PERLAPI(1)

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.

Perl was originally written to handle US-ASCII only (that is characters whose ordinal numbers are in the range 0 - 127). And documentation and comments may still use the term ASCII, when sometimes in fact the entire range from 0 - 255 is meant.

Note that Perl can be compiled and run under EBCDIC (See perlebcdic) or ASCII. Most of the documentation (and even comments in the code) ignore the EBCDIC possibility. For almost all purposes the differences are transparent. As an example, under EBCDIC, instead of UTF-8, UTF-EBCDIC is used to encode Unicode strings, and so whenever this documentation refers to "utf8" (and variants of that name, including in function names), it also (essentially transparently) means "UTF-EBCDIC". But the ordinals of characters differ between ASCII, EBCDIC, and the UTF- encodings, and a string encoded in UTF-EBCDIC may occupy more bytes than in UTF-8.

Also, on some EBCDIC machines, functions that are documented as operating on US-ASCII (or Basic Latin in Unicode terminology) may in fact operate on all 256 characters in the EBCDIC range, not just the subset corresponding to US-ASCII.

The listing below 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 *av)

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 *av, 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 *av, I32 key)

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

            void    av_extend(AV *av, 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 *av, 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 *av, 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(AV *av)

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 **strp)

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

            SV*     av_pop(AV *av)

av_push
    Pushes an SV onto the end of the array. The array will grow automatically to accommodate the addition. Like "av_store", this takes ownership of one reference count.

            void    av_push(AV *av, SV *val)

av_shift
    Shifts an SV off the beginning of the array. Returns &PL_sv_undef if the array is empty.

            SV*     av_shift(AV *av)

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 *av, I32 key, SV *val)

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

            void    av_undef(AV *av)

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 *av, I32 num)

get_av
    Returns the AV of the specified Perl array. "flags" are passed to "gv_fetchpv". If "GV_ADD" is set and the Perl variable does not exist then it will be created. If "flags" is zero 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 flags)

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, VOL 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 a US-ASCII (Basic Latin) alphanumeric character (including underscore) or digit.

            bool    isALNUM(char ch)

isALPHA
    Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) alphabetic character.

            bool    isALPHA(char ch)

isDIGIT
    Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) digit.

            bool    isDIGIT(char ch)

isLOWER
    Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) lowercase character.

            bool    isLOWER(char ch)

isSPACE
    Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) whitespace.

            bool    isSPACE(char ch)

isUPPER
    Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) uppercase character.

            bool    isUPPER(char ch)

toLOWER
    Converts the specified character to lowercase. Characters outside the US-ASCII (Basic Latin) range are viewed as not having any case.

            char    toLOWER(char ch)

toUPPER
    Converts the specified character to uppercase. Characters outside the US-ASCII (Basic Latin) range are viewed as not having any case.

            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 *proto_perl, 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". They must be terminated with a final NULL pointer. Note that this list can only be omitted when the PERL_LOADMOD_NOIMPORT flag has been used. Otherwise at least a single NULL pointer to designate the default import list is required.

            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 *my_perl)

perl_destruct
    Shuts down a Perl interpreter. See perlembed.

            int     perl_destruct(PerlInterpreter *my_perl)

perl_free
    Releases a Perl interpreter. See perlembed.

            void    perl_free(PerlInterpreter *my_perl)

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

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

perl_run
    Tells a Perl interpreter to run. See perlembed.

            int     perl_run(PerlInterpreter *my_perl)

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
    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
    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.

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

pv_pretty
    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.

            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 *dsv, SV *ssv)

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 *lp)

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 *lp)

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 *lp)

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 perl.h

PERL_SYS_INIT
    Provides system-specific tune up of the C runtime environment necessary to run Perl interpreters. This should be called only once, before creating any Perl interpreters.

            void    PERL_SYS_INIT(int argc, char** argv)

PERL_SYS_INIT3
    Provides system-specific tune up of the C runtime environment necessary to run Perl interpreters. This should be called only once, before creating any Perl interpreters.

            void    PERL_SYS_INIT3(int argc, char** argv, char** env)

PERL_SYS_TERM
    Provides system-specific clean up of the C runtime environment after running Perl interpreters. This should be called only once, after freeing any remaining Perl interpreters.

            void    PERL_SYS_TERM()

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)

Functions in file pp_sys.c

setdefout
    Sets PL_defoutgv, the default file handle for output, to the passed in typeglob. As PL_defoutgv "owns" a reference on its typeglob, the reference count of the passed in typeglob is increased by one, and the reference count of the typeglob that PL_defoutgv points to is decreased by one.

            void    setdefout(GV* gv)

Global Variables

PL_keyword_plugin
    Function pointer, pointing at a function used to handle extended keywords. The function should be declared as

            int keyword_plugin_function(pTHX_
                    char *keyword_ptr, STRLEN keyword_len,
                    OP **op_ptr)

    The function is called from the tokeniser, whenever a possible keyword is seen. "keyword_ptr" points at the word in the parser's input buffer, and "keyword_len" gives its length; it is not null-terminated. The function is expected to examine the word, and possibly other state such as %^H, to decide whether it wants to handle it as an extended keyword. If it does not, the function should return "KEYWORD_PLUGIN_DECLINE", and the normal parser process will continue.

    If the function wants to handle the keyword, it first must parse anything following the keyword that is part of the syntax introduced by the keyword. See "Lexer interface" for details.

    When a keyword is being handled, the plugin function must build a tree of "OP" structures, representing the code that was parsed. The root of the tree must be stored in *op_ptr. The function then returns a contant indicating the syntactic role of the construct that it has parsed: "KEYWORD_PLUGIN_STMT" if it is a complete statement, or "KEYWORD_PLUGIN_EXPR" if it is an expression. Note that a statement construct cannot be used inside an expression (except via "do BLOCK" and similar), and an expression is not a complete statement (it requires at least a terminating semicolon).

    When a keyword is handled, the plugin function may also have (compile-time) side effects. It may modify "%^H", define functions, and so on. Typically, if side effects are the main purpose of a handler, it does not wish to generate any ops to be included in the normal compilation. In this case it is still required to supply an op tree, but it suffices to generate a single null op.

    That's how the *PL_keyword_plugin function needs to behave overall. Conventionally, however, one does not completely replace the existing handler function. Instead, take a copy of "PL_keyword_plugin" before assigning your own function pointer to it. Your handler function should look for keywords that it is interested in and handle those. Where it is not interested, it should call the saved plugin function, passing on the arguments it received. Thus "PL_keyword_plugin" actually points at a chain of handler functions, all of which have an opportunity to handle keywords, and only the last function in the chain (built into the Perl core) will normally return "KEYWORD_PLUGIN_DECLINE".

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

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.

    (deprecated - use "(AV *)NULL" instead)

Nullch
    Null character pointer. (No longer available when "PERL_CORE" is defined.)

Nullcv
    Null CV pointer.

    (deprecated - use "(CV *)NULL" instead)

Nullhv
    Null HV pointer.

    (deprecated - use "(HV *)NULL" instead)

Nullsv
    Null SV pointer. (No longer available when "PERL_CORE" is defined.)

Hash Manipulation Functions

get_hv
    Returns the HV of the specified Perl hash. "flags" are passed to "gv_fetchpv". If "GV_ADD" is set and the Perl variable does not exist then it will be created. If "flags" is zero 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 flags)

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. See also "HeUTF8".

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

            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)

HeUTF8
    Returns whether the "char *" value returned by "HePV" is encoded in UTF-8, doing any necessary dereferencing of possibly "SV*" keys. The value returned will be 0 or non-0, not necessarily 1 (or even a value with any low bits set), so do not blindly assign this to a "bool" variable, as "bool" may be a typedef for "char".

            char*   HeUTF8(HE* he)

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 *hv)

hv_clear
    Clears a hash, making it empty.

            void    hv_clear(HV *hv)

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 *hv)

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 *hv, 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 *hv, SV *keysv, 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 *hv, 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 *hv, SV *keysv, 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 *hv, 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 *hv, SV *keysv, 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 *hv)

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 *hv)

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 *hv, I32 flags)

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

            SV*     hv_iterval(HV *hv, 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 *hv, 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 *hv, SV *key, SV *val, U32 hash)

hv_undef
    Undefines the hash.

            void    hv_undef(HV *hv)

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

            HV*     newHV()

Lexer interface

lex_bufutf8
    Indicates whether the octets in the lexer buffer ("PL_parser->linestr") should be interpreted as the UTF-8 encoding of Unicode characters. If not, they should be interpreted as Latin-1 characters. This is analogous to the "SvUTF8" flag for scalars.

    In UTF-8 mode, it is not guaranteed that the lexer buffer actually contains valid UTF-8. Lexing code must be robust in the face of invalid encoding.

    The actual "SvUTF8" flag of the "PL_parser->linestr" scalar is significant, but not the whole story regarding the input character encoding. Normally, when a file is being read, the scalar contains octets and its "SvUTF8" flag is off, but the octets should be interpreted as UTF-8 if the "use utf8" pragma is in effect. During a string eval, however, the scalar may have the "SvUTF8" flag on, and in this case its octets should be interpreted as UTF-8 unless the "use bytes" pragma is in effect. This logic may change in the future; use this function instead of implementing the logic yourself.

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

            bool    lex_bufutf8()

lex_discard_to
    Discards the first part of the "PL_parser->linestr" buffer, up to ptr. The remaining content of the buffer will be moved, and all pointers into the buffer updated appropriately. ptr must not be later in the buffer than the position of "PL_parser->bufptr": it is not permitted to discard text that has yet to be lexed.

    Normally it is not necessarily to do this directly, because it suffices to use the implicit discarding behaviour of "lex_next_chunk" and things based on it. However, if a token stretches across multiple lines, and the lexing code has kept multiple lines of text in the buffer fof that purpose, then after completion of the token it would be wise to explicitly discard the now-unneeded earlier lines, to avoid future multi-line tokens growing the buffer without bound.

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

            void    lex_discard_to(char *ptr)

lex_grow_linestr
    Reallocates the lexer buffer ("PL_parser->linestr") to accommodate at least len octets (including terminating NUL). Returns a pointer to the reallocated buffer. This is necessary before making any direct modification of the buffer that would increase its length. "lex_stuff_pvn" provides a more convenient way to insert text into the buffer.

    Do not use "SvGROW" or "sv_grow" directly on "PL_parser->linestr"; this function updates all of the lexer's variables that point directly into the buffer.

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

            char *  lex_grow_linestr(STRLEN len)

lex_next_chunk
    Reads in the next chunk of text to be lexed, appending it to "PL_parser->linestr". This should be called when lexing code has looked to the end of the current chunk and wants to know more. It is usual, but not necessary, for lexing to have consumed the entirety of the current chunk at this time.

    If "PL_parser->bufptr" is pointing to the very end of the current chunk (i.e., the current chunk has been entirely consumed), normally the current chunk will be discarded at the same time that the new chunk is read in. If flags includes "LEX_KEEP_PREVIOUS", the current chunk will not be discarded. If the current chunk has not been entirely consumed, then it will not be discarded regardless of the flag.

    Returns true if some new text was added to the buffer, or false if the buffer has reached the end of the input text.

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

            bool    lex_next_chunk(U32 flags)

lex_peek_unichar
    Looks ahead one (Unicode) character in the text currently being lexed. Returns the codepoint (unsigned integer value) of the next character, or -1 if lexing has reached the end of the input text. To consume the peeked character, use "lex_read_unichar".

    If the next character is in (or extends into) the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags includes "LEX_KEEP_PREVIOUS" then the current chunk will not be discarded.

    If the input is being interpreted as UTF-8 and a UTF-8 encoding error is encountered, an exception is generated.

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

            I32     lex_peek_unichar(U32 flags)

lex_read_space
    Reads optional spaces, in Perl style, in the text currently being lexed. The spaces may include ordinary whitespace characters and Perl-style comments. "#line" directives are processed if encountered. "PL_parser->bufptr" is moved past the spaces, so that it points at a non-space character (or the end of the input text).

    If spaces extend into the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags includes "LEX_KEEP_PREVIOUS" then the current chunk will not be discarded.

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

            void    lex_read_space(U32 flags)

lex_read_to
    Consume text in the lexer buffer, from "PL_parser->bufptr" up to ptr. This advances "PL_parser->bufptr" to match ptr, performing the correct bookkeeping whenever a newline character is passed. This is the normal way to consume lexed text.

    Interpretation of the buffer's octets can be abstracted out by using the slightly higher-level functions "lex_peek_unichar" and "lex_read_unichar".

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

            void    lex_read_to(char *ptr)

lex_read_unichar
    Reads the next (Unicode) character in the text currently being lexed. Returns the codepoint (unsigned integer value) of the character read, and moves "PL_parser->bufptr" past the character, or returns -1 if lexing has reached the end of the input text. To non-destructively examine the next character, use "lex_peek_unichar" instead.

    If the next character is in (or extends into) the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags includes "LEX_KEEP_PREVIOUS" then the current chunk will not be discarded.

    If the input is being interpreted as UTF-8 and a UTF-8 encoding error is encountered, an exception is generated.

