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NAME

perlapi - autogenerated documentation for the perl public API

DESCRIPTION

This file contains most of the documentation of the perl public API, as generated by embed.pl. Specifically, it is a listing of functions, macros, flags, and variables that may be used by extension writers. Some specialized items are instead documented in config.h, perlapio, perlcall, perlclib, perlfilter, perlguts, perlmroapi, perlxs, perlxstut, and warnings.

At the end is a list of functions which have yet to be documented. Patches welcome! The interfaces of these are subject to change without notice.

Anything not listed here is not part of the public API, and should not be used by extension writers at all. For these reasons, blindly using functions listed in proto.h is to be avoided when writing extensions.

In Perl, unlike C, a string of characters may generally contain embedded "NUL" characters. Sometimes in the documentation a Perl string is referred to as a "buffer" to distinguish it from a C string, but sometimes they are both just referred to as strings.

Note that all Perl API global variables must be referenced with the "PL_" prefix. Again, those not listed here are not to be used by extension writers, and can be changed or removed without notice; same with macros. 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.

The non-ASCII characters below 256 can have various meanings, depending on various things. (See, most notably, perllocale.) But usually the whole range can be referred to as ISO-8859-1. Often, the term "Latin-1" (or "Latin1") is used as an equivalent for ISO-8859-1. But some people treat "Latin1" as referring just to the characters in the range 128 through 255, or somethimes from 160 through 255. This documentation uses "Latin1" and "Latin-1" to refer to all 256 characters.

Note that Perl can be compiled and run under either ASCII or EBCDIC (See perlebcdic). 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 a different number of bytes than in UTF-8.

The listing below is alphabetical, case insensitive.

Array Manipulation Functions

av_clear

Frees the all the elements of an array, leaving it empty. The XS equivalent of "@array = ()". See also "av_undef".

Note that it is possible that the actions of a destructor called directly or indirectly by freeing an element of the array could cause the reference count of the array itself to be reduced (e.g. by deleting an entry in the symbol table). So it is a possibility that the AV could have been freed (or even reallocated) on return from the call unless you hold a reference to it.

        void    av_clear(AV *av)

av_create_and_push

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

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 must be explicitly called as Perl_av_create_and_push with an aTHX_ parameter.

        void    Perl_av_create_and_push(pTHX_ AV **const avp,
                                        SV *const val)

av_create_and_unshift_one

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

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 must be explicitly called as Perl_av_create_and_unshift_one with an aTHX_ parameter.

        SV**    Perl_av_create_and_unshift_one(pTHX_
                                               AV **const avp,
                                               SV *const val)

av_delete

Deletes the element indexed by "key" from the array, makes the element mortal, and returns it. If "flags" equals "G_DISCARD", the element is freed and NULL is returned. NULL is also returned if "key" is out of range.

Perl equivalent: "splice(@myarray, $key, 1, undef)" (with the "splice" in void context if "G_DISCARD" is present).

        SV*     av_delete(AV *av, SSize_t 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 "NULL".

Perl equivalent: "exists($myarray[$key])".

        bool    av_exists(AV *av, SSize_t key)

av_extend

Pre-extend an array so that it is capable of storing values at indexes "0..key". Thus "av_extend(av,99)" guarantees that the array can store 100 elements, i.e. that "av_store(av, 0, sv)" through "av_store(av, 99, sv)" on a plain array will work without any further memory allocation.

If the av argument is a tied array then will call the "EXTEND" tied array method with an argument of "(key+1)".

        void    av_extend(AV *av, SSize_t key)

av_fetch

Returns the SV at the specified index in the array. The "key" is the index. If lval is true, you are guaranteed to get a real SV back (in case it wasn’t real before), which you can then modify. 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.

The rough perl equivalent is $myarray[$key].

        SV**    av_fetch(AV *av, SSize_t key, I32 lval)

        int     AvFILL(AV* av)

The number of elements in the array will be "fill + 1" after "av_fill()" returns. If the array was previously shorter, then the additional elements appended are set to NULL. 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, SSize_t fill)

        SSize_t av_len(AV *av)

Perl equivalent: "my @new_array = ($scalar1, $scalar2, $scalar3...);"

AV* av_make(SSize_t size, SV **strp)

Perl equivalent: "pop(@myarray);"

SV* av_pop(AV *av)

Perl equivalent: "push @myarray, $val;".

        void    av_push(AV *av, SV *val)

av_shift

Removes one SV from the start of the array, reducing its size by one and returning the SV (transferring control of one reference count) to the caller. Returns &PL_sv_undef if the array is empty.

Perl equivalent: "shift(@myarray);"

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 "SV*" that was stored there (= "val")).

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".

Approximate Perl equivalent: "splice(@myarray, $key, 1, $val)".

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, SSize_t key, SV *val)

av_tindex

Same as "av_top_index()".

        SSize_t av_tindex(AV *av)

av_top_index

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

The Perl equivalent for this is $#myarray.

(A slightly shorter form is "av_tindex".)

        SSize_t av_top_index(AV *av)

av_undef

Undefines the array. The XS equivalent of "undef(@array)".

As well as freeing all the elements of the array (like "av_clear()"), this also frees the memory used by the av to store its list of scalars.

See "av_clear" for a note about the array possibly being invalid on return.

        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.

Perl equivalent: "unshift @myarray, ((undef) x $num);"

void av_unshift(AV *av, SSize_t num)

Perl equivalent: "@{"$name"}".

NOTE: the perl_ form of this function is deprecated.

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

Perl equivalent: "my @array;".

        AV*     newAV()

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

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

Callback Functions

call_argv

Performs a callback to the specified named and package-scoped Perl subroutine with "argv" (a "NULL"-terminated array of strings) as arguments. See perlcall.

Approximate Perl equivalent: "&{"$sub_name"}(@$argv)".

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)

NOTE: the perl_ form of this function is deprecated.

        I32     call_pv(const char* sub_name, I32 flags)

If neither the "G_METHOD" nor "G_METHOD_NAMED" flag is supplied, the SV may be any of a CV, a GV, a reference to a CV, a reference to a GV or "SvPV(sv)" will be used as the name of the sub to call.

If the "G_METHOD" flag is supplied, the SV may be a reference to a CV or "SvPV(sv)" will be used as the name of the method to call.

If the "G_METHOD_NAMED" flag is supplied, "SvPV(sv)" will be used as the name of the method to call.

Some other values are treated specially for internal use and should not be depended on.

See perlcall.

NOTE: the perl_ form of this function is deprecated.

        I32     call_sv(SV* sv, volatile I32 flags)

                ENTER;

ENTER_with_name

Same as "ENTER", but when debugging is enabled it also associates the given literal string with the new scope.

                ENTER_with_name("name");

NOTE: the perl_ form of this function is deprecated.

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

The "G_RETHROW" flag can be used if you only need eval_sv() to execute code specified by a string, but not catch any errors.

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;

LEAVE_with_name

Same as "LEAVE", but when debugging is enabled it first checks that the scope has the given name. "name" must be a literal string.

                LEAVE_with_name("name");

SAVETMPS

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

                SAVETMPS;

Character case changing

Perl uses "full" Unicode case mappings. This means that converting a single character to another case may result in a sequence of more than one character. For example, the uppercase of "ß" ( LATIN SMALL LETTER SHARP S ) is the two character sequence "SS". This presents some complications The lowercase of all characters in the range 0..255 is a single character, and thus "toLOWER_L1" is furnished. But, "toUPPER_L1" can’t exist, as it couldn’t return a valid result for all legal inputs. Instead "toUPPER_uvchr" has an API that does allow every possible legal result to be returned.) Likewise no other function that is crippled by not being able to give the correct results for the full range of possible inputs has been implemented here.

        U8      toFOLD(U8 ch)

toFOLD_utf8

Converts the first UTF-8 encoded character in the sequence starting at "p" and extending no further than "e - 1" to its foldcase version, and stores that in UTF-8 in "s", and its length in bytes in "lenp". Note that the buffer pointed to by "s" needs to be at least "UTF8_MAXBYTES_CASE+1" bytes since the foldcase version may be longer than the original character.

The first code point of the foldcased version is returned (but note, as explained at the top of this section, that there may be more).

It will not attempt to read beyond "e - 1", provided that the constraint "s < e" is true (this is asserted for in "-DDEBUGGING" builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

        UV      toFOLD_utf8(U8* p, U8* e, U8* s, STRLEN* lenp)

toFOLD_utf8_safe

Same as "toFOLD_utf8".

        UV      toFOLD_utf8_safe(U8* p, U8* e, U8* s,
                                 STRLEN* lenp)

toFOLD_uvchr

Converts the code point "cp" to its foldcase version, and stores that in UTF-8 in "s", and its length in bytes in "lenp". The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by "s" needs to be at least "UTF8_MAXBYTES_CASE+1" bytes since the foldcase version may be longer than the original character.

The first code point of the foldcased version is returned (but note, as explained at the top of this section, that there may be more).

        UV      toFOLD_uvchr(UV cp, U8* s, STRLEN* lenp)

        U8      toLOWER(U8 ch)

toLOWER_L1

Converts the specified Latin1 character to lowercase. The results are undefined if the input doesn’t fit in a byte.

        U8      toLOWER_L1(U8 ch)

toLOWER_LC

Converts the specified character to lowercase using the current locale’s rules, if possible; otherwise returns the input character itself.

        U8      toLOWER_LC(U8 ch)

toLOWER_utf8

Converts the first UTF-8 encoded character in the sequence starting at "p" and extending no further than "e - 1" to its lowercase version, and stores that in UTF-8 in "s", and its length in bytes in "lenp". Note that the buffer pointed to by "s" needs to be at least "UTF8_MAXBYTES_CASE+1" bytes since the lowercase version may be longer than the original character.

The first code point of the lowercased version is returned (but note, as explained at the top of this section, that there may be more). It will not attempt to read beyond "e - 1", provided that the constraint "s < e" is true (this is asserted for in "-DDEBUGGING" builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

        UV      toLOWER_utf8(U8* p, U8* e, U8* s, STRLEN* lenp)

toLOWER_utf8_safe

Same as "toLOWER_utf8".

        UV      toLOWER_utf8_safe(U8* p, U8* e, U8* s,
                                  STRLEN* lenp)

toLOWER_uvchr

Converts the code point "cp" to its lowercase version, and stores that in UTF-8 in "s", and its length in bytes in "lenp". The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by "s" needs to be at least "UTF8_MAXBYTES_CASE+1" bytes since the lowercase version may be longer than the original character.

The first code point of the lowercased version is returned (but note, as explained at the top of this section, that there may be more).

        UV      toLOWER_uvchr(UV cp, U8* s, STRLEN* lenp)

        U8      toTITLE(U8 ch)

toTITLE_utf8

Converts the first UTF-8 encoded character in the sequence starting at "p" and extending no further than "e - 1" to its titlecase version, and stores that in UTF-8 in "s", and its length in bytes in "lenp". Note that the buffer pointed to by "s" needs to be at least "UTF8_MAXBYTES_CASE+1" bytes since the titlecase version may be longer than the original character.

The first code point of the titlecased version is returned (but note, as explained at the top of this section, that there may be more).

It will not attempt to read beyond "e - 1", provided that the constraint "s < e" is true (this is asserted for in "-DDEBUGGING" builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

        UV      toTITLE_utf8(U8* p, U8* e, U8* s, STRLEN* lenp)

toTITLE_utf8_safe

Same as "toTITLE_utf8".

        UV      toTITLE_utf8_safe(U8* p, U8* e, U8* s,
                                  STRLEN* lenp)

toTITLE_uvchr

Converts the code point "cp" to its titlecase version, and stores that in UTF-8 in "s", and its length in bytes in "lenp". The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by "s" needs to be at least "UTF8_MAXBYTES_CASE+1" bytes since the titlecase version may be longer than the original character.

The first code point of the titlecased version is returned (but note, as explained at the top of this section, that there may be more).

        UV      toTITLE_uvchr(UV cp, U8* s, STRLEN* lenp)

        U8      toUPPER(int ch)

toUPPER_utf8

Converts the first UTF-8 encoded character in the sequence starting at "p" and extending no further than "e - 1" to its uppercase version, and stores that in UTF-8 in "s", and its length in bytes in "lenp". Note that the buffer pointed to by "s" needs to be at least "UTF8_MAXBYTES_CASE+1" bytes since the uppercase version may be longer than the original character.

The first code point of the uppercased version is returned (but note, as explained at the top of this section, that there may be more).

It will not attempt to read beyond "e - 1", provided that the constraint "s < e" is true (this is asserted for in "-DDEBUGGING" builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

        UV      toUPPER_utf8(U8* p, U8* e, U8* s, STRLEN* lenp)

toUPPER_utf8_safe

Same as "toUPPER_utf8".

        UV      toUPPER_utf8_safe(U8* p, U8* e, U8* s,
                                  STRLEN* lenp)

toUPPER_uvchr

Converts the code point "cp" to its uppercase version, and stores that in UTF-8 in "s", and its length in bytes in "lenp". The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by "s" needs to be at least "UTF8_MAXBYTES_CASE+1" bytes since the uppercase version may be longer than the original character.

The first code point of the uppercased version is returned (but note, as explained at the top of this section, that there may be more.)

        UV      toUPPER_uvchr(UV cp, U8* s, STRLEN* lenp)

WIDEST_UTYPE

Yields the widest unsigned integer type on the platform, currently either "U32" or 64. This can be used in declarations such as

 WIDEST_UTYPE my_uv;

or casts

 my_uv = (WIDEST_UTYPE) val;

Character classification

This section is about functions (really macros) that classify characters into types, such as punctuation versus alphabetic, etc. Most of these are analogous to regular expression character classes. (See " POSIX Character Classes" in perlrecharclass.) There are several variants for each class. (Not all macros have all variants; each item below lists the ones valid for it.) None are affected by "use bytes", and only the ones with "LC" in the name are affected by the current locale.

The base function, e.g., "isALPHA()", takes any signed or unsigned value, treating it as a code point, and returns a boolean as to whether or not the character represented by it is (or on non-ASCII platforms, corresponds to) an ASCII character in the named class based on platform, Unicode, and Perl rules. If the input is a number that doesn’t fit in an octet, FALSE is returned.

Variant "isFOO_A" (e.g., "isALPHA_A()") is identical to the base function with no suffix "_A". This variant is used to emphasize by its name that only ASCII-range characters can return TRUE.

Variant "isFOO_L1" imposes the Latin-1 (or EBCDIC equivalent) character set onto the platform. That is, the code points that are ASCII are unaffected, since ASCII is a subset of Latin-1. But the non-ASCII code points are treated as if they are Latin-1 characters. For example, "isWORDCHAR_L1()" will return true when called with the code point 0xDF, which is a word character in both ASCII and EBCDIC (though it represents different characters in each). If the input is a number that doesn’t fit in an octet, FALSE is returned. (Perl’s documentation uses a colloquial definition of Latin-1, to include all code points below 256.)

Variant "isFOO_uvchr" is exactly like the "isFOO_L1" variant, for inputs below 256, but if the code point is larger than 255, Unicode rules are used to determine if it is in the character class. For example, "isWORDCHAR_uvchr(0x100)" returns TRUE, since 0x100 is LATIN CAPITAL LETTER A WITH MACRON in Unicode, and is a word character.

Variants "isFOO_utf8" and "isFOO_utf8_safe" are like "isFOO_uvchr", but are used for UTF-8 encoded strings. The two forms are different names for the same thing. Each call to one of these classifies the first character of the string starting at "p". The second parameter, "e", points to anywhere in the string beyond the first character, up to one byte past the end of the entire string. Although both variants are identical, the suffix "_safe" in one name emphasizes that it will not attempt to read beyond "e - 1", provided that the constraint "s < e" is true (this is asserted for in "-DDEBUGGING" builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return FALSE, at the discretion of the implementation, and subject to change in future releases.

