Manpages - B.3perl

For descriptions of the class hierarchy of these objects and the methods that can be called on them, see below, OVERVIEW OF CLASSES and SV-RELATED CLASSES.

sv_undef

Returns the SV object corresponding to the C variable sv_undef.

sv_yes

Returns the SV object corresponding to the C variable sv_yes.

sv_no

Returns the SV object corresponding to the C variable sv_no.

svref_2object(SVREF)

Takes a reference to any Perl value, and turns the referred-to value into an object in the appropriate B::OP-derived or B::SV-derived class. Apart from functions such as main_root, this is the primary way to get an initial handle on an internal perl data structure which can then be followed with the other access methods. The returned object will only be valid as long as the underlying OPs and SVs continue to exist. Do not attempt to use the object after the underlying structures are freed.

amagic_generation

Returns the SV object corresponding to the C variable amagic_generation. As of Perl 5.18, this is just an alias to PL_na, so its value is meaningless.

init_av

Returns the AV object (i.e. in class B::AV) representing INIT blocks.

check_av

Returns the AV object (i.e. in class B::AV) representing CHECK blocks.

unitcheck_av

Returns the AV object (i.e. in class B::AV) representing UNITCHECK blocks.

begin_av

Returns the AV object (i.e. in class B::AV) representing BEGIN blocks.

end_av

Returns the AV object (i.e. in class B::AV) representing END blocks.

comppadlist

Returns the PADLIST object (i.e. in class B::PADLIST) of the global comppadlist. In Perl 5.16 and earlier it returns an AV object (class B::AV).

regex_padav

Only when perl was compiled with ithreads.

main_cv

Return the (faked) CV corresponding to the main part of the Perl program.

walksymtable(SYMREF, METHOD, RECURSE, PREFIX)

Walk the symbol table starting at SYMREF and call METHOD on each symbol (a B::GV object) visited. When the walk reaches package symbols (such as Foo::) it invokes RECURSE, passing in the symbol name, and only recurses into the package if that sub returns true. PREFIX is the name of the SYMREF you’re walking. For example: # Walk CGIs symbol table calling print_subs on each symbol. # Recurse only into CGI::Util:: walksymtable(\%CGI::, print_subs, sub { $_[0] eq CGI::Util:: }, CGI::); print_subs() is a B::GV method you have declared. Also see B::GV Methods, below.

For descriptions of the class hierarchy of these objects and the methods that can be called on them, see below, OVERVIEW OF CLASSES and OP-RELATED CLASSES.

main_root

Returns the root op (i.e. an object in the appropriate B::OP-derived class) of the main part of the Perl program.

main_start

Returns the starting op of the main part of the Perl program.

walkoptree(OP, METHOD)

Does a tree-walk of the syntax tree based at OP and calls METHOD on each op it visits. Each node is visited before its children. If walkoptree_debug (see below) has been called to turn debugging on then the method walkoptree_debug is called on each op before METHOD is called.

walkoptree_debug(DEBUG)

Returns the current debugging flag for walkoptree. If the optional DEBUG argument is non-zero, it sets the debugging flag to that. See the description of walkoptree above for what the debugging flag does.

ppname(OPNUM)

Return the PP function name (e.g. pp_add) of op number OPNUM.

hash(STR)

Returns a string in the form 0x… representing the value of the internal hash function used by perl on string STR.

cast_I32(I)

Casts I to the internal I32 type used by that perl.

minus_c

Does the equivalent of the -c command-line option. Obviously, this is only useful in a BEGIN block or else the flag is set too late.

cstring(STR)

Returns a double-quote-surrounded escaped version of STR which can be used as a string in C source code.

perlstring(STR)

Returns a double-quote-surrounded escaped version of STR which can be used as a string in Perl source code.

safename(STR)

This function returns the string with the first character modified if it is a control character. It converts it to ^X format first, so that \cG becomes ^G. This is used internally by B::GV::SAFENAME, but you can call it directly.

class(OBJ)

Returns the class of an object without the part of the classname preceding the first "::". This is used to turn "B::UNOP" into "UNOP" for example.

threadsv_names

This used to provide support for the old 5.005 threading module. It now does nothing.

1. my $op_type = $optype[$op_type_num]; A simple mapping of the op type number to its type (like ’COP’ or ’BINOP’).
2. my $sv_name = $specialsv_name[$sv_index]; Certain SV types are considered ’special’. They’re represented by B::SPECIAL and are referred to by a number from the specialsv_list. This array maps that number back to the name of the SV (like ’Nullsv’ or ’&PL_sv_undef’).

B::IV, B::NV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::PVLV, B::AV, B::HV, B::CV, B::GV, B::FM, B::IO. These classes correspond in the obvious way to the underlying C structures of similar names. The inheritance hierarchy mimics the underlying C inheritance:

B::SV | -------------------–—+ | | | B::PV B::IV B::NV / \ / / / \ / / B::INVLIST B::PVIV / \ / \ / \ / B::PVNV | | B::PVMG | -----------------------------–—+ | | | | | | B::AV B::GV B::HV B::CV B::IO B::REGEXP | | | | B::PVLV B::FM

Access methods correspond to the underlying C macros for field access, usually with the leading class indication prefix removed (Sv, Av, Hv, …). The leading prefix is only left in cases where its removal would cause a clash in method name. For example, GvREFCNT stays as-is since its abbreviation would clash with the superclass method REFCNT (corresponding to the C function SvREFCNT).

