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.
10 our $VERSION = '1.01';
16 # walkoptree_slow comes from B.pm (you are there),
17 # walkoptree comes from B.xs
18 @EXPORT_OK = qw(minus_c ppname save_BEGINs
19 class peekop cast_I32 cstring cchar hash threadsv_names
20 main_root main_start main_cv svref_2object opnumber
21 amagic_generation perlstring
22 walkoptree_slow walkoptree walkoptree_exec walksymtable
23 parents comppadlist sv_undef compile_stats timing_info
24 begin_av init_av end_av regex_padav);
28 @B::SV::ISA = 'B::OBJECT';
29 @B::NULL::ISA = 'B::SV';
30 @B::PV::ISA = 'B::SV';
31 @B::IV::ISA = 'B::SV';
32 @B::NV::ISA = 'B::IV';
33 @B::RV::ISA = 'B::SV';
34 @B::PVIV::ISA = qw(B::PV B::IV);
35 @B::PVNV::ISA = qw(B::PV B::NV);
36 @B::PVMG::ISA = 'B::PVNV';
37 @B::PVLV::ISA = 'B::PVMG';
38 @B::BM::ISA = 'B::PVMG';
39 @B::AV::ISA = 'B::PVMG';
40 @B::GV::ISA = 'B::PVMG';
41 @B::HV::ISA = 'B::PVMG';
42 @B::CV::ISA = 'B::PVMG';
43 @B::IO::ISA = 'B::PVMG';
44 @B::FM::ISA = 'B::CV';
46 @B::OP::ISA = 'B::OBJECT';
47 @B::UNOP::ISA = 'B::OP';
48 @B::BINOP::ISA = 'B::UNOP';
49 @B::LOGOP::ISA = 'B::UNOP';
50 @B::LISTOP::ISA = 'B::BINOP';
51 @B::SVOP::ISA = 'B::OP';
52 @B::PADOP::ISA = 'B::OP';
53 @B::PVOP::ISA = 'B::OP';
54 @B::CVOP::ISA = 'B::OP';
55 @B::LOOP::ISA = 'B::LISTOP';
56 @B::PMOP::ISA = 'B::LISTOP';
57 @B::COP::ISA = 'B::OP';
59 @B::SPECIAL::ISA = 'B::OBJECT';
62 # Stop "-w" from complaining about the lack of a real B::OBJECT class
67 my $name = (shift())->NAME;
69 # The regex below corresponds to the isCONTROLVAR macro
72 $name =~ s/^([\cA-\cZ\c\\c[\c]\c?\c_\c^])/"^".
73 chr( utf8::unicode_to_native( 64 ^ ord($1) ))/e;
75 # When we say unicode_to_native we really mean ascii_to_native,
76 # which matters iff this is a non-ASCII platform (EBCDIC).
81 sub B::IV::int_value {
83 return (($self->FLAGS() & SVf_IVisUV()) ? $self->UVX : $self->IV);
86 sub B::NULL::as_string() {""}
87 sub B::IV::as_string() {goto &B::IV::int_value}
88 sub B::PV::as_string() {goto &B::PV::PV}
95 my ($class, $value) = @_;
97 walkoptree_debug($value);
107 sub parents { \@parents }
112 return sprintf("%s (0x%x) %s", class($op), $$op, $op->name);
115 sub walkoptree_slow {
116 my($op, $method, $level) = @_;
117 $op_count++; # just for statistics
119 warn(sprintf("walkoptree: %d. %s\n", $level, peekop($op))) if $debug;
120 $op->$method($level);
121 if ($$op && ($op->flags & OPf_KIDS)) {
123 unshift(@parents, $op);
124 for ($kid = $op->first; $$kid; $kid = $kid->sibling) {
125 walkoptree_slow($kid, $method, $level + 1);
129 if (class($op) eq 'PMOP' && $op->pmreplroot && ${$op->pmreplroot}) {
130 unshift(@parents, $op);
131 walkoptree_slow($op->pmreplroot, $method, $level + 1);
137 return "Total number of OPs processed: $op_count\n";
141 my ($sec, $min, $hr) = localtime;
