3 # Copyright (c) 1996, 1997, 1998 Malcolm Beattie
5 # You may distribute under the terms of either the GNU General Public
6 # License or the Artistic License, as specified in the README file.
12 @B::ISA = qw(Exporter);
14 # walkoptree_slow comes from B.pm (you are there),
15 # walkoptree comes from B.xs
21 # Our BOOT code needs $VERSION set, and will append to @EXPORT_OK.
22 # Want our constants loaded before the compiler meets OPf_KIDS below, as
23 # the combination of having the constant stay a Proxy Constant Subroutine
24 # and its value being inlined saves a little over .5K
30 push @B::EXPORT_OK, (qw(minus_c ppname save_BEGINs
31 class peekop cast_I32 cstring cchar hash threadsv_names
32 main_root main_start main_cv svref_2object opnumber
33 sub_generation amagic_generation perlstring
34 walkoptree_slow walkoptree walkoptree_exec walksymtable
35 parents comppadlist sv_undef compile_stats timing_info
36 begin_av init_av check_av end_av regex_padav dowarn
37 defstash curstash warnhook diehook inc_gv @optype
38 @specialsv_name unitcheck_av safename));
40 @B::SV::ISA = 'B::OBJECT';
41 @B::NULL::ISA = 'B::SV';
42 @B::PV::ISA = 'B::SV';
43 @B::IV::ISA = 'B::SV';
44 @B::NV::ISA = 'B::SV';
45 # RV is eliminated with 5.11.0, but effectively is a specialisation of IV now.
46 @B::RV::ISA = $] >= 5.011 ? 'B::IV' : 'B::SV';
47 @B::PVIV::ISA = qw(B::PV B::IV);
48 @B::PVNV::ISA = qw(B::PVIV B::NV);
49 @B::PVMG::ISA = 'B::PVNV';
50 @B::REGEXP::ISA = 'B::PVMG' if $] >= 5.011;
51 @B::INVLIST::ISA = 'B::PV' if $] >= 5.019;
52 @B::PVLV::ISA = 'B::GV';
53 @B::BM::ISA = 'B::GV';
54 @B::AV::ISA = 'B::PVMG';
55 @B::GV::ISA = 'B::PVMG';
56 @B::HV::ISA = 'B::PVMG';
57 @B::CV::ISA = 'B::PVMG';
58 @B::IO::ISA = 'B::PVMG';
59 @B::FM::ISA = 'B::CV';
61 @B::OP::ISA = 'B::OBJECT';
62 @B::UNOP::ISA = 'B::OP';
63 @B::UNOP_AUX::ISA = 'B::UNOP';
64 @B::BINOP::ISA = 'B::UNOP';
65 @B::LOGOP::ISA = 'B::UNOP';
66 @B::LISTOP::ISA = 'B::BINOP';
67 @B::SVOP::ISA = 'B::OP';
68 @B::PADOP::ISA = 'B::OP';
69 @B::PVOP::ISA = 'B::OP';
70 @B::LOOP::ISA = 'B::LISTOP';
71 @B::PMOP::ISA = 'B::LISTOP';
72 @B::COP::ISA = 'B::OP';
73 @B::METHOP::ISA = 'B::OP';
75 @B::SPECIAL::ISA = 'B::OBJECT';
77 @B::optype = qw(OP UNOP BINOP LOGOP LISTOP PMOP SVOP PADOP PVOP LOOP COP
79 # bytecode.pl contained the following comment:
80 # Nullsv *must* come first in the following so that the condition
81 # ($$sv == 0) can continue to be used to test (sv == Nullsv).
82 @B::specialsv_name = qw(Nullsv &PL_sv_undef &PL_sv_yes &PL_sv_no
83 (SV*)pWARN_ALL (SV*)pWARN_NONE (SV*)pWARN_STD);
86 # Stop "-w" from complaining about the lack of a real B::OBJECT class
91 safename(shift()->NAME);
97 # The regex below corresponds to the isCONTROLVAR macro
101 or $name =~ s/^([\cA-\cZ\c\\c[\c]\c_\c^])/
102 "^" . chr( utf8::unicode_to_native( 64 ^ ord($1) ))/e;
104 # When we say unicode_to_native we really mean ascii_to_native,
105 # which matters iff this is a non-ASCII platform (EBCDIC). '\c?' would
106 # not have to be special cased, except for non-ASCII.