Variant "isFOO_LC" is like the "isFOO_A" and "isFOO_L1" variants, but the result is based on the current locale, which is what "LC" in the name stands for. If Perl can determine that the current locale is a UTF-8 locale, it uses the published Unicode rules; otherwise, it uses the C library function that gives the named classification. For example, "isDIGIT_LC()" when not in a UTF-8 locale returns the result of calling "isdigit()". FALSE is always returned if the input won’t fit into an octet. On some platforms where the C library function is known to be defective, Perl changes its result to follow the POSIX standard’s rules.

Variant "isFOO_LC_uvchr" acts exactly like "isFOO_LC" for inputs less than 256, but for larger ones it returns the Unicode classification of the code point.

Variants "isFOO_LC_utf8" and "isFOO_LC_utf8_safe" are like "isFOO_LC_uvchr", but are used for UTF-8 encoded strings. The two forms are different names for the same thing. Each call to one of these classifies the first character of the string starting at "p". The second parameter, "e", points to anywhere in the string beyond the first character, up to one byte past the end of the entire string. Although both variants are identical, the suffix "_safe" in one name emphasizes that it will not attempt to read beyond "e - 1", provided that the constraint "s < e" is true (this is asserted for in "-DDEBUGGING" builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return FALSE, at the discretion of the implementation, and subject to change in future releases.

        bool    isALPHA(int ch)

isALPHANUMERIC

Returns a boolean indicating whether the specified character is one of "[A-Za-z0-9]", analogous to "m/[[:alnum:]]/". See the top of this section for an explanation of variants "isALPHANUMERIC_A", "isALPHANUMERIC_L1", "isALPHANUMERIC_uvchr", "isALPHANUMERIC_utf8", "isALPHANUMERIC_utf8_safe", "isALPHANUMERIC_LC", "isALPHANUMERIC_LC_uvchr", "isALPHANUMERIC_LC_utf8", and "isALPHANUMERIC_LC_utf8_safe".

A (discouraged from use) synonym is "isALNUMC" (where the "C" suffix means this corresponds to the C language alphanumeric definition). Also there are the variants "isALNUMC_A", "isALNUMC_L1" "isALNUMC_LC", and "isALNUMC_LC_uvchr".

        bool    isALPHANUMERIC(int ch)

        bool    isASCII(int ch)

        bool    isBLANK(char ch)

        bool    isCNTRL(char ch)

        bool    isDIGIT(char ch)

        bool    isGRAPH(char ch)

isIDCONT

Returns a boolean indicating whether the specified character can be the second or succeeding character of an identifier. This is very close to, but not quite the same as the official Unicode property "XID_Continue". The difference is that this returns true only if the input character also matches "isWORDCHAR". See the top of this section for an explanation of variants "isIDCONT_A", "isIDCONT_L1", "isIDCONT_uvchr", "isIDCONT_utf8", "isIDCONT_utf8_safe", "isIDCONT_LC", "isIDCONT_LC_uvchr", "isIDCONT_LC_utf8", and "isIDCONT_LC_utf8_safe".

        bool    isIDCONT(char ch)

isIDFIRST

Returns a boolean indicating whether the specified character can be the first character of an identifier. This is very close to, but not quite the same as the official Unicode property "XID_Start". The difference is that this returns true only if the input character also matches "isWORDCHAR". See the top of this section for an explanation of variants "isIDFIRST_A", "isIDFIRST_L1", "isIDFIRST_uvchr", "isIDFIRST_utf8", "isIDFIRST_utf8_safe", "isIDFIRST_LC", "isIDFIRST_LC_uvchr", "isIDFIRST_LC_utf8", and "isIDFIRST_LC_utf8_safe".

        bool    isIDFIRST(char ch)

        bool    isLOWER(char ch)

        bool    isOCTAL(char ch)

        bool    isPRINT(char ch)

isPSXSPC

(short for Posix Space) Starting in 5.18, this is identical in all its forms to the corresponding "isSPACE()" macros. The locale forms of this macro are identical to their corresponding "isSPACE()" forms in all Perl releases. In releases prior to 5.18, the non-locale forms differ from their "isSPACE()" forms only in that the "isSPACE()" forms don’t match a Vertical Tab, and the "isPSXSPC()" forms do. Otherwise they are identical. Thus this macro is analogous to what "m/[[:space:]]/" matches in a regular expression. See the top of this section for an explanation of variants "isPSXSPC_A", "isPSXSPC_L1", "isPSXSPC_uvchr", "isPSXSPC_utf8", "isPSXSPC_utf8_safe", "isPSXSPC_LC", "isPSXSPC_LC_uvchr", "isPSXSPC_LC_utf8", and "isPSXSPC_LC_utf8_safe".

        bool    isPSXSPC(char ch)

        bool    isPUNCT(char ch)

        bool    isSPACE(char ch)

        bool    isUPPER(char ch)

isWORDCHAR

Returns a boolean indicating whether the specified character is a character that is a word character, analogous to what "m/\w/" and "m/[[:word:]]/" match in a regular expression. A word character is an alphabetic character, a decimal digit, a connecting punctuation character (such as an underscore), or a "mark" character that attaches to one of those (like some sort of accent). "isALNUM()" is a synonym provided for backward compatibility, even though a word character includes more than the standard C language meaning of alphanumeric. See the top of this section for an explanation of variants "isWORDCHAR_A", "isWORDCHAR_L1", "isWORDCHAR_uvchr", "isWORDCHAR_utf8", and "isWORDCHAR_utf8_safe". "isWORDCHAR_LC", "isWORDCHAR_LC_uvchr", "isWORDCHAR_LC_utf8", and "isWORDCHAR_LC_utf8_safe" are also as described there, but additionally include the platform’s native underscore.

        bool    isWORDCHAR(char ch)

isXDIGIT

Returns a boolean indicating whether the specified character is a hexadecimal digit. In the ASCII range these are "[0-9A-Fa-f]". Variants "isXDIGIT_A()" and "isXDIGIT_L1()" are identical to "isXDIGIT()". See the top of this section for an explanation of variants "isXDIGIT_uvchr", "isXDIGIT_utf8", "isXDIGIT_utf8_safe", "isXDIGIT_LC", "isXDIGIT_LC_uvchr", "isXDIGIT_LC_utf8", and "isXDIGIT_LC_utf8_safe".

        bool    isXDIGIT(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;". A reason to keep it around is if you want to dup some of your own variables which are outside the graph that perl scans.

"CLONEf_CLONE_HOST" - This is a win32 thing, it is ignored on unix, it tells perl’s 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
                         )

Compile-time scope hooks

BhkDISABLE

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

Temporarily disable an entry in this BHK structure, by clearing the appropriate flag. "which" is a preprocessor token indicating which entry to disable.

        void    BhkDISABLE(BHK *hk, which)

BhkENABLE

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

Re-enable an entry in this BHK structure, by setting the appropriate flag. "which" is a preprocessor token indicating which entry to enable. This will assert (under -DDEBUGGING) if the entry doesn’t contain a valid pointer.

        void    BhkENABLE(BHK *hk, which)

BhkENTRY_set

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

Set an entry in the BHK structure, and set the flags to indicate it is valid. "which" is a preprocessing token indicating which entry to set. The type of "ptr" depends on the entry.

        void    BhkENTRY_set(BHK *hk, which, void *ptr)

blockhook_register

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

Register a set of hooks to be called when the Perl lexical scope changes at compile time. See "Compile-time scope hooks" in perlguts.

NOTE: this function must be explicitly called as Perl_blockhook_register with an aTHX_ parameter.

        void    Perl_blockhook_register(pTHX_ BHK *hk)

COP Hint Hashes

cophh_2hv

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

Generates and returns a standard Perl hash representing the full set of key/value pairs in the cop hints hash "cophh". "flags" is currently unused and must be zero.

        HV *    cophh_2hv(const COPHH *cophh, U32 flags)

cophh_copy

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

Make and return a complete copy of the cop hints hash "cophh".

        COPHH * cophh_copy(COPHH *cophh)

cophh_delete_pv

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

Like "cophh_delete_pvn", but takes a nul-terminated string instead of a string/length pair.

        COPHH * cophh_delete_pv(const COPHH *cophh,
                                const char *key, U32 hash,
                                U32 flags)

cophh_delete_pvn

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

Delete a key and its associated value from the cop hints hash "cophh", and returns the modified hash. The returned hash pointer is in general not the same as the hash pointer that was passed in. The input hash is consumed by the function, and the pointer to it must not be subsequently used. Use "cophh_copy" if you need both hashes.

The key is specified by "keypv" and "keylen". If "flags" has the "COPHH_KEY_UTF8" bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. "hash" is a precomputed hash of the key string, or zero if it has not been precomputed.

        COPHH * cophh_delete_pvn(COPHH *cophh,
                                 const char *keypv,
                                 STRLEN keylen, U32 hash,
                                 U32 flags)

cophh_delete_pvs

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

Like "cophh_delete_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

        COPHH * cophh_delete_pvs(const COPHH *cophh, "key",
                                 U32 flags)

cophh_delete_sv

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

Like "cophh_delete_pvn", but takes a Perl scalar instead of a string/length pair.

        COPHH * cophh_delete_sv(const COPHH *cophh, SV *key,
                                U32 hash, U32 flags)

cophh_fetch_pv

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

Like "cophh_fetch_pvn", but takes a nul-terminated string instead of a string/length pair.

        SV *    cophh_fetch_pv(const COPHH *cophh,
                               const char *key, U32 hash,
                               U32 flags)

cophh_fetch_pvn

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

Look up the entry in the cop hints hash "cophh" with the key specified by "keypv" and "keylen". If "flags" has the "COPHH_KEY_UTF8" bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. "hash" is a precomputed hash of the key string, or zero if it has not been precomputed. Returns a mortal scalar copy of the value associated with the key, or &PL_sv_placeholder if there is no value associated with the key.

        SV *    cophh_fetch_pvn(const COPHH *cophh,
                                const char *keypv,
                                STRLEN keylen, U32 hash,
                                U32 flags)

cophh_fetch_pvs

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

Like "cophh_fetch_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

        SV *    cophh_fetch_pvs(const COPHH *cophh, "key",
                                U32 flags)

cophh_fetch_sv

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

Like "cophh_fetch_pvn", but takes a Perl scalar instead of a string/length pair.

        SV *    cophh_fetch_sv(const COPHH *cophh, SV *key,
                               U32 hash, U32 flags)

cophh_free

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

Discard the cop hints hash "cophh", freeing all resources associated with it.

        void    cophh_free(COPHH *cophh)

cophh_new_empty

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

Generate and return a fresh cop hints hash containing no entries.

        COPHH * cophh_new_empty()

cophh_store_pv

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

Like "cophh_store_pvn", but takes a nul-terminated string instead of a string/length pair.

        COPHH * cophh_store_pv(const COPHH *cophh,
                               const char *key, U32 hash,
                               SV *value, U32 flags)

cophh_store_pvn

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

Stores a value, associated with a key, in the cop hints hash "cophh", and returns the modified hash. The returned hash pointer is in general not the same as the hash pointer that was passed in. The input hash is consumed by the function, and the pointer to it must not be subsequently used. Use "cophh_copy" if you need both hashes.

The key is specified by "keypv" and "keylen". If "flags" has the "COPHH_KEY_UTF8" bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. "hash" is a precomputed hash of the key string, or zero if it has not been precomputed.

"value" is the scalar value to store for this key. "value" is copied by this function, which thus does not take ownership of any reference to it, and later changes to the scalar will not be reflected in the value visible in the cop hints hash. Complex types of scalar will not be stored with referential integrity, but will be coerced to strings.

        COPHH * cophh_store_pvn(COPHH *cophh, const char *keypv,
                                STRLEN keylen, U32 hash,
                                SV *value, U32 flags)

cophh_store_pvs

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

Like "cophh_store_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

        COPHH * cophh_store_pvs(const COPHH *cophh, "key",
                                SV *value, U32 flags)

cophh_store_sv

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

Like "cophh_store_pvn", but takes a Perl scalar instead of a string/length pair.

        COPHH * cophh_store_sv(const COPHH *cophh, SV *key,
                               U32 hash, SV *value, U32 flags)

COP Hint Reading

cop_hints_2hv

Generates and returns a standard Perl hash representing the full set of hint entries in the cop "cop". "flags" is currently unused and must be zero.

        HV *    cop_hints_2hv(const COP *cop, U32 flags)

cop_hints_fetch_pv

Like "cop_hints_fetch_pvn", but takes a nul-terminated string instead of a string/length pair.

        SV *    cop_hints_fetch_pv(const COP *cop,
                                   const char *key, U32 hash,
                                   U32 flags)

cop_hints_fetch_pvn

Look up the hint entry in the cop "cop" with the key specified by "keypv" and "keylen". If "flags" has the "COPHH_KEY_UTF8" bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. "hash" is a precomputed hash of the key string, or zero if it has not been precomputed. Returns a mortal scalar copy of the value associated with the key, or &PL_sv_placeholder if there is no value associated with the key.

        SV *    cop_hints_fetch_pvn(const COP *cop,
                                    const char *keypv,
                                    STRLEN keylen, U32 hash,
                                    U32 flags)

cop_hints_fetch_pvs

Like "cop_hints_fetch_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

        SV *    cop_hints_fetch_pvs(const COP *cop, "key",
                                    U32 flags)

cop_hints_fetch_sv

Like "cop_hints_fetch_pvn", but takes a Perl scalar instead of a string/length pair.

        SV *    cop_hints_fetch_sv(const COP *cop, SV *key,
                                   U32 hash, U32 flags)

CopLABEL

Returns the label attached to a cop.

        const char * CopLABEL(COP *const cop)

CopLABEL_len

Returns the label attached to a cop, and stores its length in bytes into *len.

        const char * CopLABEL_len(COP *const cop, STRLEN *len)

CopLABEL_len_flags

Returns the label attached to a cop, and stores its length in bytes into *len. Upon return, *flags will be set to either "SVf_UTF8" or 0.

        const char * CopLABEL_len_flags(COP *const cop,
                                        STRLEN *len, U32 *flags)

Custom Operators

custom_op_register

Register a custom op. See "Custom Operators" in perlguts.

NOTE: this function must be explicitly called as Perl_custom_op_register with an aTHX_ parameter.

        void    Perl_custom_op_register(pTHX_
                                        Perl_ppaddr_t ppaddr,
                                        const XOP *xop)

Perl_custom_op_xop

Return the XOP structure for a given custom op. This macro should be considered internal to "OP_NAME" and the other access macros: use them instead. This macro does call a function. Prior to 5.19.6, this was implemented as a function.

        const XOP * Perl_custom_op_xop(pTHX_ const OP *o)

XopDISABLE

Temporarily disable a member of the XOP, by clearing the appropriate flag.

        void    XopDISABLE(XOP *xop, which)

XopENABLE

Reenable a member of the XOP which has been disabled.

        void    XopENABLE(XOP *xop, which)

XopENTRY

Return a member of the XOP structure. "which" is a cpp token indicating which entry to return. If the member is not set this will return a default value. The return type depends on "which". This macro evaluates its arguments more than once. If you are using "Perl_custom_op_xop" to retreive a "XOP *" from a "OP *", use the more efficient "XopENTRYCUSTOM" instead.

                XopENTRY(XOP *xop, which)

XopENTRYCUSTOM

Exactly like "XopENTRY(XopENTRY(Perl_custom_op_xop(aTHX_ o), which)" but more efficient. The "which" parameter is identical to "XopENTRY".

                XopENTRYCUSTOM(const OP *o, which)

XopENTRY_set

Set a member of the XOP structure. "which" is a cpp token indicating which entry to set. See "Custom Operators" in perlguts for details about the available members and how they are used. This macro evaluates its argument more than once.

        void    XopENTRY_set(XOP *xop, which, value)

XopFLAGS

Return the XOP ’s flags.

        U32     XopFLAGS(XOP *xop)

CV Manipulation Functions

This section documents functions to manipulate CVs which are code-values, or subroutines. For more information, see perlguts.
caller_cx

The XSUB-writer’s equivalent of caller(). The returned "PERL_CONTEXT" structure can be interrogated to find all the information returned to Perl by "caller". Note that XSUBs don’t get a stack frame, so "caller_cx(0, NULL)" will return information for the immediately-surrounding Perl code.