142 my ($user, $sys) = times;
143 sprintf("%02d:%02d:%02d user=$user sys=$sys",
144 $hr, $min, $sec, $user, $sys);
154 my ($obj, $value) = @_;
155 # warn(sprintf("savesym: sym_%x => %s\n", $$obj, $value)); # debug
156 $symtable{sprintf("sym_%x", $$obj)} = $value;
161 return $symtable{sprintf("sym_%x", $$obj)};
164 sub walkoptree_exec {
165 my ($op, $method, $level) = @_;
168 my $prefix = " " x $level;
169 for (; $$op; $op = $op->next) {
172 print $prefix, "goto $sym\n";
175 savesym($op, sprintf("%s (0x%lx)", class($op), $$op));
176 $op->$method($level);
179 /^(or|and|mapwhile|grepwhile|entertry|range|cond_expr)$/)
181 print $prefix, uc($1), " => {\n";
182 walkoptree_exec($op->other, $method, $level + 1);
183 print $prefix, "}\n";
184 } elsif ($ppname eq "match" || $ppname eq "subst") {
185 my $pmreplstart = $op->pmreplstart;
187 print $prefix, "PMREPLSTART => {\n";
188 walkoptree_exec($pmreplstart, $method, $level + 1);
189 print $prefix, "}\n";
191 } elsif ($ppname eq "substcont") {
192 print $prefix, "SUBSTCONT => {\n";
193 walkoptree_exec($op->other->pmreplstart, $method, $level + 1);
194 print $prefix, "}\n";
196 } elsif ($ppname eq "enterloop") {
197 print $prefix, "REDO => {\n";
198 walkoptree_exec($op->redoop, $method, $level + 1);
199 print $prefix, "}\n", $prefix, "NEXT => {\n";
200 walkoptree_exec($op->nextop, $method, $level + 1);
201 print $prefix, "}\n", $prefix, "LAST => {\n";
202 walkoptree_exec($op->lastop, $method, $level + 1);
203 print $prefix, "}\n";
204 } elsif ($ppname eq "subst") {
205 my $replstart = $op->pmreplstart;
207 print $prefix, "SUBST => {\n";
208 walkoptree_exec($replstart, $method, $level + 1);
209 print $prefix, "}\n";
216 my ($symref, $method, $recurse, $prefix) = @_;
221 $prefix = '' unless defined $prefix;
222 while (($sym, $ref) = each %$symref) {
223 $fullname = "*main::".$prefix.$sym;
225 $sym = $prefix . $sym;
226 if ($sym ne "main::" && $sym ne "<none>::" && &$recurse($sym)) {
227 walksymtable(\%$fullname, $method, $recurse, $sym);
230 svref_2object(\*$fullname)->$method();
241 my ($class, $section, $symtable, $default) = @_;
242 $output_fh ||= FileHandle->new_tmpfile;
243 my $obj = bless [-1, $section, $symtable, $default], $class;
244 $sections{$section} = $obj;
249 my ($class, $section) = @_;
250 return $sections{$section};
255 while (defined($_ = shift)) {
256 print $output_fh "$section->[1]\t$_\n";
263 return $section->[0];
268 return $section->[1];
273 return $section->[2];
278 return $section->[3];
282 my ($section, $fh, $format) = @_;
283 my $name = $section->name;
284 my $sym = $section->symtable || {};
285 my $default = $section->default;
287 seek($output_fh, 0, 0);
288 while (<$output_fh>) {
293 exists($sym->{$1}) ? $sym->{$1} : $default;
295 printf $fh $format, $_;
