1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
|
# B.pm
#
# Copyright (c) 1996, 1997, 1998 Malcolm Beattie
#
# You may distribute under the terms of either the GNU General Public
# License or the Artistic License, as specified in the README file.
#
package B;
our $VERSION = '1.00';
use XSLoader ();
require Exporter;
@ISA = qw(Exporter);
# walkoptree_slow comes from B.pm (you are there),
# walkoptree comes from B.xs
@EXPORT_OK = qw(minus_c ppname save_BEGINs
class peekop cast_I32 cstring cchar hash threadsv_names
main_root main_start main_cv svref_2object opnumber
amagic_generation
walkoptree_slow walkoptree walkoptree_exec walksymtable
parents comppadlist sv_undef compile_stats timing_info
begin_av init_av end_av regex_padav);
sub OPf_KIDS ();
use strict;
@B::SV::ISA = 'B::OBJECT';
@B::NULL::ISA = 'B::SV';
@B::PV::ISA = 'B::SV';
@B::IV::ISA = 'B::SV';
@B::NV::ISA = 'B::IV';
@B::RV::ISA = 'B::SV';
@B::PVIV::ISA = qw(B::PV B::IV);
@B::PVNV::ISA = qw(B::PV B::NV);
@B::PVMG::ISA = 'B::PVNV';
@B::PVLV::ISA = 'B::PVMG';
@B::BM::ISA = 'B::PVMG';
@B::AV::ISA = 'B::PVMG';
@B::GV::ISA = 'B::PVMG';
@B::HV::ISA = 'B::PVMG';
@B::CV::ISA = 'B::PVMG';
@B::IO::ISA = 'B::PVMG';
@B::FM::ISA = 'B::CV';
@B::OP::ISA = 'B::OBJECT';
@B::UNOP::ISA = 'B::OP';
@B::BINOP::ISA = 'B::UNOP';
@B::LOGOP::ISA = 'B::UNOP';
@B::LISTOP::ISA = 'B::BINOP';
@B::SVOP::ISA = 'B::OP';
@B::PADOP::ISA = 'B::OP';
@B::PVOP::ISA = 'B::OP';
@B::CVOP::ISA = 'B::OP';
@B::LOOP::ISA = 'B::LISTOP';
@B::PMOP::ISA = 'B::LISTOP';
@B::COP::ISA = 'B::OP';
@B::SPECIAL::ISA = 'B::OBJECT';
{
# Stop "-w" from complaining about the lack of a real B::OBJECT class
package B::OBJECT;
}
sub B::GV::SAFENAME {
my $name = (shift())->NAME;
# The regex below corresponds to the isCONTROLVAR macro
# from toke.c
$name =~ s/^([\cA-\cZ\c\\c[\c]\c?\c_\c^])/"^".
chr( utf8::unicode_to_native( 64 ^ ord($1) ))/e;