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

            I32     lex_read_unichar(U32 flags)

lex_stuff_pvn
    Insert characters into the lexer buffer ("PL_parser->linestr"), immediately after the current lexing point ("PL_parser->bufptr"), reallocating the buffer if necessary. This means that lexing code that runs later will see the characters as if they had appeared in the input. It is not recommended to do this as part of normal parsing, and most uses of this facility run the risk of the inserted characters being interpreted in an unintended manner.

    The string to be inserted is represented by len octets starting at pv. These octets are interpreted as either UTF-8 or Latin-1, according to whether the "LEX_STUFF_UTF8" flag is set in flags. The characters are recoded for the lexer buffer, according to how the buffer is currently being interpreted ("lex_bufutf8"). If a string to be interpreted is available as a Perl scalar, the "lex_stuff_sv" function is more convenient.

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

            void    lex_stuff_pvn(char *pv, STRLEN len, U32 flags)

lex_stuff_sv
    Insert characters into the lexer buffer ("PL_parser->linestr"), immediately after the current lexing point ("PL_parser->bufptr"), reallocating the buffer if necessary. This means that lexing code that runs later will see the characters as if they had appeared in the input. It is not recommended to do this as part of normal parsing, and most uses of this facility run the risk of the inserted characters being interpreted in an unintended manner.

    The string to be inserted is the string value of sv. The characters are recoded for the lexer buffer, according to how the buffer is currently being interpreted ("lex_bufutf8"). If a string to be interpreted is not already a Perl scalar, the "lex_stuff_pvn" function avoids the need to construct a scalar.

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

            void    lex_stuff_sv(SV *sv, U32 flags)

lex_unstuff
    Discards text about to be lexed, from "PL_parser->bufptr" up to ptr. Text following ptr will be moved, and the buffer shortened. This hides the discarded text from any lexing code that runs later, as if the text had never appeared.

    This is not the normal way to consume lexed text. For that, use "lex_read_to".

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

            void    lex_unstuff(char *ptr)

PL_parser
    Pointer to a structure encapsulating the state of the parsing operation currently in progress. The pointer can be locally changed to perform a nested parse without interfering with the state of an outer parse. Individual members of "PL_parser" have their own documentation.

PL_parser->bufend
    Direct pointer to the end of the chunk of text currently being lexed, the end of the lexer buffer. This is equal to "SvPVX(PL_parser->linestr) + SvCUR(PL_parser->linestr)". A NUL character (zero octet) is always located at the end of the buffer, and does not count as part of the buffer's contents.

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

PL_parser->bufptr
    Points to the current position of lexing inside the lexer buffer. Characters around this point may be freely examined, within the range delimited by "SvPVX("PL_parser->linestr")" and "PL_parser->bufend". The octets of the buffer may be intended to be interpreted as either UTF-8 or Latin-1, as indicated by "lex_bufutf8".

    Lexing code (whether in the Perl core or not) moves this pointer past the characters that it consumes. It is also expected to perform some bookkeeping whenever a newline character is consumed. This movement can be more conveniently performed by the function "lex_read_to", which handles newlines appropriately.

    Interpretation of the buffer's octets can be abstracted out by using the slightly higher-level functions "lex_peek_unichar" and "lex_read_unichar".

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

PL_parser->linestart
    Points to the start of the current line inside the lexer buffer. This is useful for indicating at which column an error occurred, and not much else. This must be updated by any lexing code that consumes a newline; the function "lex_read_to" handles this detail.

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

PL_parser->linestr
    Buffer scalar containing the chunk currently under consideration of the text currently being lexed. This is always a plain string scalar (for which "SvPOK" is true). It is not intended to be used as a scalar by normal scalar means; instead refer to the buffer directly by the pointer variables described below.

    The lexer maintains various "char*" pointers to things in the "PL_parser->linestr" buffer. If "PL_parser->linestr" is ever reallocated, all of these pointers must be updated. Don't attempt to do this manually, but rather use "lex_grow_linestr" if you need to reallocate the buffer.

    The content of the text chunk in the buffer is commonly exactly one complete line of input, up to and including a newline terminator, but there are situations where it is otherwise. The octets of the buffer may be intended to be interpreted as either UTF-8 or Latin-1. The function "lex_bufutf8" tells you which. Do not use the "SvUTF8" flag on this scalar, which may disagree with it.

    For direct examination of the buffer, the variable "PL_parser->bufend" points to the end of the buffer. The current lexing position is pointed to by "PL_parser->bufptr". Direct use of these pointers is usually preferable to examination of the scalar through normal scalar means.

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

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* littlestr, 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)

prescan_version
            const char*     prescan_version(const char *s, bool strict, const char** errstr, bool *sqv, int *ssaw_decimal, int *swidth, bool *salpha)

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 *s, SV *rv, 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 *lhv, SV *rhv)

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)

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)

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)

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)

MRO Functions

mro_get_linear_isa
    Returns either "mro_get_linear_isa_c3" or "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 "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)

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 "PL_sub_generation++" in perl source outside of "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, "mro::method_changed_in(classname)".

            void    mro_method_changed_in(HV* stash)

Multicall Functions

dMULTICALL
    Declare local variables for a multicall. See "Lightweight Callbacks" in perlcall.

                    dMULTICALL;

MULTICALL
    Make a lightweight callback. See "Lightweight Callbacks" in perlcall.

                    MULTICALL;

POP_MULTICALL
    Closing bracket for a lightweight callback. See "Lightweight Callbacks" in perlcall.

                    POP_MULTICALL;

PUSH_MULTICALL
    Opening bracket for a lightweight callback. See "Lightweight Callbacks" in perlcall.

                    PUSH_MULTICALL;

Numeric functions

grok_bin
    converts a string representing a binary number to numeric form.

    On entry start and *len give the string to scan, *flags gives conversion flags, and 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 "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *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 *result. If the value is > UV_MAX "grok_bin" returns UV_MAX, sets "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

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

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

grok_hex
    converts a string representing a hex number to numeric form.

    On entry start and *len give the string to scan, *flags gives conversion flags, and 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 "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *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 *result. If the value is > UV_MAX "grok_hex" returns UV_MAX, sets "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

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

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

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)

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

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

grok_oct
    converts a string representing an octal number to numeric form.

    On entry start and *len give the string to scan, *flags gives conversion flags, and 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 "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *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 *result. If the value is > UV_MAX "grok_oct" returns UV_MAX, sets "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

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

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

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)

scan_bin
    For backwards compatibility. Use "grok_bin" instead.

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

scan_hex
    For backwards compatibility. Use "grok_hex" instead.

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

scan_oct
    For backwards compatibility. Use "grok_oct" instead.

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

Optree Manipulation Functions

cv_const_sv
    If "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 "newCONSTSUB" or as described in "Constant Functions" in perlsub.

            SV*     cv_const_sv(const CV *const cv)

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

    Passing NULL for SV creates a constant sub equivalent to "sub BAR () {}", which won't be called if used as a destructor, but will suppress the overhead of a call to "AUTOLOAD". (This form, however, isn't eligible for inlining at compile time.)

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

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

Pad Data Structures

pad_findmy
    Given a lexical name, try to find its offset, first in the current pad, or failing that, in the pads of any lexically enclosing subs (including the complications introduced by eval). If the name is found in an outer pad, then a fake entry is added to the current pad. Returns the offset in the current pad, or NOT_IN_PAD on failure.

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

            PADOFFSET       pad_findmy(const char* name, STRLEN len, U32 flags)

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)

Per-Interpreter Variables

PL_modglobal
    "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

PL_na
    A convenience variable which is typically used with "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 "SvPV_nolen" macro.

            STRLEN  PL_na

PL_opfreehook
    When non-"NULL", the function pointed by this variable will be called each time an OP is freed with the corresponding OP as the argument. This allows extensions to free any extra attribute they have locally attached to an OP. It is also assured to first fire for the parent OP and then for its kids.

    When you replace this variable, it is considered a good practice to store the possibly previously installed hook and that you recall it inside your own.

            Perl_ophook_t   PL_opfreehook

PL_sv_no
    This is the "false" SV. See "PL_sv_yes". Always refer to this as &PL_sv_no.

            SV      PL_sv_no

PL_sv_undef
    This is the "undef" SV. Always refer to this as &PL_sv_undef.

            SV      PL_sv_undef

PL_sv_yes
    This is the "true" SV. See "PL_sv_no". Always refer to this as &PL_sv_yes.

            SV      PL_sv_yes

REGEXP Functions

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)

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)

Simple Exception Handling Macros

dXCPT
    Set up necessary local variables for exception handling. See "Exception Handling" in perlguts.

                    dXCPT;

XCPT_CATCH
    Introduces a catch block. See "Exception Handling" in perlguts.

XCPT_RETHROW
    Rethrows a previously caught exception. See "Exception Handling" in perlguts.

                    XCPT_RETHROW;

XCPT_TRY_END
    Ends a try block. See "Exception Handling" in perlguts.

XCPT_TRY_START
    Starts a try block. See "Exception Handling" in perlguts.

Stack Manipulation Macros

dMARK
    Declare a stack marker variable, "mark", for the XSUB. See "MARK" and "dORIGMARK".

                    dMARK;

dORIGMARK
    Saves the original stack mark for the XSUB. See "ORIGMARK".

                    dORIGMARK;

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

                    dSP;

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

            void    EXTEND(SP, int nitems)

MARK
    Stack marker variable for the XSUB. See "dMARK".

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

            void    mPUSHi(IV iv)

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

            void    mPUSHn(NV nv)

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

            void    mPUSHp(char* str, STRLEN len)

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

            void    mPUSHs(SV* sv)

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

            void    mPUSHu(UV uv)

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

            void    mXPUSHi(IV iv)

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

            void    mXPUSHn(NV nv)

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

            void    mXPUSHp(char* str, STRLEN len)

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

            void    mXPUSHs(SV* sv)

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

            void    mXPUSHu(UV uv)

ORIGMARK
    The original stack mark for the XSUB. See "dORIGMARK".

POPi
    Pops an integer off the stack.

            IV      POPi

POPl
    Pops a long off the stack.

            long    POPl

POPn
    Pops a double off the stack.

            NV      POPn

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

            char*   POPp

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

            char*   POPpbytex

POPpx
    Pops a string off the stack.

            char*   POPpx

POPs
    Pops an SV off the stack.

            SV*     POPs

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

            void    PUSHi(IV iv)

PUSHMARK
    Opening bracket for arguments on a callback. See "PUTBACK" and perlcall.

            void    PUSHMARK(SP)

PUSHmortal
    Push a new mortal SV onto the stack. The stack must have room for this element. Does not use "TARG". See also "PUSHs", "XPUSHmortal" and "XPUSHs".

            void    PUSHmortal()

PUSHn
    Push a double onto the stack. The stack must have room for this element. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mPUSHn" instead. See also "XPUSHn" and "mXPUSHn".

            void    PUSHn(NV nv)

PUSHp
    Push a string onto the stack. The stack must have room for this element. The "len" indicates the length of the string. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mPUSHp" instead. See also "XPUSHp" and "mXPUSHp".

            void    PUSHp(char* str, STRLEN len)

PUSHs
    Push an SV onto the stack. The stack must have room for this element. Does not handle 'set' magic. Does not use "TARG". See also "PUSHmortal", "XPUSHs" and "XPUSHmortal".

            void    PUSHs(SV* sv)

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

            void    PUSHu(UV uv)

PUTBACK
    Closing bracket for XSUB arguments. This is usually handled by "xsubpp". See "PUSHMARK" and perlcall for other uses.

                    PUTBACK;

SP  Stack pointer. This is usually handled by "xsubpp". See "dSP" and "SPAGAIN".

SPAGAIN
    Refetch the stack pointer. Used after a callback. See perlcall.

                    SPAGAIN;

XPUSHi
    Push an integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mXPUSHi" instead. See also "PUSHi" and "mPUSHi".

            void    XPUSHi(IV iv)

XPUSHmortal
    Push a new mortal SV onto the stack, extending the stack if necessary. Does not use "TARG". See also "XPUSHs", "PUSHmortal" and "PUSHs".

            void    XPUSHmortal()

XPUSHn
    Push a double onto the stack, extending the stack if necessary. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mXPUSHn" instead. See also "PUSHn" and "mPUSHn".

            void    XPUSHn(NV nv)

XPUSHp
    Push a string onto the stack, extending the stack if necessary. The "len" indicates the length of the string. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mXPUSHp" instead. See also "PUSHp" and "mPUSHp".

            void    XPUSHp(char* str, STRLEN len)

XPUSHs
    Push an SV onto the stack, extending the stack if necessary. Does not handle 'set' magic. Does not use "TARG". See also "XPUSHmortal", "PUSHs" and "PUSHmortal".

            void    XPUSHs(SV* sv)

XPUSHu
    Push an unsigned integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mXPUSHu" instead. See also "PUSHu" and "mPUSHu".

            void    XPUSHu(UV uv)

XSRETURN
    Return from XSUB, indicating number of items on the stack. This is usually handled by "xsubpp".

            void    XSRETURN(int nitems)

XSRETURN_EMPTY
    Return an empty list from an XSUB immediately.