309 B - The Perl Compiler
317 The C<B> module supplies classes which allow a Perl program to delve
318 into its own innards. It is the module used to implement the
319 "backends" of the Perl compiler. Usage of the compiler does not
320 require knowledge of this module: see the F<O> module for the
321 user-visible part. The C<B> module is of use to those who want to
322 write new compiler backends. This documentation assumes that the
323 reader knows a fair amount about perl's internals including such
324 things as SVs, OPs and the internal symbol table and syntax tree
327 =head1 OVERVIEW OF CLASSES
329 The C structures used by Perl's internals to hold SV and OP
330 information (PVIV, AV, HV, ..., OP, SVOP, UNOP, ...) are modelled on a
331 class hierarchy and the C<B> module gives access to them via a true
332 object hierarchy. Structure fields which point to other objects
333 (whether types of SV or types of OP) are represented by the C<B>
334 module as Perl objects of the appropriate class. The bulk of the C<B>
335 module is the methods for accessing fields of these structures. Note
336 that all access is read-only: you cannot modify the internals by
339 =head2 SV-RELATED CLASSES
341 B::IV, B::NV, B::RV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::BM, B::PVLV,
342 B::AV, B::HV, B::CV, B::GV, B::FM, B::IO. These classes correspond in
343 the obvious way to the underlying C structures of similar names. The
344 inheritance hierarchy mimics the underlying C "inheritance". Access
345 methods correspond to the underlying C macros for field access,
346 usually with the leading "class indication" prefix removed (Sv, Av,
347 Hv, ...). The leading prefix is only left in cases where its removal
348 would cause a clash in method name. For example, C<GvREFCNT> stays
349 as-is since its abbreviation would clash with the "superclass" method
350 C<REFCNT> (corresponding to the C function C<SvREFCNT>).
368 Returns the value of the IV, I<interpreted as
369 a signed integer>. This will be misleading
370 if C<FLAGS & SVf_IVisUV>. Perhaps you want the
371 C<int_value> method instead?
379 This method returns the value of the IV as an integer.
380 It differs from C<IV> in that it returns the correct
381 value regardless of whether it's stored signed or
414 This method is the one you usually want. It constructs a
415 string using the length and offset information in the struct:
416 for ordinary scalars it will return the string that you'd see
417 from Perl, even if it contains null characters.
421 Same as B::RV::RV, except that it will die() if the PV isn't
426 This method is less often useful. It assumes that the string
427 stored in the struct is null-terminated, and disregards the
430 It is the appropriate method to use if you need to get the name
431 of a lexical variable from a padname array. Lexical variable names
432 are always stored with a null terminator, and the length field
433 (SvCUR) is overloaded for other purposes and can't be relied on here.
437 =head2 B::PVMG METHODS
447 =head2 B::MAGIC METHODS
455 Only valid on r-magic, returns the string that generated the regexp.
465 Will die() if called on r-magic.
471 Only valid on r-magic, returns the integer value of the REGEX stored
476 =head2 B::PVLV METHODS
510 This method returns TRUE if the GP field of the GV is NULL.
516 This method returns the name of the glob, but if the first
517 character of the name is a control character, then it converts
518 it to ^X first, so that *^G would return "^G" rather than "\cG".
520 It's useful if you want to print out the name of a variable.
521 If you restrict yourself to globs which exist at compile-time
522 then the result ought to be unambiguous, because code like
523 C<${"^G"} = 1> is compiled as two ops - a constant string and
524 a dereference (rv2gv) - so that the glob is created at runtime.
526 If you're working with globs at runtime, and need to disambiguate
527 *^G from *{"^G"}, then you should use the raw NAME method.
591 Takes one arguments ( 'stdin' | 'stdout' | 'stderr' ) and returns true
592 if the IoIFP of the object is equal to the handle whose name was
593 passed as argument ( i.e. $io->IsSTD('stderr') is true if
594 IoIFP($io) == PerlIO_stdin() ).
638 For constant subroutines, returns the constant SV returned by the subroutine.
666 =head2 OP-RELATED CLASSES
668 B::OP, B::UNOP, B::BINOP, B::LOGOP, B::LISTOP, B::PMOP,
669 B::SVOP, B::PADOP, B::PVOP, B::CVOP, B::LOOP, B::COP.
670 These classes correspond in
671 the obvious way to the underlying C structures of similar names. The
672 inheritance hierarchy mimics the underlying C "inheritance". Access
673 methods correspond to the underlying C structre field names, with the
674 leading "class indication" prefix removed (op_).
686 This returns the op name as a string (e.g. "add", "rv2av").
690 This returns the function name as a string (e.g. "PL_ppaddr[OP_ADD]",
691 "PL_ppaddr[OP_RV2AV]").