This function skips over the automatic calls to &DB::sub made on the behalf of the debugger. If the stack frame requested was a sub called by "DB::sub", the return value will be the frame for the call to "DB::sub", since that has the correct line number/etc. for the call site. If dbcxp is non-"NULL", it will be set to a pointer to the frame for the sub call itself.

        const PERL_CONTEXT * caller_cx(
                                 I32 level,
                                 const PERL_CONTEXT **dbcxp
                             )

This also has a special use with XS AUTOLOAD subs. See "Autoloading with XSUBs" in perlguts.

        HV*     CvSTASH(CV* cv)

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. (This 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)

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.

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

"xsubpp" variables and internal functions

        I32     ax

        char*   CLASS

                dAX;

                dAXMARK;

                dITEMS;

dUNDERBAR

Sets up any variable needed by the "UNDERBAR" macro. It used to define "padoff_du", but it is currently a noop. However, it is strongly advised to still use it for ensuring past and future compatibility.

                dUNDERBAR;

                dXSARGS;

                dXSI32;

        I32     items

        I32     ix

        (whatever)      RETVAL

        SV*     ST(int ix)

        (whatever)      THIS

UNDERBAR

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

XS_EXTERNAL

Macro to declare an XSUB and its C parameter list explicitly exporting the symbols.

XS_INTERNAL

Macro to declare an XSUB and its C parameter list without exporting the symbols. This is handled by "xsubpp" and generally preferable over exporting the XSUB symbols unnecessarily.

Debugging Utilities

dump_all

Dumps the entire optree of the current program starting at "PL_main_root" to "STDERR". Also dumps the optrees for all visible subroutines in "PL_defstash".

        void    dump_all()

dump_packsubs

Dumps the optrees for all visible subroutines in "stash".

        void    dump_packsubs(const HV* stash)

op_class

Given an op, determine what type of struct it has been allocated as. Returns one of the OPclass enums, such as OPclass_LISTOP.

        OPclass op_class(const OP *o)

        void    op_dump(const OP *o)

For an example of its output, see Devel::Peek.

        void    sv_dump(SV* sv)

Display and Dump functions

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. The number of bytes escaped will be returned in the "STRLEN *escaped" parameter if it is not null. When the "dsv" parameter is null no escaping actually occurs, but the number of bytes that would be escaped were it not null will be calculated.

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 UTF-8 if "PERL_PV_ESCAPE_UNI_DETECT" is set then the input string is scanned using "is_utf8_string()" to determine if it is UTF-8.

If "PERL_PV_ESCAPE_ALL" is set then all input chars will be output using "\x01F1" style escapes, otherwise if "PERL_PV_ESCAPE_NONASCII" is set, only non-ASCII chars will be escaped using this style; otherwise, only chars above 255 will be so escaped; other non printable chars will use octal or common escaped patterns like "\n". Otherwise, 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, regardless of max. If the output is to be in hex, 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 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)

Embedding Functions

cv_clone

Clone a CV, making a lexical closure. "proto" supplies the prototype of the function: its code, pad structure, and other attributes. The prototype is combined with a capture of outer lexicals to which the code refers, which are taken from the currently-executing instance of the immediately surrounding code.

        CV*     cv_clone(CV* proto)

An SV may be passed as a second argument. If so, the name will be assigned to it and it will be returned. Otherwise the returned SV will be a new mortal.

If "flags" has the "CV_NAME_NOTQUAL" bit set, then the package name will not be included. If the first argument is neither a CV nor a GV, this flag is ignored (subject to change).

        SV *    cv_name(CV *cv, SV *sv, U32 flags)

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)

find_rundefsv

Returns the global variable $_.

        SV*     find_rundefsv()

find_rundefsvoffset

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Until the lexical $_ feature was removed, this function would find the position of the lexical $_ in the pad of the currently-executing function and return the offset in the current pad, or "NOT_IN_PAD".

Now it always returns "NOT_IN_PAD".

        PADOFFSET find_rundefsvoffset()

intro_my

"Introduce" "my" variables to visible status. This is called during parsing at the end of each statement to make lexical variables visible to subsequent statements.

        U32     intro_my()

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". ver, if specified and not NULL, provides version semantics similar to "use Foo::Bar VERSION". The optional trailing arguments can be used to specify arguments to the module’s "import()" method, similar to "use Foo::Bar VERSION LIST"; their precise handling depends on the flags. The flags argument is a bitwise-ORed collection of any of "PERL_LOADMOD_DENY", "PERL_LOADMOD_NOIMPORT", or "PERL_LOADMOD_IMPORT_OPS" (or 0 for no flags).

If "PERL_LOADMOD_NOIMPORT" is set, the module is loaded as if with an empty import list, as in "use Foo::Bar ()"; this is the only circumstance in which the trailing optional arguments may be omitted entirely. Otherwise, if "PERL_LOADMOD_IMPORT_OPS" is set, the trailing arguments must consist of exactly one "OP*", containing the op tree that produces the relevant import arguments. Otherwise, the trailing arguments must all be "SV*" values that will be used as import arguments; and the list must be terminated with "(SV*) NULL". If neither "PERL_LOADMOD_NOIMPORT" nor "PERL_LOADMOD_IMPORT_OPS" is set, the trailing "NULL" pointer is needed even if no import arguments are desired. The reference count for each specified "SV*" argument is decremented. In addition, the "name" argument is modified.

If "PERL_LOADMOD_DENY" is set, the module is loaded as if with "no" rather than "use".

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

        void    my_exit(U32 status)

newPADNAMELIST

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

Creates a new pad name list. "max" is the highest index for which space is allocated.

        PADNAMELIST * newPADNAMELIST(size_t max)

newPADNAMEouter

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

Constructs and returns a new pad name. Only use this function for names that refer to outer lexicals. (See also "newPADNAMEpvn".) "outer" is the outer pad name that this one mirrors. The returned pad name has the "PADNAMEt_OUTER" flag already set.

        PADNAME * newPADNAMEouter(PADNAME *outer)

newPADNAMEpvn

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

Constructs and returns a new pad name. "s" must be a UTF-8 string. Do not use this for pad names that point to outer lexicals. See "newPADNAMEouter".

        PADNAME * newPADNAMEpvn(const char *s, STRLEN len)

nothreadhook

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

        int     nothreadhook()

pad_add_anon

Allocates a place in the currently-compiling pad (via "pad_alloc") for an anonymous function that is lexically scoped inside the currently-compiling function. The function "func" is linked into the pad, and its "CvOUTSIDE" link to the outer scope is weakened to avoid a reference loop.

One reference count is stolen, so you may need to do "SvREFCNT_inc(func)".

"optype" should be an opcode indicating the type of operation that the pad entry is to support. This doesn’t affect operational semantics, but is used for debugging.

        PADOFFSET pad_add_anon(CV* func, I32 optype)

pad_add_name_pv

Exactly like "pad_add_name_pvn", but takes a nul-terminated string instead of a string/length pair.

        PADOFFSET pad_add_name_pv(const char *name,
                                  const U32 flags,
                                  HV *typestash, HV *ourstash)

pad_add_name_pvn

Allocates a place in the currently-compiling pad for a named lexical variable. Stores the name and other metadata in the name part of the pad, and makes preparations to manage the variable’s lexical scoping. Returns the offset of the allocated pad slot.

"namepv"/"namelen" specify the variable’s name, including leading sigil. If "typestash" is non-null, the name is for a typed lexical, and this identifies the type. If "ourstash" is non-null, it’s a lexical reference to a package variable, and this identifies the package. The following flags can be OR ’ed together:

 padadd_OUR          redundantly specifies if it's a package var
 padadd_STATE        variable will retain value persistently
 padadd_NO_DUP_CHECK skip check for lexical shadowing
        PADOFFSET pad_add_name_pvn(const char *namepv,
                                   STRLEN namelen, U32 flags,
                                   HV *typestash, HV *ourstash)

pad_add_name_sv

Exactly like "pad_add_name_pvn", but takes the name string in the form of an SV instead of a string/length pair.

        PADOFFSET pad_add_name_sv(SV *name, U32 flags,
                                  HV *typestash, HV *ourstash)

pad_alloc

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

Allocates a place in the currently-compiling pad, returning the offset of the allocated pad slot. No name is initially attached to the pad slot. "tmptype" is a set of flags indicating the kind of pad entry required, which will be set in the value SV for the allocated pad entry:

    SVs_PADMY    named lexical variable ("my", "our", "state")
    SVs_PADTMP   unnamed temporary store
    SVf_READONLY constant shared between recursion levels

"SVf_READONLY" has been supported here only since perl 5.20. To work with earlier versions as well, use "SVf_READONLY|SVs_PADTMP". "SVf_READONLY" does not cause the SV in the pad slot to be marked read-only, but simply tells "pad_alloc" that it will be made read-only (by the caller), or at least should be treated as such.

"optype" should be an opcode indicating the type of operation that the pad entry is to support. This doesn’t affect operational semantics, but is used for debugging.

        PADOFFSET pad_alloc(I32 optype, U32 tmptype)

pad_findmy_pv

Exactly like "pad_findmy_pvn", but takes a nul-terminated string instead of a string/length pair.

        PADOFFSET pad_findmy_pv(const char* name, U32 flags)

pad_findmy_pvn

Given the name of a lexical variable, find its position in the currently-compiling pad. "namepv"/"namelen" specify the variable’s name, including leading sigil. "flags" is reserved and must be zero. If it is not in the current pad but appears in the pad of any lexically enclosing scope, then a pseudo-entry for it is added in the current pad. Returns the offset in the current pad, or "NOT_IN_PAD" if no such lexical is in scope.

        PADOFFSET pad_findmy_pvn(const char* namepv,
                                 STRLEN namelen, U32 flags)

pad_findmy_sv

Exactly like "pad_findmy_pvn", but takes the name string in the form of an SV instead of a string/length pair.

        PADOFFSET pad_findmy_sv(SV* name, U32 flags)

padnamelist_fetch

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

Fetches the pad name from the given index.

        PADNAME * padnamelist_fetch(PADNAMELIST *pnl,
                                    SSize_t key)

padnamelist_store

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

Stores the pad name (which may be null) at the given index, freeing any existing pad name in that slot.

        PADNAME ** padnamelist_store(PADNAMELIST *pnl,
                                     SSize_t key, PADNAME *val)

pad_setsv

Set the value at offset "po" in the current (compiling or executing) pad. Use the macro "PAD_SETSV()" rather than calling this function directly.

        void    pad_setsv(PADOFFSET po, SV* sv)

        SV*     pad_sv(PADOFFSET po)

pad_tidy

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

Tidy up a pad at the end of compilation of the code to which it belongs. Jobs performed here are: remove most stuff from the pads of anonsub prototypes; give it a @_; mark temporaries as such. "type" indicates the kind of subroutine:

    padtidy_SUB        ordinary subroutine
    padtidy_SUBCLONE   prototype for lexical closure
    padtidy_FORMAT     format
        void    pad_tidy(padtidy_type type)

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 for a tutorial.

"my_perl" points to the Perl interpreter. It must have been previously created through the use of "perl_alloc" and "perl_construct". It may have been initialised through "perl_parse", and may have been used through "perl_run" and other means. This function should be called for any Perl interpreter that has been constructed with "perl_construct", even if subsequent operations on it failed, for example if "perl_parse" returned a non-zero value.

If the interpreter’s "PL_exit_flags" word has the "PERL_EXIT_DESTRUCT_END" flag set, then this function will execute code in "END" blocks before performing the rest of destruction. If it is desired to make any use of the interpreter between "perl_parse" and "perl_destruct" other than just calling "perl_run", then this flag should be set early on. This matters if "perl_run" will not be called, or if anything else will be done in addition to calling "perl_run".

Returns a value be a suitable value to pass to the C library function "exit" (or to return from "main"), to serve as an exit code indicating the nature of the way the interpreter terminated. This takes into account any failure of "perl_parse" and any early exit from "perl_run". The exit code is of the type required by the host operating system, so because of differing exit code conventions it is not portable to interpret specific numeric values as having specific meanings.

        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. This performs most of the initialisation of a Perl interpreter. See perlembed for a tutorial.

"my_perl" points to the Perl interpreter that is to parse the script. It must have been previously created through the use of "perl_alloc" and "perl_construct". "xsinit" points to a callback function that will be called to set up the ability for this Perl interpreter to load XS extensions, or may be null to perform no such setup.

"argc" and "argv" supply a set of command-line arguments to the Perl interpreter, as would normally be passed to the "main" function of a C program. "argv[argc]" must be null. These arguments are where the script to parse is specified, either by naming a script file or by providing a script in a "-e" option. If $0 will be written to in the Perl interpreter, then the argument strings must be in writable memory, and so mustn’t just be string constants.

"env" specifies a set of environment variables that will be used by this Perl interpreter. If non-null, it must point to a null-terminated array of environment strings. If null, the Perl interpreter will use the environment supplied by the "environ" global variable.

This function initialises the interpreter, and parses and compiles the script specified by the command-line arguments. This includes executing code in "BEGIN", "UNITCHECK", and "CHECK" blocks. It does not execute "INIT" blocks or the main program.

Returns an integer of slightly tricky interpretation. The correct use of the return value is as a truth value indicating whether there was a failure in initialisation. If zero is returned, this indicates that initialisation was successful, and it is safe to proceed to call "perl_run" and make other use of it. If a non-zero value is returned, this indicates some problem that means the interpreter wants to terminate. The interpreter should not be just abandoned upon such failure; the caller should proceed to shut the interpreter down cleanly with "perl_destruct" and free it with "perl_free".

For historical reasons, the non-zero return value also attempts to be a suitable value to pass to the C library function "exit" (or to return from "main"), to serve as an exit code indicating the nature of the way initialisation terminated. However, this isn’t portable, due to differing exit code conventions. A historical bug is preserved for the time being: if the Perl built-in "exit" is called during this function’s execution, with a type of exit entailing a zero exit code under the host operating system’s conventions, then this function returns zero rather than a non-zero value. This bug, [perl #2754], leads to "perl_run" being called (and therefore "INIT" blocks and the main program running) despite a call to "exit". It has been preserved because a popular module-installing module has come to rely on it and needs time to be fixed. This issue is [perl #132577], and the original bug is due to be fixed in Perl 5.30.

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

perl_run

Tells a Perl interpreter to run its main program. See perlembed for a tutorial.

"my_perl" points to the Perl interpreter. It must have been previously created through the use of "perl_alloc" and "perl_construct", and initialised through "perl_parse". This function should not be called if "perl_parse" returned a non-zero value, indicating a failure in initialisation or compilation.

This function executes code in "INIT" blocks, and then executes the main program. The code to be executed is that established by the prior call to "perl_parse". If the interpreter’s "PL_exit_flags" word does not have the "PERL_EXIT_DESTRUCT_END" flag set, then this function will also execute code in "END" blocks. If it is desired to make any further use of the interpreter after calling this function, then "END" blocks should be postponed to "perl_destruct" time by setting that flag.

Returns an integer of slightly tricky interpretation. The correct use of the return value is as a truth value indicating whether the program terminated non-locally. If zero is returned, this indicates that the program ran to completion, and it is safe to make other use of the interpreter (provided that the "PERL_EXIT_DESTRUCT_END" flag was set as described above). If a non-zero value is returned, this indicates that the interpreter wants to terminate early. The interpreter should not be just abandoned because of this desire to terminate; the caller should proceed to shut the interpreter down cleanly with "perl_destruct" and free it with "perl_free".

For historical reasons, the non-zero return value also attempts to be a suitable value to pass to the C library function "exit" (or to return from "main"), to serve as an exit code indicating the nature of the way the program terminated. However, this isn’t portable, due to differing exit code conventions. An attempt is made to return an exit code of the type required by the host operating system, but because it is constrained to be non-zero, it is not necessarily possible to indicate every type of exit. It is only reliable on Unix, where a zero exit code can be augmented with a set bit that will be ignored. In any case, this function is not the correct place to acquire an exit code: one should get that from "perl_destruct".