# When we say unicode_to_native we really mean ascii_to_native,
# which matters iff this is a non-ASCII platform (EBCDIC).
return $name;
}
sub B::IV::int_value {
my ($self) = @_;
return (($self->FLAGS() & SVf_IVisUV()) ? $self->UVX : $self->IV);
}
sub B::NULL::as_string() {""}
sub B::IV::as_string() {goto &B::IV::int_value}
sub B::PV::as_string() {goto &B::PV::PV}
my $debug;
my $op_count = 0;
my @parents = ();
sub debug {
my ($class, $value) = @_;
$debug = $value;
walkoptree_debug($value);
}
sub class {
my $obj = shift;
my $name = ref $obj;
$name =~ s/^.*:://;
return $name;
}
sub parents { \@parents }
# For debugging
sub peekop {
my $op = shift;
return sprintf("%s (0x%x) %s", class($op), $$op, $op->name);
}
sub walkoptree_slow {
my($op, $method, $level) = @_;
$op_count++; # just for statistics
$level ||= 0;
warn(sprintf("walkoptree: %d. %s\n", $level, peekop($op))) if $debug;
$op->$method($level);
if ($$op && ($op->flags & OPf_KIDS)) {
my $kid;
unshift(@parents, $op);
for ($kid = $op->first; $$kid; $kid = $kid->sibling) {
walkoptree_slow($kid, $method, $level + 1);
}
shift @parents;
}
}
sub compile_stats {
return "Total number of OPs processed: $op_count\n";
}
sub timing_info {
my ($sec, $min, $hr) = localtime;
my ($user, $sys) = times;
sprintf("%02d:%02d:%02d user=$user sys=$sys",
$hr, $min, $sec, $user, $sys);
}
my %symtable;
sub clearsym {
%symtable = ();
}
sub savesym {
my ($obj, $value) = @_;
# warn(sprintf("savesym: sym_%x => %s\n", $$obj, $value)); # debug
$symtable{sprintf("sym_%x", $$obj)} = $value;
}
sub objsym {
my $obj = shift;
return $symtable{sprintf("sym_%x", $$obj)};
}
sub walkoptree_exec {
my ($op, $method, $level) = @_;
$level ||= 0;
my ($sym, $ppname);
my $prefix = " " x $level;
for (; $$op; $op = $op->next) {
$sym = objsym($op);
if (defined($sym)) {
print $prefix, "goto $sym\n";
return;
}
savesym($op, sprintf("%s (0x%lx)", class($op), $$op));
$op->$method($level);
$ppname = $op->name;
if ($ppname =~
/^(or|and|mapwhile|grepwhile|entertry|range|cond_expr)$/)
{
print $prefix, uc($1), " => {\n";
walkoptree_exec($op->other, $method, $level + 1);
print $prefix, "}\n";
} elsif ($ppname eq "match" || $ppname eq "subst") {
my $pmreplstart = $op->pmreplstart;
if ($$pmreplstart) {
print $prefix, "PMREPLSTART => {\n";
walkoptree_exec($pmreplstart, $method, $level + 1);
print $prefix, "}\n";
}
} elsif ($ppname eq "substcont") {
print $prefix, "SUBSTCONT => {\n";
walkoptree_exec($op->other->pmreplstart, $method, $level + 1);
print $prefix, "}\n";
$op = $op->other;
} elsif ($ppname eq "enterloop") {
print $prefix, "REDO => {\n";
walkoptree_exec($op->redoop, $method, $level + 1);
print $prefix, "}\n", $prefix, "NEXT => {\n";
walkoptree_exec($op->nextop, $method, $level + 1);
print $prefix, "}\n", $prefix, "LAST => {\n";
walkoptree_exec($op->lastop, $method, $level + 1);
print $prefix, "}\n";
} elsif ($ppname eq "subst") {
my $replstart = $op->pmreplstart;
if ($$replstart) {
print $prefix, "SUBST => {\n";
walkoptree_exec($replstart, $method, $level + 1);
print $prefix, "}\n";
}
}
}
}
sub walksymtable {
my ($symref, $method, $recurse, $prefix) = @_;
my $sym;
my $ref;
my $fullname;
no strict 'refs';
$prefix = '' unless defined $prefix;
while (($sym, $ref) = each %$symref) {
$fullname = "*main::".$prefix.$sym;
if ($sym =~ /::$/) {
$sym = $prefix . $sym;
if ($sym ne "main::" && $sym ne "<none>::" && &$recurse($sym)) {
walksymtable(\%$fullname, $method, $recurse, $sym);
}
} else {
svref_2object(\*$fullname)->$method();
}
}
}
{
package B::Section;
my $output_fh;
my %sections;
sub new {
my ($class, $section, $symtable, $default) = @_;
$output_fh ||= FileHandle->new_tmpfile;
my $obj = bless [-1, $section, $symtable, $default], $class;
$sections{$section} = $obj;
return $obj;
}
sub get {
my ($class, $section) = @_;
return $sections{$section};
}
sub add {
my $section = shift;
while (defined($_ = shift)) {
print $output_fh "$section->[1]\t$_\n";
$section->[0]++;
}
}
sub index {
my $section = shift;
return $section->[0];
}
sub name {
my $section = shift;
return $section->[1];
}
sub symtable {
my $section = shift;
return $section->[2];
}
sub default {
my $section = shift;
return $section->[3];
}
sub output {
my ($section, $fh, $format) = @_;
my $name = $section->name;
my $sym = $section->symtable || {};
my $default = $section->default;
seek($output_fh, 0, 0);
while (<$output_fh>) {
chomp;
s/^(.*?)\t//;
if ($1 eq $name) {
s{(s\\_[0-9a-f]+)} {
exists($sym->{$1}) ? $sym->{$1} : $default;
}ge;
printf $fh $format, $_;
}
}
}
}
XSLoader::load 'B';
1;
__END__
=head1 NAME
B - The Perl Compiler
=head1 SYNOPSIS
use B;
=head1 DESCRIPTION
The C<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 F<O> module for the
user-visible part. The C<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.
