c

=item mg_get
X<mg_get>

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

	int	mg_get(SV* sv)

=for hackers
Found in file mg.c

=item mg_length
X<mg_length>

Report on the SV's length.  See C<sv_magic>.

	U32	mg_length(SV* sv)

=for hackers
Found in file mg.c

=item mg_magical
X<mg_magical>

Turns on the magical status of an SV.  See C<sv_magic>.

	void	mg_magical(SV* sv)

=for hackers
Found in file mg.c

=item mg_set
X<mg_set>

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

	int	mg_set(SV* sv)

=for hackers
Found in file mg.c

=item SvGETMAGIC
X<SvGETMAGIC>

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

	void	SvGETMAGIC(SV* sv)

=for hackers
Found in file sv.h

=item SvLOCK
X<SvLOCK>

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

	void	SvLOCK(SV* sv)

=for hackers
Found in file sv.h

=item SvSETMAGIC
X<SvSETMAGIC>

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

	void	SvSETMAGIC(SV* sv)

=for hackers
Found in file sv.h

=item SvSetMagicSV
X<SvSetMagicSV>

Like C<SvSetSV>, but does any set magic required afterwards.

	void	SvSetMagicSV(SV* dsb, SV* ssv)

=for hackers
Found in file sv.h

=item SvSetMagicSV_nosteal
X<SvSetMagicSV_nosteal>

Like C<SvSetSV_nosteal>, but does any set magic required afterwards.

	void	SvSetMagicSV_nosteal(SV* dsv, SV* ssv)

=for hackers
Found in file sv.h

=item SvSetSV
X<SvSetSV>

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

	void	SvSetSV(SV* dsb, SV* ssv)

=for hackers
Found in file sv.h

=item SvSetSV_nosteal
X<SvSetSV_nosteal>

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

	void	SvSetSV_nosteal(SV* dsv, SV* ssv)

=for hackers
Found in file sv.h

=item SvSHARE
X<SvSHARE>

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

	void	SvSHARE(SV* sv)

=for hackers
Found in file sv.h

=item SvUNLOCK
X<SvUNLOCK>

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

	void	SvUNLOCK(SV* sv)

=for hackers
Found in file sv.h


=back

=head1 Memory Management

=over 8

=item Copy
X<Copy>

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

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

=for hackers
Found in file handy.h

=item CopyD
X<CopyD>

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

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

=for hackers
Found in file handy.h

=item Move
X<Move>

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

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

=for hackers
Found in file handy.h

=item MoveD
X<MoveD>

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

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

=for hackers
Found in file handy.h

=item Newx
X<Newx>

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

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

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

=for hackers
Found in file handy.h

=item Newxc
X<Newxc>

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

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

=for hackers
Found in file handy.h

=item Newxz
X<Newxz>

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

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

=for hackers
Found in file handy.h

=item Poison
X<Poison>

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

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

=for hackers
Found in file handy.h

=item PoisonFree
X<PoisonFree>

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

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

=for hackers
Found in file handy.h

=item PoisonNew
X<PoisonNew>

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

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

=for hackers
Found in file handy.h

=item PoisonWith
X<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)

=for hackers
Found in file handy.h

=item Renew
X<Renew>

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

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

=for hackers
Found in file handy.h

=item Renewc
X<Renewc>

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

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

=for hackers
Found in file handy.h

=item Safefree
X<Safefree>

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

	void	Safefree(void* ptr)

=for hackers
Found in file handy.h

=item savepv
X<savepv>

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

	char*	savepv(const char* pv)

=for hackers
Found in file util.c

=item savepvn
X<savepvn>

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

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

=for hackers
Found in file util.c

=item savepvs
X<savepvs>

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

	char*	savepvs(const char* s)

=for hackers
Found in file handy.h

=item savesharedpv
X<savesharedpv>

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

	char*	savesharedpv(const char* pv)

=for hackers
Found in file util.c

=item savesharedpvn
X<savesharedpvn>

A version of C<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)

=for hackers
Found in file util.c

=item savesvpv
X<savesvpv>

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

	char*	savesvpv(SV* sv)