                    XSRETURN_EMPTY;

XSRETURN_IV
    Return an integer from an XSUB immediately. Uses "XST_mIV".

            void    XSRETURN_IV(IV iv)

XSRETURN_NO
    Return &PL_sv_no from an XSUB immediately. Uses "XST_mNO".

                    XSRETURN_NO;

XSRETURN_NV
    Return a double from an XSUB immediately. Uses "XST_mNV".

            void    XSRETURN_NV(NV nv)

XSRETURN_PV
    Return a copy of a string from an XSUB immediately. Uses "XST_mPV".

            void    XSRETURN_PV(char* str)

XSRETURN_UNDEF
    Return &PL_sv_undef from an XSUB immediately. Uses "XST_mUNDEF".

                    XSRETURN_UNDEF;

XSRETURN_UV
    Return an integer from an XSUB immediately. Uses "XST_mUV".

            void    XSRETURN_UV(IV uv)

XSRETURN_YES
    Return &PL_sv_yes from an XSUB immediately. Uses "XST_mYES".

                    XSRETURN_YES;

XST_mIV
    Place an integer into the specified position "pos" on the stack. The value is stored in a new mortal SV.

            void    XST_mIV(int pos, IV iv)

XST_mNO
    Place &PL_sv_no into the specified position "pos" on the stack.

            void    XST_mNO(int pos)

XST_mNV
    Place a double into the specified position "pos" on the stack. The value is stored in a new mortal SV.

            void    XST_mNV(int pos, NV nv)

XST_mPV
    Place a copy of a string into the specified position "pos" on the stack. The value is stored in a new mortal SV.

            void    XST_mPV(int pos, char* str)

XST_mUNDEF
    Place &PL_sv_undef into the specified position "pos" on the stack.

            void    XST_mUNDEF(int pos)

XST_mYES
    Place &PL_sv_yes into the specified position "pos" on the stack.

            void    XST_mYES(int pos)

SV Flags

svtype
    An enum of flags for Perl types. These are found in the file sv.h in the "svtype" enum. Test these flags with the "SvTYPE" macro.

SVt_IV
    Integer type flag for scalars. See "svtype".

SVt_NV
    Double type flag for scalars. See "svtype".

SVt_PV
    Pointer type flag for scalars. See "svtype".

SVt_PVAV
    Type flag for arrays. See "svtype".

SVt_PVCV
    Type flag for code refs. See "svtype".

SVt_PVHV
    Type flag for hashes. See "svtype".

SVt_PVMG
    Type flag for blessed scalars. See "svtype".

SV Manipulation Functions

croak_xs_usage
    A specialised variant of "croak()" for emitting the usage message for xsubs

        croak_xs_usage(cv, "eee_yow");

    works out the package name and subroutine name from "cv", and then calls "croak()". Hence if "cv" is &ouch::awk, it would call "croak" as:

        Perl_croak(aTHX_ "Usage %s::%s(%s)", "ouch" "awk", "eee_yow");

            void    croak_xs_usage(const CV *const cv, const char *const params)

get_sv
    Returns the SV of the specified Perl scalar. "flags" are passed to "gv_fetchpv". If "GV_ADD" is set and the Perl variable does not exist then it will be created. If "flags" is zero and the variable does not exist then NULL is returned.

    NOTE: the perl_ form of this function is deprecated.

            SV*     get_sv(const char *name, I32 flags)

newRV_inc
    Creates an RV wrapper for an SV. The reference count for the original SV is incremented.

            SV*     newRV_inc(SV* sv)

newSVpvn_utf8
    Creates a new SV and copies a string into it. If utf8 is true, calls "SvUTF8_on" on the new SV. Implemented as a wrapper around "newSVpvn_flags".

            SV*     newSVpvn_utf8(NULLOK const char* s, STRLEN len, U32 utf8)

SvCUR
    Returns the length of the string which is in the SV. See "SvLEN".

            STRLEN  SvCUR(SV* sv)

SvCUR_set
    Set the current length of the string which is in the SV. See "SvCUR" and "SvIV_set".

            void    SvCUR_set(SV* sv, STRLEN len)

SvEND
    Returns a pointer to the last character in the string which is in the SV. See "SvCUR". Access the character as *(SvEND(sv)).

            char*   SvEND(SV* sv)

SvGAMAGIC
    Returns true if the SV has get magic or overloading. If either is true then the scalar is active data, and has the potential to return a new value every time it is accessed. Hence you must be careful to only read it once per user logical operation and work with that returned value. If neither is true then the scalar's value cannot change unless written to.

            U32     SvGAMAGIC(SV* sv)

SvGROW
    Expands the character buffer in the SV so that it has room for the indicated number of bytes (remember to reserve space for an extra trailing NUL character). Calls "sv_grow" to perform the expansion if necessary. Returns a pointer to the character buffer.

            char *  SvGROW(SV* sv, STRLEN len)

SvIOK
    Returns a U32 value indicating whether the SV contains an integer.

            U32     SvIOK(SV* sv)

SvIOKp
    Returns a U32 value indicating whether the SV contains an integer. Checks the private setting. Use "SvIOK" instead.

            U32     SvIOKp(SV* sv)

SvIOK_notUV
    Returns a boolean indicating whether the SV contains a signed integer.

            bool    SvIOK_notUV(SV* sv)

SvIOK_off
    Unsets the IV status of an SV.

            void    SvIOK_off(SV* sv)

SvIOK_on
    Tells an SV that it is an integer.

            void    SvIOK_on(SV* sv)

SvIOK_only
    Tells an SV that it is an integer and disables all other OK bits.

            void    SvIOK_only(SV* sv)

SvIOK_only_UV
    Tells and SV that it is an unsigned integer and disables all other OK bits.

            void    SvIOK_only_UV(SV* sv)

SvIOK_UV
    Returns a boolean indicating whether the SV contains an unsigned integer.

            bool    SvIOK_UV(SV* sv)

SvIsCOW
    Returns a boolean indicating whether the SV is Copy-On-Write. (either shared hash key scalars, or full Copy On Write scalars if 5.9.0 is configured for COW)

            bool    SvIsCOW(SV* sv)

SvIsCOW_shared_hash
    Returns a boolean indicating whether the SV is Copy-On-Write shared hash key scalar.

            bool    SvIsCOW_shared_hash(SV* sv)

SvIV
    Coerces the given SV to an integer and returns it. See "SvIVx" for a version which guarantees to evaluate sv only once.

            IV      SvIV(SV* sv)

SvIVX
    Returns the raw value in the SV's IV slot, without checks or conversions. Only use when you are sure SvIOK is true. See also "SvIV()".

            IV      SvIVX(SV* sv)

SvIVx
    Coerces the given SV to an integer and returns it. Guarantees to evaluate "sv" only once. Only use this if "sv" is an expression with side effects, otherwise use the more efficient "SvIV".

            IV      SvIVx(SV* sv)

SvIV_nomg
    Like "SvIV" but doesn't process magic.

            IV      SvIV_nomg(SV* sv)

SvIV_set
    Set the value of the IV pointer in sv to val. It is possible to perform the same function of this macro with an lvalue assignment to "SvIVX". With future Perls, however, it will be more efficient to use "SvIV_set" instead of the lvalue assignment to "SvIVX".

            void    SvIV_set(SV* sv, IV val)

SvLEN
    Returns the size of the string buffer in the SV, not including any part attributable to "SvOOK". See "SvCUR".

            STRLEN  SvLEN(SV* sv)

SvLEN_set
    Set the actual length of the string which is in the SV. See "SvIV_set".

            void    SvLEN_set(SV* sv, STRLEN len)

SvMAGIC_set
    Set the value of the MAGIC pointer in sv to val. See "SvIV_set".

            void    SvMAGIC_set(SV* sv, MAGIC* val)

SvNIOK
    Returns a U32 value indicating whether the SV contains a number, integer or double.

            U32     SvNIOK(SV* sv)

SvNIOKp
    Returns a U32 value indicating whether the SV contains a number, integer or double. Checks the private setting. Use "SvNIOK" instead.

            U32     SvNIOKp(SV* sv)

SvNIOK_off
    Unsets the NV/IV status of an SV.

            void    SvNIOK_off(SV* sv)

SvNOK
    Returns a U32 value indicating whether the SV contains a double.

            U32     SvNOK(SV* sv)

SvNOKp
    Returns a U32 value indicating whether the SV contains a double. Checks the private setting. Use "SvNOK" instead.

            U32     SvNOKp(SV* sv)

SvNOK_off
    Unsets the NV status of an SV.

            void    SvNOK_off(SV* sv)

SvNOK_on
    Tells an SV that it is a double.

            void    SvNOK_on(SV* sv)

SvNOK_only
    Tells an SV that it is a double and disables all other OK bits.

            void    SvNOK_only(SV* sv)

SvNV
    Coerce the given SV to a double and return it. See "SvNVx" for a version which guarantees to evaluate sv only once.

            NV      SvNV(SV* sv)

SvNVX
    Returns the raw value in the SV's NV slot, without checks or conversions. Only use when you are sure SvNOK is true. See also "SvNV()".

            NV      SvNVX(SV* sv)

SvNVx
    Coerces the given SV to a double and returns it. Guarantees to evaluate "sv" only once. Only use this if "sv" is an expression with side effects, otherwise use the more efficient "SvNV".

            NV      SvNVx(SV* sv)

SvNV_set
    Set the value of the NV pointer in sv to val. See "SvIV_set".

            void    SvNV_set(SV* sv, NV val)

SvOK
    Returns a U32 value indicating whether the value is defined. This is only meaningful for scalars.

            U32     SvOK(SV* sv)

SvOOK
    Returns a U32 indicating whether the pointer to the string buffer is offset. This hack is used internally to speed up removal of characters from the beginning of a SvPV. When SvOOK is true, then the start of the allocated string buffer is actually "SvOOK_offset()" bytes before SvPVX. This offset used to be stored in SvIVX, but is now stored within the spare part of the buffer.

            U32     SvOOK(SV* sv)

SvOOK_offset
    Reads into len the offset from SvPVX back to the true start of the allocated buffer, which will be non-zero if "sv_chop" has been used to efficiently remove characters from start of the buffer. Implemented as a macro, which takes the address of len, which must be of type "STRLEN". Evaluates sv more than once. Sets len to 0 if "SvOOK(sv)" is false.

            void    SvOOK_offset(NN SV*sv, STRLEN len)

SvPOK
    Returns a U32 value indicating whether the SV contains a character string.

            U32     SvPOK(SV* sv)

SvPOKp
    Returns a U32 value indicating whether the SV contains a character string. Checks the private setting. Use "SvPOK" instead.

            U32     SvPOKp(SV* sv)

SvPOK_off
    Unsets the PV status of an SV.

            void    SvPOK_off(SV* sv)

SvPOK_on
    Tells an SV that it is a string.

            void    SvPOK_on(SV* sv)

SvPOK_only
    Tells an SV that it is a string and disables all other OK bits. Will also turn off the UTF-8 status.

            void    SvPOK_only(SV* sv)

SvPOK_only_UTF8
    Tells an SV that it is a string and disables all other OK bits, and leaves the UTF-8 status as it was.

            void    SvPOK_only_UTF8(SV* sv)

SvPV
    Returns a pointer to the string in the SV, or a stringified form of the SV if the SV does not contain a string. The SV may cache the stringified version becoming "SvPOK". Handles 'get' magic. See also "SvPVx" for a version which guarantees to evaluate sv only once.

            char*   SvPV(SV* sv, STRLEN len)

SvPVbyte
    Like "SvPV", but converts sv to byte representation first if necessary.

            char*   SvPVbyte(SV* sv, STRLEN len)

SvPVbytex
    Like "SvPV", but converts sv to byte representation first if necessary. Guarantees to evaluate sv only once; use the more efficient "SvPVbyte" otherwise.

            char*   SvPVbytex(SV* sv, STRLEN len)

SvPVbytex_force
    Like "SvPV_force", but converts sv to byte representation first if necessary. Guarantees to evaluate sv only once; use the more efficient "SvPVbyte_force" otherwise.

            char*   SvPVbytex_force(SV* sv, STRLEN len)

SvPVbyte_force
    Like "SvPV_force", but converts sv to byte representation first if necessary.

            char*   SvPVbyte_force(SV* sv, STRLEN len)

SvPVbyte_nolen
    Like "SvPV_nolen", but converts sv to byte representation first if necessary.

            char*   SvPVbyte_nolen(SV* sv)

SvPVutf8
    Like "SvPV", but converts sv to utf8 first if necessary.

            char*   SvPVutf8(SV* sv, STRLEN len)

SvPVutf8x
    Like "SvPV", but converts sv to utf8 first if necessary. Guarantees to evaluate sv only once; use the more efficient "SvPVutf8" otherwise.

            char*   SvPVutf8x(SV* sv, STRLEN len)

SvPVutf8x_force
    Like "SvPV_force", but converts sv to utf8 first if necessary. Guarantees to evaluate sv only once; use the more efficient "SvPVutf8_force" otherwise.

            char*   SvPVutf8x_force(SV* sv, STRLEN len)

SvPVutf8_force
    Like "SvPV_force", but converts sv to utf8 first if necessary.

            char*   SvPVutf8_force(SV* sv, STRLEN len)

SvPVutf8_nolen
    Like "SvPV_nolen", but converts sv to utf8 first if necessary.

            char*   SvPVutf8_nolen(SV* sv)

SvPVX
    Returns a pointer to the physical string in the SV. The SV must contain a string.

            char*   SvPVX(SV* sv)

SvPVx
    A version of "SvPV" which guarantees to evaluate "sv" only once. Only use this if "sv" is an expression with side effects, otherwise use the more efficient "SvPVX".

            char*   SvPVx(SV* sv, STRLEN len)

SvPV_force
    Like "SvPV" but will force the SV into containing just a string ("SvPOK_only"). You want force if you are going to update the "SvPVX" directly.

            char*   SvPV_force(SV* sv, STRLEN len)

SvPV_force_nomg
    Like "SvPV" but will force the SV into containing just a string ("SvPOK_only"). You want force if you are going to update the "SvPVX" directly. Doesn't process magic.

            char*   SvPV_force_nomg(SV* sv, STRLEN len)

SvPV_nolen
    Returns a pointer to the string in the SV, or a stringified form of the SV if the SV does not contain a string. The SV may cache the stringified form becoming "SvPOK". Handles 'get' magic.

            char*   SvPV_nolen(SV* sv)

SvPV_nomg
    Like "SvPV" but doesn't process magic.

            char*   SvPV_nomg(SV* sv, STRLEN len)

SvPV_set
    Set the value of the PV pointer in sv to val. See "SvIV_set".

            void    SvPV_set(SV* sv, char* val)

SvREFCNT
    Returns the value of the object's reference count.