REFCNT

FLAGS

object_2svref

Returns a reference to the regular scalar corresponding to this B::SV object. In other words, this method is the inverse operation to the svref_2object() subroutine. This scalar and other data it points at should be considered read-only: modifying them is neither safe nor guaranteed to have a sensible effect.

1. Returns the value of the IV, interpreted as a signed integer. This will be misleading if FLAGS & SVf_IVisUV. Perhaps you want the int_value method instead?

This method returns the value of the IV as an integer. It differs from IV in that it returns the correct value regardless of whether it’s stored signed or unsigned.

needs64bits

packiv

NV

NVX

COP_SEQ_RANGE_LOW

COP_SEQ_RANGE_HIGH

These last two are only valid for pad name SVs. They only existed in the B::NV class before Perl 5.22. In 5.22 they were moved to the B::PADNAME class.

RV

PV

This method is the one you usually want. It constructs a string using the length and offset information in the struct: for ordinary scalars it will return the string that you’d see from Perl, even if it contains null characters.

RV

Same as B::RV::RV, except that it will die() if the PV isn’t a reference.

PVX

This method is less often useful. It assumes that the string stored in the struct is null-terminated, and disregards the length information. It is the appropriate method to use if you need to get the name of a lexical variable from a padname array. Lexical variable names are always stored with a null terminator, and the length field (CUR) is overloaded for other purposes and can’t be relied on here.

CUR

This method returns the internal length field, which consists of the number of internal bytes, not necessarily the number of logical characters.

LEN

This method returns the number of bytes allocated (via malloc) for storing the string. This is 0 if the scalar does not own the string.

MAGIC

SvSTASH

MOREMAGIC

precomp

Only valid on r-magic, returns the string that generated the regexp.

PRIVATE

TYPE

FLAGS

OBJ

Will die() if called on r-magic.

PTR

REGEX

Only valid on r-magic, returns the integer value of the REGEX stored in the MAGIC.

prev_index

Returns the cache result of previous invlist_search() (internal usage)

is_offset

Returns a boolean value (0 or 1) to know if the invlist is using an offset. When false the list begins with the code point U+0000. When true the list begins with the following elements.

array_len

Returns an integer with the size of the array used to define the invlist.

get_invlist_array

This method returns a list of integers representing the array used by the invlist. Note: this cannot be used while in middle of iterating on an invlist and croaks.

TARGOFF

TARGLEN

TYPE

TARG

USEFUL

PREVIOUS

RARE

TABLE

REGEX

precomp

qr_anoncv

compflags

The last two were added in Perl 5.22.

is_empty

This method returns TRUE if the GP field of the GV is NULL.

NAME

SAFENAME

This method returns the name of the glob, but if the first character of the name is a control character, then it converts it to ^X first, so that *^G would return ^G rather than \cG. It’s useful if you want to print out the name of a variable. If you restrict yourself to globs which exist at compile-time then the result ought to be unambiguous, because code like ${"^G"} = 1 is compiled as two ops - a constant string and a dereference (rv2gv) - so that the glob is created at runtime. If you’re working with globs at runtime, and need to disambiguate *^G from *{^G}, then you should use the raw NAME method.

STASH

SV

IO

FORM

AV

HV

EGV

(no term)

CVGEN

LINE

FILE

FILEGV

GvREFCNT

FLAGS

GPFLAGS

This last one is present only in perl 5.22.0 and higher.

B::IO objects derive from IO objects and you will get more information from the IO object itself.

For example:

$gvio = B::svref_2object(\*main::stdin)->IO; $IO = $gvio->object_2svref(); $fd = $IO->fileno();

LINES

PAGE

PAGE_LEN

LINES_LEFT

TOP_NAME

TOP_GV

FMT_NAME

FMT_GV

BOTTOM_NAME

BOTTOM_GV

SUBPROCESS

IoTYPE

A character symbolizing the type of IO Handle. - STDIN/OUT I STDIN/OUT/ERR < read-only > write-only a append + read and write s socket | pipe I IMPLICIT # NUMERIC space closed handle \0 closed internal handle

IoFLAGS

IsSTD

Takes one argument ( ’stdin’ | ’stdout’ | ’stderr’ ) and returns true if the IoIFP of the object is equal to the handle whose name was passed as argument; i.e., $io->IsSTD(’stderr’) is true if IoIFP($io) == PerlIO_stderr().

FILL

MAX

ARRAY

ARRAYelt

Like ARRAY, but takes an index as an argument to get only one element, rather than a list of all of them.

STASH

START

ROOT

GV

FILE

DEPTH

PADLIST

Returns a B::PADLIST object.