=for hackers
Found in file util.c

=item StructCopy
X<StructCopy>

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

	void	StructCopy(type src, type dest, type)

=for hackers
Found in file handy.h

=item Zero
X<Zero>

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

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

=for hackers
Found in file handy.h

=item ZeroD
X<ZeroD>

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

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

=for hackers
Found in file handy.h


=back

=head1 Miscellaneous Functions

=over 8

=item fbm_compile
X<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)

=for hackers
Found in file util.c

=item fbm_instr
X<fbm_instr>

Returns the location of the SV in the string delimited by C<str> and
C<strend>.  It returns C<NULL> if the string can't be found.  The C<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)

=for hackers
Found in file util.c

=item form
X<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, ...)

=for hackers
Found in file util.c

=item getcwd_sv
X<getcwd_sv>

Fill the sv with current working directory

	int	getcwd_sv(SV* sv)

=for hackers
Found in file util.c

=item my_snprintf
X<my_snprintf>

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

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

=for hackers
Found in file util.c

=item my_sprintf
X<my_sprintf>

The C library C<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 C<sprintf>.

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

=for hackers
Found in file util.c

=item my_vsnprintf
X<my_vsnprintf>

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

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

=for hackers
Found in file util.c

=item new_version
X<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)

=for hackers
Found in file util.c

=item scan_version
X<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)

=for hackers
Found in file util.c

=item strEQ
X<strEQ>

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

	bool	strEQ(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strGE
X<strGE>

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

	bool	strGE(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strGT
X<strGT>

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

	bool	strGT(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strLE
X<strLE>

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

	bool	strLE(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strLT
X<strLT>

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

	bool	strLT(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strNE
X<strNE>

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

	bool	strNE(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strnEQ
X<strnEQ>

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

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

=for hackers
Found in file handy.h

=item strnNE
X<strnNE>

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

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

=for hackers
Found in file handy.h

=item sv_destroyable
X<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)

=for hackers
Found in file util.c

=item sv_nosharing
X<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)

=for hackers
Found in file util.c

=item upg_version
X<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)

=for hackers
Found in file util.c

=item vcmp
X<vcmp>

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

	int	vcmp(SV *lvs, SV *rvs)

=for hackers
Found in file util.c

=item vnormal
X<vnormal>

Accepts a version object and returns the normalized string
representation.  Call like:

    sv = vnormal(rv);

NOTE: you can pass either the object directly or the SV
contained within the RV.

	SV*	vnormal(SV *vs)

=for hackers
Found in file util.c

=item vnumify
X<vnumify>

Accepts a version object and returns the normalized floating
point representation.  Call like:

    sv = vnumify(rv);

NOTE: you can pass either the object directly or the SV
contained within the RV.

	SV*	vnumify(SV *vs)

=for hackers
Found in file util.c

=item vstringify
X<vstringify>

In order to maintain maximum compatibility with earlier versions
of Perl, this function will return either the floating point
notation or the multiple dotted notation, depending on whether
the original version contained 1 or more dots, respectively

	SV*	vstringify(SV *vs)

=for hackers
Found in file util.c

=item vverify
X<vverify>

Validates that the SV contains a valid version object.

    bool vverify(SV *vobj);

Note that it only confirms the bare minimum structure (so as not to get
confused by derived classes which may contain additional hash entries):

	bool	vverify(SV *vs)

=for hackers
Found in file util.c


=back

=head1 MRO Functions

=over 8

=item mro_get_linear_isa
X<mro_get_linear_isa>

Returns either C<mro_get_linear_isa_c3> or
C<mro_get_linear_isa_dfs> for the given stash,
dependant upon which MRO is in effect
for that stash.  The return value is a
read-only AV*.

You are responsible for C<SvREFCNT_inc()> 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(HV* stash)

=for hackers
Found in file mro.c

=item mro_method_changed_in
X<mro_method_changed_in>

Invalidates method caching on any child classes
of the given stash, so that they might notice
the changes in this one.

