# 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 = '1.02'; 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 perlstring walkoptree_slow walkoptree walkoptree_exec walksymtable parents comppadlist sv_undef compile_stats timing_info begin_av init_av check_av end_av regex_padav dowarn defstash curstash warnhook diehook inc_gv ); 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::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; $$kid; $kid = $kid->sibling) { walkoptree_slow($kid, $method, $level + 1); } shift @parents; } if (class($op) eq 'PMOP' && $op->pmreplroot && ${$op->pmreplroot}) { unshift(@parents, $op); walkoptree_slow($op->pmreplroot, $method, $level + 1); shift @parents; } } sub compile_stats { return "Total number of OPs processed: $op_count\n"; } sub timing_info { my ($sec, $min, $hr) = localtime; my ($user, $sys) = times; sprintf("%02d:%02d:%02d user=$user sys=$sys", $hr, $min, $sec, $user, $sys); } my %symtable; sub clearsym { %symtable = (); } sub savesym { my ($obj, $value) = @_; # warn(sprintf("savesym: sym_%x => %s\n", $$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(assign)?|and(assign)?|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::" && $sym ne "::" && &$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 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 module for the user-visible part. The C 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 The C module contains a set of utility functions for querying the current state of the Perl interpreter; typically these functions return objects from the B::SV and B::OP classes, or their derived classes. These classes in turn define methods for querying the resulting objects about their own internal state. =head1 Utility Functions The C 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. =head2 Functions Returning C, C, C, and C objects For descriptions of the class hierachy of these objects and the methods that can be called on them, see below, L<"OVERVIEW OF CLASSES"> and L<"SV-RELATED CLASSES">. =over 4 =item sv_undef Returns the SV object corresponding to the C variable C. =item sv_yes Returns the SV object corresponding to the C variable C. =item sv_no Returns the SV object corresponding to the C variable C. =item svref_2object(SVREF) Takes a reference to any Perl value, and turns the referred-to value into an object in the appropriate B::OP-derived or B::SV-derived class. Apart from functions such as C, 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 amagic_generation Returns the SV object corresponding to the C variable C. =item init_av Returns the AV object (i.e. in class B::AV) representing INIT blocks. =item check_av Returns the AV object (i.e. in class B::AV) representing CHECK 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 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 main_cv Return the (faked) CV corresponding to the main part of the Perl program. =back =head2 Functions for Examining the Symbol Table =over 4 =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. # Recurse only into CGI::Util:: walksymtable(\%CGI::, 'print_subs', sub { $_[0] eq 'CGI::Util::' }, 'CGI::'); print_subs() is a B::GV method you have declared. Also see L<"B::GV Methods">, below. =back =head2 Functions Returning C objects or for walking op trees For descriptions of the class hierachy of these objects and the methods that can be called on them, see below, L<"OVERVIEW OF CLASSES"> and L<"OP-RELATED CLASSES">. =over 4 =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 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 (see below) has been called to turn debugging on then the method C is called on each op before METHOD is called. =item walkoptree_debug(DEBUG) Returns the current debugging flag for C. If the optional DEBUG argument is non-zero, it sets the debugging flag to that. See the description of C above for what the debugging flag does. =back =head2 Miscellaneous Utility Functions =over 4 =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 perlstring(STR) Returns a double-quote-surrounded escaped version of STR which can be used as a string in Perl source code. =item class(OBJ) Returns the class of an object without the part of the classname preceding the first C<"::">. This is used to turn C<"B::UNOP"> into C<"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 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 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 module as Perl objects of the appropriate class. The bulk of the C 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": B::SV | +--------------+----------------------+ | | | B::PV B::IV B::RV | \ / \ | \ / \ | B::PVIV B::NV \ / \____ __/ \ / B::PVNV | | B::PVMG | +------+-----+----+------+-----+-----+ | | | | | | | B::PVLV B::BM B::AV B::GV B::HV B::CV B::IO | | B::FM 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 stays as-is since its abbreviation would clash with the "superclass" method C (corresponding to the C function C). =head2 B::SV Methods =over 4 =item REFCNT =item FLAGS =item object_2svref Returns a reference to the regular scalar corresponding to this B::SV object. In other words, this method is the inverse operation to the svref_2object() subroutine. This scalar and other data it points at should be considered read-only: modifying them is neither safe nor guaranteed to have a sensible effect. =back =head2 B::IV Methods =over 4 =item IV Returns the value of the IV, I. This will be misleading if C. Perhaps you want the C method instead? =item IVX =item UVX =item int_value This method returns the value of the IV as an integer. It differs from C 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 ARRAYelt Like C, but takes an index as an argument to get only one element, rather than a list of all of them. =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 OUTSIDE_SEQ =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 C, C, C, C, C, C, C, C, C, C, C. These classes correspond in the obvious way to the underlying C structures of similar names. The inheritance hierarchy mimics the underlying C "inheritance": B::OP | +---------------+--------+--------+ | | | | B::UNOP B::SVOP B::PADOP B::COP ,' `-. / `--. B::BINOP B::LOGOP | | B::LISTOP ,' `. / \ B::LOOP B::PMOP Access methods correspond to the underlying C structre field names, with the leading "class indication" prefix (C<"op_">) removed. =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 pmoffset 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 stashpv =item file =item cop_seq =item arybase =item line =item warnings =item io =back =head1 AUTHOR Malcolm Beattie, C =cut