        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)

Exception Handling (simple) Macros

                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.

Functions in file vutil.c

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

Validate that a given string can be parsed as a version object, but doesn’t actually perform the parsing. Can use either strict or lax validation rules. Can optionally set a number of hint variables to save the parsing code some time when tokenizing.

        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)

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)

        int     vcmp(SV *lhv, SV *rhv)

    sv = vnormal(rv);

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

The SV returned has a refcount of 1.

        SV*     vnormal(SV *vs)

    sv = vnumify(rv);

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

The SV returned has a refcount of 1.

        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.

The SV returned has a refcount of 1.

        SV*     vstringify(SV *vs)

    SV *hv = vverify(sv);

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

        SV*     vverify(SV *vs)

"Gimme" Values

G_DISCARD

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

        U32     GIMME

        U32     GIMME_V

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.

Global Variables

These variables are global to an entire process. They are shared between all interpreters and all threads in a process. Any variables not documented here may be changed or removed without notice, so don’t use them! If you feel you really do need to use an unlisted variable, first send email to perl5-porters [AT] perl.org <mailto:perl5-porters [AT] perl.org>. It may be that someone there will point out a way to accomplish what you need without using an internal variable. But if not, you should get a go-ahead to document and then use the variable.
PL_check

Array, indexed by opcode, of functions that will be called for the "check" phase of optree building during compilation of Perl code. For most (but not all) types of op, once the op has been initially built and populated with child ops it will be filtered through the check function referenced by the appropriate element of this array. The new op is passed in as the sole argument to the check function, and the check function returns the completed op. The check function may (as the name suggests) check the op for validity and signal errors. It may also initialise or modify parts of the ops, or perform more radical surgery such as adding or removing child ops, or even throw the op away and return a different op in its place.

This array of function pointers is a convenient place to hook into the compilation process. An XS module can put its own custom check function in place of any of the standard ones, to influence the compilation of a particular type of op. However, a custom check function must never fully replace a standard check function (or even a custom check function from another module). A module modifying checking must instead wrap the preexisting check function. A custom check function must be selective about when to apply its custom behaviour. In the usual case where it decides not to do anything special with an op, it must chain the preexisting op function. Check functions are thus linked in a chain, with the core’s base checker at the end.

For thread safety, modules should not write directly to this array. Instead, use the function "wrap_op_checker".

PL_keyword_plugin

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

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 constant 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".

For thread safety, modules should not set this variable directly. Instead, use the function "wrap_keyword_plugin".

PL_phase

A value that indicates the current Perl interpreter’s phase. Possible values include "PERL_PHASE_CONSTRUCT", "PERL_PHASE_START", "PERL_PHASE_CHECK", "PERL_PHASE_INIT", "PERL_PHASE_RUN", "PERL_PHASE_END", and "PERL_PHASE_DESTRUCT".

For example, the following determines whether the interpreter is in global destruction:

    if (PL_phase == PERL_PHASE_DESTRUCT) {
        // we are in global destruction
    }

"PL_phase" was introduced in Perl 5.14; in prior perls you can use "PL_dirty" (boolean) to determine whether the interpreter is in global destruction. (Use of "PL_dirty" is discouraged since 5.14.)

        enum perl_phase PL_phase

GV Functions

A GV is a structure which corresponds to to a Perl typeglob, ie *foo. It is a structure that holds a pointer to a scalar, an array, a hash etc, corresponding to $foo, @foo, %foo.

GVs are usually found as values in stashes (symbol table hashes) where Perl stores its global variables.

        AV*     GvAV(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)

        CV*     GvCV(GV* gv)

gv_fetchmeth

Like "gv_fetchmeth_pvn", but lacks a flags parameter.

        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 as a side effect to do this.

These functions have the same side-effects as "gv_fetchmeth" with "level==0". The warning against passing the GV returned by "gv_fetchmeth" to "call_sv" applies equally to these functions.

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

gv_fetchmeth_autoload

This is the old form of "gv_fetchmeth_pvn_autoload", which has no flags parameter.

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

gv_fetchmeth_pv

Exactly like "gv_fetchmeth_pvn", but takes a nul-terminated string instead of a string/length pair.

        GV*     gv_fetchmeth_pv(HV* stash, const char* name,
                                I32 level, U32 flags)

gv_fetchmeth_pvn

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.

The only significant values for "flags" are "GV_SUPER" and "SVf_UTF8".

"GV_SUPER" indicates that we want to look up the method in the superclasses of the "stash".

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_pvn(HV* stash, const char* name,
                                 STRLEN len, I32 level,
                                 U32 flags)

gv_fetchmeth_pvn_autoload

Same as "gv_fetchmeth_pvn()", 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.

Currently, the only significant value for "flags" is "SVf_UTF8".

        GV*     gv_fetchmeth_pvn_autoload(HV* stash,
                                          const char* name,
                                          STRLEN len, I32 level,
                                          U32 flags)

gv_fetchmeth_pv_autoload

Exactly like "gv_fetchmeth_pvn_autoload", but takes a nul-terminated string instead of a string/length pair.

        GV*     gv_fetchmeth_pv_autoload(HV* stash,
                                         const char* name,
                                         I32 level, U32 flags)

gv_fetchmeth_sv

Exactly like "gv_fetchmeth_pvn", but takes the name string in the form of an SV instead of a string/length pair.

        GV*     gv_fetchmeth_sv(HV* stash, SV* namesv,
                                I32 level, U32 flags)

gv_fetchmeth_sv_autoload

Exactly like "gv_fetchmeth_pvn_autoload", but takes the name string in the form of an SV instead of a string/length pair.

        GV*     gv_fetchmeth_sv_autoload(HV* stash, SV* namesv,
                                         I32 level, U32 flags)

        HV*     GvHV(GV* gv)

        void    gv_init(GV* gv, HV* stash, const char* name,
                        STRLEN len, int multi)

gv_init_pv

Same as "gv_init_pvn()", but takes a nul-terminated string for the name instead of separate char * and length parameters.

        void    gv_init_pv(GV* gv, HV* stash, const char* name,
                           U32 flags)

gv_init_pvn

Converts a scalar into a typeglob. This is an incoercible typeglob; assigning a reference to it will assign to one of its slots, instead of overwriting it as happens with typeglobs created by "SvSetSV". Converting any scalar that is "SvOK()" may produce unpredictable results and is reserved for perl’s internal use.

"gv" is the scalar to be converted.

"stash" is the parent stash/package, if any.

"name" and "len" give the name. The name must be unqualified; that is, it must not include the package name. If "gv" is a stash element, it is the caller’s responsibility to ensure that the name passed to this function matches the name of the element. If it does not match, perl’s internal bookkeeping will get out of sync.

"flags" can be set to "SVf_UTF8" if "name" is a UTF-8 string, or the return value of SvUTF8(sv). It can also take the "GV_ADDMULTI" flag, which means to pretend that the GV has been seen before (i.e., suppress "Used once" warnings).

        void    gv_init_pvn(GV* gv, HV* stash, const char* name,
                            STRLEN len, U32 flags)

gv_init_sv

Same as "gv_init_pvn()", but takes an SV * for the name instead of separate char * and length parameters. "flags" is currently unused.

        void    gv_init_sv(GV* gv, HV* stash, SV* namesv,
                           U32 flags)

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.

Flags may be one of:

    GV_ADD
    SVf_UTF8
    GV_NOADD_NOINIT
    GV_NOINIT
    GV_NOEXPAND
    GV_ADDMG

The most important of which are probably "GV_ADD" and "SVf_UTF8".

Note, use of "gv_stashsv" instead of "gv_stashpvn" where possible is strongly recommended for performance reasons.

        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("name", I32 create)

gv_stashsv

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

Note this interface is strongly preferred over "gv_stashpvn" for performance reasons.

        HV*     gv_stashsv(SV* sv, I32 flags)

        SV*     GvSV(GV* gv)

If empty is true, replace the GP with a new GP.

If empty is false, mark gv with GVf_INTRO so the next reference assigned is localized, which is how " local *foo = $someref; " works.

        void    save_gp(GV* gv, I32 empty)

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)

Handy Values

C_ARRAY_END

Returns a pointer to one element past the final element of the input C array.

        void *  C_ARRAY_END(void *a)

C_ARRAY_LENGTH

Returns the number of elements in the input C array (so you want your zero-based indices to be less than but not equal to).

        STRLEN  C_ARRAY_LENGTH(void *a)

"(bool)!!(cbool)" in a ternary triggers a bug in xlc on AIX

        bool    cBOOL(bool expr)

Null AV pointer.

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

Null CV pointer.

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

Null HV pointer.

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

STR_WITH_LEN

Returns two comma separated tokens of the input literal string, and its length. This is convenience macro which helps out in some API calls. Note that it can’t be used as an argument to macros or functions that under some configurations might be macros, which means that it requires the full Perl_xxx(aTHX_ ...) form for any API calls where it’s used.

        pair    STR_WITH_LEN("literal string")

__ASSERT_

This is a helper macro to avoid preprocessor issues, replaced by nothing unless under DEBUGGING, where it expands to an assert of its argument, followed by a comma (hence the comma operator). If we just used a straight assert(), we would get a comma with nothing before it when not DEBUGGING.

        void    __ASSERT_(bool expr)

Hash Manipulation Functions

A HV structure represents a Perl hash. It consists mainly of an array of pointers, each of which points to a linked list of HE structures. The array is indexed by the hash function of the key, so each linked list represents all the hash entries with the same hash value. Each HE contains a pointer to the actual value, plus a pointer to a HEK structure which holds the key and hash value.
cop_fetch_label

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

Returns the label attached to a cop, and stores its length in bytes into *len. Upon return, *flags will be set to either "SVf_UTF8" or 0.

Alternatively, use the macro ""CopLABEL_len_flags""; or if you don’t need to know if the label is UTF-8 or not, the macro ""CopLABEL_len""; or if you additionally dont need to know the length, ""CopLABEL"".

        const char * cop_fetch_label(COP *const cop,
                                     STRLEN *len, U32 *flags)

cop_store_label

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

Save a label into a "cop_hints_hash". You need to set flags to "SVf_UTF8" for a UTF-8 label. Any other flag is ignored.

        void    cop_store_label(COP *const cop,
                                const char *label, STRLEN len,
                                U32 flags)

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).

        U32     HeHASH(HE* he)

        void*   HeKEY(HE* he)

        STRLEN  HeKLEN(HE* he)

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)

        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)

        U32     HeUTF8(HE* he)

  SV *foo= HeVAL(hv);
  HeVAL(hv)= sv;
        SV*     HeVAL(HE* he)

hv_assert

Check that a hash is in an internally consistent state.

NOTE: this function must be explicitly called as Perl_hv_assert with an aTHX_ parameter.

        void    Perl_hv_assert(pTHX_ HV *hv)

hv_bucket_ratio

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

If the hash is tied dispatches through to the SCALAR tied method, otherwise if the hash contains no keys returns 0, otherwise returns a mortal sv containing a string specifying the number of used buckets, followed by a slash, followed by the number of available buckets.

This function is expensive, it must scan all of the buckets to determine which are used, and the count is NOT cached. In a large hash this could be a lot of buckets.

        SV*     hv_bucket_ratio(HV *hv)

hv_clear

Frees the all the elements of a hash, leaving it empty. The XS equivalent of "%hash = ()". See also "hv_undef".

See "av_clear" for a note about the hash possibly being invalid on return.

        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_copy_hints_hv

A specialised version of "newHVhv" for copying "%^H". "ohv" must be a pointer to a hash (which may have "%^H" magic, but should be generally non-magical), or "NULL" (interpreted as an empty hash). The content of "ohv" is copied to a new hash, which has the "%^H"-specific magic added to it. A pointer to the new hash is returned.

        HV *    hv_copy_hints_hv(HV *const ohv)

hv_delete

Deletes a key/value pair in the hash. The value’s SV is removed from the hash, made mortal, and returned to the caller. The absolute value of "klen" is the length of the key. If "klen" is negative the key is assumed to be in UTF-8-encoded Unicode. The "flags" value will normally be zero; if set to "G_DISCARD" then "NULL" will be returned. "NULL" will also be returned if the key is not found.

        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, made mortal, and returned to the caller. The "flags" value will normally be zero; if set to "G_DISCARD" then "NULL" will be returned. "NULL" will also be returned if the key is not found. "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)

        char*   HvENAME(HV* stash)

HvENAMELEN

Returns the length of the stash’s effective name.

        STRLEN  HvENAMELEN(HV *stash)

HvENAMEUTF8

Returns true if the effective name is in UTF-8 encoding.

        unsigned char HvENAMEUTF8(HV *stash)

hv_exists

Returns a boolean indicating whether the specified hash key exists. The absolute value of "klen" is the length of the key. If "klen" is negative the key is assumed to be in UTF-8-encoded Unicode.

        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 absolute value of "klen" is the length of the key. If "klen" is negative the key is assumed to be in UTF-8-encoded Unicode. If "lval" is set then the fetch will be part of a store. This means that if there is no value in the hash associated with the given key, then one is created and a pointer to it is returned. The "SV*" it points to can be assigned to. But always 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, "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 "hv" 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)

        STRLEN  HvFILL(HV *const hv)

This function is wrapped by the macro "HvFILL".

As of perl 5.25 this function is used only for debugging purposes, and the number of used hash buckets is not in any way cached, thus this function can be costly to execute as it must iterate over all the buckets in the hash.

NOTE: this function must be explicitly called as Perl_hv_fill with an aTHX_ parameter.

        STRLEN  Perl_hv_fill(pTHX_ HV *const hv)

hv_iterinit

Prepares a starting point to traverse a hash table. Returns the number of keys in the hash, including placeholders (i.e. the same as "HvTOTALKEYS(hv)"). 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(hv)".

        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

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

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 &PL_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.

        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)

        char*   HvNAME(HV* stash)

HvNAMELEN

Returns the length of the stash’s name.

        STRLEN  HvNAMELEN(HV *stash)

HvNAMEUTF8

Returns true if the name is in UTF-8 encoding.

        unsigned char HvNAMEUTF8(HV *stash)

hv_scalar

Evaluates the hash in scalar context and returns the result.

When the hash is tied dispatches through to the SCALAR method, otherwise returns a mortal SV containing the number of keys in the hash.

Note, prior to 5.25 this function returned what is now returned by the hv_bucket_ratio() function.

        SV*     hv_scalar(HV *hv)

hv_store

Stores an SV in a hash. The hash key is specified as "key" and the absolute value of "klen" is the length of the key. If "klen" is negative the key is assumed to be in UTF-8-encoded Unicode. 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, "key", 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. The reason it does not take ownership, is that "key" is not used after this function returns, and so can be freed immediately. "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. The XS equivalent of "undef(%hash)".

As well as freeing all the elements of the hash (like "hv_clear()"), this also frees any auxiliary data and storage associated with the hash.

See "av_clear" for a note about the hash possibly being invalid on return.

        void    hv_undef(HV *hv)

        HV*     newHV()

Hook manipulation

These functions provide convenient and thread-safe means of manipulating hook variables.
wrap_op_checker

Puts a C function into the chain of check functions for a specified op type. This is the preferred way to manipulate the "PL_check" array. "opcode" specifies which type of op is to be affected. "new_checker" is a pointer to the C function that is to be added to that opcode’s check chain, and "old_checker_p" points to the storage location where a pointer to the next function in the chain will be stored. The value of "new_checker" is written into the "PL_check" array, while the value previously stored there is written to *old_checker_p.

"PL_check" is global to an entire process, and a module wishing to hook op checking may find itself invoked more than once per process, typically in different threads. To handle that situation, this function is idempotent. The location *old_checker_p must initially (once per process) contain a null pointer. A C variable of static duration (declared at file scope, typically also marked "static" to give it internal linkage) will be implicitly initialised appropriately, if it does not have an explicit initialiser. This function will only actually modify the check chain if it finds *old_checker_p to be null. This function is also thread safe on the small scale. It uses appropriate locking to avoid race conditions in accessing "PL_check".