Ideally, all instances of C<PL_sub_generation++> in
perl source outside of C<mro.c> should be
replaced by calls to this.

Perl automatically handles most of the common
ways a method might be redefined.  However, there
are a few ways you could change a method in a stash
without the cache code noticing, in which case you
need to call this method afterwards:

1) Directly manipulating the stash HV entries from
XS code.

2) Assigning a reference to a readonly scalar
constant into a stash entry in order to create
a constant subroutine (like constant.pm
does).

This same method is available from pure perl
via, C<mro::method_changed_in(classname)>.

	void	mro_method_changed_in(HV* stash)

=for hackers
Found in file mro.c


=back

=head1 Multicall Functions

=over 8

=item dMULTICALL
X<dMULTICALL>

Declare local variables for a multicall. See L<perlcall/Lightweight Callbacks>.

		dMULTICALL;

=for hackers
Found in file cop.h

=item MULTICALL
X<MULTICALL>

Make a lightweight callback. See L<perlcall/Lightweight Callbacks>.

		MULTICALL;

=for hackers
Found in file cop.h

=item POP_MULTICALL
X<POP_MULTICALL>

Closing bracket for a lightweight callback.
See L<perlcall/Lightweight Callbacks>.

		POP_MULTICALL;

=for hackers
Found in file cop.h

=item PUSH_MULTICALL
X<PUSH_MULTICALL>

Opening bracket for a lightweight callback.
See L<perlcall/Lightweight Callbacks>.

		PUSH_MULTICALL;

=for hackers
Found in file cop.h


=back

=head1 Numeric functions

=over 8

=item grok_bin
X<grok_bin>

converts a string representing a binary number to numeric form.

On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
invalid character will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.

If the value is <= C<UV_MAX> it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_bin>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).

The binary number may optionally be prefixed with "0b" or "b" unless
C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the binary
number may use '_' characters to separate digits.

	UV	grok_bin(const char* start, STRLEN* len_p, I32* flags, NV *result)

=for hackers
Found in file numeric.c

=item grok_hex
X<grok_hex>

converts a string representing a hex number to numeric form.

On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
invalid character will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_hex>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).

The hex number may optionally be prefixed with "0x" or "x" unless
C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the hex
number may use '_' characters to separate digits.

	UV	grok_hex(const char* start, STRLEN* len_p, I32* flags, NV *result)

=for hackers
Found in file numeric.c

=item grok_number
X<grok_number>

Recognise (or not) a number.  The type of the number is returned
(0 if unrecognised), otherwise it is a bit-ORed combination of
IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT,
IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).

If the value of the number can fit an in UV, it is returned in the *valuep
IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV
will never be set unless *valuep is valid, but *valuep may have been assigned
to during processing even though IS_NUMBER_IN_UV is not set on return.
If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when
valuep is non-NULL, but no actual assignment (or SEGV) will occur.

IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were
seen (in which case *valuep gives the true value truncated to an integer), and
IS_NUMBER_NEG if the number is negative (in which case *valuep holds the
absolute value).  IS_NUMBER_IN_UV is not set if e notation was used or the
number is larger than a UV.

	int	grok_number(const char *pv, STRLEN len, UV *valuep)

=for hackers
Found in file numeric.c

=item grok_numeric_radix
X<grok_numeric_radix>

Scan and skip for a numeric decimal separator (radix).

	bool	grok_numeric_radix(const char **sp, const char *send)

=for hackers
Found in file numeric.c

=item grok_oct
X<grok_oct>

converts a string representing an octal number to numeric form.

On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
invalid character will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_oct>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).

If C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the octal
number may use '_' characters to separate digits.

	UV	grok_oct(const char* start, STRLEN* len_p, I32* flags, NV *result)

=for hackers
Found in file numeric.c

=item Perl_signbit
X<Perl_signbit>

Return a non-zero integer if the sign bit on an NV is set, and 0 if
it is not.  