            U32     SvREFCNT(SV* sv)

SvREFCNT_dec
    Decrements the reference count of the given SV.

            void    SvREFCNT_dec(SV* sv)

SvREFCNT_inc
    Increments the reference count of the given SV.

    All of the following SvREFCNT_inc* macros are optimized versions of SvREFCNT_inc, and can be replaced with SvREFCNT_inc.

            SV*     SvREFCNT_inc(SV* sv)

SvREFCNT_inc_NN
    Same as SvREFCNT_inc, but can only be used if you know sv is not NULL. Since we don't have to check the NULLness, it's faster and smaller.

            SV*     SvREFCNT_inc_NN(SV* sv)

SvREFCNT_inc_simple
    Same as SvREFCNT_inc, but can only be used with expressions without side effects. Since we don't have to store a temporary value, it's faster.

            SV*     SvREFCNT_inc_simple(SV* sv)

SvREFCNT_inc_simple_NN
    Same as SvREFCNT_inc_simple, but can only be used if you know sv is not NULL. Since we don't have to check the NULLness, it's faster and smaller.

            SV*     SvREFCNT_inc_simple_NN(SV* sv)

SvREFCNT_inc_simple_void
    Same as SvREFCNT_inc_simple, but can only be used if you don't need the return value. The macro doesn't need to return a meaningful value.

            void    SvREFCNT_inc_simple_void(SV* sv)

SvREFCNT_inc_simple_void_NN
    Same as SvREFCNT_inc, but can only be used if you don't need the return value, and you know that sv is not NULL. The macro doesn't need to return a meaningful value, or check for NULLness, so it's smaller and faster.

            void    SvREFCNT_inc_simple_void_NN(SV* sv)

SvREFCNT_inc_void
    Same as SvREFCNT_inc, but can only be used if you don't need the return value. The macro doesn't need to return a meaningful value.

            void    SvREFCNT_inc_void(SV* sv)

SvREFCNT_inc_void_NN
    Same as SvREFCNT_inc, but can only be used if you don't need the return value, and you know that sv is not NULL. The macro doesn't need to return a meaningful value, or check for NULLness, so it's smaller and faster.

            void    SvREFCNT_inc_void_NN(SV* sv)

SvROK
    Tests if the SV is an RV.

            U32     SvROK(SV* sv)

SvROK_off
    Unsets the RV status of an SV.

            void    SvROK_off(SV* sv)

SvROK_on
    Tells an SV that it is an RV.

            void    SvROK_on(SV* sv)

SvRV
    Dereferences an RV to return the SV.

            SV*     SvRV(SV* sv)

SvRV_set
    Set the value of the RV pointer in sv to val. See "SvIV_set".

            void    SvRV_set(SV* sv, SV* val)

SvSTASH
    Returns the stash of the SV.

            HV*     SvSTASH(SV* sv)

SvSTASH_set
    Set the value of the STASH pointer in sv to val. See "SvIV_set".

            void    SvSTASH_set(SV* sv, HV* val)

SvTAINT
    Taints an SV if tainting is enabled.

            void    SvTAINT(SV* sv)

SvTAINTED
    Checks to see if an SV is tainted. Returns TRUE if it is, FALSE if not.

            bool    SvTAINTED(SV* sv)

SvTAINTED_off
    Untaints an SV. Be very careful with this routine, as it short-circuits some of Perl's fundamental security features. XS module authors should not use this function unless they fully understand all the implications of unconditionally untainting the value. Untainting should be done in the standard perl fashion, via a carefully crafted regexp, rather than directly untainting variables.

            void    SvTAINTED_off(SV* sv)

SvTAINTED_on
    Marks an SV as tainted if tainting is enabled.

            void    SvTAINTED_on(SV* sv)

SvTRUE
    Returns a boolean indicating whether Perl would evaluate the SV as true or false. See SvOK() for a defined/undefined test. Does not handle 'get' magic.

            bool    SvTRUE(SV* sv)

SvTYPE
    Returns the type of the SV. See "svtype".

            svtype  SvTYPE(SV* sv)

SvUOK
    Returns a boolean indicating whether the SV contains an unsigned integer.

            bool    SvUOK(SV* sv)

SvUPGRADE
    Used to upgrade an SV to a more complex form. Uses "sv_upgrade" to perform the upgrade if necessary. See "svtype".

            void    SvUPGRADE(SV* sv, svtype type)

SvUTF8
    Returns a U32 value indicating whether the SV contains UTF-8 encoded data. Call this after SvPV() in case any call to string overloading updates the internal flag.

            U32     SvUTF8(SV* sv)

SvUTF8_off
    Unsets the UTF-8 status of an SV.

            void    SvUTF8_off(SV *sv)

SvUTF8_on
    Turn on the UTF-8 status of an SV (the data is not changed, just the flag). Do not use frivolously.

            void    SvUTF8_on(SV *sv)

SvUV
    Coerces the given SV to an unsigned integer and returns it. See "SvUVx" for a version which guarantees to evaluate sv only once.

            UV      SvUV(SV* sv)

SvUVX
    Returns the raw value in the SV's UV slot, without checks or conversions. Only use when you are sure SvIOK is true. See also "SvUV()".

            UV      SvUVX(SV* sv)

SvUVx
    Coerces the given SV to an unsigned integer and returns it. Guarantees to "sv" only once. Only use this if "sv" is an expression with side effects, otherwise use the more efficient "SvUV".

            UV      SvUVx(SV* sv)

SvUV_nomg
    Like "SvUV" but doesn't process magic.

            UV      SvUV_nomg(SV* sv)

SvUV_set
    Set the value of the UV pointer in sv to val. See "SvIV_set".

            void    SvUV_set(SV* sv, UV val)

SvVOK
    Returns a boolean indicating whether the SV contains a v-string.

            bool    SvVOK(SV* sv)

sv_catpvn_nomg
    Like "sv_catpvn" but doesn't process magic.

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

sv_catsv_nomg
    Like "sv_catsv" but doesn't process magic.

            void    sv_catsv_nomg(SV* dsv, SV* ssv)

sv_derived_from
    Returns a boolean indicating whether the SV is derived from the specified class at the C level. To check derivation at the Perl level, call "isa()" as a normal Perl method.

            bool    sv_derived_from(SV* sv, const char *const name)

sv_does
    Returns a boolean indicating whether the SV performs a specific, named role. The SV can be a Perl object or the name of a Perl class.

            bool    sv_does(SV* sv, const char *const name)

sv_report_used
    Dump the contents of all SVs not yet freed. (Debugging aid).

            void    sv_report_used()

sv_setsv_nomg
    Like "sv_setsv" but doesn't process magic.

            void    sv_setsv_nomg(SV* dsv, SV* ssv)

sv_utf8_upgrade_nomg
    Like sv_utf8_upgrade, but doesn't do magic on "sv"

            STRLEN  sv_utf8_upgrade_nomg(NN SV *sv)

SV-Body Allocation

looks_like_number
    Test if the content of an SV looks like a number (or is a number). "Inf" and "Infinity" are treated as numbers (so will not issue a non-numeric warning), even if your atof() doesn't grok them.

            I32     looks_like_number(SV *const sv)

newRV_noinc
    Creates an RV wrapper for an SV. The reference count for the original SV is not incremented.

            SV*     newRV_noinc(SV *const sv)

newSV
    Creates a new SV. A non-zero "len" parameter indicates the number of bytes of preallocated string space the SV should have. An extra byte for a trailing NUL is also reserved. (SvPOK is not set for the SV even if string space is allocated.) The reference count for the new SV is set to 1.

    In 5.9.3, newSV() replaces the older NEWSV() 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.

            SV*     newSV(const STRLEN len)

newSVhek
    Creates a new SV from the hash key structure. It will generate scalars that point to the shared string table where possible. Returns a new (undefined) SV if the hek is NULL.

            SV*     newSVhek(const HEK *const hek)

newSViv
    Creates a new SV and copies an integer into it. The reference count for the SV is set to 1.

            SV*     newSViv(const IV i)

newSVnv
    Creates a new SV and copies a floating point value into it. The reference count for the SV is set to 1.

            SV*     newSVnv(const NV n)

newSVpv
    Creates a new SV and copies a string into it. The reference count for the SV is set to 1. If "len" is zero, Perl will compute the length using strlen(). For efficiency, consider using "newSVpvn" instead.

            SV*     newSVpv(const char *const s, const STRLEN len)

newSVpvf
    Creates a new SV and initializes it with the string formatted like "sprintf".

            SV*     newSVpvf(const char *const pat, ...)

newSVpvn
    Creates a new SV and copies a string into it. The reference count for the SV is set to 1. Note that if "len" is zero, Perl will create a zero length string. You are responsible for ensuring that the source string is at least "len" bytes long. If the "s" argument is NULL the new SV will be undefined.

            SV*     newSVpvn(const char *const s, const STRLEN len)

newSVpvn_flags
    Creates a new SV and copies a string into it. The reference count for the SV is set to 1. Note that if "len" is zero, Perl will create a zero length string. You are responsible for ensuring that the source string is at least "len" bytes long. If the "s" argument is NULL the new SV will be undefined. Currently the only flag bits accepted are "SVf_UTF8" and "SVs_TEMP". If "SVs_TEMP" is set, then "sv2mortal()" is called on the result before returning. If "SVf_UTF8" is set, "s" is considered to be in UTF-8 and the "SVf_UTF8" flag will be set on the new SV. "newSVpvn_utf8()" is a convenience wrapper for this function, defined as

        #define newSVpvn_utf8(s, len, u)                    \
            newSVpvn_flags((s), (len), (u) ? SVf_UTF8 : 0)

            SV*     newSVpvn_flags(const char *const s, const STRLEN len, const U32 flags)

newSVpvn_share
    Creates a new SV with its SvPVX_const pointing to a shared string in the string table. If the string does not already exist in the table, it is created first. Turns on READONLY and FAKE. If the "hash" parameter is non-zero, that value is used; otherwise the hash is computed. The string's hash can be later be retrieved from the SV with the "SvSHARED_HASH()" macro. The idea here is that as the string table is used for shared hash keys these strings will have SvPVX_const == HeKEY and hash lookup will avoid string compare.

            SV*     newSVpvn_share(const char* s, I32 len, U32 hash)

newSVpvs
    Like "newSVpvn", but takes a literal string instead of a string/length pair.

            SV*     newSVpvs(const char* s)

newSVpvs_flags
    Like "newSVpvn_flags", but takes a literal string instead of a string/length pair.

            SV*     newSVpvs_flags(const char* s, U32 flags)

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

            SV*     newSVpvs_share(const char* s)

newSVrv
    Creates a new SV for the RV, "rv", to point to. If "rv" is not an RV then it will be upgraded to one. If "classname" is non-null then the new SV will be blessed in the specified package. The new SV is returned and its reference count is 1.

            SV*     newSVrv(SV *const rv, const char *const classname)

newSVsv
    Creates a new SV which is an exact duplicate of the original SV. (Uses "sv_setsv").

            SV*     newSVsv(SV *const old)

newSVuv
    Creates a new SV and copies an unsigned integer into it. The reference count for the SV is set to 1.

            SV*     newSVuv(const UV u)

newSV_type
    Creates a new SV, of the type specified. The reference count for the new SV is set to 1.

