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 @EXPORT_OK = qw(minus_c ppname
13 class peekop cast_I32 cstring cchar hash threadsv_names
14 main_root main_start main_cv svref_2object opnumber amagic_generation
15 walkoptree walkoptree_slow walkoptree_exec walksymtable
16 parents comppadlist sv_undef compile_stats timing_info init_av);
19 @B::SV::ISA = 'B::OBJECT';
20 @B::NULL::ISA = 'B::SV';
21 @B::PV::ISA = 'B::SV';
22 @B::IV::ISA = 'B::SV';
23 @B::NV::ISA = 'B::IV';
24 @B::RV::ISA = 'B::SV';
25 @B::PVIV::ISA = qw(B::PV B::IV);
26 @B::PVNV::ISA = qw(B::PV B::NV);
27 @B::PVMG::ISA = 'B::PVNV';
28 @B::PVLV::ISA = 'B::PVMG';
29 @B::BM::ISA = 'B::PVMG';
30 @B::AV::ISA = 'B::PVMG';
31 @B::GV::ISA = 'B::PVMG';
32 @B::HV::ISA = 'B::PVMG';
33 @B::CV::ISA = 'B::PVMG';
34 @B::IO::ISA = 'B::PVMG';
35 @B::FM::ISA = 'B::CV';
37 @B::OP::ISA = 'B::OBJECT';
38 @B::UNOP::ISA = 'B::OP';
39 @B::BINOP::ISA = 'B::UNOP';
40 @B::LOGOP::ISA = 'B::UNOP';
41 @B::LISTOP::ISA = 'B::BINOP';
42 @B::SVOP::ISA = 'B::OP';
43 @B::PADOP::ISA = 'B::OP';
44 @B::PVOP::ISA = 'B::OP';
45 @B::CVOP::ISA = 'B::OP';
46 @B::LOOP::ISA = 'B::LISTOP';
47 @B::PMOP::ISA = 'B::LISTOP';
48 @B::COP::ISA = 'B::OP';
50 @B::SPECIAL::ISA = 'B::OBJECT';
53 # Stop "-w" from complaining about the lack of a real B::OBJECT class
62 my ($class, $value) = @_;
64 walkoptree_debug($value);
74 sub parents { \@parents }
79 return sprintf("%s (0x%x) %s", class($op), $$op, $op->name);
83 my($op, $method, $level) = @_;
84 $op_count++; # just for statistics
86 warn(sprintf("walkoptree: %d. %s\n", $level, peekop($op))) if $debug;
88 if ($$op && ($op->flags & OPf_KIDS)) {
90 unshift(@parents, $op);
91 for ($kid = $op->first; $$kid; $kid = $kid->sibling) {
92 walkoptree_slow($kid, $method, $level + 1);
99 return "Total number of OPs processed: $op_count\n";
103 my ($sec, $min, $hr) = localtime;
104 my ($user, $sys) = times;
105 sprintf("%02d:%02d:%02d user=$user sys=$sys",
106 $hr, $min, $sec, $user, $sys);
116 my ($obj, $value) = @_;
117 # warn(sprintf("savesym: sym_%x => %s\n", $$obj, $value)); # debug
118 $symtable{sprintf("sym_%x", $$obj)} = $value;
123 return $symtable{sprintf("sym_%x", $$obj)};
126 sub walkoptree_exec {
127 my ($op, $method, $level) = @_;
129 my $prefix = " " x $level;
130 for (; $$op; $op = $op->next) {
133 print $prefix, "goto $sym\n";
136 savesym($op, sprintf("%s (0x%lx)", class($op), $$op));
137 $op->$method($level);
140 /^(or|and|mapwhile|grepwhile|entertry|range|cond_expr)$/)
142 print $prefix, uc($1), " => {\n";
143 walkoptree_exec($op->other, $method, $level + 1);
144 print $prefix, "}\n";
145 } elsif ($ppname eq "match" || $ppname eq "subst") {
146 my $pmreplstart = $op->pmreplstart;
148 print $prefix, "PMREPLSTART => {\n";
149 walkoptree_exec($pmreplstart, $method, $level + 1);
150 print $prefix, "}\n";
152 } elsif ($ppname eq "substcont") {
153 print $prefix, "SUBSTCONT => {\n";
154 walkoptree_exec($op->other->pmreplstart, $method, $level + 1);
155 print $prefix, "}\n";
157 } elsif ($ppname eq "enterloop") {
158 print $prefix, "REDO => {\n";
159 walkoptree_exec($op->redoop, $method, $level + 1);
160 print $prefix, "}\n", $prefix, "NEXT => {\n";
161 walkoptree_exec($op->nextop, $method, $level + 1);
162 print $prefix, "}\n", $prefix, "LAST => {\n";
163 walkoptree_exec($op->lastop, $method, $level + 1);
164 print $prefix, "}\n";
165 } elsif ($ppname eq "subst") {
166 my $replstart = $op->pmreplstart;
168 print $prefix, "SUBST => {\n";
169 walkoptree_exec($replstart, $method, $level + 1);
170 print $prefix, "}\n";