If Configure detects this system has a signbit() that will work with
our NVs, then we just use it via the #define in perl.h.  Otherwise,
fall back on this implementation.  As a first pass, this gets everything
right except -0.0.  Alas, catching -0.0 is the main use for this function,
so this is not too helpful yet.  Still, at least we have the scaffolding
in place to support other systems, should that prove useful.


Configure notes:  This function is called 'Perl_signbit' instead of a
plain 'signbit' because it is easy to imagine a system having a signbit()
function or macro that doesn't happen to work with our particular choice
of NVs.  We shouldn't just re-#define signbit as Perl_signbit and expect
the standard system headers to be happy.  Also, this is a no-context
function (no pTHX_) because Perl_signbit() is usually re-#defined in
perl.h as a simple macro call to the system's signbit().
Users should just always call Perl_signbit().

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

	int	Perl_signbit(NV f)

=for hackers
Found in file numeric.c

=item scan_bin
X<scan_bin>

For backwards compatibility. Use C<grok_bin> instead.

	NV	scan_bin(const char* start, STRLEN len, STRLEN* retlen)

=for hackers
Found in file numeric.c

=item scan_hex
X<scan_hex>

For backwards compatibility. Use C<grok_hex> instead.

	NV	scan_hex(const char* start, STRLEN len, STRLEN* retlen)

=for hackers
Found in file numeric.c

=item scan_oct
X<scan_oct>

For backwards compatibility. Use C<grok_oct> instead.

	NV	scan_oct(const char* start, STRLEN len, STRLEN* retlen)

=for hackers
Found in file numeric.c


=back

=head1 Optree Manipulation Functions

=over 8

=item cv_const_sv
X<cv_const_sv>

If C<cv> is a constant sub eligible for inlining. returns the constant
value returned by the sub.  Otherwise, returns NULL.

Constant subs can be created with C<newCONSTSUB> or as described in
L<perlsub/"Constant Functions">.

	SV*	cv_const_sv(CV* cv)

=for hackers
Found in file op.c

=item newCONSTSUB
X<newCONSTSUB>

Creates a constant sub equivalent to Perl C<sub FOO () { 123 }> which is
eligible for inlining at compile-time.

	CV*	newCONSTSUB(HV* stash, const char* name, SV* sv)

=for hackers
Found in file op.c

=item newXS
X<newXS>

Used by C<xsubpp> to hook up XSUBs as Perl subs.  I<filename> needs to be
static storage, as it is used directly as CvFILE(), without a copy being made.

=for hackers
Found in file op.c


=back

=head1 Pad Data Structures

=over 8

=item pad_sv
X<pad_sv>

Get the value at offset po in the current pad.
Use macro PAD_SV instead of calling this function directly.

	SV*	pad_sv(PADOFFSET po)

=for hackers
Found in file pad.c


=back

=head1 Per-Interpreter Variables

=over 8

=item PL_modglobal
X<PL_modglobal>

C<PL_modglobal> is a general purpose, interpreter global HV for use by
extensions that need to keep information on a per-interpreter basis.
In a pinch, it can also be used as a symbol table for extensions
to share data among each other.  It is a good idea to use keys
prefixed by the package name of the extension that owns the data.

	HV*	PL_modglobal

=for hackers
Found in file intrpvar.h

=item PL_na
X<PL_na>

A convenience variable which is typically used with C<SvPV> when one
doesn't care about the length of the string.  It is usually more efficient
to either declare a local variable and use that instead or to use the
C<SvPV_nolen> macro.

	STRLEN	PL_na

=for hackers
Found in file intrpvar.h

=item PL_sv_no
X<PL_sv_no>

This is the C<false> SV.  See C<PL_sv_yes>.  Always refer to this as
C<&PL_sv_no>.

	SV	PL_sv_no

=for hackers
Found in file intrpvar.h

=item PL_sv_undef
X<PL_sv_undef>

This is the C<undef> SV.  Always refer to this as C<&PL_sv_undef>.

	SV	PL_sv_undef

=for hackers
Found in file intrpvar.h

=item PL_sv_yes
X<PL_sv_yes>

This is the C<true> SV.  See C<PL_sv_no>.  Always refer to this as
C<&PL_sv_yes>.