            SV*     newSV_type(const svtype type)

sv_2bool
    This function is only called on magical items, and is only used by sv_true() or its macro equivalent.

            bool    sv_2bool(SV *const sv)

sv_2cv
    Using various gambits, try to get a CV from an SV; in addition, try if possible to set *st and *gvp to the stash and GV associated with it. The flags in "lref" are passed to gv_fetchsv.

            CV*     sv_2cv(SV* sv, HV **const st, GV **const gvp, const I32 lref)

sv_2io
    Using various gambits, try to get an IO from an SV: the IO slot if its a GV; or the recursive result if we're an RV; or the IO slot of the symbol named after the PV if we're a string.

            IO*     sv_2io(SV *const sv)

sv_2iv_flags
    Return the integer value of an SV, doing any necessary string conversion. If flags includes SV_GMAGIC, does an mg_get() first. Normally used via the "SvIV(sv)" and "SvIVx(sv)" macros.

            IV      sv_2iv_flags(SV *const sv, const I32 flags)

sv_2mortal
    Marks an existing SV as mortal. The SV will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. SvTEMP() is turned on which means that the SV's string buffer can be "stolen" if this SV is copied. See also "sv_newmortal" and "sv_mortalcopy".

            SV*     sv_2mortal(SV *const sv)

sv_2nv
    Return the num value of an SV, doing any necessary string or integer conversion, magic etc. Normally used via the "SvNV(sv)" and "SvNVx(sv)" macros.

            NV      sv_2nv(SV *const sv)

sv_2pvbyte
    Return a pointer to the byte-encoded representation of the SV, and set *lp to its length. May cause the SV to be downgraded from UTF-8 as a side-effect.

    Usually accessed via the "SvPVbyte" macro.

            char*   sv_2pvbyte(SV *const sv, STRLEN *const lp)

sv_2pvutf8
    Return a pointer to the UTF-8-encoded representation of the SV, and set *lp to its length. May cause the SV to be upgraded to UTF-8 as a side-effect.

    Usually accessed via the "SvPVutf8" macro.

            char*   sv_2pvutf8(SV *const sv, STRLEN *const lp)

sv_2pv_flags
    Returns a pointer to the string value of an SV, and sets *lp to its length. If flags includes SV_GMAGIC, does an mg_get() first. Coerces sv to a string if necessary. Normally invoked via the "SvPV_flags" macro. "sv_2pv()" and "sv_2pv_nomg" usually end up here too.

            char*   sv_2pv_flags(SV *const sv, STRLEN *const lp, const I32 flags)

sv_2uv_flags
    Return the unsigned integer value of an SV, doing any necessary string conversion. If flags includes SV_GMAGIC, does an mg_get() first. Normally used via the "SvUV(sv)" and "SvUVx(sv)" macros.

            UV      sv_2uv_flags(SV *const sv, const I32 flags)

sv_backoff
    Remove any string offset. You should normally use the "SvOOK_off" macro wrapper instead.

            int     sv_backoff(SV *const sv)

sv_bless
    Blesses an SV into a specified package. The SV must be an RV. The package must be designated by its stash (see "gv_stashpv()"). The reference count of the SV is unaffected.

            SV*     sv_bless(SV *const sv, HV *const stash)

sv_catpv
    Concatenates the string onto the end of the string which is in the SV. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpv_mg".

            void    sv_catpv(SV *const sv, const char* ptr)

sv_catpvf
    Processes its arguments like "sprintf" and appends the formatted output to an SV. If the appended data contains "wide" characters (including, but not limited to, SVs with a UTF-8 PV formatted with %s, and characters >255 formatted with %c), the original SV might get upgraded to UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpvf_mg". If the original SV was UTF-8, the pattern should be valid UTF-8; if the original SV was bytes, the pattern should be too.

            void    sv_catpvf(SV *const sv, const char *const pat, ...)

sv_catpvf_mg
    Like "sv_catpvf", but also handles 'set' magic.

            void    sv_catpvf_mg(SV *const sv, const char *const pat, ...)

sv_catpvn
    Concatenates the string onto the end of the string which is in the SV. The "len" indicates number of bytes to copy. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpvn_mg".

            void    sv_catpvn(SV *dsv, const char *sstr, STRLEN len)

sv_catpvn_flags
    Concatenates the string onto the end of the string which is in the SV. The "len" indicates number of bytes to copy. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. If "flags" has "SV_GMAGIC" bit set, will "mg_get" on "dsv" if appropriate, else not. "sv_catpvn" and "sv_catpvn_nomg" are implemented in terms of this function.

            void    sv_catpvn_flags(SV *const dstr, const char *sstr, const STRLEN len, const I32 flags)

sv_catpvs
    Like "sv_catpvn", but takes a literal string instead of a string/length pair.

            void    sv_catpvs(SV* sv, const char* s)

sv_catpv_mg
    Like "sv_catpv", but also handles 'set' magic.

            void    sv_catpv_mg(SV *const sv, const char *const ptr)

sv_catsv
    Concatenates the string from SV "ssv" onto the end of the string in SV "dsv". Modifies "dsv" but not "ssv". Handles 'get' magic, but not 'set' magic. See "sv_catsv_mg".

            void    sv_catsv(SV *dstr, SV *sstr)

sv_catsv_flags
    Concatenates the string from SV "ssv" onto the end of the string in SV "dsv". Modifies "dsv" but not "ssv". If "flags" has "SV_GMAGIC" bit set, will "mg_get" on the SVs if appropriate, else not. "sv_catsv" and "sv_catsv_nomg" are implemented in terms of this function.

            void    sv_catsv_flags(SV *const dsv, SV *const ssv, const I32 flags)

sv_chop
    Efficient removal of characters from the beginning of the string buffer. SvPOK(sv) must be true and the "ptr" must be a pointer to somewhere inside the string buffer. The "ptr" becomes the first character of the adjusted string. Uses the "OOK hack". Beware: after this function returns, "ptr" and SvPVX_const(sv) may no longer refer to the same chunk of data.

            void    sv_chop(SV *const sv, const char *const ptr)

sv_clear
    Clear an SV: call any destructors, free up any memory used by the body, and free the body itself. The SV's head is not freed, although its type is set to all 1's so that it won't inadvertently be assumed to be live during global destruction etc. This function should only be called when REFCNT is zero. Most of the time you'll want to call "sv_free()" (or its macro wrapper "SvREFCNT_dec") instead.

            void    sv_clear(SV *const sv)

sv_cmp
    Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the string in "sv1" is less than, equal to, or greater than the string in "sv2". Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. See also "sv_cmp_locale".

            I32     sv_cmp(SV *const sv1, SV *const sv2)

sv_cmp_locale
    Compares the strings in two SVs in a locale-aware manner. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. See also "sv_cmp".

            I32     sv_cmp_locale(SV *const sv1, SV *const sv2)

sv_collxfrm
    Add Collate Transform magic to an SV if it doesn't already have it.

    Any scalar variable may carry PERL_MAGIC_collxfrm magic that contains the scalar data of the variable, but transformed to such a format that a normal memory comparison can be used to compare the data according to the locale settings.

            char*   sv_collxfrm(SV *const sv, STRLEN *const nxp)

sv_copypv
    Copies a stringified representation of the source SV into the destination SV. Automatically performs any necessary mg_get and coercion of numeric values into strings. Guaranteed to preserve UTF8 flag even from overloaded objects. Similar in nature to sv_2pv[_flags] but operates directly on an SV instead of just the string. Mostly uses sv_2pv_flags to do its work, except when that would lose the UTF-8'ness of the PV.

            void    sv_copypv(SV *const dsv, SV *const ssv)

sv_dec
    Auto-decrement of the value in the SV, doing string to numeric conversion if necessary. Handles 'get' magic.

            void    sv_dec(SV *const sv)

sv_eq
    Returns a boolean indicating whether the strings in the two SVs are identical. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary.

            I32     sv_eq(SV* sv1, SV* sv2)

sv_force_normal_flags
    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; if we're a copy-on-write scalar, this is the on-write time when we do the copy, and is also used locally. If "SV_COW_DROP_PV" is set then a copy-on-write scalar drops its PV buffer (if any) and becomes SvPOK_off rather than making a copy. (Used where this scalar is about to be set to some other value.) In addition, the "flags" parameter gets passed to "sv_unref_flags()" when unrefing. "sv_force_normal" calls this function with flags set to 0.

            void    sv_force_normal_flags(SV *const sv, const U32 flags)

sv_free
    Decrement an SV's reference count, and if it drops to zero, call "sv_clear" to invoke destructors and free up any memory used by the body; finally, deallocate the SV's head itself. Normally called via a wrapper macro "SvREFCNT_dec".

            void    sv_free(SV *const sv)

sv_gets
    Get a line from the filehandle and store it into the SV, optionally appending to the currently-stored string.

            char*   sv_gets(SV *const sv, PerlIO *const fp, I32 append)

sv_grow
    Expands the character buffer in the SV. If necessary, uses "sv_unref" and upgrades the SV to "SVt_PV". Returns a pointer to the character buffer. Use the "SvGROW" wrapper instead.

            char*   sv_grow(SV *const sv, STRLEN newlen)

sv_inc
    Auto-increment of the value in the SV, doing string to numeric conversion if necessary. Handles 'get' magic.

            void    sv_inc(SV *const sv)

sv_insert
    Inserts a string at the specified offset/length within the SV. Similar to the Perl substr() function. Handles get magic.

            void    sv_insert(SV *const bigstr, const STRLEN offset, const STRLEN len, const char *const little, const STRLEN littlelen)

sv_insert_flags
    Same as "sv_insert", but the extra "flags" are passed the "SvPV_force_flags" that applies to "bigstr".

            void    sv_insert_flags(SV *const bigstr, const STRLEN offset, const STRLEN len, const char *const little, const STRLEN littlelen, const U32 flags)

sv_isa
    Returns a boolean indicating whether the SV is blessed into the specified class. This does not check for subtypes; use "sv_derived_from" to verify an inheritance relationship.

            int     sv_isa(SV* sv, const char *const name)

sv_isobject
    Returns a boolean indicating whether the SV is an RV pointing to a blessed object. If the SV is not an RV, or if the object is not blessed, then this will return false.

            int     sv_isobject(SV* sv)

sv_len
    Returns the length of the string in the SV. Handles magic and type coercion. See also "SvCUR", which gives raw access to the xpv_cur slot.

            STRLEN  sv_len(SV *const sv)

sv_len_utf8
    Returns the number of characters in the string in an SV, counting wide UTF-8 bytes as a single character. Handles magic and type coercion.

            STRLEN  sv_len_utf8(SV *const sv)

sv_magic
    Adds magic to an SV. First upgrades "sv" to type "SVt_PVMG" if necessary, then adds a new magic item of type "how" to the head of the magic list.

    See "sv_magicext" (which "sv_magic" now calls) for a description of the handling of the "name" and "namlen" arguments.

    You need to use "sv_magicext" to add magic to SvREADONLY SVs and also to add more than one instance of the same 'how'.

            void    sv_magic(SV *const sv, SV *const obj, const int how, const char *const name, const I32 namlen)

sv_magicext
    Adds magic to an SV, upgrading it if necessary. Applies the supplied vtable and returns a pointer to the magic added.

    Note that "sv_magicext" will allow things that "sv_magic" will not. In particular, you can add magic to SvREADONLY SVs, and add more than one instance of the same 'how'.

    If "namlen" is greater than zero then a "savepvn" copy of "name" is stored, if "namlen" is zero then "name" is stored as-is and - as another special case - if "(name && namlen == HEf_SVKEY)" then "name" is assumed to contain an "SV*" and is stored as-is with its REFCNT incremented.

    (This is now used as a subroutine by "sv_magic".)

            MAGIC * sv_magicext(SV *const sv, SV *const obj, const int how, const MGVTBL *const vtbl, const char *const name, const I32 namlen)

sv_mortalcopy
    Creates a new SV which is a copy of the original SV (using "sv_setsv"). The new SV is marked as mortal. It will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. See also "sv_newmortal" and "sv_2mortal".

            SV*     sv_mortalcopy(SV *const oldsv)

sv_newmortal
    Creates a new null SV which is mortal. The reference count of the SV is set to 1. It will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. See also "sv_mortalcopy" and "sv_2mortal".

            SV*     sv_newmortal()

sv_newref
    Increment an SV's reference count. Use the "SvREFCNT_inc()" wrapper instead.

            SV*     sv_newref(SV *const sv)

sv_pos_b2u
    Converts the value pointed to by offsetp from a count of bytes from the start of the string, to a count of the equivalent number of UTF-8 chars. Handles magic and type coercion.

            void    sv_pos_b2u(SV *const sv, I32 *const offsetp)

sv_pos_u2b
    Converts the value pointed to by offsetp from a count of UTF-8 chars from the start of the string, to a count of the equivalent number of bytes; if lenp is non-zero, it does the same to lenp, but this time starting from the offset, rather than from the start of the string. Handles magic and type coercion.