When this function is called, the function referenced by "new_checker" must be ready to be called, except for *old_checker_p being unfilled. In a threading situation, "new_checker" may be called immediately, even before this function has returned. *old_checker_p will always be appropriately set before "new_checker" is called. If "new_checker" decides not to do anything special with an op that it is given (which is the usual case for most uses of op check hooking), it must chain the check function referenced by *old_checker_p.

Taken all together, XS code to hook an op checker should typically look something like this:

    static Perl_check_t nxck_frob;
    static OP *myck_frob(pTHX_ OP *op) {
        ...
        op = nxck_frob(aTHX_ op);
        ...
        return op;
    }
    BOOT:
        wrap_op_checker(OP_FROB, myck_frob, &nxck_frob);

If you want to influence compilation of calls to a specific subroutine, then use "cv_set_call_checker_flags" rather than hooking checking of all "entersub" ops.

        void    wrap_op_checker(Optype opcode,
                                Perl_check_t new_checker,
                                Perl_check_t *old_checker_p)

Lexer interface

This is the lower layer of the Perl parser, managing characters and tokens.
lex_bufutf8

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

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.

        bool    lex_bufutf8()

lex_discard_to

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

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 for 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.

        void    lex_discard_to(char* ptr)

lex_grow_linestr

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

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.

        char*   lex_grow_linestr(STRLEN len)

lex_next_chunk

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

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" has the "LEX_KEEP_PREVIOUS" bit set, 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.

        bool    lex_next_chunk(U32 flags)

lex_peek_unichar

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

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" has the "LEX_KEEP_PREVIOUS" bit set, 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.

        I32     lex_peek_unichar(U32 flags)

lex_read_space

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

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" has the "LEX_KEEP_PREVIOUS" bit set, then the current chunk will not be discarded.

        void    lex_read_space(U32 flags)

lex_read_to

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

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".

        void    lex_read_to(char* ptr)

lex_read_unichar

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

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" has the "LEX_KEEP_PREVIOUS" bit set, 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.

        I32     lex_read_unichar(U32 flags)

lex_start

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

Creates and initialises a new lexer/parser state object, supplying a context in which to lex and parse from a new source of Perl code. A pointer to the new state object is placed in "PL_parser". An entry is made on the save stack so that upon unwinding, the new state object will be destroyed and the former value of "PL_parser" will be restored. Nothing else need be done to clean up the parsing context.

The code to be parsed comes from "line" and "rsfp". "line", if non-null, provides a string (in SV form) containing code to be parsed. A copy of the string is made, so subsequent modification of "line" does not affect parsing. "rsfp", if non-null, provides an input stream from which code will be read to be parsed. If both are non-null, the code in "line" comes first and must consist of complete lines of input, and "rsfp" supplies the remainder of the source.

The "flags" parameter is reserved for future use. Currently it is only used by perl internally, so extensions should always pass zero.

        void    lex_start(SV* line, PerlIO *rsfp, U32 flags)

lex_stuff_pv

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

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 octets starting at "pv" and continuing to the first nul. 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 it is not convenient to nul-terminate a string to be inserted, the "lex_stuff_pvn" function is more appropriate.

        void    lex_stuff_pv(const char* pv, U32 flags)

lex_stuff_pvn

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

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 inserted is available as a Perl scalar, the "lex_stuff_sv" function is more convenient.

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

lex_stuff_pvs

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

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

        void    lex_stuff_pvs("pv", U32 flags)

lex_stuff_sv

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

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 inserted is not already a Perl scalar, the "lex_stuff_pvn" function avoids the need to construct a scalar.

        void    lex_stuff_sv(SV* sv, U32 flags)

lex_unstuff

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

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".

        void    lex_unstuff(char* ptr)

parse_arithexpr

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

Parse a Perl arithmetic expression. This may contain operators of precedence down to the bit shift operators. The expression must be followed (and thus terminated) either by a comparison or lower-precedence operator or by something that would normally terminate an expression such as semicolon. If "flags" has the "PARSE_OPTIONAL" bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

        OP*     parse_arithexpr(U32 flags)

parse_barestmt

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

Parse a single unadorned Perl statement. This may be a normal imperative statement or a declaration that has compile-time effect. It does not include any label or other affixture. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the statement is returned. This may be a null pointer if the statement is null, for example if it was actually a subroutine definition (which has compile-time side effects). If not null, it will be ops directly implementing the statement, suitable to pass to "newSTATEOP". It will not normally include a "nextstate" or equivalent op (except for those embedded in a scope contained entirely within the statement).

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The "flags" parameter is reserved for future use, and must always be zero.

        OP*     parse_barestmt(U32 flags)

parse_block

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

Parse a single complete Perl code block. This consists of an opening brace, a sequence of statements, and a closing brace. The block constitutes a lexical scope, so "my" variables and various compile-time effects can be contained within it. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the code block is returned. This is always a real op, never a null pointer. It will normally be a "lineseq" list, including "nextstate" or equivalent ops. No ops to construct any kind of runtime scope are included by virtue of it being a block.

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The "flags" parameter is reserved for future use, and must always be zero.

        OP*     parse_block(U32 flags)

parse_fullexpr

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

Parse a single complete Perl expression. This allows the full expression grammar, including the lowest-precedence operators such as "or". The expression must be followed (and thus terminated) by a token that an expression would normally be terminated by: end-of-file, closing bracketing punctuation, semicolon, or one of the keywords that signals a postfix expression-statement modifier. If "flags" has the "PARSE_OPTIONAL" bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

        OP*     parse_fullexpr(U32 flags)

parse_fullstmt

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

Parse a single complete Perl statement. This may be a normal imperative statement or a declaration that has compile-time effect, and may include optional labels. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the statement is returned. This may be a null pointer if the statement is null, for example if it was actually a subroutine definition (which has compile-time side effects). If not null, it will be the result of a "newSTATEOP" call, normally including a "nextstate" or equivalent op.

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The "flags" parameter is reserved for future use, and must always be zero.

        OP*     parse_fullstmt(U32 flags)

parse_label

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

Parse a single label, possibly optional, of the type that may prefix a Perl statement. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed. If "flags" has the "PARSE_OPTIONAL" bit set, then the label is optional, otherwise it is mandatory.

The name of the label is returned in the form of a fresh scalar. If an optional label is absent, a null pointer is returned.

If an error occurs in parsing, which can only occur if the label is mandatory, a valid label is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred.

        SV*     parse_label(U32 flags)

parse_listexpr

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

Parse a Perl list expression. This may contain operators of precedence down to the comma operator. The expression must be followed (and thus terminated) either by a low-precedence logic operator such as "or" or by something that would normally terminate an expression such as semicolon. If "flags" has the "PARSE_OPTIONAL" bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

        OP*     parse_listexpr(U32 flags)

parse_stmtseq

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

Parse a sequence of zero or more Perl statements. These may be normal imperative statements, including optional labels, or declarations that have compile-time effect, or any mixture thereof. The statement sequence ends when a closing brace or end-of-file is encountered in a place where a new statement could have validly started. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statements.

The op tree representing the statement sequence is returned. This may be a null pointer if the statements were all null, for example if there were no statements or if there were only subroutine definitions (which have compile-time side effects). If not null, it will be a "lineseq" list, normally including "nextstate" or equivalent ops.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The "flags" parameter is reserved for future use, and must always be zero.

        OP*     parse_stmtseq(U32 flags)

parse_subsignature

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

Parse a subroutine signature declaration. This is the contents of the parentheses following a named or anonymous subroutine declaration when the "signatures" feature is enabled. Note that this function neither expects nor consumes the opening and closing parentheses around the signature; it is the caller’s job to handle these.

This function must only be called during parsing of a subroutine; after "start_subparse" has been called. It might allocate lexical variables on the pad for the current subroutine.

The op tree to unpack the arguments from the stack at runtime is returned. This op tree should appear at the beginning of the compiled function. The caller may wish to use "op_append_list" to build their function body after it, or splice it together with the body before calling "newATTRSUB".

The "flags" parameter is reserved for future use, and must always be zero.

        OP*     parse_subsignature(U32 flags)

parse_termexpr

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

Parse a Perl term expression. This may contain operators of precedence down to the assignment operators. The expression must be followed (and thus terminated) either by a comma or lower-precedence operator or by something that would normally terminate an expression such as semicolon. If "flags" has the "PARSE_OPTIONAL" bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

        OP*     parse_termexpr(U32 flags)

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

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

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.

PL_parser->bufptr

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

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".

PL_parser->linestart

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

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.

PL_parser->linestr

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

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.

wrap_keyword_plugin

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

Puts a C function into the chain of keyword plugins. This is the preferred way to manipulate the "PL_keyword_plugin" variable. "new_plugin" is a pointer to the C function that is to be added to the keyword plugin chain, and "old_plugin_p" points to the storage location where a pointer to the next function in the chain will be stored. The value of "new_plugin" is written into the "PL_keyword_plugin" variable, while the value previously stored there is written to *old_plugin_p.

"PL_keyword_plugin" is global to an entire process, and a module wishing to hook keyword parsing may find itself invoked more than once per process, typically in different threads. To handle that situation, this function is idempotent. The location *old_plugin_p must initially (once per process) contain a null pointer. A C variable of static duration (declared at file scope, typically also marked "static" to give it internal linkage) will be implicitly initialised appropriately, if it does not have an explicit initialiser. This function will only actually modify the plugin chain if it finds *old_plugin_p to be null. This function is also thread safe on the small scale. It uses appropriate locking to avoid race conditions in accessing "PL_keyword_plugin".

When this function is called, the function referenced by "new_plugin" must be ready to be called, except for *old_plugin_p being unfilled. In a threading situation, "new_plugin" may be called immediately, even before this function has returned. *old_plugin_p will always be appropriately set before "new_plugin" is called. If "new_plugin" decides not to do anything special with the identifier that it is given (which is the usual case for most calls to a keyword plugin), it must chain the plugin function referenced by *old_plugin_p.

Taken all together, XS code to install a keyword plugin should typically look something like this:

    static Perl_keyword_plugin_t next_keyword_plugin;
    static OP *my_keyword_plugin(pTHX_
        char *keyword_ptr, STRLEN keyword_len, OP **op_ptr)
    {
        if (memEQs(keyword_ptr, keyword_len,
                   "my_new_keyword")) {
            ...
        } else {
            return next_keyword_plugin(aTHX_
                keyword_ptr, keyword_len, op_ptr);
        }
    }
    BOOT:
        wrap_keyword_plugin(my_keyword_plugin,
                            &next_keyword_plugin);

Direct access to "PL_keyword_plugin" should be avoided.

        void    wrap_keyword_plugin(
                    Perl_keyword_plugin_t new_plugin,
                    Perl_keyword_plugin_t *old_plugin_p
                )

Locale-related functions and macros

DECLARATION_FOR_LC_NUMERIC_MANIPULATION

This macro should be used as a statement. It declares a private variable (whose name begins with an underscore) that is needed by the other macros in this section. Failing to include this correctly should lead to a syntax error. For compatibility with C89 C compilers it should be placed in a block before any executable statements.

        void    DECLARATION_FOR_LC_NUMERIC_MANIPULATION

IN_LOCALE

Evaluates to TRUE if the plain locale pragma without a parameter ("use locale") is in effect.

        bool    IN_LOCALE

IN_LOCALE_COMPILETIME

Evaluates to TRUE if, when compiling a perl program (including an "eval") if the plain locale pragma without a parameter ("use locale") is in effect.

        bool    IN_LOCALE_COMPILETIME

IN_LOCALE_RUNTIME

Evaluates to TRUE if, when executing a perl program (including an "eval") if the plain locale pragma without a parameter ("use locale") is in effect.

        bool    IN_LOCALE_RUNTIME

Perl_langinfo

This is an (almost) drop-in replacement for the system nl_langinfo(3), taking the same "item" parameter values, and returning the same information. But it is more thread-safe than regular "nl_langinfo()", and hides the quirks of Perl’s locale handling from your code, and can be used on systems that lack a native "nl_langinfo".

Expanding on these:

It is important to note that when called with an item that is recovered by using "localeconv", the buffer from any previous explicit call to "localeconv" will be overwritten. This means you must save that buffer’s contents if you need to access them after a call to this function. (But note that you might not want to be using "localeconv()" directly anyway, because of issues like the ones listed in the second item of this list (above) for "RADIXCHAR" and "THOUSEP". You can use the methods given in perlcall to call "localeconv" in POSIX and avoid all the issues, but then you have a hash to unpack).

The details for those items which may deviate from what this emulation returns and what a native "nl_langinfo()" would return are specified in I18N::Langinfo.

When using "Perl_langinfo" on systems that don’t have a native "nl_langinfo()", you must

 #include "perl_langinfo.h"

before the "perl.h" "#include". You can replace your "langinfo.h" "#include" with this one. (Doing it this way keeps out the symbols that plain "langinfo.h" would try to import into the namespace for code that doesn’t need it.)

The original impetus for "Perl_langinfo()" was so that code that needs to find out the current currency symbol, floating point radix character, or digit grouping separator can use, on all systems, the simpler and more thread-friendly "nl_langinfo" API instead of localeconv(3) which is a pain to make thread-friendly. For other fields returned by "localeconv", it is better to use the methods given in perlcall to call "POSIX::localeconv()", which is thread-friendly.

        const char* Perl_langinfo(const nl_item item)

Perl_setlocale

This is an (almost) drop-in replacement for the system setlocale(3), taking the same parameters, and returning the same information, except that it returns the correct underlying "LC_NUMERIC" locale. Regular "setlocale" will instead return "C" if the underlying locale has a non-dot decimal point character, or a non-empty thousands separator for displaying floating point numbers. This is because perl keeps that locale category such that it has a dot and empty separator, changing the locale briefly during the operations where the underlying one is required. "Perl_setlocale" knows about this, and compensates; regular "setlocale" doesn’t.

Another reason it isn’t completely a drop-in replacement is that it is declared to return "const char *", whereas the system setlocale omits the "const" (presumably because its API was specified long ago, and can’t be updated; it is illegal to change the information "setlocale" returns; doing so leads to segfaults.)

Finally, "Perl_setlocale" works under all circumstances, whereas plain "setlocale" can be completely ineffective on some platforms under some configurations.

"Perl_setlocale" should not be used to change the locale except on systems where the predefined variable "${^SAFE_LOCALES}" is 1. On some such systems, the system "setlocale()" is ineffective, returning the wrong information, and failing to actually change the locale. "Perl_setlocale", however works properly in all circumstances.

The return points to a per-thread static buffer, which is overwritten the next time "Perl_setlocale" is called from the same thread.

        const char* Perl_setlocale(const int category,
                                   const char* locale)

RESTORE_LC_NUMERIC

This is used in conjunction with one of the macros " STORE_LC_NUMERIC_SET_TO_NEEDED" and " STORE_LC_NUMERIC_FORCE_TO_UNDERLYING" to properly restore the "LC_NUMERIC" state.

A call to " DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro and the two "STORE" ones. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

 {
    DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
     ...
    RESTORE_LC_NUMERIC();
     ...
 }
        void    RESTORE_LC_NUMERIC()

STORE_LC_NUMERIC_FORCE_TO_UNDERLYING

This is used by XS code that is "LC_NUMERIC" locale-aware to force the locale for category "LC_NUMERIC" to be what perl thinks is the current underlying locale. (The perl interpreter could be wrong about what the underlying locale actually is if some C or XS code has called the C library function setlocale(3) behind its back; calling "sync_locale" before calling this macro will update perl’s records.)

A call to " DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

 {
    DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
     ...
    STORE_LC_NUMERIC_FORCE_TO_UNDERLYING();
     ...
    RESTORE_LC_NUMERIC();
     ...
 }

The private variable is used to save the current locale state, so that the requisite matching call to " RESTORE_LC_NUMERIC" can restore it.