=head1 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 C<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 C<B>
module as Perl objects of the appropriate class. The bulk of the C<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.
=head2 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, C<GvREFCNT> stays
as-is since its abbreviation would clash with the "superclass" method
C<REFCNT> (corresponding to the C function C<SvREFCNT>).
=head2 B::SV METHODS
=over 4
=item REFCNT
=item FLAGS
=back
=head2 B::IV METHODS
=over 4
=item IV
Returns the value of the IV, I<interpreted as
a signed integer>. This will be misleading
if C<FLAGS & SVf_IVisUV>. Perhaps you want the
C<int_value> method instead?
=item IVX
=item UVX
=item int_value
This method returns the value of the IV as an integer.
It differs from C<IV> in that it returns the correct
value regardless of whether it's stored signed or
unsigned.
=item needs64bits
=item packiv
=back
=head2 B::NV METHODS
=over 4
=item NV
=item NVX
=back
=head2 B::RV METHODS
=over 4
=item RV
=back
=head2 B::PV METHODS
=over 4
=item 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.
=item RV
Same as B::RV::RV, except that it will die() if the PV isn't
a reference.
=item 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.
=back
=head2 B::PVMG METHODS
=over 4
=item MAGIC
=item SvSTASH
=back
=head2 B::MAGIC METHODS
=over 4
=item MOREMAGIC
=item precomp
Only valid on r-magic, returns the string that generated the regexp.
=item PRIVATE
=item TYPE
=item FLAGS
=item OBJ
Will die() if called on r-magic.
=item PTR
=item REGEX
Only valid on r-magic, returns the integer value of the REGEX stored
in the MAGIC.
=back
=head2 B::PVLV METHODS
=over 4
=item TARGOFF
=item TARGLEN
=item TYPE
=item TARG
=back
=head2 B::BM METHODS
=over 4
=item USEFUL
=item PREVIOUS
=item RARE
=item TABLE
=back
=head2 B::GV METHODS
=over 4
=item is_empty
This method returns TRUE if the GP field of the GV is NULL.
=item NAME
=item 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
C<${"^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.
=item STASH
=item SV
=item IO
=item FORM
=item AV
=item HV
=item EGV
=item CV
=item CVGEN
=item LINE
=item FILE
=item FILEGV
=item GvREFCNT
=item FLAGS
=back
=head2 B::IO METHODS
=over 4
=item LINES
=item PAGE
=item PAGE_LEN
=item LINES_LEFT
=item TOP_NAME
=item TOP_GV
=item FMT_NAME
=item FMT_GV
=item BOTTOM_NAME
=item BOTTOM_GV
=item SUBPROCESS
=item IoTYPE
=item IoFLAGS
=item IsSTD
Takes one arguments ( '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_stdin() ).
=back
=head2 B::AV METHODS
=over 4
=item FILL
=item MAX
=item OFF
=item ARRAY
=item AvFLAGS
=back
=head2 B::CV METHODS
=over 4
=item STASH
=item START
=item ROOT
=item GV
=item FILE
=item DEPTH
=item PADLIST
=item OUTSIDE
=item XSUB
=item XSUBANY
For constant subroutines, returns the constant SV returned by the subroutine.
=item CvFLAGS
=item const_sv
=back
=head2 B::HV METHODS
=over 4
=item FILL
=item MAX
=item KEYS
=item RITER
=item NAME
=item PMROOT
=item ARRAY
=back
=head2 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_).