695 This returns the op description from the global C PL_op_desc array
696 (e.g. "addition" "array deref").
710 =head2 B::UNOP METHOD
718 =head2 B::BINOP METHOD
726 =head2 B::LOGOP METHOD
734 =head2 B::LISTOP METHOD
742 =head2 B::PMOP METHODS
764 Only when perl was compiled with ithreads.
768 =head2 B::SVOP METHOD
778 =head2 B::PADOP METHOD
786 =head2 B::PVOP METHOD
794 =head2 B::LOOP METHODS
806 =head2 B::COP METHODS
824 =head1 FUNCTIONS EXPORTED BY C<B>
826 The C<B> module exports a variety of functions: some are simple
827 utility functions, others provide a Perl program with a way to
828 get an initial "handle" on an internal object.
834 Return the (faked) CV corresponding to the main part of the Perl
839 Returns the AV object (i.e. in class B::AV) representing INIT blocks.
843 Returns the AV object (i.e. in class B::AV) representing BEGIN blocks.
847 Returns the AV object (i.e. in class B::AV) representing END blocks.
851 Returns the root op (i.e. an object in the appropriate B::OP-derived
852 class) of the main part of the Perl program.
856 Returns the starting op of the main part of the Perl program.
860 Returns the AV object (i.e. in class B::AV) of the global comppadlist.
864 Only when perl was compiled with ithreads.
868 Returns the SV object corresponding to the C variable C<sv_undef>.
872 Returns the SV object corresponding to the C variable C<sv_yes>.
876 Returns the SV object corresponding to the C variable C<sv_no>.
878 =item amagic_generation
880 Returns the SV object corresponding to the C variable C<amagic_generation>.
882 =item walkoptree(OP, METHOD)
884 Does a tree-walk of the syntax tree based at OP and calls METHOD on
885 each op it visits. Each node is visited before its children. If
886 C<walkoptree_debug> (q.v.) has been called to turn debugging on then
887 the method C<walkoptree_debug> is called on each op before METHOD is
890 =item walkoptree_debug(DEBUG)
892 Returns the current debugging flag for C<walkoptree>. If the optional
893 DEBUG argument is non-zero, it sets the debugging flag to that. See
894 the description of C<walkoptree> above for what the debugging flag
897 =item walksymtable(SYMREF, METHOD, RECURSE, PREFIX)
899 Walk the symbol table starting at SYMREF and call METHOD on each
900 symbol (a B::GV object) visited. When the walk reaches package
901 symbols (such as "Foo::") it invokes RECURSE, passing in the symbol
902 name, and only recurses into the package if that sub returns true.
904 PREFIX is the name of the SYMREF you're walking.
908 # Walk CGI's symbol table calling print_subs on each symbol.
909 # Only recurse into CGI::Util::
910 walksymtable(\%CGI::, 'print_subs', sub { $_[0] eq 'CGI::Util::' },
913 print_subs() is a B::GV method you have declared.
916 =item svref_2object(SV)
918 Takes any Perl variable and turns it into an object in the
919 appropriate B::OP-derived or B::SV-derived class. Apart from functions
920 such as C<main_root>, this is the primary way to get an initial
921 "handle" on an internal perl data structure which can then be followed
922 with the other access methods.
926 Return the PP function name (e.g. "pp_add") of op number OPNUM.
930 Returns a string in the form "0x..." representing the value of the
931 internal hash function used by perl on string STR.
935 Casts I to the internal I32 type used by that perl.
940 Does the equivalent of the C<-c> command-line option. Obviously, this
941 is only useful in a BEGIN block or else the flag is set too late.
946 Returns a double-quote-surrounded escaped version of STR which can
947 be used as a string in C source code.
949 =item perlstring(STR)
951 Returns a double-quote-surrounded escaped version of STR which can
952 be used as a string in Perl source code.
956 Returns the class of an object without the part of the classname
957 preceding the first "::". This is used to turn "B::UNOP" into
962 In a perl compiled for threads, this returns a list of the special
963 per-thread threadsv variables.
969 Malcolm Beattie, C<mbeattie@sable.ox.ac.uk>