b.pm

UNIX下perl实现代码

#      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;
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);

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(64 ^ ord($1))/e;
  return $name;
}

sub B::IV::int_value {
  my ($self) = @_;
  return (($self->FLAGS() & SVf_IVisUV()) ? $self->UVX : $self->IV);
}

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;
    no strict 'vars';
    local(*glob);
    $prefix = '' unless defined $prefix;
    while (($sym, $ref) = each %$symref) {
	*glob = "*main::".$prefix.$sym;
	if ($sym =~ /::$/) {
	    $sym = $prefix . $sym;
	    if ($sym ne "main::" && $sym ne "<none>::" && &$recurse($sym)) {
		walksymtable(\%glob, $method, $recurse, $sym);
	    }
	} else {
	    svref_2object(\*glob)->EGV->$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 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 PRIVATE

=item TYPE

=item FLAGS

=item OBJ

=item PTR

=back

=head2 B::PVLV METHODS

=over 4

=item TARGOFF