On threaded perls not operating with thread-safe functionality, this macro uses a mutex to force a critical section. Therefore the matching RESTORE should be close by, and guaranteed to be called.

        void    STORE_LC_NUMERIC_FORCE_TO_UNDERLYING()

STORE_LC_NUMERIC_SET_TO_NEEDED

This is used to help wrap XS or C code that is "LC_NUMERIC" locale-aware. This locale category is generally kept set to a locale where the decimal radix character is a dot, and the separator between groups of digits is empty. This is because most XS code that reads floating point numbers is expecting them to have this syntax.

This macro makes sure the current "LC_NUMERIC" state is set properly, to be aware of locale if the call to the XS or C code from the Perl program is from within the scope of a "use locale"; or to ignore locale if the call is instead from outside such scope.

This macro is the start of wrapping the C or XS code; the wrap ending is done by calling the " RESTORE_LC_NUMERIC" macro after the operation. Otherwise the state can be changed that will adversely affect other XS code.

A call to " DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

 {
    DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
     ...
    STORE_LC_NUMERIC_SET_TO_NEEDED();
     ...
    RESTORE_LC_NUMERIC();
     ...
 }

On threaded perls not operating with thread-safe functionality, this macro uses a mutex to force a critical section. Therefore the matching RESTORE should be close by, and guaranteed to be called; see " WITH_LC_NUMERIC_SET_TO_NEEDED" for a more contained way to ensure that.

        void    STORE_LC_NUMERIC_SET_TO_NEEDED()

STORE_LC_NUMERIC_SET_TO_NEEDED_IN

Same as " STORE_LC_NUMERIC_SET_TO_NEEDED" with in_lc_numeric provided as the precalculated value of "IN_LC(LC_NUMERIC)". It is the caller’s responsibility to ensure that the status of "PL_compiling" and "PL_hints" cannot have changed since the precalculation.

        void    STORE_LC_NUMERIC_SET_TO_NEEDED_IN(
                    bool in_lc_numeric
                )

switch_to_global_locale

On systems without locale support, or on typical single-threaded builds, or on platforms that do not support per-thread locale operations, this function does nothing. On such systems that do have locale support, only a locale global to the whole program is available.

On multi-threaded builds on systems that do have per-thread locale operations, this function converts the thread it is running in to use the global locale. This is for code that has not yet or cannot be updated to handle multi-threaded locale operation. As long as only a single thread is so-converted, everything works fine, as all the other threads continue to ignore the global one, so only this thread looks at it.

However, on Windows systems this isn’t quite true prior to Visual Studio 15, at which point Microsoft fixed a bug. A race can occur if you use the following operations on earlier Windows platforms:
POSIX::localeconv
I18N::Langinfo, items "CRNCYSTR" and "THOUSEP"
"Perl_langinfo" in perlapi, items "CRNCYSTR" and "THOUSEP"

The first item is not fixable (except by upgrading to a later Visual Studio release), but it would be possible to work around the latter two items by using the Windows API functions "GetNumberFormat" and "GetCurrencyFormat"; patches welcome.

Without this function call, threads that use the setlocale(3) system function will not work properly, as all the locale-sensitive functions will look at the per-thread locale, and "setlocale" will have no effect on this thread.

Perl code should convert to either call "Perl_setlocale" (which is a drop-in for the system "setlocale") or use the methods given in perlcall to call "POSIX::setlocale". Either one will transparently properly handle all cases of single- vs multi-thread, POSIX 2008-supported or not.

Non-Perl libraries, such as "gtk", that call the system "setlocale" can continue to work if this function is called before transferring control to the library.

Upon return from the code that needs to use the global locale, "sync_locale()" should be called to restore the safe multi-thread operation.

        void    switch_to_global_locale()

sync_locale

"Perl_setlocale" can be used at any time to query or change the locale (though changing the locale is antisocial and dangerous on multi-threaded systems that don’t have multi-thread safe locale operations. (See "Multi-threaded operation" in perllocale). Using the system setlocale(3) should be avoided. Nevertheless, certain non-Perl libraries called from XS, such as "Gtk" do so, and this can’t be changed. When the locale is changed by XS code that didn’t use "Perl_setlocale", Perl needs to be told that the locale has changed. Use this function to do so, before returning to Perl.

The return value is a boolean: TRUE if the global locale at the time of call was in effect; and FALSE if a per-thread locale was in effect. This can be used by the caller that needs to restore things as-they-were to decide whether or not to call "Perl_switch_to_global_locale".

        bool    sync_locale()

WITH_LC_NUMERIC_SET_TO_NEEDED

This macro invokes the supplied statement or block within the context of a " STORE_LC_NUMERIC_SET_TO_NEEDED" .. " RESTORE_LC_NUMERIC" pair if required, so eg:

  WITH_LC_NUMERIC_SET_TO_NEEDED(
    SNPRINTF_G(fv, ebuf, sizeof(ebuf), precis)
  );

is equivalent to:

  {
#ifdef USE_LOCALE_NUMERIC
    DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
    STORE_LC_NUMERIC_SET_TO_NEEDED();
#endif
    SNPRINTF_G(fv, ebuf, sizeof(ebuf), precis);
#ifdef USE_LOCALE_NUMERIC
    RESTORE_LC_NUMERIC();
#endif
  }
        void    WITH_LC_NUMERIC_SET_TO_NEEDED(block)

WITH_LC_NUMERIC_SET_TO_NEEDED_IN

Same as " WITH_LC_NUMERIC_SET_TO_NEEDED" with in_lc_numeric provided as the precalculated value of "IN_LC(LC_NUMERIC)". It is the caller’s responsibility to ensure that the status of "PL_compiling" and "PL_hints" cannot have changed since the precalculation.

        void    WITH_LC_NUMERIC_SET_TO_NEEDED_IN(
                    bool in_lc_numeric, block
                )

Magical Functions

mg_clear

Clear something magical that the SV represents. See "sv_magic".

        int     mg_clear(SV* sv)

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

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

mg_findext

Finds the magic pointer of "type" with the given "vtbl" for the "SV". See "sv_magicext".

        MAGIC*  mg_findext(const SV* sv, int type,
                           const MGVTBL *vtbl)

        int     mg_free(SV* sv)

mg_freeext

Remove any magic of type "how" using virtual table "vtbl" from the SV "sv". See "sv_magic".

"mg_freeext(sv, how, NULL)" is equivalent to "mg_free_type(sv, how)".

        void    mg_freeext(SV* sv, int how, const MGVTBL *vtbl)

mg_free_type

Remove any magic of type "how" from the SV "sv". See "sv_magic".

        void    mg_free_type(SV* sv, int how)

        int     mg_get(SV* sv)

mg_length

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Reports on the SV ’s length in bytes, calling length magic if available, but does not set the UTF8 flag on "sv". It will fall back to ’get’ magic if there is no ’length’ magic, but with no indication as to whether it called ’get’ magic. It assumes "sv" is a "PVMG" or higher. Use "sv_len()" instead.

        U32     mg_length(SV* sv)

mg_magical

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

        void    mg_magical(SV* sv)

        int     mg_set(SV* sv)

SvGETMAGIC

Invokes "mg_get" on an SV if it has ’get’ magic. For example, this will call "FETCH" on a tied variable. This macro evaluates its argument more than once.

        void    SvGETMAGIC(SV* sv)

        void    SvLOCK(SV* sv)

SvSETMAGIC

Invokes "mg_set" on an SV if it has ’set’ magic. This is necessary after modifying a scalar, in case it is a magical variable like $| or a tied variable (it calls "STORE"). 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* dsv, SV* ssv)

SvSetMagicSV_nosteal

Like "SvSetSV_nosteal", but does any set magic required afterwards.

        void    SvSetMagicSV_nosteal(SV* dsv, SV* ssv)

        void    SvSetSV(SV* dsv, 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)

        void    SvSHARE(SV* sv)

sv_string_from_errnum

Generates the message string describing an OS error and returns it as an SV. "errnum" must be a value that "errno" could take, identifying the type of error.

If "tgtsv" is non-null then the string will be written into that SV (overwriting existing content) and it will be returned. If "tgtsv" is a null pointer then the string will be written into a new mortal SV which will be returned.

The message will be taken from whatever locale would be used by $!, and will be encoded in the SV in whatever manner would be used by $!. The details of this process are subject to future change. Currently, the message is taken from the C locale by default (usually producing an English message), and from the currently selected locale when in the scope of the "use locale" pragma. A heuristic attempt is made to decode the message from the locale’s character encoding, but it will only be decoded as either UTF-8 or ISO-8859-1. It is always correctly decoded in a UTF-8 locale, usually in an ISO-8859-1 locale, and never in any other locale.

The SV is always returned containing an actual string, and with no other OK bits set. Unlike $!, a message is even yielded for "errnum" zero (meaning success), and if no useful message is available then a useless string (currently empty) is returned.

        SV*     sv_string_from_errnum(int errnum, SV* tgtsv)

SvUNLOCK

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

        void    SvUNLOCK(SV* sv)

Memory Management

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

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

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

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

Memory obtained by this should ONLY be freed with "Safefree".

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 perlhacktips). The older API is still there for use in XS modules supporting older perls.

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

Memory obtained by this should ONLY be freed with "Safefree".

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

Memory obtained by this should ONLY be freed with "Safefree".

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

        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)

Memory obtained by this should ONLY be freed with "Safefree".

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

Memory obtained by this should ONLY be freed with "Safefree".

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

Safefree

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

This should ONLY be used on memory obtained using "Newx" and friends.

        void    Safefree(void* ptr)

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedpv".

        char*   savepv(const char* pv)

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedpvn".

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

        char*   savepvs("literal string")

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)

savesharedpvs

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

        char*   savesharedpvs("literal string")

savesharedsvpv

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

        char*   savesharedsvpv(SV *sv)

savesvpv

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

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedsvpv".

        char*   savesvpv(SV* sv)

StructCopy

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

        void    StructCopy(type *src, type *dest, type)

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

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

Miscellaneous Functions

dump_c_backtrace

Dumps the C backtrace to the given "fp".

Returns true if a backtrace could be retrieved, false if not.

        bool    dump_c_backtrace(PerlIO* fp, int max_depth,
                                 int skip)

fbm_compile

Analyzes 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 "big" and "bigend" ("bigend") is the char following the last char). 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)

        I32     foldEQ(const char* a, const char* b, I32 len)

foldEQ_locale

Returns true if the leading "len" bytes of the strings "s1" and "s2" are the same case-insensitively in the current locale; false otherwise.

        I32     foldEQ_locale(const char* a, const char* b,
                              I32 len)

    (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 "sv" with current working directory

        int     getcwd_sv(SV* sv)

get_c_backtrace_dump

Returns a SV containing a dump of "depth" frames of the call stack, skipping the "skip" innermost ones. "depth" of 20 is usually enough.

The appended output looks like:

... 1 10e004812:0082 Perl_croak util.c:1716 /usr/bin/perl 2 10df8d6d2:1d72 perl_parse perl.c:3975 /usr/bin/perl ...

The fields are tab-separated. The first column is the depth (zero being the innermost non-skipped frame). In the hex:offset, the hex is where the program counter was in "S_parse_body", and the :offset (might be missing) tells how much inside the "S_parse_body" the program counter was.

The "util.c:1716" is the source code file and line number.

The /usr/bin/perl is obvious (hopefully).

Unknowns are "-". Unknowns can happen unfortunately quite easily: if the platform doesn’t support retrieving the information; if the binary is missing the debug information; if the optimizer has transformed the code by for example inlining.

        SV*     get_c_backtrace_dump(int max_depth, int skip)

I32 ibcmp(const char* a, const char* b, I32 len)

ibcmp_locale

This is a synonym for "(! foldEQ_locale())"

I32 ibcmp_locale(const char* a, const char* b,
I32 len)

        char*   instr(const char* big, const char* little)

IS_SAFE_SYSCALL

Same as "is_safe_syscall".

        bool    IS_SAFE_SYSCALL(NN const char *pv, STRLEN len,
                                NN const char *what,
                                NN const char *op_name)

is_safe_syscall

Test that the given "pv" (with length "len") doesn’t contain any internal "NUL" characters. If it does, set "errno" to "ENOENT", optionally warn using the "syscalls" category, and return FALSE.

Return TRUE if the name is safe.

"what" and "op_name" are used in any warning.

Used by the "IS_SAFE_SYSCALL()" macro.

        bool    is_safe_syscall(const char *pv, STRLEN len,
                                const char *what,
                                const char *op_name)

        bool    memCHRs("list", char c)

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

        bool    memEQs(char* s1, STRLEN l1, "s2")

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

        bool    memNEs(char* s1, STRLEN l1, "s2")

Normally, the resulting message is returned in a new mortal SV. During global destruction a single SV may be shared between uses of this function.

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

"basemsg" is the initial message or object. If it is a reference, it will be used as-is and will be the result of this function. Otherwise it is used as a string, and if it already ends with a newline, it is taken to be complete, and the result of this function will be the same string. If the message does not end with a newline, then a segment such as "at foo.pl line 37" will be appended, and possibly other clauses indicating the current state of execution. The resulting message will end with a dot and a newline.

Normally, the resulting message is returned in a new mortal SV. During global destruction a single SV may be shared between uses of this function. If "consume" is true, then the function is permitted (but not required) to modify and return "basemsg" instead of allocating a new SV.

        SV*     mess_sv(SV* basemsg, bool consume)

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

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Do NOT use this due to the possibility of overflowing "buffer". Instead use my_snprintf()

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

my_strlcat

The C library "strlcat" if available, or a Perl implementation of it. This operates on C "NUL"-terminated strings.

"my_strlcat()" appends string "src" to the end of "dst". It will append at most "size - strlen(dst) - 1" characters. It will then "NUL"-terminate, unless "size" is 0 or the original "dst" string was longer than "size" (in practice this should not happen as it means that either "size" is incorrect or that "dst" is not a proper "NUL"-terminated string).

Note that "size" is the full size of the destination buffer and the result is guaranteed to be "NUL"-terminated if there is room. Note that room for the "NUL" should be included in "size".

The return value is the total length that "dst" would have if "size" is sufficiently large. Thus it is the initial length of "dst" plus the length of "src". If "size" is smaller than the return, the excess was not appended.

        Size_t  my_strlcat(char *dst, const char *src,
                           Size_t size)

my_strlcpy

The C library "strlcpy" if available, or a Perl implementation of it. This operates on C "NUL"-terminated strings.

"my_strlcpy()" copies up to "size - 1" characters from the string "src" to "dst", "NUL"-terminating the result if "size" is not 0.

The return value is the total length "src" would be if the copy completely succeeded. If it is larger than "size", the excess was not copied.

        Size_t  my_strlcpy(char *dst, const char *src,
                           Size_t size)

my_strnlen

The C library "strnlen" if available, or a Perl implementation of it.

"my_strnlen()" computes the length of the string, up to "maxlen" characters. It will never attempt to address more than "maxlen" characters, making it suitable for use with strings that are not guaranteed to be NUL-terminated.

        Size_t  my_strnlen(const char *str, Size_t maxlen)

my_vsnprintf

The C library "vsnprintf" if available and standards-compliant. 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_vsnprintf(char *buffer, const Size_t len,
                             const char *format, va_list ap)

Another way of thinking about this function is finding a needle in a haystack. "big" points to the first byte in the haystack. "big_end" points to one byte beyond the final byte in the haystack. "little" points to the first byte in the needle. "little_end" points to one byte beyond the final byte in the needle. All the parameters must be non-"NULL".

The function returns "NULL" if there is no occurrence of "little" within "big". If "little" is the empty string, "big" is returned.

Because this function operates at the byte level, and because of the inherent characteristics of UTF-8 (or UTF-EBCDIC), it will work properly if both the needle and the haystack are strings with the same UTF-8ness, but not if the UTF-8ness differs.

        char*   ninstr(const char* big, const char* bigend,
                       const char* little, const char* lend)

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()

READ_XDIGIT

Returns the value of an ASCII-range hex digit and advances the string pointer. Behaviour is only well defined when isXDIGIT(*str) is true.

        U8      READ_XDIGIT(char str*)

        char*   rninstr(const char* big, const char* bigend,
                        const char* little, const char* lend)

STMT_START

 STMT_START { statements; } STMT_END;

can be used as a single statement, as in

 if (x) STMT_START { ... } STMT_END; else ...

