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Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :

ISBN : 978-2-7460-9712-4
EAN : 9782746097124
(Editions ENI)

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CentOS 2.1AS

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B(3pm)


B

B

NAME
SYNOPSIS
DESCRIPTION
OVERVIEW OF CLASSES
FUNCTIONS EXPORTED BY "B"
AUTHOR

NAME

B − The Perl Compiler

SYNOPSIS

        use B;

DESCRIPTION

The "B" module supplies classes which allow a Perl program to delve into its own innards. It is the module used to implement the "backends" of the Perl compiler. Usage of the compiler does not require knowledge of this module: see the O module for the user-visible part. The "B" module is of use to those who want to write new compiler backends. This documentation assumes that the reader knows a fair amount about perl’s internals including such things as SVs, OPs and the internal symbol table and syntax tree of a program.

OVERVIEW OF CLASSES

The C structures used by Perl’s internals to hold SV and OP information ( PVIV , AV , HV , ..., OP , SVOP , UNOP , ...) are modelled on a class hierarchy and the "B" module gives access to them via a true object hierarchy. Structure fields which point to other objects (whether types of SV or types of OP ) are represented by the "B" module as Perl objects of the appropriate class. The bulk of the "B" module is the methods for accessing fields of these structures. Note that all access is read-only: you cannot modify the internals by using this module.

SV-RELATED CLASSES

B::IV, B::NV, B::RV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::BM, 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". 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").

B::SV METHODS
REFCNT
FLAGS

B::IV METHODS

IV

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?

IVX

UVX

int_value

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

B::NV METHODS

NV

NVX

B::RV METHODS

RV

B::PV METHODS

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.

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 (SvCUR) is overloaded for other purposes and can’t be relied on here.

B::PVMG METHODS
MAGIC

SvSTASH

B::MAGIC METHODS
MOREMAGIC
PRIVATE
TYPE
FLAGS

OBJ

PTR

B::PVLV METHODS
TARGOFF
TARGLEN
TYPE
TARG

B::BM METHODS
USEFUL
PREVIOUS
RARE
TABLE

B::GV METHODS
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

CV

CVGEN
LINE
FILE
FILEGV

GvREFCNT
FLAGS

B::IO METHODS
LINES
PAGE
PAGE_LEN
LINES_LEFT
TOP_NAME
TOP_GV
FMT_NAME
FMT_GV
BOTTOM_NAME
BOTTOM_GV
SUBPROCESS

IoTYPE
IoFLAGS

B::AV METHODS
FILL

MAX

OFF

ARRAY
AvFLAGS

B::CV METHODS
STASH
START
ROOT

GV

FILE
DEPTH
PADLIST
OUTSIDE
XSUB
XSUBANY

CvFLAGS

B::HV METHODS
FILL

MAX

KEYS
RITER
NAME
PMROOT
ARRAY

OP-RELATED CLASSES

B::OP, B::UNOP, B::BINOP, B::LOGOP, B::LISTOP, B::PMOP, B::SVOP, B::PADOP, B::PVOP, B::CVOP, B::LOOP, B::COP. These classes correspond in the obvious way to the underlying C structures of similar names. The inheritance hierarchy mimics the underlying C "inheritance". Access methods correspond to the underlying C structre field names, with the leading "class indication" prefix removed (op_).

B::OP METHODS
next
sibling
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

seq

flags
private

B::UNOP METHOD
first

B::BINOP METHOD
last

B::LOGOP METHOD
other

B::LISTOP METHOD
children

B::PMOP METHODS
pmreplroot
pmreplstart
pmnext
pmregexp
pmflags
pmpermflags
precomp

B::SVOP METHOD

sv

gv

B::PADOP METHOD
padix

B::PVOP METHOD

pv

B::LOOP METHODS
redoop
nextop
lastop

B::COP METHODS
label
stash
file
cop_seq
arybase
line

FUNCTIONS EXPORTED BY "B"

The "B" module exports a variety of functions: some are simple utility functions, others provide a Perl program with a way to get an initial "handle" on an internal object.
main_cv

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

init_av

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

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.

comppadlist

Returns the AV object (i.e. in class B::AV) of the global comppadlist.

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".

amagic_generation

Returns the SV object corresponding to the C variable "amagic_generation".

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" (q.v.) 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.

walksymtable( SYMREF , METHOD , RECURSE )

Walk the symbol table starting at SYMREF and call METHOD on each symbol visited. When the walk reached package symbols "Foo::" it invokes RECURSE and only recurses into the package if that sub returns true.

svref_2object( SV )

Takes any Perl variable and turns it 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 a internal perl data structure which can then be followed with the other access methods.

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.

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

In a perl compiled for threads, this returns a list of the special per-thread threadsv variables.

AUTHOR

Malcolm Beattie, "mbeattie@sable.ox.ac.uk"



B(3pm)