    Use "sv_pos_u2b_flags" in preference, which correctly handles strings longer than 2Gb.

            void    sv_pos_u2b(SV *const sv, I32 *const offsetp, I32 *const lenp)

sv_pos_u2b_flags
    Converts the value pointed to by offsetp from a count of UTF-8 chars from the start of the string, to a count of the equivalent number of bytes; if lenp is non-zero, it does the same to lenp, but this time starting from the offset, rather than from the start of the string. Handles type coercion. flags is passed to "SvPV_flags", and usually should be "SV_GMAGIC|SV_CONST_RETURN" to handle magic.

            STRLEN  sv_pos_u2b_flags(SV *const sv, STRLEN uoffset, STRLEN *const lenp, U32 flags)

sv_pvbyten_force
    The backend for the "SvPVbytex_force" macro. Always use the macro instead.

            char*   sv_pvbyten_force(SV *const sv, STRLEN *const lp)

sv_pvn_force
    Get a sensible string out of the SV somehow. A private implementation of the "SvPV_force" macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

            char*   sv_pvn_force(SV* sv, STRLEN* lp)

sv_pvn_force_flags
    Get a sensible string out of the SV somehow. If "flags" has "SV_GMAGIC" bit set, will "mg_get" on "sv" if appropriate, else not. "sv_pvn_force" and "sv_pvn_force_nomg" are implemented in terms of this function. You normally want to use the various wrapper macros instead: see "SvPV_force" and "SvPV_force_nomg"

            char*   sv_pvn_force_flags(SV *const sv, STRLEN *const lp, const I32 flags)

sv_pvutf8n_force
    The backend for the "SvPVutf8x_force" macro. Always use the macro instead.

            char*   sv_pvutf8n_force(SV *const sv, STRLEN *const lp)

sv_reftype
    Returns a string describing what the SV is a reference to.

            const char*     sv_reftype(const SV *const sv, const int ob)

sv_replace
    Make the first argument a copy of the second, then delete the original. The target SV physically takes over ownership of the body of the source SV and inherits its flags; however, the target keeps any magic it owns, and any magic in the source is discarded. Note that this is a rather specialist SV copying operation; most of the time you'll want to use "sv_setsv" or one of its many macro front-ends.

            void    sv_replace(SV *const sv, SV *const nsv)

sv_reset
    Underlying implementation for the "reset" Perl function. Note that the perl-level function is vaguely deprecated.

            void    sv_reset(const char* s, HV *const stash)

sv_rvweaken
    Weaken a reference: set the "SvWEAKREF" flag on this RV; give the referred-to SV "PERL_MAGIC_backref" magic if it hasn't already; and push a back-reference to this RV onto the array of backreferences associated with that magic. If the RV is magical, set magic will be called after the RV is cleared.

            SV*     sv_rvweaken(SV *const sv)

sv_setiv
    Copies an integer into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setiv_mg".

            void    sv_setiv(SV *const sv, const IV num)

sv_setiv_mg
    Like "sv_setiv", but also handles 'set' magic.

            void    sv_setiv_mg(SV *const sv, const IV i)

sv_setnv
    Copies a double into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setnv_mg".

            void    sv_setnv(SV *const sv, const NV num)

sv_setnv_mg
    Like "sv_setnv", but also handles 'set' magic.

            void    sv_setnv_mg(SV *const sv, const NV num)

sv_setpv
    Copies a string into an SV. The string must be null-terminated. Does not handle 'set' magic. See "sv_setpv_mg".

            void    sv_setpv(SV *const sv, const char *const ptr)

sv_setpvf
    Works like "sv_catpvf" but copies the text into the SV instead of appending it. Does not handle 'set' magic. See "sv_setpvf_mg".

            void    sv_setpvf(SV *const sv, const char *const pat, ...)

sv_setpvf_mg
    Like "sv_setpvf", but also handles 'set' magic.

            void    sv_setpvf_mg(SV *const sv, const char *const pat, ...)

sv_setpviv
    Copies an integer into the given SV, also updating its string value. Does not handle 'set' magic. See "sv_setpviv_mg".

            void    sv_setpviv(SV *const sv, const IV num)

sv_setpviv_mg
    Like "sv_setpviv", but also handles 'set' magic.

            void    sv_setpviv_mg(SV *const sv, const IV iv)

sv_setpvn
    Copies a string into an SV. The "len" parameter indicates the number of bytes to be copied. If the "ptr" argument is NULL the SV will become undefined. Does not handle 'set' magic. See "sv_setpvn_mg".

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

sv_setpvn_mg
    Like "sv_setpvn", but also handles 'set' magic.

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

sv_setpvs
    Like "sv_setpvn", but takes a literal string instead of a string/length pair.

            void    sv_setpvs(SV* sv, const char* s)

sv_setpv_mg
    Like "sv_setpv", but also handles 'set' magic.

            void    sv_setpv_mg(SV *const sv, const char *const ptr)

sv_setref_iv
    Copies an integer into a new SV, optionally blessing the SV. The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

            SV*     sv_setref_iv(SV *const rv, const char *const classname, const IV iv)

sv_setref_nv
    Copies a double into a new SV, optionally blessing the SV. The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

            SV*     sv_setref_nv(SV *const rv, const char *const classname, const NV nv)

sv_setref_pv
    Copies a pointer into a new SV, optionally blessing the SV. The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. If the "pv" argument is NULL then "PL_sv_undef" will be placed into the SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

    Do not use with other Perl types such as HV, AV, SV, CV, because those objects will become corrupted by the pointer copy process.

    Note that "sv_setref_pvn" copies the string while this copies the pointer.

            SV*     sv_setref_pv(SV *const rv, const char *const classname, void *const pv)

sv_setref_pvn
    Copies a string into a new SV, optionally blessing the SV. The length of the string must be specified with "n". The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

    Note that "sv_setref_pv" copies the pointer while this copies the string.

            SV*     sv_setref_pvn(SV *const rv, const char *const classname, const char *const pv, const STRLEN n)

sv_setref_uv
    Copies an unsigned integer into a new SV, optionally blessing the SV. The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

            SV*     sv_setref_uv(SV *const rv, const char *const classname, const UV uv)

sv_setsv
    Copies the contents of the source SV "ssv" into the destination SV "dsv". The source SV may be destroyed if it is mortal, so don't use this function if the source SV needs to be reused. Does not handle 'set' magic. Loosely speaking, it performs a copy-by-value, obliterating any previous content of the destination.

    You probably want to use one of the assortment of wrappers, such as "SvSetSV", "SvSetSV_nosteal", "SvSetMagicSV" and "SvSetMagicSV_nosteal".

            void    sv_setsv(SV *dstr, SV *sstr)

sv_setsv_flags
    Copies the contents of the source SV "ssv" into the destination SV "dsv". The source SV may be destroyed if it is mortal, so don't use this function if the source SV needs to be reused. Does not handle 'set' magic. Loosely speaking, it performs a copy-by-value, obliterating any previous content of the destination. If the "flags" parameter has the "SV_GMAGIC" bit set, will "mg_get" on "ssv" if appropriate, else not. If the "flags" parameter has the "NOSTEAL" bit set then the buffers of temps will not be stolen. <sv_setsv> and "sv_setsv_nomg" are implemented in terms of this function.

    You probably want to use one of the assortment of wrappers, such as "SvSetSV", "SvSetSV_nosteal", "SvSetMagicSV" and "SvSetMagicSV_nosteal".

    This is the primary function for copying scalars, and most other copy-ish functions and macros use this underneath.

            void    sv_setsv_flags(SV *dstr, SV *sstr, const I32 flags)

sv_setsv_mg
    Like "sv_setsv", but also handles 'set' magic.

            void    sv_setsv_mg(SV *const dstr, SV *const sstr)

sv_setuv
    Copies an unsigned integer into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setuv_mg".

            void    sv_setuv(SV *const sv, const UV num)

sv_setuv_mg
    Like "sv_setuv", but also handles 'set' magic.

            void    sv_setuv_mg(SV *const sv, const UV u)

sv_tainted
    Test an SV for taintedness. Use "SvTAINTED" instead.
        bool    sv_tainted(SV *const sv)

sv_true
    Returns true if the SV has a true value by Perl's rules. Use the "SvTRUE" macro instead, which may call "sv_true()" or may instead use an in-line version.

            I32     sv_true(SV *const sv)

sv_unmagic
    Removes all magic of type "type" from an SV.

            int     sv_unmagic(SV *const sv, const int type)

sv_unref_flags
    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". The "cflags" argument can contain "SV_IMMEDIATE_UNREF" to force the reference count to be decremented (otherwise the decrementing is conditional on the reference count being different from one or the reference being a readonly SV). See "SvROK_off".

            void    sv_unref_flags(SV *const ref, const U32 flags)

sv_untaint
    Untaint an SV. Use "SvTAINTED_off" instead.
        void    sv_untaint(SV *const sv)

sv_upgrade
    Upgrade an SV to a more complex form. Generally adds a new body type to the SV, then copies across as much information as possible from the old body. You generally want to use the "SvUPGRADE" macro wrapper. See also "svtype".

            void    sv_upgrade(SV *const sv, svtype new_type)

sv_usepvn_flags
    Tells an SV to use "ptr" to find its string value. Normally the string is stored inside the SV but sv_usepvn allows the SV to use an outside string. The "ptr" should point to memory that was allocated by "malloc". The string length, "len", must be supplied. By default this function will realloc (i.e. move) the memory pointed to by "ptr", so that pointer should not be freed or used by the programmer after giving it to sv_usepvn, and neither should any pointers from "behind" that pointer (e.g. ptr + 1) be used.

    If "flags" & SV_SMAGIC is true, will call SvSETMAGIC. If "flags" & SV_HAS_TRAILING_NUL is true, then "ptr[len]" must be NUL, and the realloc will be skipped. (i.e. the buffer is actually at least 1 byte longer than "len", and already meets the requirements for storing in "SvPVX")

            void    sv_usepvn_flags(SV *const sv, char* ptr, const STRLEN len, const U32 flags)

sv_utf8_decode
    If the PV of the SV is an octet sequence in UTF-8 and contains a multiple-byte character, the "SvUTF8" flag is turned on so that it looks like a character. If the PV contains only single-byte characters, the "SvUTF8" flag stays being off. Scans PV for validity and returns false if the PV is invalid UTF-8.

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

            bool    sv_utf8_decode(SV *const sv)

sv_utf8_downgrade
    Attempts to convert the PV of an SV from characters to bytes. If the PV contains a character that cannot fit in a byte, this conversion will fail; in this case, either returns false or, if "fail_ok" is not true, croaks.

    This is not as a general purpose Unicode to byte encoding interface: use the Encode extension for that.

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

            bool    sv_utf8_downgrade(SV *const sv, const bool fail_ok)

sv_utf8_encode
    Converts the PV of an SV to UTF-8, but then turns the "SvUTF8" flag off so that it looks like octets again.

            void    sv_utf8_encode(SV *const sv)

sv_utf8_upgrade
    Converts the PV of an SV to its UTF-8-encoded form. Forces the SV to string form if it is not already. Will "mg_get" on "sv" if appropriate. Always sets the SvUTF8 flag to avoid future validity checks even if the whole string is the same in UTF-8 as not. Returns the number of bytes in the converted string

    This is not as a general purpose byte encoding to Unicode interface: use the Encode extension for that.

            STRLEN  sv_utf8_upgrade(SV *sv)

sv_utf8_upgrade_flags
    Converts the PV of an SV to its UTF-8-encoded form. Forces the SV to string form if it is not already. Always sets the SvUTF8 flag to avoid future validity checks even if all the bytes are invariant in UTF-8. If "flags" has "SV_GMAGIC" bit set, will "mg_get" on "sv" if appropriate, else not. Returns the number of bytes in the converted string "sv_utf8_upgrade" and "sv_utf8_upgrade_nomg" are implemented in terms of this function.

    This is not as a general purpose byte encoding to Unicode interface: use the Encode extension for that.

            STRLEN  sv_utf8_upgrade_flags(SV *const sv, const I32 flags)

sv_utf8_upgrade_nomg
    Like sv_utf8_upgrade, but doesn't do magic on "sv"

            STRLEN  sv_utf8_upgrade_nomg(SV *sv)

sv_vcatpvf
    Processes its arguments like "vsprintf" and appends the formatted output to an SV. Does not handle 'set' magic. See "sv_vcatpvf_mg".

    Usually used via its frontend "sv_catpvf".

            void    sv_vcatpvf(SV *const sv, const char *const pat, va_list *const args)

sv_vcatpvfn
    Processes its arguments like "vsprintf" and appends the formatted output to an SV. Uses an array of SVs if the C style variable argument list is missing (NULL). When running with taint checks enabled, indicates via "maybe_tainted" if results are untrustworthy (often due to the use of locales).

    Usually used via one of its frontends "sv_vcatpvf" and "sv_vcatpvf_mg".

            void    sv_vcatpvfn(SV *const sv, const char *const pat, const STRLEN patlen, va_list *const args, SV **const svargs, const I32 svmax, bool *const maybe_tainted)

sv_vcatpvf_mg
    Like "sv_vcatpvf", but also handles 'set' magic.