111 sub B::IV::int_value {
113 return (($self->FLAGS() & SVf_IVisUV()) ? $self->UVX : $self->IV);
116 sub B::NULL::as_string() {""}
117 *B::IV::as_string = \*B::IV::int_value;
118 *B::PV::as_string = \*B::PV::PV;
120 # The input typemap checking makes no distinction between different SV types,
121 # so the XS body will generate the same C code, despite the different XS
122 # "types". So there is no change in behaviour from doing "newXS" like this,
123 # compared with the old approach of having a (near) duplicate XS body.
124 # We should fix the typemap checking.
125 *B::IV::RV = \*B::PV::RV if $] > 5.012;
132 my ($class, $value) = @_;
134 walkoptree_debug($value);
144 sub parents { \@parents }
149 return sprintf("%s (0x%x) %s", class($op), $$op, $op->name);
152 sub walkoptree_slow {
153 my($op, $method, $level) = @_;
154 $op_count++; # just for statistics
156 warn(sprintf("walkoptree: %d. %s\n", $level, peekop($op))) if $debug;
157 $op->$method($level) if $op->can($method);
158 if ($$op && ($op->flags & OPf_KIDS)) {
160 unshift(@parents, $op);
161 for ($kid = $op->first; $$kid; $kid = $kid->sibling) {
162 walkoptree_slow($kid, $method, $level + 1);
166 if (class($op) eq 'PMOP'
167 && ref($op->pmreplroot)
168 && ${$op->pmreplroot}
169 && $op->pmreplroot->isa( 'B::OP' ))
171 unshift(@parents, $op);
172 walkoptree_slow($op->pmreplroot, $method, $level + 1);
178 return "Total number of OPs processed: $op_count\n";
182 my ($sec, $min, $hr) = localtime;
183 my ($user, $sys) = times;
184 sprintf("%02d:%02d:%02d user=$user sys=$sys",
185 $hr, $min, $sec, $user, $sys);
195 my ($obj, $value) = @_;
196 # warn(sprintf("savesym: sym_%x => %s\n", $$obj, $value)); # debug
197 $symtable{sprintf("sym_%x", $$obj)} = $value;
202 return $symtable{sprintf("sym_%x", $$obj)};
205 sub walkoptree_exec {
206 my ($op, $method, $level) = @_;
209 my $prefix = " " x $level;
210 for (; $$op; $op = $op->next) {
213 print $prefix, "goto $sym\n";
216 savesym($op, sprintf("%s (0x%lx)", class($op), $$op));
217 $op->$method($level);
220 /^(d?or(assign)?|and(assign)?|mapwhile|grepwhile|entertry|range|cond_expr)$/)
222 print $prefix, uc($1), " => {\n";
223 walkoptree_exec($op->other, $method, $level + 1);
224 print $prefix, "}\n";
225 } elsif ($ppname eq "match" || $ppname eq "subst") {
226 my $pmreplstart = $op->pmreplstart;
228 print $prefix, "PMREPLSTART => {\n";
229 walkoptree_exec($pmreplstart, $method, $level + 1);
230 print $prefix, "}\n";
232 } elsif ($ppname eq "substcont") {
233 print $prefix, "SUBSTCONT => {\n";
234 walkoptree_exec($op->other->pmreplstart, $method, $level + 1);
235 print $prefix, "}\n";
237 } elsif ($ppname eq "enterloop") {
238 print $prefix, "REDO => {\n";
239 walkoptree_exec($op->redoop, $method, $level + 1);
240 print $prefix, "}\n", $prefix, "NEXT => {\n";
241 walkoptree_exec($op->nextop, $method, $level + 1);
242 print $prefix, "}\n", $prefix, "LAST => {\n";
243 walkoptree_exec($op->lastop, $method, $level + 1);
244 print $prefix, "}\n";
245 } elsif ($ppname eq "subst") {
246 my $replstart = $op->pmreplstart;
248 print $prefix, "SUBST => {\n";
249 walkoptree_exec($replstart, $method, $level + 1);
250 print $prefix, "}\n";
257 my ($symref, $method, $recurse, $prefix) = @_;