	SV	PL_sv_yes

=for hackers
Found in file intrpvar.h


=back

=head1 REGEXP Functions

=over 8

=item SvRX
X<SvRX>

Convenience macro to get the REGEXP from a SV. This is approximately
equivalent to the following snippet:

    if (SvMAGICAL(sv))
        mg_get(sv);
    if (SvROK(sv) &&
        (tmpsv = (SV*)SvRV(sv)) &&
        SvTYPE(tmpsv) == SVt_PVMG &&
        (tmpmg = mg_find(tmpsv, PERL_MAGIC_qr)))
    {
        return (REGEXP *)tmpmg->mg_obj;
    }

NULL will be returned if a REGEXP* is not found.

	REGEXP *	SvRX(SV *sv)

=for hackers
Found in file regexp.h

=item SvRXOK
X<SvRXOK>

Returns a boolean indicating whether the SV contains qr magic
(PERL_MAGIC_qr).

If you want to do something with the REGEXP* later use SvRX instead
and check for NULL.

	bool	SvRXOK(SV* sv)

=for hackers
Found in file regexp.h


=back

=head1 Simple Exception Handling Macros

=over 8

=item dXCPT
X<dXCPT>

Set up necessary local variables for exception handling.
See L<perlguts/"Exception Handling">.

		dXCPT;

=for hackers
Found in file XSUB.h

=item XCPT_CATCH
X<XCPT_CATCH>

Introduces a catch block.  See L<perlguts/"Exception Handling">.

=for hackers
Found in file XSUB.h

=item XCPT_RETHROW
X<XCPT_RETHROW>

Rethrows a previously caught exception.  See L<perlguts/"Exception Handling">.

		XCPT_RETHROW;

=for hackers
Found in file XSUB.h

=item XCPT_TRY_END
X<XCPT_TRY_END>

Ends a try block.  See L<perlguts/"Exception Handling">.

=for hackers
Found in file XSUB.h

=item XCPT_TRY_START
X<XCPT_TRY_START>

Starts a try block.  See L<perlguts/"Exception Handling">.

=for hackers
Found in file XSUB.h


=back

=head1 Stack Manipulation Macros

=over 8

=item dMARK
X<dMARK>

Declare a stack marker variable, C<mark>, for the XSUB.  See C<MARK> and
C<dORIGMARK>.

		dMARK;

=for hackers
Found in file pp.h

=item dORIGMARK
X<dORIGMARK>

Saves the original stack mark for the XSUB.  See C<ORIGMARK>.

		dORIGMARK;

=for hackers
Found in file pp.h

=item dSP
X<dSP>

Declares a local copy of perl's stack pointer for the XSUB, available via
the C<SP> macro.  See C<SP>.

		dSP;

=for hackers
Found in file pp.h

=item EXTEND
X<EXTEND>

Used to extend the argument stack for an XSUB's return values. Once
used, guarantees that there is room for at least C<nitems> to be pushed
onto the stack.

	void	EXTEND(SP, int nitems)

=for hackers
Found in file pp.h

=item MARK
X<MARK>

Stack marker variable for the XSUB.  See C<dMARK>.

=for hackers
Found in file pp.h

=item mPUSHi
X<mPUSHi>

Push an integer onto the stack.  The stack must have room for this element.
Does not use C<TARG>.  See also C<PUSHi>, C<mXPUSHi> and C<XPUSHi>.

	void	mPUSHi(IV iv)

=for hackers
Found in file pp.h

=item mPUSHn
X<mPUSHn>

Push a double onto the stack.  The stack must have room for this element.
Does not use C<TARG>.  See also C<PUSHn>, C<mXPUSHn> and C<XPUSHn>.

	void	mPUSHn(NV nv)

=for hackers
Found in file pp.h

=item mPUSHp
X<mPUSHp>

Push a string onto the stack.  The stack must have room for this element.
The C<len> indicates the length of the string.  Does not use C<TARG>.
See also C<PUSHp>, C<mXPUSHp> and C<XPUSHp>.