These are often used in macro definitions. Note that you can’t return a value out of them.

        bool    strEQ(char* s1, char* s2)

        bool    strGE(char* s1, char* s2)

        bool    strGT(char* s1, char* s2)

        bool    strLE(char* s1, char* s2)

        bool    strLT(char* s1, char* s2)

        bool    strNE(char* s1, char* s2)

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

        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)

UNLIKELY

Returns the input unchanged, but at the same time it gives a branch prediction hint to the compiler that this condition is likely to be false.

Normally, the resulting message is returned in a new mortal SV. During global destruction a single SV may be shared between uses of this function.

        SV*     vmess(const char* pat, va_list* args)

MRO Functions

These functions are related to the method resolution order of perl classes Also see perlmroapi.
mro_get_linear_isa

Returns the mro linearisation for the given stash. By default, this will be whatever "mro_get_linear_isa_dfs" returns unless some other MRO is in effect for the 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)

mro_register

Registers a custom mro plugin. See perlmroapi for details on this and other mro functions.

NOTE: this function must be explicitly called as Perl_mro_register with an aTHX_ parameter.

        void    Perl_mro_register(pTHX_
                                  const struct mro_alg *mro)

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(CV* the_cv);

Numeric functions

grok_bin

converts a string representing a binary number to numeric form.

On entry "start" and *len_p 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 at just before the first invalid character. Unless "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character (except NUL ) will also trigger a warning. On return *len_p 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 an approximation of the correct value into *result (which is an NV ; or the approximation 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 any or all pairs of digits may be separated from each other by a single underscore; also a single leading underscore is accepted.

        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_p 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 at just before the first invalid character. Unless "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character (except NUL ) will also trigger a warning. On return *len_p 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 an approximation of the correct value into *result (which is an NV ; or the approximation 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 any or all pairs of digits may be separated from each other by a single underscore; also a single leading underscore is accepted.

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

grok_infnan

Helper for "grok_number()", accepts various ways of spelling "infinity" or "not a number", and returns one of the following flag combinations:

  IS_NUMBER_INFINITY
  IS_NUMBER_NAN
  IS_NUMBER_INFINITY | IS_NUMBER_NEG
  IS_NUMBER_NAN | IS_NUMBER_NEG
  0

possibly |-ed with "IS_NUMBER_TRAILING".

If an infinity or a not-a-number is recognized, *sp will point to one byte past the end of the recognized string. If the recognition fails, zero is returned, and *sp will not move.

        int     grok_infnan(const char** sp, const char *send)

grok_number

Identical to "grok_number_flags()" with "flags" set to zero.

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

grok_number_flags

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 in a UV, it is returned in *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.

"flags" allows only "PERL_SCAN_TRAILING", which allows for trailing non-numeric text on an otherwise successful grok, setting "IS_NUMBER_TRAILING" on the result.

        int     grok_number_flags(const char *pv, STRLEN len,
                                  UV *valuep, U32 flags)

GROK_NUMERIC_RADIX

A synonym for "grok_numeric_radix"

        bool    GROK_NUMERIC_RADIX(NN const char **sp,
                                   NN const char *send)

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_p 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 at just before the first invalid character. Unless "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character (except NUL ) will also trigger a warning. On return *len_p 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 an approximation of the correct value into *result (which is an NV ; or the approximation is discarded if "result" is NULL ).

If "PERL_SCAN_ALLOW_UNDERSCORES" is set in *flags then any or all pairs of digits may be separated from each other by a single underscore; also a single leading underscore is accepted.

The "PERL_SCAN_DISALLOW_PREFIX" flag is always treated as being set for this function.

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

isinfnan

"Perl_isinfnan()" is a utility function that returns true if the NV argument is either an infinity or a "NaN", false otherwise. To test in more detail, use "Perl_isinf()" and "Perl_isnan()".

This is also the logical inverse of Perl_isfinite().

        bool    isinfnan(NV nv)

IS_NUMBER_GREATER_THAN_UV_MAX bool IS_NUMBER_GREATER_THAN_UV_MAX
IS_NUMBER_INFINITY bool IS_NUMBER_INFINITY
IS_NUMBER_IN_UV bool IS_NUMBER_IN_UV
IS_NUMBER_NAN bool IS_NUMBER_NAN
IS_NUMBER_NEG bool IS_NUMBER_NEG
IS_NUMBER_NOT_INT

        bool    IS_NUMBER_NOT_INT

my_strtod

This function is equivalent to the libc strtod() function, and is available even on platforms that lack plain strtod(). Its return value is the best available precision depending on platform capabilities and Configure options.

It properly handles the locale radix character, meaning it expects a dot except when called from within the scope of "use locale", in which case the radix character should be that specified by the current locale.

The synonym Strtod() may be used instead.

        NV      my_strtod(const char * const s, char ** e)

PERL_ABS

Typeless "abs" or "fabs", etc. (The usage below indicates it is for integers, but it works for any type.) Use instead of these, since the C library ones force their argument to be what it is expecting, potentially leading to disaster. But also beware that this evaluates its argument twice, so no "x++".

        int     PERL_ABS(int)

PERL_INT_MAX

This and "PERL_INT_MIN", "PERL_LONG_MAX", "PERL_LONG_MIN", "PERL_QUAD_MAX", "PERL_SHORT_MAX", "PERL_SHORT_MIN", "PERL_UCHAR_MAX", "PERL_UCHAR_MIN", "PERL_UINT_MAX", "PERL_ULONG_MAX", "PERL_ULONG_MIN", "PERL_UQUAD_MAX", "PERL_UQUAD_MIN", "PERL_USHORT_MAX", "PERL_USHORT_MIN", "PERL_QUAD_MIN" give the largest and smallest number representable in the current platform in variables of the corresponding types.

For signed types, the smallest representable number is the most negative number, the one furthest away from zero.

For C99 and later compilers, these correspond to things like "INT_MAX", which are available to the C code. But these constants, furnished by Perl, allow code compiled on earlier compilers to portably have access to the same constants.

Perl_signbit

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

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. The main use of this function is catching "-0.0".

"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()".

        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)

        NV      Strtod(NN const char * const s,
                       NULLOK char ** e)

        NV      Strtol(NN const char * const s,
                       NULLOK char ** e, int base)

        NV      Strtoul(NN const char * const s,
                        NULLOK char ** e, int base)

Obsolete backwards compatibility functions

Some of these are also deprecated. You can exclude these from your compiled Perl by adding this option to Configure: "-Accflags='-DNO_MATHOMS'"
custom_op_desc

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Return the description of a given custom op. This was once used by the "OP_DESC" macro, but is no longer: it has only been kept for compatibility, and should not be used.

        const char * custom_op_desc(const OP *o)

custom_op_name

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Return the name for a given custom op. This was once used by the "OP_NAME" macro, but is no longer: it has only been kept for compatibility, and should not be used.

        const char * custom_op_name(const OP *o)

gv_fetchmethod

See "gv_fetchmethod_autoload".

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

is_utf8_char

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

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.

This function is deprecated due to the possibility that malformed input could cause reading beyond the end of the input buffer. Use "isUTF8_CHAR" instead.

        STRLEN  is_utf8_char(const U8 *s)

is_utf8_char_buf

This is identical to the macro "isUTF8_CHAR" in perlapi.

        STRLEN  is_utf8_char_buf(const U8 *buf,
                                 const U8 *buf_end)

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)

pad_compname_type

Looks up the type of the lexical variable at position "po" in the currently-compiling pad. If the variable is typed, the stash of the class to which it is typed is returned. If not, "NULL" is returned.

        HV*     pad_compname_type(const PADOFFSET po)

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)

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

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

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

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

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)

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)

        char*   sv_pv(SV *sv)

sv_pvbyte

Use "SvPVbyte_nolen" instead.

        char*   sv_pvbyte(SV *sv)

sv_pvbyten

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

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)

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

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

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)

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

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

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.

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

utf8_to_uvchr

DEPRECATED ! It is planned to remove this function from a future release of Perl. Do not use it for new code; remove it from existing code.

Returns the native 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.

Some, but not all, UTF-8 malformations are detected, and in fact, some malformed input could cause reading beyond the end of the input buffer, which is why this function is deprecated. Use "utf8_to_uvchr_buf" instead.

If "s" points to one of the detected malformations, and UTF8 warnings are enabled, zero is returned and *retlen is set (if "retlen" isn’t "NULL") to -1. If those warnings are off, the computed value if well-defined (or the Unicode REPLACEMENT CHARACTER, if not) is silently returned, and *retlen is set (if "retlen" isn’t NULL ) so that ("s" + *retlen) is the next possible position in "s" that could begin a non-malformed character. See "utf8n_to_uvchr" for details on when the REPLACEMENT CHARACTER is returned.

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

Optree construction

newASSIGNOP

Constructs, checks, and returns an assignment op. "left" and "right" supply the parameters of the assignment; they are consumed by this function and become part of the constructed op tree.

If "optype" is "OP_ANDASSIGN", "OP_ORASSIGN", or "OP_DORASSIGN", then a suitable conditional optree is constructed. If "optype" is the opcode of a binary operator, such as "OP_BIT_OR", then an op is constructed that performs the binary operation and assigns the result to the left argument. Either way, if "optype" is non-zero then "flags" has no effect.

If "optype" is zero, then a plain scalar or list assignment is constructed. Which type of assignment it is is automatically determined. "flags" gives the eight bits of "op_flags", except that "OPf_KIDS" will be set automatically, and, shifted up eight bits, the eight bits of "op_private", except that the bit with value 1 or 2 is automatically set as required.

        OP*     newASSIGNOP(I32 flags, OP* left, I32 optype,
                            OP* right)

newBINOP

Constructs, checks, and returns an op of any binary type. "type" is the opcode. "flags" gives the eight bits of "op_flags", except that "OPf_KIDS" will be set automatically, and, shifted up eight bits, the eight bits of "op_private", except that the bit with value 1 or 2 is automatically set as required. "first" and "last" supply up to two ops to be the direct children of the binary op; they are consumed by this function and become part of the constructed op tree.

        OP*     newBINOP(I32 type, I32 flags, OP* first,
                         OP* last)

newCONDOP

Constructs, checks, and returns a conditional-expression ("cond_expr") op. "flags" gives the eight bits of "op_flags", except that "OPf_KIDS" will be set automatically, and, shifted up eight bits, the eight bits of "op_private", except that the bit with value 1 is automatically set. "first" supplies the expression selecting between the two branches, and "trueop" and "falseop" supply the branches; they are consumed by this function and become part of the constructed op tree.

        OP*     newCONDOP(I32 flags, OP* first, OP* trueop,
                          OP* falseop)

newDEFSVOP

Constructs and returns an op to access $_.

        OP*     newDEFSVOP()

newFOROP

Constructs, checks, and returns an op tree expressing a "foreach" loop (iteration through a list of values). This is a heavyweight loop, with structure that allows exiting the loop by "last" and suchlike.

"sv" optionally supplies the variable that will be aliased to each item in turn; if null, it defaults to $_. "expr" supplies the list of values to iterate over. "block" supplies the main body of the loop, and "cont" optionally supplies a "continue" block that operates as a second half of the body. All of these optree inputs are consumed by this function and become part of the constructed op tree.

"flags" gives the eight bits of "op_flags" for the "leaveloop" op and, shifted up eight bits, the eight bits of "op_private" for the "leaveloop" op, except that (in both cases) some bits will be set automatically.

        OP*     newFOROP(I32 flags, OP* sv, OP* expr, OP* block,
                         OP* cont)

newGIVENOP

Constructs, checks, and returns an op tree expressing a "given" block. "cond" supplies the expression to whose value $_ will be locally aliased, and "block" supplies the body of the "given" construct; they are consumed by this function and become part of the constructed op tree. "defsv_off" must be zero (it used to identity the pad slot of lexical $_).

        OP*     newGIVENOP(OP* cond, OP* block,
                           PADOFFSET defsv_off)

        OP*     newGVOP(I32 type, I32 flags, GV* gv)

newLISTOP

Constructs, checks, and returns an op of any list type. "type" is the opcode. "flags" gives the eight bits of "op_flags", except that "OPf_KIDS" will be set automatically if required. "first" and "last" supply up to two ops to be direct children of the list op; they are consumed by this function and become part of the constructed op tree.

For most list operators, the check function expects all the kid ops to be present already, so calling "newLISTOP(OP_JOIN, ...)" (e.g.) is not appropriate. What you want to do in that case is create an op of type "OP_LIST", append more children to it, and then call "op_convert_list". See "op_convert_list" for more information.

        OP*     newLISTOP(I32 type, I32 flags, OP* first,
                          OP* last)

newLOGOP

Constructs, checks, and returns a logical (flow control) op. "type" is the opcode. "flags" gives the eight bits of "op_flags", except that "OPf_KIDS" will be set automatically, and, shifted up eight bits, the eight bits of "op_private", except that the bit with value 1 is automatically set. "first" supplies the expression controlling the flow, and "other" supplies the side (alternate) chain of ops; they are consumed by this function and become part of the constructed op tree.

        OP*     newLOGOP(I32 optype, I32 flags, OP *first,
                         OP *other)

newLOOPEX

Constructs, checks, and returns a loop-exiting op (such as "goto" or "last"). "type" is the opcode. "label" supplies the parameter determining the target of the op; it is consumed by this function and becomes part of the constructed op tree.

        OP*     newLOOPEX(I32 type, OP* label)

newLOOPOP

Constructs, checks, and returns an op tree expressing a loop. This is only a loop in the control flow through the op tree; it does not have the heavyweight loop structure that allows exiting the loop by "last" and suchlike. "flags" gives the eight bits of "op_flags" for the top-level op, except that some bits will be set automatically as required. "expr" supplies the expression controlling loop iteration, and "block" supplies the body of the loop; they are consumed by this function and become part of the constructed op tree. "debuggable" is currently unused and should always be 1.

        OP*     newLOOPOP(I32 flags, I32 debuggable, OP* expr,
                          OP* block)

newMETHOP

Constructs, checks, and returns an op of method type with a method name evaluated at runtime. "type" is the opcode. "flags" gives the eight bits of "op_flags", except that "OPf_KIDS" will be set automatically, and, shifted up eight bits, the eight bits of "op_private", except that the bit with value 1 is automatically set. "dynamic_meth" supplies an op which evaluates method name; it is consumed by this function and become part of the constructed op tree. Supported optypes: "OP_METHOD".

        OP*     newMETHOP(I32 type, I32 flags, OP* dynamic_meth)

newMETHOP_named

Constructs, checks, and returns an op of method type with a constant method name. "type" is the opcode. "flags" gives the eight bits of "op_flags", and, shifted up eight bits, the eight bits of "op_private". "const_meth" supplies a constant method name; it must be a shared COW string. Supported optypes: "OP_METHOD_NAMED".

        OP*     newMETHOP_named(I32 type, I32 flags,
                                SV* const_meth)

newNULLLIST

Constructs, checks, and returns a new "stub" op, which represents an empty list expression.

        OP*     newNULLLIST()

        OP*     newOP(I32 optype, I32 flags)

newPADOP

Constructs, checks, and returns an op of any type that involves a reference to a pad element. "type" is the opcode. "flags" gives the eight bits of "op_flags". A pad slot is automatically allocated, and is populated with "sv"; this function takes ownership of one reference to it.

This function only exists if Perl has been compiled to use ithreads.

        OP*     newPADOP(I32 type, I32 flags, SV* sv)

        OP*     newPMOP(I32 type, I32 flags)

        OP*     newPVOP(I32 type, I32 flags, char* pv)

newRANGE

Constructs and returns a "range" op, with subordinate "flip" and "flop" ops. "flags" gives the eight bits of "op_flags" for the "flip" op and, shifted up eight bits, the eight bits of "op_private" for both the "flip" and "range" ops, except that the bit with value 1 is automatically set. "left" and "right" supply the expressions controlling the endpoints of the range; they are consumed by this function and become part of the constructed op tree.