262 $prefix = '' unless defined $prefix;
263 foreach my $sym ( sort keys %$symref ) {
264 $ref= $symref->{$sym};
265 $fullname = "*main::".$prefix.$sym;
267 $sym = $prefix . $sym;
268 if (svref_2object(\*$sym)->NAME ne "main::" && $sym ne "<none>::" && &$recurse($sym)) {
269 walksymtable(\%$fullname, $method, $recurse, $sym);
272 svref_2object(\*$fullname)->$method();
283 my ($class, $section, $symtable, $default) = @_;
284 $output_fh ||= FileHandle->new_tmpfile;
285 my $obj = bless [-1, $section, $symtable, $default], $class;
286 $sections{$section} = $obj;
291 my ($class, $section) = @_;
292 return $sections{$section};
297 while (defined($_ = shift)) {
298 print $output_fh "$section->[1]\t$_\n";
305 return $section->[0];
310 return $section->[1];
315 return $section->[2];
320 return $section->[3];
324 my ($section, $fh, $format) = @_;
325 my $name = $section->name;
326 my $sym = $section->symtable || {};
327 my $default = $section->default;
329 seek($output_fh, 0, 0);
330 while (<$output_fh>) {
335 exists($sym->{$1}) ? $sym->{$1} : $default;
337 printf $fh $format, $_;
349 B - The Perl Compiler Backend
357 The C<B> module supplies classes which allow a Perl program to delve
358 into its own innards. It is the module used to implement the
359 "backends" of the Perl compiler. Usage of the compiler does not
360 require knowledge of this module: see the F<O> module for the
361 user-visible part. The C<B> module is of use to those who want to
362 write new compiler backends. This documentation assumes that the
363 reader knows a fair amount about perl's internals including such
364 things as SVs, OPs and the internal symbol table and syntax tree
369 The C<B> module contains a set of utility functions for querying the
370 current state of the Perl interpreter; typically these functions
371 return objects from the B::SV and B::OP classes, or their derived
372 classes. These classes in turn define methods for querying the
373 resulting objects about their own internal state.
375 =head1 Utility Functions
377 The C<B> module exports a variety of functions: some are simple
378 utility functions, others provide a Perl program with a way to
379 get an initial "handle" on an internal object.
381 =head2 Functions Returning C<B::SV>, C<B::AV>, C<B::HV>, and C<B::CV> objects
383 For descriptions of the class hierarchy of these objects and the
384 methods that can be called on them, see below, L<"OVERVIEW OF
385 CLASSES"> and L<"SV-RELATED CLASSES">.
391 Returns the SV object corresponding to the C variable C<sv_undef>.
395 Returns the SV object corresponding to the C variable C<sv_yes>.
399 Returns the SV object corresponding to the C variable C<sv_no>.
401 =item svref_2object(SVREF)
403 Takes a reference to any Perl value, and turns the referred-to value
404 into an object in the appropriate B::OP-derived or B::SV-derived
405 class. Apart from functions such as C<main_root>, this is the primary
406 way to get an initial "handle" on an internal perl data structure
407 which can then be followed with the other access methods.
409 The returned object will only be valid as long as the underlying OPs
410 and SVs continue to exist. Do not attempt to use the object after the
411 underlying structures are freed.