=head2 B::OP METHODS
=over 4
=item next
=item sibling
=item name
This returns the op name as a string (e.g. "add", "rv2av").
=item ppaddr
This returns the function name as a string (e.g. "PL_ppaddr[OP_ADD]",
"PL_ppaddr[OP_RV2AV]").
=item desc
This returns the op description from the global C PL_op_desc array
(e.g. "addition" "array deref").
=item targ
=item type
=item seq
=item flags
=item private
=back
=head2 B::UNOP METHOD
=over 4
=item first
=back
=head2 B::BINOP METHOD
=over 4
=item last
=back
=head2 B::LOGOP METHOD
=over 4
=item other
=back
=head2 B::LISTOP METHOD
=over 4
=item children
=back
=head2 B::PMOP METHODS
=over 4
=item pmreplroot
=item pmreplstart
=item pmnext
=item pmregexp
=item pmflags
=item pmdynflags
=item pmpermflags
=item precomp
=item pmoffet
Only when perl was compiled with ithreads.
=back
=head2 B::SVOP METHOD
=over 4
=item sv
=item gv
=back
=head2 B::PADOP METHOD
=over 4
=item padix
=back
=head2 B::PVOP METHOD
=over 4
=item pv
=back
=head2 B::LOOP METHODS
=over 4
=item redoop
=item nextop
=item lastop
=back
=head2 B::COP METHODS
=over 4
=item label
=item stash
=item file
=item cop_seq
=item arybase
=item line
=back
=head1 FUNCTIONS EXPORTED BY C<B>
The C<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.
=over 4
=item main_cv
Return the (faked) CV corresponding to the main part of the Perl
program.
=item init_av
Returns the AV object (i.e. in class B::AV) representing INIT blocks.
=item begin_av
Returns the AV object (i.e. in class B::AV) representing BEGIN blocks.
=item end_av
Returns the AV object (i.e. in class B::AV) representing END blocks.
=item 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.
=item main_start
Returns the starting op of the main part of the Perl program.
=item comppadlist
Returns the AV object (i.e. in class B::AV) of the global comppadlist.
=item regex_padav
Only when perl was compiled with ithreads.
=item sv_undef
Returns the SV object corresponding to the C variable C<sv_undef>.
=item sv_yes
Returns the SV object corresponding to the C variable C<sv_yes>.
=item sv_no
Returns the SV object corresponding to the C variable C<sv_no>.
=item amagic_generation
Returns the SV object corresponding to the C variable C<amagic_generation>.
=item 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
C<walkoptree_debug> (q.v.) has been called to turn debugging on then
the method C<walkoptree_debug> is called on each op before METHOD is
called.
=item walkoptree_debug(DEBUG)
Returns the current debugging flag for C<walkoptree>. If the optional
DEBUG argument is non-zero, it sets the debugging flag to that. See
the description of C<walkoptree> above for what the debugging flag
does.
=item 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 CGI's symbol table calling print_subs on each symbol.
# Only recurse into CGI::Util::
walksymtable(\%CGI::, 'print_subs', sub { $_[0] eq 'CGI::Util::' },
'CGI::');
print_subs() is a B::GV method you have declared.
=item 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 C<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.
=item ppname(OPNUM)
Return the PP function name (e.g. "pp_add") of op number OPNUM.
=item hash(STR)
Returns a string in the form "0x..." representing the value of the
internal hash function used by perl on string STR.
=item cast_I32(I)
Casts I to the internal I32 type used by that perl.
=item minus_c
Does the equivalent of the C<-c> command-line option. Obviously, this
is only useful in a BEGIN block or else the flag is set too late.
=item cstring(STR)
Returns a double-quote-surrounded escaped version of STR which can
be used as a string in C source code.
=item 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.
=item threadsv_names
In a perl compiled for threads, this returns a list of the special
per-thread threadsv variables.
=back
=head1 AUTHOR
Malcolm Beattie, C<mbeattie@sable.ox.ac.uk>
=cut
|