    Usually used via its frontend "sv_catpvf_mg".

            void    sv_vcatpvf_mg(SV *const sv, const char *const pat, va_list *const args)

sv_vsetpvf
    Works like "sv_vcatpvf" but copies the text into the SV instead of appending it. Does not handle 'set' magic. See "sv_vsetpvf_mg".

    Usually used via its frontend "sv_setpvf".

            void    sv_vsetpvf(SV *const sv, const char *const pat, va_list *const args)

sv_vsetpvfn
    Works like "sv_vcatpvfn" but copies the text into the SV instead of appending it.

    Usually used via one of its frontends "sv_vsetpvf" and "sv_vsetpvf_mg".

            void    sv_vsetpvfn(SV *const sv, const char *const pat, const STRLEN patlen, va_list *const args, SV **const svargs, const I32 svmax, bool *const maybe_tainted)

sv_vsetpvf_mg
    Like "sv_vsetpvf", but also handles 'set' magic.

    Usually used via its frontend "sv_setpvf_mg".

            void    sv_vsetpvf_mg(SV *const sv, const char *const pat, va_list *const args)

Unicode Support

bytes_from_utf8
    Converts a string "s" of length "len" from UTF-8 into native byte encoding. Unlike "utf8_to_bytes" but like "bytes_to_utf8", returns a pointer to the newly-created string, and updates "len" to contain the new length. Returns the original string if no conversion occurs, "len" is unchanged. Do nothing if "is_utf8" points to 0. Sets "is_utf8" to 0 if "s" is converted or consisted entirely of characters that are invariant in utf8 (i.e., US-ASCII on non-EBCDIC machines).

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

            U8*     bytes_from_utf8(const U8 *s, STRLEN *len, bool *is_utf8)

bytes_to_utf8
    Converts a string "s" of length "len" from the native encoding into UTF-8. Returns a pointer to the newly-created string, and sets "len" to reflect the new length.

    A NUL character will be written after the end of the string.

    If you want to convert to UTF-8 from encodings other than the native (Latin1 or EBCDIC), see sv_recode_to_utf8().

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

            U8*     bytes_to_utf8(const U8 *s, STRLEN *len)

ibcmp_utf8
    Return true if the strings s1 and s2 differ case-insensitively, false if not (if they are equal case-insensitively). If u1 is true, the string s1 is assumed to be in UTF-8-encoded Unicode. If u2 is true, the string s2 is assumed to be in UTF-8-encoded Unicode. If u1 or u2 are false, the respective string is assumed to be in native 8-bit encoding.

    If the pe1 and pe2 are non-NULL, the scanning pointers will be copied in there (they will point at the beginning of the next character). If the pointers behind pe1 or pe2 are non-NULL, they are the end pointers beyond which scanning will not continue under any circumstances. If the byte lengths l1 and l2 are non-zero, s1+l1 and s2+l2 will be used as goal end pointers that will also stop the scan, and which qualify towards defining a successful match: all the scans that define an explicit length must reach their goal pointers for a match to succeed).

    For case-insensitiveness, the "casefolding" of Unicode is used instead of upper/lowercasing both the characters, see http://www.unicode.org/unicode/reports/tr21/ (Case Mappings).

            I32     ibcmp_utf8(const char *s1, char **pe1, UV l1, bool u1, const char *s2, char **pe2, UV l2, bool u2)

is_ascii_string
    Returns true if first "len" bytes of the given string are ASCII (i.e. none of them even raise the question of UTF-8-ness).

    See also is_utf8_string(), is_utf8_string_loclen(), and is_utf8_string_loc().

            bool    is_ascii_string(const U8 *s, STRLEN len)

is_utf8_char
    Tests if some arbitrary number of bytes begins in a valid UTF-8 character. Note that an INVARIANT (i.e. ASCII on non-EBCDIC machines) character is a valid UTF-8 character. The actual number of bytes in the UTF-8 character will be returned if it is valid, otherwise 0.

            STRLEN  is_utf8_char(const U8 *s)

is_utf8_string
    Returns true if first "len" bytes of the given string form a valid UTF-8 string, false otherwise. Note that 'a valid UTF-8 string' does not mean 'a string that contains code points above 0x7F encoded in UTF-8' because a valid ASCII string is a valid UTF-8 string.

    See also is_ascii_string(), is_utf8_string_loclen(), and is_utf8_string_loc().

            bool    is_utf8_string(const U8 *s, STRLEN len)

is_utf8_string_loc
    Like is_utf8_string() but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the "ep".

    See also is_utf8_string_loclen() and is_utf8_string().

            bool    is_utf8_string_loc(const U8 *s, STRLEN len, const U8 **p)

is_utf8_string_loclen
    Like is_utf8_string() but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the "ep", and the number of UTF-8 encoded characters in the "el".

    See also is_utf8_string_loc() and is_utf8_string().

            bool    is_utf8_string_loclen(const U8 *s, STRLEN len, const U8 **ep, STRLEN *el)

pv_uni_display
    Build to the scalar dsv a displayable version of the string spv, length len, the displayable version being at most pvlim bytes long (if longer, the rest is truncated and "..." will be appended).

    The flags argument can have UNI_DISPLAY_ISPRINT set to display isPRINT()able characters as themselves, UNI_DISPLAY_BACKSLASH to display the \\[nrfta\\] as the backslashed versions (like '\n') (UNI_DISPLAY_BACKSLASH is preferred over UNI_DISPLAY_ISPRINT for \\). UNI_DISPLAY_QQ (and its alias UNI_DISPLAY_REGEX) have both UNI_DISPLAY_BACKSLASH and UNI_DISPLAY_ISPRINT turned on.

    The pointer to the PV of the dsv is returned.

            char*   pv_uni_display(SV *dsv, const U8 *spv, STRLEN len, STRLEN pvlim, UV flags)

sv_cat_decode
    The encoding is assumed to be an Encode object, the PV of the ssv is assumed to be octets in that encoding and decoding the input starts from the position which (PV + *offset) pointed to. The dsv will be concatenated the decoded UTF-8 string from ssv. Decoding will terminate when the string tstr appears in decoding output or the input ends on the PV of the ssv. The value which the offset points will be modified to the last input position on the ssv.

    Returns TRUE if the terminator was found, else returns FALSE.

            bool    sv_cat_decode(SV* dsv, SV *encoding, SV *ssv, int *offset, char* tstr, int tlen)

sv_recode_to_utf8
    The encoding is assumed to be an Encode object, on entry the PV of the sv is assumed to be octets in that encoding, and the sv will be converted into Unicode (and UTF-8).

    If the sv already is UTF-8 (or if it is not POK), or if the encoding is not a reference, nothing is done to the sv. If the encoding is not an "Encode::XS" Encoding object, bad things will happen. (See lib/encoding.pm and Encode).

    The PV of the sv is returned.

            char*   sv_recode_to_utf8(SV* sv, SV *encoding)

sv_uni_display
    Build to the scalar dsv a displayable version of the scalar sv, the displayable version being at most pvlim bytes long (if longer, the rest is truncated and "..." will be appended).

    The flags argument is as in pv_uni_display().

    The pointer to the PV of the dsv is returned.

            char*   sv_uni_display(SV *dsv, SV *ssv, STRLEN pvlim, UV flags)

to_utf8_case
    The "p" contains the pointer to the UTF-8 string encoding the character that is being converted.

    The "ustrp" is a pointer to the character buffer to put the conversion result to. The "lenp" is a pointer to the length of the result.

    The "swashp" is a pointer to the swash to use.

    Both the special and normal mappings are stored lib/unicore/To/Foo.pl, and loaded by SWASHNEW, using lib/utf8_heavy.pl. The special (usually, but not always, a multicharacter mapping), is tried first.

    The "special" is a string like "utf8::ToSpecLower", which means the hash %utf8::ToSpecLower. The access to the hash is through Perl_to_utf8_case().

    The "normal" is a string like "ToLower" which means the swash %utf8::ToLower.

            UV      to_utf8_case(const U8 *p, U8* ustrp, STRLEN *lenp, SV **swashp, const char *normal, const char *special)

to_utf8_fold
    Convert the UTF-8 encoded character at p to its foldcase version and store that in UTF-8 in ustrp and its length in bytes in lenp. Note that the ustrp needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the foldcase version may be longer than the original character (up to three characters).

    The first character of the foldcased version is returned (but note, as explained above, that there may be more.)

            UV      to_utf8_fold(const U8 *p, U8* ustrp, STRLEN *lenp)

to_utf8_lower
    Convert the UTF-8 encoded character at p to its lowercase version and store that in UTF-8 in ustrp and its length in bytes in lenp. Note that the ustrp needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the lowercase version may be longer than the original character.

    The first character of the lowercased version is returned (but note, as explained above, that there may be more.)

            UV      to_utf8_lower(const U8 *p, U8* ustrp, STRLEN *lenp)

to_utf8_title
    Convert the UTF-8 encoded character at p to its titlecase version and store that in UTF-8 in ustrp and its length in bytes in lenp. Note that the ustrp needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the titlecase version may be longer than the original character.

    The first character of the titlecased version is returned (but note, as explained above, that there may be more.)

            UV      to_utf8_title(const U8 *p, U8* ustrp, STRLEN *lenp)

to_utf8_upper
    Convert the UTF-8 encoded character at p to its uppercase version and store that in UTF-8 in ustrp and its length in bytes in lenp. Note that the ustrp needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the uppercase version may be longer than the original character.

    The first character of the uppercased version is returned (but note, as explained above, that there may be more.)

            UV      to_utf8_upper(const U8 *p, U8* ustrp, STRLEN *lenp)

utf8n_to_uvchr
    flags

    Returns the native character value of the first character in the string "s" which is assumed to be in UTF-8 encoding; "retlen" will be set to the length, in bytes, of that character.

    Allows length and flags to be passed to low level routine.

            UV      utf8n_to_uvchr(const U8 *s, STRLEN curlen, STRLEN *retlen, U32 flags)

utf8n_to_uvuni
    Bottom level UTF-8 decode routine. Returns the Unicode code point value of the first character in the string "s" which is assumed to be in UTF-8 encoding and no longer than "curlen"; "retlen" will be set to the length, in bytes, of that character.

    If "s" does not point to a well-formed UTF-8 character, the behaviour is dependent on the value of "flags": if it contains UTF8_CHECK_ONLY, it is assumed that the caller will raise a warning, and this function will silently just set "retlen" to "-1" and return zero. If the "flags" does not contain UTF8_CHECK_ONLY, warnings about malformations will be given, "retlen" will be set to the expected length of the UTF-8 character in bytes, and zero will be returned.

    The "flags" can also contain various flags to allow deviations from the strict UTF-8 encoding (see utf8.h).

    Most code should use utf8_to_uvchr() rather than call this directly.

            UV      utf8n_to_uvuni(const U8 *s, STRLEN curlen, STRLEN *retlen, U32 flags)

utf8_distance
    Returns the number of UTF-8 characters between the UTF-8 pointers "a" and "b".

    WARNING: use only if you *know* that the pointers point inside the same UTF-8 buffer.

            IV      utf8_distance(const U8 *a, const U8 *b)

utf8_hop
    Return the UTF-8 pointer "s" displaced by "off" characters, either forward or backward.

    WARNING: do not use the following unless you *know* "off" is within the UTF-8 data pointed to by "s" *and* that on entry "s" is aligned on the first byte of character or just after the last byte of a character.

            U8*     utf8_hop(const U8 *s, I32 off)

utf8_length
    Return the length of the UTF-8 char encoded string "s" in characters. Stops at "e" (inclusive). If "e < s" or if the scan would end up past "e", croaks.

            STRLEN  utf8_length(const U8* s, const U8 *e)

utf8_to_bytes
    Converts a string "s" of length "len" from UTF-8 into native byte encoding. Unlike "bytes_to_utf8", this over-writes the original string, and updates len to contain the new length. Returns zero on failure, setting "len" to -1.

    If you need a copy of the string, see "bytes_from_utf8".

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

            U8*     utf8_to_bytes(U8 *s, STRLEN *len)

utf8_to_uvchr
    Returns the native character value of the first character in the string "s" which is assumed to be in UTF-8 encoding; "retlen" will be set to the length, in bytes, of that character.

    If "s" does not point to a well-formed UTF-8 character, zero is returned and retlen is set, if possible, to -1.

            UV      utf8_to_uvchr(const U8 *s, STRLEN *retlen)

utf8_to_uvuni
    Returns the Unicode code point of the first character in the string "s" which is assumed to be in UTF-8 encoding; "retlen" will be set to the length, in bytes, of that character.

    This function should only be used when the returned UV is considered an index into the Unicode semantic tables (e.g. swashes).

    If "s" does not point to a well-formed UTF-8 character, zero is returned and retlen is set, if possible, to -1.