413 =item amagic_generation
415 Returns the SV object corresponding to the C variable C<amagic_generation>.
416 As of Perl 5.18, this is just an alias to C<PL_na>, so its value is
421 Returns the AV object (i.e. in class B::AV) representing INIT blocks.
425 Returns the AV object (i.e. in class B::AV) representing CHECK blocks.
429 Returns the AV object (i.e. in class B::AV) representing UNITCHECK blocks.
433 Returns the AV object (i.e. in class B::AV) representing BEGIN blocks.
437 Returns the AV object (i.e. in class B::AV) representing END blocks.
441 Returns the PADLIST object (i.e. in class B::PADLIST) of the global
442 comppadlist. In Perl 5.16 and earlier it returns an AV object (class
447 Only when perl was compiled with ithreads.
451 Return the (faked) CV corresponding to the main part of the Perl
456 =head2 Functions for Examining the Symbol Table
460 =item walksymtable(SYMREF, METHOD, RECURSE, PREFIX)
462 Walk the symbol table starting at SYMREF and call METHOD on each
463 symbol (a B::GV object) visited. When the walk reaches package
464 symbols (such as "Foo::") it invokes RECURSE, passing in the symbol
465 name, and only recurses into the package if that sub returns true.
467 PREFIX is the name of the SYMREF you're walking.
471 # Walk CGI's symbol table calling print_subs on each symbol.
472 # Recurse only into CGI::Util::
473 walksymtable(\%CGI::, 'print_subs',
474 sub { $_[0] eq 'CGI::Util::' }, 'CGI::');
476 print_subs() is a B::GV method you have declared. Also see L<"B::GV
481 =head2 Functions Returning C<B::OP> objects or for walking op trees
483 For descriptions of the class hierarchy of these objects and the
484 methods that can be called on them, see below, L<"OVERVIEW OF
485 CLASSES"> and L<"OP-RELATED CLASSES">.
491 Returns the root op (i.e. an object in the appropriate B::OP-derived
492 class) of the main part of the Perl program.
496 Returns the starting op of the main part of the Perl program.
498 =item walkoptree(OP, METHOD)
500 Does a tree-walk of the syntax tree based at OP and calls METHOD on
501 each op it visits. Each node is visited before its children. If
502 C<walkoptree_debug> (see below) has been called to turn debugging on then
503 the method C<walkoptree_debug> is called on each op before METHOD is
506 =item walkoptree_debug(DEBUG)
508 Returns the current debugging flag for C<walkoptree>. If the optional
509 DEBUG argument is non-zero, it sets the debugging flag to that. See
510 the description of C<walkoptree> above for what the debugging flag
515 =head2 Miscellaneous Utility Functions
521 Return the PP function name (e.g. "pp_add") of op number OPNUM.
525 Returns a string in the form "0x..." representing the value of the
526 internal hash function used by perl on string STR.
530 Casts I to the internal I32 type used by that perl.
534 Does the equivalent of the C<-c> command-line option. Obviously, this
535 is only useful in a BEGIN block or else the flag is set too late.
539 Returns a double-quote-surrounded escaped version of STR which can
540 be used as a string in C source code.
542 =item perlstring(STR)
544 Returns a double-quote-surrounded escaped version of STR which can
545 be used as a string in Perl source code.
549 This function returns the string with the first character modified if it
550 is a control character. It converts it to ^X format first, so that "\cG"
551 becomes "^G". This is used internally by L<B::GV::SAFENAME|/SAFENAME>, but
552 you can call it directly.
556 Returns the class of an object without the part of the classname
557 preceding the first C<"::">. This is used to turn C<"B::UNOP"> into
558 C<"UNOP"> for example.
562 This used to provide support for the old 5.005 threading module. It now
567 =head2 Exported utility variables
573 my $op_type = $optype[$op_type_num];
575 A simple mapping of the op type number to its type (like 'COP' or 'BINOP').
577 =item @specialsv_name
579 my $sv_name = $specialsv_name[$sv_index];
581 Certain SV types are considered 'special'. They're represented by
582 B::SPECIAL and are referred to by a number from the specialsv_list.
583 This array maps that number back to the name of the SV (like 'Nullsv'
589 =head1 OVERVIEW OF CLASSES
591 The C structures used by Perl's internals to hold SV and OP
592 information (PVIV, AV, HV, ..., OP, SVOP, UNOP, ...) are modelled on a
593 class hierarchy and the C<B> module gives access to them via a true
594 object hierarchy. Structure fields which point to other objects
595 (whether types of SV or types of OP) are represented by the C<B>
596 module as Perl objects of the appropriate class.