177 my ($symref, $method, $recurse, $prefix) = @_;
182 $prefix = '' unless defined $prefix;
183 while (($sym, $ref) = each %$symref) {
184 *glob = "*main::".$prefix.$sym;
186 $sym = $prefix . $sym;
187 if ($sym ne "main::" && &$recurse($sym)) {
188 walksymtable(\%glob, $method, $recurse, $sym);
191 svref_2object(\*glob)->EGV->$method();
202 my ($class, $section, $symtable, $default) = @_;
203 $output_fh ||= FileHandle->new_tmpfile;
204 my $obj = bless [-1, $section, $symtable, $default], $class;
205 $sections{$section} = $obj;
210 my ($class, $section) = @_;
211 return $sections{$section};
216 while (defined($_ = shift)) {
217 print $output_fh "$section->[1]\t$_\n";
224 return $section->[0];
229 return $section->[1];
234 return $section->[2];
239 return $section->[3];
243 my ($section, $fh, $format) = @_;
244 my $name = $section->name;
245 my $sym = $section->symtable || {};
246 my $default = $section->default;
248 seek($output_fh, 0, 0);
249 while (<$output_fh>) {
254 exists($sym->{$1}) ? $sym->{$1} : $default;
256 printf $fh $format, $_;
270 B - The Perl Compiler
278 The C<B> module supplies classes which allow a Perl program to delve
279 into its own innards. It is the module used to implement the
280 "backends" of the Perl compiler. Usage of the compiler does not
281 require knowledge of this module: see the F<O> module for the
282 user-visible part. The C<B> module is of use to those who want to
283 write new compiler backends. This documentation assumes that the
284 reader knows a fair amount about perl's internals including such
285 things as SVs, OPs and the internal symbol table and syntax tree
288 =head1 OVERVIEW OF CLASSES
290 The C structures used by Perl's internals to hold SV and OP
291 information (PVIV, AV, HV, ..., OP, SVOP, UNOP, ...) are modelled on a
292 class hierarchy and the C<B> module gives access to them via a true
293 object hierarchy. Structure fields which point to other objects
294 (whether types of SV or types of OP) are represented by the C<B>
295 module as Perl objects of the appropriate class. The bulk of the C<B>
296 module is the methods for accessing fields of these structures. Note
297 that all access is read-only: you cannot modify the internals by
300 =head2 SV-RELATED CLASSES
302 B::IV, B::NV, B::RV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::BM, B::PVLV,
303 B::AV, B::HV, B::CV, B::GV, B::FM, B::IO. These classes correspond in
304 the obvious way to the underlying C structures of similar names. The
305 inheritance hierarchy mimics the underlying C "inheritance". Access
306 methods correspond to the underlying C macros for field access,
307 usually with the leading "class indication" prefix removed (Sv, Av,
308 Hv, ...). The leading prefix is only left in cases where its removal
309 would cause a clash in method name. For example, C<GvREFCNT> stays
310 as-is since its abbreviation would clash with the "superclass" method
311 C<REFCNT> (corresponding to the C function C<SvREFCNT>).
363 =head2 B::PVMG METHODS
373 =head2 B::MAGIC METHODS
391 =head2 B::PVLV METHODS
425 This method returns TRUE if the GP field of the GV is NULL.
555 =head2 OP-RELATED CLASSES
557 B::OP, B::UNOP, B::BINOP, B::LOGOP, B::LISTOP, B::PMOP,
558 B::SVOP, B::PADOP, B::PVOP, B::CVOP, B::LOOP, B::COP.
559 These classes correspond in
560 the obvious way to the underlying C structures of similar names. The
561 inheritance hierarchy mimics the underlying C "inheritance". Access
562 methods correspond to the underlying C structre field names, with the
563 leading "class indication" prefix removed (op_).