	void	mPUSHp(char* str, STRLEN len)

=for hackers
Found in file pp.h

=item mPUSHs
X<mPUSHs>

Push an SV onto the stack and mortalizes the SV.  The stack must have room
for this element.  Does not use C<TARG>.  See also C<PUSHs> and C<mXPUSHs>.

	void	mPUSHs(SV* sv)

=for hackers
Found in file pp.h

=item mPUSHu
X<mPUSHu>

Push an unsigned integer onto the stack.  The stack must have room for this
element.  Does not use C<TARG>.  See also C<PUSHu>, C<mXPUSHu> and C<XPUSHu>.

	void	mPUSHu(UV uv)

=for hackers
Found in file pp.h

=item mXPUSHi
X<mXPUSHi>

Push an integer onto the stack, extending the stack if necessary.
Does not use C<TARG>.  See also C<XPUSHi>, C<mPUSHi> and C<PUSHi>.

	void	mXPUSHi(IV iv)

=for hackers
Found in file pp.h

=item mXPUSHn
X<mXPUSHn>

Push a double onto the stack, extending the stack if necessary.
Does not use C<TARG>.  See also C<XPUSHn>, C<mPUSHn> and C<PUSHn>.

	void	mXPUSHn(NV nv)

=for hackers
Found in file pp.h

=item mXPUSHp
X<mXPUSHp>

Push a string onto the stack, extending the stack if necessary.  The C<len>
indicates the length of the string.  Does not use C<TARG>.  See also C<XPUSHp>,
C<mPUSHp> and C<PUSHp>.

	void	mXPUSHp(char* str, STRLEN len)

=for hackers
Found in file pp.h

=item mXPUSHs
X<mXPUSHs>

Push an SV onto the stack, extending the stack if necessary and mortalizes
the SV.  Does not use C<TARG>.  See also C<XPUSHs> and C<mPUSHs>.

	void	mXPUSHs(SV* sv)

=for hackers
Found in file pp.h

=item mXPUSHu
X<mXPUSHu>

Push an unsigned integer onto the stack, extending the stack if necessary.
Does not use C<TARG>.  See also C<XPUSHu>, C<mPUSHu> and C<PUSHu>.

	void	mXPUSHu(UV uv)

=for hackers
Found in file pp.h

=item ORIGMARK
X<ORIGMARK>

The original stack mark for the XSUB.  See C<dORIGMARK>.

=for hackers
Found in file pp.h

=item POPi
X<POPi>

Pops an integer off the stack.

	IV	POPi

=for hackers
Found in file pp.h

=item POPl
X<POPl>

Pops a long off the stack.

	long	POPl

=for hackers
Found in file pp.h

=item POPn
X<POPn>

Pops a double off the stack.

	NV	POPn

=for hackers
Found in file pp.h

=item POPp
X<POPp>

Pops a string off the stack. Deprecated. New code should use POPpx.

	char*	POPp

=for hackers
Found in file pp.h

=item POPpbytex
X<POPpbytex>

Pops a string off the stack which must consist of bytes i.e. characters < 256.

	char*	POPpbytex

=for hackers
Found in file pp.h

=item POPpx
X<POPpx>

Pops a string off the stack.

	char*	POPpx

=for hackers
Found in file pp.h

=item POPs
X<POPs>

Pops an SV off the stack.

	SV*	POPs

=for hackers
Found in file pp.h

=item PUSHi
X<PUSHi>

Push an integer onto the stack.  The stack must have room for this element.
Handles 'set' magic.  Uses C<TARG>, so C<dTARGET> or C<dXSTARG> should be
called to declare it.  Do not call multiple C<TARG>-oriented macros to 
return lists from XSUB's - see C<mPUSHi> instead.  See also C<XPUSHi> and
C<mXPUSHi>.

	void	PUSHi(IV iv)

=for hackers
Found in file pp.h

=item PUSHMARK
X<PUSHMARK>

Opening bracket for arguments on a callback.  See C<PUTBACK> and
L<perlcall>.