598 The bulk of the C<B> module is the methods for accessing fields of
601 Note that all access is read-only. You cannot modify the internals by
602 using this module. Also, note that the B::OP and B::SV objects created
603 by this module are only valid for as long as the underlying objects
604 exist; their creation doesn't increase the reference counts of the
605 underlying objects. Trying to access the fields of a freed object will
606 give incomprehensible results, or worse.
608 =head2 SV-RELATED CLASSES
610 B::IV, B::NV, B::RV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::BM (5.9.5 and
611 earlier), B::PVLV, B::AV, B::HV, B::CV, B::GV, B::FM, B::IO. These classes
612 correspond in the obvious way to the underlying C structures of similar names.
613 The inheritance hierarchy mimics the underlying C "inheritance". For the
614 5.10.x branch, (I<ie> 5.10.0, 5.10.1 I<etc>) this is:
618 +------------+------------+------------+
620 B::PV B::IV B::NV B::RV
632 +-----+-----+-----+-----+
634 B::AV B::GV B::HV B::CV B::IO
639 For 5.9.0 and earlier, PVLV is a direct subclass of PVMG, and BM is still
640 present as a distinct type, so the base of this diagram is
647 +------+-----+-----+-----+-----+-----+
649 B::PVLV B::BM B::AV B::GV B::HV B::CV B::IO
654 For 5.11.0 and later, B::RV is abolished, and IVs can be used to store
655 references, and a new type B::REGEXP is introduced, giving this structure:
659 +------------+------------+
673 +-------+-------+---+---+-------+-------+
675 B::AV B::GV B::HV B::CV B::IO B::REGEXP
681 Access methods correspond to the underlying C macros for field access,
682 usually with the leading "class indication" prefix removed (Sv, Av,
683 Hv, ...). The leading prefix is only left in cases where its removal
684 would cause a clash in method name. For example, C<GvREFCNT> stays
685 as-is since its abbreviation would clash with the "superclass" method
686 C<REFCNT> (corresponding to the C function C<SvREFCNT>).
698 Returns a reference to the regular scalar corresponding to this
699 B::SV object. In other words, this method is the inverse operation
700 to the svref_2object() subroutine. This scalar and other data it points
701 at should be considered read-only: modifying them is neither safe nor
702 guaranteed to have a sensible effect.
712 Returns the value of the IV, I<interpreted as
713 a signed integer>. This will be misleading
714 if C<FLAGS & SVf_IVisUV>. Perhaps you want the
715 C<int_value> method instead?
723 This method returns the value of the IV as an integer.
724 It differs from C<IV> in that it returns the correct
725 value regardless of whether it's stored signed or
742 =item COP_SEQ_RANGE_LOW
744 =item COP_SEQ_RANGE_HIGH
746 These last two are only valid for pad name SVs. They only existed in the
747 B::NV class before Perl 5.22. In 5.22 they were moved to the B::PADNAME
766 This method is the one you usually want. It constructs a
767 string using the length and offset information in the struct:
768 for ordinary scalars it will return the string that you'd see
769 from Perl, even if it contains null characters.
773 Same as B::RV::RV, except that it will die() if the PV isn't
778 This method is less often useful. It assumes that the string
779 stored in the struct is null-terminated, and disregards the
782 It is the appropriate method to use if you need to get the name
783 of a lexical variable from a padname array. Lexical variable names
784 are always stored with a null terminator, and the length field
785 (CUR) is overloaded for other purposes and can't be relied on here.
789 This method returns the internal length field, which consists of the number
790 of internal bytes, not necessarily the number of logical characters.
794 This method returns the number of bytes allocated (via malloc) for storing
795 the string. This is 0 if the scalar does not "own" the string.
799 =head2 B::PVMG Methods
809 =head2 B::MAGIC Methods
817 Only valid on r-magic, returns the string that generated the regexp.
827 Will die() if called on r-magic.
833 Only valid on r-magic, returns the integer value of the REGEX stored
838 =head2 B::PVLV Methods
866 =head2 B::REGEXP Methods
878 The last two were added in Perl 5.22.
888 This method returns TRUE if the GP field of the GV is NULL.
894 This method returns the name of the glob, but if the first
895 character of the name is a control character, then it converts
896 it to ^X first, so that *^G would return "^G" rather than "\cG".