OUTSIDE

OUTSIDE_SEQ

XSUB

XSUBANY

For constant subroutines, returns the constant SV returned by the subroutine.

CvFLAGS

const_sv

NAME_HEK

Returns the name of a lexical sub, otherwise undef.

FILL

MAX

KEYS

RITER

NAME

ARRAY

B::OP, B::UNOP, B::UNOP_AUX, B::BINOP, B::LOGOP, B::LISTOP, B::PMOP, B::SVOP, B::PADOP, B::PVOP, B::LOOP, B::COP, B::METHOP.

These classes correspond in the obvious way to the underlying C structures of similar names. The inheritance hierarchy mimics the underlying C inheritance:

B::OP | ------------------------------------------- | | | | | | B::UNOP B::SVOP B::PADOP B::COP B::PVOP B::METHOP | ---------------

B::LOOP B::PMOP

Access methods correspond to the underlying C structure field names, with the leading class indication prefix ("op_") removed.

These methods get the values of similarly named fields within the OP data structure. See top of op.h for more info.

next

sibling

parent

Returns the OP’s parent. If it has no parent, or if your perl wasn’t built with -DPERL_OP_PARENT, returns NULL. Note that the global variable $B::OP::does_parent is undefined on older perls that don’t support the parent method, is defined but false on perls that support the method but were built without -DPERL_OP_PARENT, and is true otherwise.

name

This returns the op name as a string (e.g. add, rv2av).

ppaddr

This returns the function name as a string (e.g. PL_ppaddr[OP_ADD], PL_ppaddr[OP_RV2AV]).

desc

This returns the op description from the global C PL_op_desc array (e.g. addition array deref).

targ

type

opt

flags

private

spare

first

aux_list(cv)

This returns a list of the elements of the op’s aux data structure, or a null list if there is no aux. What will be returned depends on the object’s type, but will typically be a collection of B::IV, B::GV, etc. objects. cv is the B::CV object representing the sub that the op is contained within.

string(cv)

This returns a textual representation of the object (likely to b useful for deparsing and debugging), or an empty string if the op type doesn’t support this. cv is the B::CV object representing the sub that the op is contained within.

last

other

children

pmreplroot

pmreplstart

pmflags

precomp

pmoffset

Only when perl was compiled with ithreads.

code_list

Since perl 5.17.1

pmregexp

Added in perl 5.22, this method returns the B::REGEXP associated with the op. While PMOPs do not actually have pmregexp fields under threaded builds, this method returns the regexp under threads nonetheless, for convenience.

sv

gv

padix

pv

redoop

nextop

lastop

The B::COP class is used for nextstate and dbstate ops. As of Perl 5.22, it is also used for null ops that started out as COPs.

label

stash

stashpv

stashoff (threaded only)

file

cop_seq

line

warnings

io

hints

hints_hash

first

meth_sv

Perl 5.18 introduced a new class, B::PADLIST, returned by B::CV’s PADLIST method.

Perl 5.22 introduced the B::PADNAMELIST and B::PADNAME classes.

MAX

ARRAY

A list of pads. The first one is a B::PADNAMELIST containing the names. The rest are currently B::AV objects, but that could change in future versions.

ARRAYelt

Like ARRAY, but takes an index as an argument to get only one element, rather than a list of all of them.

NAMES

This method, introduced in 5.22, returns the B::PADNAMELIST. It is equivalent to ARRAYelt with a 0 argument.

REFCNT

id

This method, introduced in 5.22, returns an ID shared by clones of the same padlist.

outid

This method, also added in 5.22, returns the ID of the outer padlist.

MAX

ARRAY

ARRAYelt

These two methods return the pad names, using B::SPECIAL objects for null pointers and B::PADNAME objects otherwise.

REFCNT

PV

PVX

LEN

REFCNT

FLAGS

For backward-compatibility, if the PADNAMEt_OUTER flag is set, the FLAGS method adds the SVf_FAKE flag, too.

TYPE

A B::HV object representing the stash for a typed lexical.

SvSTASH

A backward-compatibility alias for TYPE.

OURSTASH

A B::HV object representing the stash for ’our’ variables.

PROTOCV

The prototype CV for a ’my’ sub.

COP_SEQ_RANGE_LOW

COP_SEQ_RANGE_HIGH

Sequence numbers representing the scope within which a lexical is visible. Meaningless if PADNAMEt_OUTER is set.

PARENT_PAD_INDEX

Only meaningful if PADNAMEt_OUTER is set.

PARENT_FAKELEX_FLAGS

Only meaningful if PADNAMEt_OUTER is set.

Although the optree is read-only, there is an overlay facility that allows you to override what values the various B::*OP methods return for a particular op. $B::overlay should be set to reference a two-deep hash: indexed by OP address, then method name. Whenever a an op method is called, the value in the hash is returned if it exists. This facility is used by B::Deparse to undo some optimisations. For example:

local $B::overlay = {}; … if ($op->name eq “foo”) { $B::overlay->{$$op} = { name => bar, next => $op->next->next, }; } … $op->name # returns “bar” $op->next # returns the next op but one