        OP*     newRANGE(I32 flags, OP* left, OP* right)

newSLICEOP

Constructs, checks, and returns an "lslice" (list slice) op. "flags" gives the eight bits of "op_flags", except that "OPf_KIDS" will be set automatically, and, shifted up eight bits, the eight bits of "op_private", except that the bit with value 1 or 2 is automatically set as required. "listval" and "subscript" supply the parameters of the slice; they are consumed by this function and become part of the constructed op tree.

        OP*     newSLICEOP(I32 flags, OP* subscript, OP* listop)

newSTATEOP

Constructs a state op ( COP ). The state op is normally a "nextstate" op, but will be a "dbstate" op if debugging is enabled for currently-compiled code. The state op is populated from "PL_curcop" (or "PL_compiling"). If "label" is non-null, it supplies the name of a label to attach to the state op; this function takes ownership of the memory pointed at by "label", and will free it. "flags" gives the eight bits of "op_flags" for the state op.

If "o" is null, the state op is returned. Otherwise the state op is combined with "o" into a "lineseq" list op, which is returned. "o" is consumed by this function and becomes part of the returned op tree.

        OP*     newSTATEOP(I32 flags, char* label, OP* o)

        OP*     newSVOP(I32 type, I32 flags, SV* sv)

        OP*     newUNOP(I32 type, I32 flags, OP* first)

newUNOP_AUX

Similar to "newUNOP", but creates an "UNOP_AUX" struct instead, with "op_aux" initialised to "aux"

OP* newUNOP_AUX(I32 type, I32 flags, OP* first,
UNOP_AUX_item *aux)

newWHENOP

Constructs, checks, and returns an op tree expressing a "when" block. "cond" supplies the test expression, and "block" supplies the block that will be executed if the test evaluates to true; they are consumed by this function and become part of the constructed op tree. "cond" will be interpreted DWIMically, often as a comparison against $_, and may be null to generate a "default" block.

        OP*     newWHENOP(OP* cond, OP* block)

newWHILEOP

Constructs, checks, and returns an op tree expressing a "while" loop. This is a heavyweight loop, with structure that allows exiting the loop by "last" and suchlike.

"loop" is an optional preconstructed "enterloop" op to use in the loop; if it is null then a suitable op will be constructed automatically. "expr" supplies the loop’s controlling expression. "block" supplies the main body of the loop, and "cont" optionally supplies a "continue" block that operates as a second half of the body. All of these optree inputs are consumed by this function and become part of the constructed op tree.

"flags" gives the eight bits of "op_flags" for the "leaveloop" op and, shifted up eight bits, the eight bits of "op_private" for the "leaveloop" op, except that (in both cases) some bits will be set automatically. "debuggable" is currently unused and should always be 1. "has_my" can be supplied as true to force the loop body to be enclosed in its own scope.

        OP*     newWHILEOP(I32 flags, I32 debuggable,
                           LOOP* loop, OP* expr, OP* block,
                           OP* cont, I32 has_my)

Optree Manipulation Functions

alloccopstash

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

Available only under threaded builds, this function allocates an entry in "PL_stashpad" for the stash passed to it.

        PADOFFSET alloccopstash(HV *hv)

block_end

Handles compile-time scope exit. "floor" is the savestack index returned by "block_start", and "seq" is the body of the block. Returns the block, possibly modified.

        OP*     block_end(I32 floor, OP* seq)

block_start

Handles compile-time scope entry. Arranges for hints to be restored on block exit and also handles pad sequence numbers to make lexical variables scope right. Returns a savestack index for use with "block_end".

        int     block_start(int full)

ck_entersub_args_list

Performs the default fixup of the arguments part of an "entersub" op tree. This consists of applying list context to each of the argument ops. This is the standard treatment used on a call marked with "&", or a method call, or a call through a subroutine reference, or any other call where the callee can’t be identified at compile time, or a call where the callee has no prototype.

        OP*     ck_entersub_args_list(OP *entersubop)

ck_entersub_args_proto

Performs the fixup of the arguments part of an "entersub" op tree based on a subroutine prototype. This makes various modifications to the argument ops, from applying context up to inserting "refgen" ops, and checking the number and syntactic types of arguments, as directed by the prototype. This is the standard treatment used on a subroutine call, not marked with "&", where the callee can be identified at compile time and has a prototype.

"protosv" supplies the subroutine prototype to be applied to the call. It may be a normal defined scalar, of which the string value will be used. Alternatively, for convenience, it may be a subroutine object (a "CV*" that has been cast to "SV*") which has a prototype. The prototype supplied, in whichever form, does not need to match the actual callee referenced by the op tree.

If the argument ops disagree with the prototype, for example by having an unacceptable number of arguments, a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. In the error message, the callee is referred to by the name defined by the "namegv" parameter.

        OP*     ck_entersub_args_proto(OP *entersubop,
                                       GV *namegv, SV *protosv)

ck_entersub_args_proto_or_list

Performs the fixup of the arguments part of an "entersub" op tree either based on a subroutine prototype or using default list-context processing. This is the standard treatment used on a subroutine call, not marked with "&", where the callee can be identified at compile time.

"protosv" supplies the subroutine prototype to be applied to the call, or indicates that there is no prototype. It may be a normal scalar, in which case if it is defined then the string value will be used as a prototype, and if it is undefined then there is no prototype. Alternatively, for convenience, it may be a subroutine object (a "CV*" that has been cast to "SV*"), of which the prototype will be used if it has one. The prototype (or lack thereof) supplied, in whichever form, does not need to match the actual callee referenced by the op tree.

If the argument ops disagree with the prototype, for example by having an unacceptable number of arguments, a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. In the error message, the callee is referred to by the name defined by the "namegv" parameter.

        OP*     ck_entersub_args_proto_or_list(OP *entersubop,
                                               GV *namegv,
                                               SV *protosv)

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)

cv_get_call_checker

The original form of "cv_get_call_checker_flags", which does not return checker flags. When using a checker function returned by this function, it is only safe to call it with a genuine GV as its "namegv" argument.

        void    cv_get_call_checker(CV *cv,
                                    Perl_call_checker *ckfun_p,
                                    SV **ckobj_p)

cv_get_call_checker_flags

Retrieves the function that will be used to fix up a call to "cv". Specifically, the function is applied to an "entersub" op tree for a subroutine call, not marked with "&", where the callee can be identified at compile time as "cv".

The C-level function pointer is returned in *ckfun_p, an SV argument for it is returned in *ckobj_p, and control flags are returned in *ckflags_p. The function is intended to be called in this manner:

 entersubop = (*ckfun_p)(aTHX_ entersubop, namegv, (*ckobj_p));

In this call, "entersubop" is a pointer to the "entersub" op, which may be replaced by the check function, and "namegv" supplies the name that should be used by the check function to refer to the callee of the "entersub" op if it needs to emit any diagnostics. It is permitted to apply the check function in non-standard situations, such as to a call to a different subroutine or to a method call.

"namegv" may not actually be a GV. If the "CALL_CHECKER_REQUIRE_GV" bit is clear in *ckflags_p, it is permitted to pass a CV or other SV instead, anything that can be used as the first argument to "cv_name". If the "CALL_CHECKER_REQUIRE_GV" bit is set in *ckflags_p then the check function requires "namegv" to be a genuine GV.

By default, the check function is Perl_ck_entersub_args_proto_or_list, the SV parameter is "cv" itself, and the "CALL_CHECKER_REQUIRE_GV" flag is clear. This implements standard prototype processing. It can be changed, for a particular subroutine, by "cv_set_call_checker_flags".

If the "CALL_CHECKER_REQUIRE_GV" bit is set in "gflags" then it indicates that the caller only knows about the genuine GV version of "namegv", and accordingly the corresponding bit will always be set in *ckflags_p, regardless of the check function’s recorded requirements. If the "CALL_CHECKER_REQUIRE_GV" bit is clear in "gflags" then it indicates the caller knows about the possibility of passing something other than a GV as "namegv", and accordingly the corresponding bit may be either set or clear in *ckflags_p, indicating the check function’s recorded requirements.

"gflags" is a bitset passed into "cv_get_call_checker_flags", in which only the "CALL_CHECKER_REQUIRE_GV" bit currently has a defined meaning (for which see above). All other bits should be clear.

        void    cv_get_call_checker_flags(
                    CV *cv, U32 gflags,
                    Perl_call_checker *ckfun_p, SV **ckobj_p,
                    U32 *ckflags_p
                )

cv_set_call_checker

The original form of "cv_set_call_checker_flags", which passes it the "CALL_CHECKER_REQUIRE_GV" flag for backward-compatibility. The effect of that flag setting is that the check function is guaranteed to get a genuine GV as its "namegv" argument.

        void    cv_set_call_checker(CV *cv,
                                    Perl_call_checker ckfun,
                                    SV *ckobj)

cv_set_call_checker_flags

Sets the function that will be used to fix up a call to "cv". Specifically, the function is applied to an "entersub" op tree for a subroutine call, not marked with "&", where the callee can be identified at compile time as "cv".

The C-level function pointer is supplied in "ckfun", an SV argument for it is supplied in "ckobj", and control flags are supplied in "ckflags". The function should be defined like this:

    STATIC OP * ckfun(pTHX_ OP *op, GV *namegv, SV *ckobj)

It is intended to be called in this manner:

    entersubop = ckfun(aTHX_ entersubop, namegv, ckobj);

In this call, "entersubop" is a pointer to the "entersub" op, which may be replaced by the check function, and "namegv" supplies the name that should be used by the check function to refer to the callee of the "entersub" op if it needs to emit any diagnostics. It is permitted to apply the check function in non-standard situations, such as to a call to a different subroutine or to a method call.

"namegv" may not actually be a GV. For efficiency, perl may pass a CV or other SV instead. Whatever is passed can be used as the first argument to "cv_name". You can force perl to pass a GV by including "CALL_CHECKER_REQUIRE_GV" in the "ckflags".

"ckflags" is a bitset, in which only the "CALL_CHECKER_REQUIRE_GV" bit currently has a defined meaning (for which see above). All other bits should be clear.

The current setting for a particular CV can be retrieved by "cv_get_call_checker_flags".

        void    cv_set_call_checker_flags(
                    CV *cv, Perl_call_checker ckfun, SV *ckobj,
                    U32 ckflags
                )

LINKLIST

Given the root of an optree, link the tree in execution order using the "op_next" pointers and return the first op executed. If this has already been done, it will not be redone, and "o->op_next" will be returned. If "o->op_next" is not already set, "o" should be at least an "UNOP".

        OP*     LINKLIST(OP *o)

newCONSTSUB

Behaves like "newCONSTSUB_flags", except that "name" is nul-terminated rather than of counted length, and no flags are set. (This means that "name" is always interpreted as Latin-1.)

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

newCONSTSUB_flags

Construct a constant subroutine, also performing some surrounding jobs. A scalar constant-valued subroutine is eligible for inlining at compile-time, and in Perl code can be created by "sub FOO () { 123 }". Other kinds of constant subroutine have other treatment.

The subroutine will have an empty prototype and will ignore any arguments when called. Its constant behaviour is determined by "sv". If "sv" is null, the subroutine will yield an empty list. If "sv" points to a scalar, the subroutine will always yield that scalar. If "sv" points to an array, the subroutine will always yield a list of the elements of that array in list context, or the number of elements in the array in scalar context. This function takes ownership of one counted reference to the scalar or array, and will arrange for the object to live as long as the subroutine does. If "sv" points to a scalar then the inlining assumes that the value of the scalar will never change, so the caller must ensure that the scalar is not subsequently written to. If "sv" points to an array then no such assumption is made, so it is ostensibly safe to mutate the array or its elements, but whether this is really supported has not been determined.

The subroutine will have "CvFILE" set according to "PL_curcop". Other aspects of the subroutine will be left in their default state. The caller is free to mutate the subroutine beyond its initial state after this function has returned.

If "name" is null then the subroutine will be anonymous, with its "CvGV" referring to an "__ANON__" glob. If "name" is non-null then the subroutine will be named accordingly, referenced by the appropriate glob. "name" is a string of length "len" bytes giving a sigilless symbol name, in UTF-8 if "flags" has the "SVf_UTF8" bit set and in Latin-1 otherwise. The name may be either qualified or unqualified. If the name is unqualified then it defaults to being in the stash specified by "stash" if that is non-null, or to "PL_curstash" if "stash" is null. The symbol is always added to the stash if necessary, with "GV_ADDMULTI" semantics.

"flags" should not have bits set other than "SVf_UTF8".

If there is already a subroutine of the specified name, then the new sub will replace the existing one in the glob. A warning may be generated about the redefinition.

If the subroutine has one of a few special names, such as "BEGIN" or "END", then it will be claimed by the appropriate queue for automatic running of phase-related subroutines. In this case the relevant glob will be left not containing any subroutine, even if it did contain one before. Execution of the subroutine will likely be a no-op, unless "sv" was a tied array or the caller modified the subroutine in some interesting way before it was executed. In the case of "BEGIN", the treatment is buggy: the sub will be executed when only half built, and may be deleted prematurely, possibly causing a crash.

The function returns a pointer to the constructed subroutine. If the sub is anonymous then ownership of one counted reference to the subroutine is transferred to the caller. If the sub is named then the caller does not get ownership of a reference. In most such cases, where the sub has a non-phase name, the sub will be alive at the point it is returned by virtue of being contained in the glob that names it. A phase-named subroutine will usually be alive by virtue of the reference owned by the phase’s automatic run queue. A "BEGIN" subroutine may have been destroyed already by the time this function returns, but currently bugs occur in that case before the caller gets control. It is the caller’s responsibility to ensure that it knows which of these situations applies.

        CV*     newCONSTSUB_flags(HV* stash, const char* name,
                                  STRLEN len, U32 flags, SV* sv)

op_append_elem

Append an item to the list of ops contained directly within a list-type op, returning the lengthened list. "first" is the list-type op, and "last" is the op to append to the list. "optype" specifies the intended opcode for the list. If "first" is not already a list of the right type, it will be upgraded into one. If either "first" or "last" is null, the other is returned unchanged.

        OP*     op_append_elem(I32 optype, OP* first, OP* last)

op_append_list

Concatenate the lists of ops contained directly within two list-type ops, returning the combined list. "first" and "last" are the list-type ops to concatenate. "optype" specifies the intended opcode for the list. If either "first" or "last" is not already a list of the right type, it will be upgraded into one. If either "first" or "last" is null, the other is returned unchanged.

        OP*     op_append_list(I32 optype, OP* first, OP* last)

OP_CLASS

Return the class of the provided OP: that is, which of the *OP structures it uses. For core ops this currently gets the information out of "PL_opargs", which does not always accurately reflect the type used; in v5.26 onwards, see also the function "op_class" which can do a better job of determining the used type.

For custom ops the type is returned from the registration, and it is up to the registree to ensure it is accurate. The value returned will be one of the "OA_"* constants from op.h.

        U32     OP_CLASS(OP *o)

op_contextualize

Applies a syntactic context to an op tree representing an expression. "o" is the op tree, and "context" must be "G_SCALAR", "G_ARRAY", or "G_VOID" to specify the context to apply. The modified op tree is returned.

        OP*     op_contextualize(OP* o, I32 context)

op_convert_list

Converts "o" into a list op if it is not one already, and then converts it into the specified "type", calling its check function, allocating a target if it needs one, and folding constants.

A list-type op is usually constructed one kid at a time via "newLISTOP", "op_prepend_elem" and "op_append_elem". Then finally it is passed to "op_convert_list" to make it the right type.

        OP*     op_convert_list(I32 optype, I32 flags, OP* o)

        const char * OP_DESC(OP *o)

        void    op_free(OP* arg)

OpHAS_SIBLING

Returns true if "o" has a sibling

        bool    OpHAS_SIBLING(OP *o)

OpLASTSIB_set

Marks "o" as having no further siblings and marks o as having the specified parent. See also "OpMORESIB_set" and "OpMAYBESIB_set". For a higher-level interface, see "op_sibling_splice".

        void    OpLASTSIB_set(OP *o, OP *parent)

op_linklist