898 It's useful if you want to print out the name of a variable.
899 If you restrict yourself to globs which exist at compile-time
900 then the result ought to be unambiguous, because code like
901 C<${"^G"} = 1> is compiled as two ops - a constant string and
902 a dereference (rv2gv) - so that the glob is created at runtime.
904 If you're working with globs at runtime, and need to disambiguate
905 *^G from *{"^G"}, then you should use the raw NAME method.
937 This last one is present only in perl 5.22.0 and higher.
943 B::IO objects derive from IO objects and you will get more information from
944 the IO object itself.
948 $gvio = B::svref_2object(\*main::stdin)->IO;
949 $IO = $gvio->object_2svref();
978 A character symbolizing the type of IO Handle.
991 \0 closed internal handle
997 Takes one argument ( 'stdin' | 'stdout' | 'stderr' ) and returns true
998 if the IoIFP of the object is equal to the handle whose name was
999 passed as argument; i.e., $io->IsSTD('stderr') is true if
1000 IoIFP($io) == PerlIO_stderr().
1004 =head2 B::AV Methods
1016 Like C<ARRAY>, but takes an index as an argument to get only one element,
1017 rather than a list of all of them.
1021 This method is deprecated if running under Perl 5.8, and is no longer present
1022 if running under Perl 5.9
1026 This method returns the AV specific
1027 flags. In Perl 5.9 these are now stored
1028 in with the main SV flags, so this method is no longer present.
1032 =head2 B::CV Methods
1050 Returns a B::PADLIST object under Perl 5.18 or higher, or a B::AV in
1061 For constant subroutines, returns the constant SV returned by the subroutine.
1069 Returns the name of a lexical sub, otherwise C<undef>.
1073 =head2 B::HV Methods
1091 This method is not present if running under Perl 5.9, as the PMROOT
1092 information is no longer stored directly in the hash.
1096 =head2 OP-RELATED CLASSES
1098 C<B::OP>, C<B::UNOP>, C<B::UNOP_AUX>, C<B::BINOP>, C<B::LOGOP>,
1099 C<B::LISTOP>, C<B::PMOP>, C<B::SVOP>, C<B::PADOP>, C<B::PVOP>, C<B::LOOP>,
1100 C<B::COP>, C<B::METHOP>.
1102 These classes correspond in the obvious way to the underlying C
1103 structures of similar names. The inheritance hierarchy mimics the
1104 underlying C "inheritance":
1108 +----------+---------+--------+-------+---------+
1110 B::UNOP B::SVOP B::PADOP B::COP B::PVOP B::METHOP
1114 B::BINOP B::LOGOP B::UNOP_AUX
1123 Access methods correspond to the underlying C structure field names,
1124 with the leading "class indication" prefix (C<"op_">) removed.
1126 =head2 B::OP Methods
1128 These methods get the values of similarly named fields within the OP
1129 data structure. See top of C<op.h> for more info.
1139 Returns the OP's parent. If it has no parent, or if your perl wasn't built
1140 with C<-DPERL_OP_PARENT>, returns NULL.
1142 Note that the global variable C<$B::OP::does_parent> is undefined on older
1143 perls that don't support the C<parent> method, is defined but false on
1144 perls that support the method but were built without C<-DPERL_OP_PARENT>,
1145 and is true otherwise.
1149 This returns the op name as a string (e.g. "add", "rv2av").
1153 This returns the function name as a string (e.g. "PL_ppaddr[OP_ADD]",
1154 "PL_ppaddr[OP_RV2AV]").
1158 This returns the op description from the global C PL_op_desc array
1159 (e.g. "addition" "array deref").