575 This returns the op name as a string (e.g. "add", "rv2av").
579 This returns the function name as a string (e.g. "PL_ppaddr[OP_ADD]",
580 "PL_ppaddr[OP_RV2AV]").
584 This returns the op description from the global C PL_op_desc array
585 (e.g. "addition" "array deref").
599 =head2 B::UNOP METHOD
607 =head2 B::BINOP METHOD
615 =head2 B::LOGOP METHOD
623 =head2 B::LISTOP METHOD
631 =head2 B::PMOP METHODS
651 =head2 B::SVOP METHOD
659 =head2 B::PADOP METHOD
667 =head2 B::PVOP METHOD
675 =head2 B::LOOP METHODS
687 =head2 B::COP METHODS
705 =head1 FUNCTIONS EXPORTED BY C<B>
707 The C<B> module exports a variety of functions: some are simple
708 utility functions, others provide a Perl program with a way to
709 get an initial "handle" on an internal object.
715 Return the (faked) CV corresponding to the main part of the Perl
720 Returns the AV object (i.e. in class B::AV) representing INIT blocks.
724 Returns the root op (i.e. an object in the appropriate B::OP-derived
725 class) of the main part of the Perl program.
729 Returns the starting op of the main part of the Perl program.
733 Returns the AV object (i.e. in class B::AV) of the global comppadlist.
737 Returns the SV object corresponding to the C variable C<sv_undef>.
741 Returns the SV object corresponding to the C variable C<sv_yes>.
745 Returns the SV object corresponding to the C variable C<sv_no>.
747 =item amagic_generation
749 Returns the SV object corresponding to the C variable C<amagic_generation>.
751 =item walkoptree(OP, METHOD)
753 Does a tree-walk of the syntax tree based at OP and calls METHOD on
754 each op it visits. Each node is visited before its children. If
755 C<walkoptree_debug> (q.v.) has been called to turn debugging on then
756 the method C<walkoptree_debug> is called on each op before METHOD is
759 =item walkoptree_debug(DEBUG)
761 Returns the current debugging flag for C<walkoptree>. If the optional
762 DEBUG argument is non-zero, it sets the debugging flag to that. See
763 the description of C<walkoptree> above for what the debugging flag
766 =item walksymtable(SYMREF, METHOD, RECURSE)
768 Walk the symbol table starting at SYMREF and call METHOD on each
769 symbol visited. When the walk reached package symbols "Foo::" it
770 invokes RECURSE and only recurses into the package if that sub
773 =item svref_2object(SV)
775 Takes any Perl variable and turns it into an object in the
776 appropriate B::OP-derived or B::SV-derived class. Apart from functions
777 such as C<main_root>, this is the primary way to get an initial
778 "handle" on a internal perl data structure which can then be followed
779 with the other access methods.
783 Return the PP function name (e.g. "pp_add") of op number OPNUM.
787 Returns a string in the form "0x..." representing the value of the
788 internal hash function used by perl on string STR.
792 Casts I to the internal I32 type used by that perl.
797 Does the equivalent of the C<-c> command-line option. Obviously, this
798 is only useful in a BEGIN block or else the flag is set too late.
803 Returns a double-quote-surrounded escaped version of STR which can
804 be used as a string in C source code.
808 Returns the class of an object without the part of the classname
809 preceding the first "::". This is used to turn "B::UNOP" into
814 In a perl compiled for threads, this returns a list of the special
815 per-thread threadsv variables.
821 Malcolm Beattie, C<mbeattie@sable.ox.ac.uk>