            UV      utf8_to_uvuni(const U8 *s, STRLEN *retlen)

uvchr_to_utf8
    Adds the UTF-8 representation of the Native codepoint "uv" to the end of the string "d"; "d" should be have at least "UTF8_MAXBYTES+1" free bytes available. The return value is the pointer to the byte after the end of the new character. In other words,

        d = uvchr_to_utf8(d, uv);

    is the recommended wide native character-aware way of saying

        *(d++) = uv;

            U8*     uvchr_to_utf8(U8 *d, UV uv)

uvuni_to_utf8_flags
    Adds the UTF-8 representation of the Unicode codepoint "uv" to the end of the string "d"; "d" should be have at least "UTF8_MAXBYTES+1" free bytes available. The return value is the pointer to the byte after the end of the new character. In other words,

        d = uvuni_to_utf8_flags(d, uv, flags);

    or, in most cases,

        d = uvuni_to_utf8(d, uv);

    (which is equivalent to)

        d = uvuni_to_utf8_flags(d, uv, 0);

    is the recommended Unicode-aware way of saying

        *(d++) = uv;

            U8*     uvuni_to_utf8_flags(U8 *d, UV uv, UV flags)

Variables created by "xsubpp" and "xsubpp" internal functions

ax  Variable which is setup by "xsubpp" to indicate the stack base offset, used by the "ST", "XSprePUSH" and "XSRETURN" macros. The "dMARK" macro must be called prior to setup the "MARK" variable.

            I32     ax

CLASS
    Variable which is setup by "xsubpp" to indicate the class name for a C++ XS constructor. This is always a "char*". See "THIS".

            char*   CLASS

dAX Sets up the "ax" variable. This is usually handled automatically by "xsubpp" by calling "dXSARGS".

                    dAX;

dAXMARK
    Sets up the "ax" variable and stack marker variable "mark". This is usually handled automatically by "xsubpp" by calling "dXSARGS".

                    dAXMARK;

dITEMS
    Sets up the "items" variable. This is usually handled automatically by "xsubpp" by calling "dXSARGS".

                    dITEMS;

dUNDERBAR
    Sets up the "padoff_du" variable for an XSUB that wishes to use "UNDERBAR".

                    dUNDERBAR;

dXSARGS
    Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. Sets up the "ax" and "items" variables by calling "dAX" and "dITEMS". This is usually handled automatically by "xsubpp".

                    dXSARGS;

dXSI32
    Sets up the "ix" variable for an XSUB which has aliases. This is usually handled automatically by "xsubpp".

                    dXSI32;

items
    Variable which is setup by "xsubpp" to indicate the number of items on the stack. See "Variable-length Parameter Lists" in perlxs.

            I32     items

ix  Variable which is setup by "xsubpp" to indicate which of an XSUB's aliases was used to invoke it. See "The ALIAS: Keyword" in perlxs.

            I32     ix

newXSproto
    Used by "xsubpp" to hook up XSUBs as Perl subs. Adds Perl prototypes to the subs.

RETVAL
    Variable which is setup by "xsubpp" to hold the return value for an XSUB. This is always the proper type for the XSUB. See "The RETVAL Variable" in perlxs.

            (whatever)      RETVAL

ST  Used to access elements on the XSUB's stack.

            SV*     ST(int ix)

THIS
    Variable which is setup by "xsubpp" to designate the object in a C++ XSUB. This is always the proper type for the C++ object. See "CLASS" and "Using XS With C++" in perlxs.

            (whatever)      THIS

UNDERBAR
    The SV* corresponding to the $_ variable. Works even if there is a lexical $_ in scope.

XS  Macro to declare an XSUB and its C parameter list. This is handled by "xsubpp".

XS_VERSION
    The version identifier for an XS module. This is usually handled automatically by "ExtUtils::MakeMaker". See "XS_VERSION_BOOTCHECK".

XS_VERSION_BOOTCHECK
    Macro to verify that a PM module's $VERSION variable matches the XS module's "XS_VERSION" variable. This is usually handled automatically by "xsubpp". See "The VERSIONCHECK: Keyword" in perlxs.

                    XS_VERSION_BOOTCHECK;

Warning and Dieing

croak
    This is the XSUB-writer's interface to Perl's "die" function. Normally call this function the same way you call the C "printf" function. Calling "croak" returns control directly to Perl, sidestepping the normal C order of execution. See "warn".

    If you want to throw an exception object, assign the object to $@ and then pass "NULL" to croak():

       errsv = get_sv("@", GV_ADD);
       sv_setsv(errsv, exception_object);
       croak(NULL);

            void    croak(const char* pat, ...)

warn
    This is the XSUB-writer's interface to Perl's "warn" function. Call this function the same way you call the C "printf" function. See "croak".

            void    warn(const char* pat, ...)

Undocumented functions
These functions are currently undocumented:

GetVars
Gv_AMupdate
PerlIO_clearerr
PerlIO_close
PerlIO_context_layers
PerlIO_eof
PerlIO_error
PerlIO_fileno
PerlIO_fill
PerlIO_flush
PerlIO_get_base
PerlIO_get_bufsiz
PerlIO_get_cnt
PerlIO_get_ptr
PerlIO_read
PerlIO_seek
PerlIO_set_cnt
PerlIO_set_ptrcnt
PerlIO_setlinebuf
PerlIO_stderr
PerlIO_stdin
PerlIO_stdout
PerlIO_tell
PerlIO_unread
PerlIO_write
Slab_Alloc
Slab_Free
amagic_call
any_dup
apply_attrs_string
atfork_lock
atfork_unlock
av_arylen_p
av_iter_p
block_gimme
call_atexit
call_list
calloc
cast_i32
cast_iv
cast_ulong
cast_uv
ck_warner
ck_warner_d
ckwarn
ckwarn_d
croak_nocontext
csighandler
custom_op_desc
custom_op_name
cx_dump
cx_dup
cxinc
deb
deb_nocontext
debop
debprofdump
debstack
debstackptrs
delimcpy
despatch_signals
die
die_nocontext
dirp_dup
do_aspawn
do_binmode
do_close
do_gv_dump
do_gvgv_dump
do_hv_dump
do_join
do_magic_dump
do_op_dump
do_open
do_open9
do_openn
do_pmop_dump
do_spawn
do_spawn_nowait
do_sprintf
do_sv_dump
doing_taint
doref
dounwind
dowantarray
dump_all
dump_eval
dump_fds
dump_form
dump_indent
dump_mstats
dump_packsubs
dump_sub
dump_vindent
fetch_cop_label
filter_add
filter_del
filter_read
find_rundefsvoffset
form_nocontext
fp_dup
fprintf_nocontext
free_global_struct
free_tmps
get_context
get_mstats
get_op_descs
get_op_names
get_ppaddr
get_vtbl
gp_dup
gp_free
gp_ref
gv_AVadd
gv_HVadd
gv_IOadd
gv_SVadd
gv_add_by_type
gv_autoload4
gv_check
gv_dump
gv_efullname
gv_efullname3
gv_efullname4
gv_fetchfile
gv_fetchfile_flags
gv_fetchmethod_flags
gv_fetchpv
gv_fetchpvn_flags
gv_fetchsv
gv_fullname
gv_fullname3
gv_fullname4
gv_handler
gv_init
gv_name_set
he_dup
hek_dup
hv_common
hv_common_key_len
hv_delayfree_ent
hv_eiter_p
hv_eiter_set
hv_free_ent
hv_ksplit
hv_name_set
hv_placeholders_get
hv_placeholders_p
hv_placeholders_set
hv_riter_p
hv_riter_set
hv_store_flags
ibcmp
ibcmp_locale
init_global_struct
init_i18nl10n
init_i18nl14n
init_stacks
init_tm
instr
is_lvalue_sub
is_uni_alnum
is_uni_alnum_lc
is_uni_alpha
is_uni_alpha_lc
is_uni_ascii
is_uni_ascii_lc
is_uni_cntrl
is_uni_cntrl_lc
is_uni_digit
is_uni_digit_lc
is_uni_graph
is_uni_graph_lc
is_uni_idfirst
is_uni_idfirst_lc
is_uni_lower
is_uni_lower_lc
is_uni_print
is_uni_print_lc
is_uni_punct
is_uni_punct_lc
is_uni_space
is_uni_space_lc
is_uni_upper
is_uni_upper_lc
is_uni_xdigit
is_uni_xdigit_lc
is_utf8_alnum
is_utf8_alpha
is_utf8_ascii
is_utf8_cntrl
is_utf8_digit
is_utf8_graph
is_utf8_idcont
is_utf8_idfirst
is_utf8_lower
is_utf8_mark
is_utf8_perl_space
is_utf8_perl_word
is_utf8_posix_digit
is_utf8_print
is_utf8_punct
is_utf8_space
is_utf8_upper
is_utf8_xdigit
leave_scope
load_module_nocontext
magic_dump
malloc
markstack_grow
mess
mess_nocontext
mfree
mg_dup
mg_size
mini_mktime
moreswitches
mro_get_from_name
mro_get_private_data
mro_register
mro_set_mro
mro_set_private_data
my_atof
my_atof2
my_bcopy
my_bzero
my_chsize
my_cxt_index
my_cxt_init
my_dirfd
my_exit
my_failure_exit
my_fflush_all
my_fork
my_htonl
my_lstat
my_memcmp
my_memset
my_ntohl
my_pclose
my_popen
my_popen_list
my_setenv
my_socketpair
my_stat
my_strftime
my_strlcat
my_strlcpy
my_swap
newANONATTRSUB
newANONHASH
newANONLIST
newANONSUB
newASSIGNOP
newATTRSUB
newAVREF
newBINOP
newCONDOP
newCVREF
newFORM
newFOROP
newGIVENOP
newGVOP
newGVREF
newGVgen
newHVREF
newHVhv
newIO
newLISTOP
newLOGOP
newLOOPEX
newLOOPOP
newMYSUB
newNULLLIST
newOP
newPADOP
newPMOP
newPROG
newPVOP
newRANGE
newRV
newSLICEOP
newSTATEOP
newSUB
newSVOP
newSVREF
newSVpvf_nocontext
newUNOP
newWHENOP
newWHILEOP
newXS_flags
new_collate
new_ctype
new_numeric
new_stackinfo
ninstr
op_dump
op_free
op_null
op_refcnt_lock
op_refcnt_unlock
parser_dup
perl_alloc_using
perl_clone_using
pmop_dump
pop_scope
pregcomp
pregexec
pregfree
pregfree2
printf_nocontext
ptr_table_clear
ptr_table_fetch
ptr_table_free
ptr_table_new
ptr_table_split
ptr_table_store
push_scope
re_compile
re_dup_guts
re_intuit_start
re_intuit_string
realloc
reentrant_free
reentrant_init
reentrant_retry
reentrant_size
ref
reg_named_buff_all
reg_named_buff_exists
reg_named_buff_fetch
reg_named_buff_firstkey
reg_named_buff_nextkey
reg_named_buff_scalar
regclass_swash
regdump
regdupe_internal
regexec_flags
regfree_internal
reginitcolors
regnext
repeatcpy
rninstr
rsignal
rsignal_state
runops_debug
runops_standard
rvpv_dup
safesyscalloc
safesysfree
safesysmalloc
safesysrealloc
save_I16
save_I32
save_I8
save_adelete
save_aelem
save_aelem_flags
save_alloc
save_aptr
save_ary
save_bool
save_clearsv
save_delete
save_destructor
save_destructor_x
save_freepv
save_freesv
save_generic_pvref
save_generic_svref
save_gp
save_hash
save_hdelete
save_helem
save_helem_flags
save_hptr
save_int
save_item
save_iv
save_list
save_long
save_mortalizesv
save_nogv
save_padsv_and_mortalize
save_pptr
save_pushptr
save_re_context
save_scalar
save_set_svflags
save_shared_pvref
save_sptr
save_svref
save_vptr
savestack_grow
savestack_grow_cnt
scan_num
scan_vstring
screaminstr
seed
set_context
set_numeric_local
set_numeric_radix
set_numeric_standard
share_hek
si_dup
ss_dup
stack_grow
start_subparse
stashpv_hvname_match
str_to_version
sv_2iv
sv_2pv
sv_2uv
sv_catpvf_mg_nocontext
sv_catpvf_nocontext
sv_compile_2op
sv_dump
sv_dup
sv_peek
sv_pvn_nomg
sv_setpvf_mg_nocontext
sv_setpvf_nocontext
sv_utf8_upgrade_flags_grow
swash_fetch
swash_init
sys_init
sys_init3
sys_intern_clear
sys_intern_dup
sys_intern_init
sys_term
taint_env
taint_proper
tmps_grow
to_uni_fold
to_uni_lower
to_uni_lower_lc
to_uni_title
to_uni_title_lc
to_uni_upper
to_uni_upper_lc
unlnk
unsharepvn
utf16_to_utf8
utf16_to_utf8_reversed
uvchr_to_utf8_flags
uvuni_to_utf8
vcroak
vdeb
vform
vload_module
vmess
vnewSVpvf
vwarn
vwarner
warn_nocontext
warner
warner_nocontext
whichsig

AUTHORS
Until May 1997, this document was maintained by Jeff Okamoto <okamoto@corp.hp.com>. It is now maintained as part of Perl itself.

With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, Stephen McCamant, and Gurusamy Sarathy.

API Listing originally by Dean Roehrich <roehrich@cray.com>.

Updated to be autogenerated from comments in the source by Benjamin Stuhl.

SEE ALSO
perlguts, perlxs, perlxstut, perlintern