1175 =head2 B::UNOP Method
1183 =head2 B::UNOP_AUX Methods (since 5.22)
1189 This returns a list of the elements of the op's aux data structure,
1190 or a null list if there is no aux. What will be returned depends on the
1191 object's type, but will typically be a collection of C<B::IV>, C<B::GV>,
1192 etc. objects. C<cv> is the C<B::CV> object representing the sub that the
1193 op is contained within.
1197 This returns a textual representation of the object (likely to b useful
1198 for deparsing and debugging), or an empty string if the op type doesn't
1199 support this. C<cv> is the C<B::CV> object representing the sub that the
1200 op is contained within.
1204 =head2 B::BINOP Method
1212 =head2 B::LOGOP Method
1220 =head2 B::LISTOP Method
1228 =head2 B::PMOP Methods
1238 Only up to Perl 5.9.4
1250 Only when perl was compiled with ithreads.
1258 Added in perl 5.22, this method returns the B::REGEXP associated with the
1259 op. While PMOPs do not actually have C<pmregexp> fields under threaded
1260 builds, this method returns the regexp under threads nonetheless, for
1265 =head2 B::SVOP Methods
1275 =head2 B::PADOP Method
1283 =head2 B::PVOP Method
1291 =head2 B::LOOP Methods
1303 =head2 B::COP Methods
1305 The C<B::COP> class is used for "nextstate" and "dbstate" ops. As of Perl
1306 5.22, it is also used for "null" ops that started out as COPs.
1316 =item stashoff (threaded only)
1336 =head2 B::METHOP Methods (Since Perl 5.22)
1346 =head2 PAD-RELATED CLASSES
1348 Perl 5.18 introduced a new class, B::PADLIST, returned by B::CV's
1351 Perl 5.22 introduced the B::PADNAMELIST and B::PADNAME classes.
1353 =head2 B::PADLIST Methods
1361 A list of pads. The first one contains the names.
1363 The first one is a B::PADNAMELIST under Perl 5.22, and a B::AV under
1364 earlier versions. The rest are currently B::AV objects, but that could
1365 change in future versions.
1369 Like C<ARRAY>, but takes an index as an argument to get only one element,
1370 rather than a list of all of them.
1374 This method, introduced in 5.22, returns the B::PADNAMELIST. It is
1375 equivalent to C<ARRAYelt> with a 0 argument.
1381 This method, introduced in 5.22, returns an ID shared by clones of the same
1386 This method, also added in 5.22, returns the ID of the outer padlist.
1390 =head2 B::PADNAMELIST Methods
1400 These two methods return the pad names, using B::SPECIAL objects for null
1401 pointers and B::PADNAME objects otherwise.
1407 =head2 B::PADNAME Methods
1421 For backward-compatibility, if the PADNAMEt_OUTER flag is set, the FLAGS
1422 method adds the SVf_FAKE flag, too.
1426 A B::HV object representing the stash for a typed lexical.
1430 A backward-compatibility alias for TYPE.
1434 A B::HV object representing the stash for 'our' variables.
1438 The prototype CV for a 'my' sub.
1440 =item COP_SEQ_RANGE_LOW
1442 =item COP_SEQ_RANGE_HIGH
1444 Sequence numbers representing the scope within which a lexical is visible.
1445 Meaningless if PADNAMEt_OUTER is set.
1447 =item PARENT_PAD_INDEX
1449 Only meaningful if PADNAMEt_OUTER is set.
1451 =item PARENT_FAKELEX_FLAGS
1453 Only meaningful if PADNAMEt_OUTER is set.
1459 Although the optree is read-only, there is an overlay facility that allows
1460 you to override what values the various B::*OP methods return for a
1461 particular op. C<$B::overlay> should be set to reference a two-deep hash:
1462 indexed by OP address, then method name. Whenever a an op method is
1463 called, the value in the hash is returned if it exists. This facility is
1464 used by B::Deparse to "undo" some optimisations. For example:
1467 local $B::overlay = {};
1469 if ($op->name eq "foo") {
1470 $B::overlay->{$$op} = {
1472 next => $op->next->next,
1476 $op->name # returns "bar"
1477 $op->next # returns the next op but one
1482 Malcolm Beattie, C<mbeattie@sable.ox.ac.uk>