move tlperl.straw to tlperl

git-svn-id: svn://tug.org/texlive/trunk@18210 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 1189 insertions, 0 deletions

diff --git a/Master/tlpkg/tlperl/lib/B.pm b/Master/tlpkg/tlperl/lib/B.pm
new file mode 100755
index 00000000000..52ae05e3269
--- /dev/null
+++ b/Master/tlpkg/tlperl/lib/B.pm
@@ -0,0 +1,1189 @@
+#      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 = '1.22';
+
+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
+		sub_generation 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 @optype @specialsv_name
+		);
+push @EXPORT_OK, qw(unitcheck_av) if $] > 5.009;
+
+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::SV';
+# RV is eliminated with 5.11.0, but effectively is a specialisation of IV now.
+@B::RV::ISA = $] >= 5.011 ? 'B::IV' : 'B::SV';
+@B::PVIV::ISA = qw(B::PV B::IV);
+@B::PVNV::ISA = qw(B::PVIV B::NV);
+@B::PVMG::ISA = 'B::PVNV';
+@B::REGEXP::ISA = 'B::PVMG' if $] >= 5.011;
+# Change in the inheritance hierarchy post 5.9.0
+@B::PVLV::ISA = $] > 5.009 ? 'B::GV' : 'B::PVMG';
+# BM is eliminated post 5.9.5, but effectively is a specialisation of GV now.
+@B::BM::ISA = $] > 5.009005 ? 'B::GV' : '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';
+
+@B::optype = qw(OP UNOP BINOP LOGOP LISTOP PMOP SVOP PADOP PVOP LOOP COP);
+# bytecode.pl contained the following comment:
+# Nullsv *must* come first in the following so that the condition
+# ($$sv == 0) can continue to be used to test (sv == Nullsv).
+@B::specialsv_name = qw(Nullsv &PL_sv_undef &PL_sv_yes &PL_sv_no
+			(SV*)pWARN_ALL (SV*)pWARN_NONE (SV*)pWARN_STD);
+
+{
+    # Stop "-w" from complaining about the lack of a real B::OBJECT class
+    package B::OBJECT;
+}
+
+sub B::GV::SAFENAME {
+  my $name = (shift())->NAME;
+
+  # The regex below corresponds to the isCONTROLVAR macro
+  # from toke.c
+
+  $name =~ s/^([\cA-\cZ\c\\c[\c]\c?\c_\c^])/"^".
+	chr( utf8::unicode_to_native( 64 ^ ord($1) ))/e;
+
+  # When we say unicode_to_native we really mean ascii_to_native,
+  # which matters iff this is a non-ASCII platform (EBCDIC).
+
+  return $name;
+}
+
+sub B::IV::int_value {
+  my ($self) = @_;
+  return (($self->FLAGS() & SVf_IVisUV()) ? $self->UVX : $self->IV);
+}
+
+sub B::NULL::as_string() {""}
+sub B::IV::as_string()   {goto &B::IV::int_value}
+sub B::PV::as_string()   {goto &B::PV::PV}
+
+my $debug;
+my $op_count = 0;
+my @parents = ();
+
+sub debug {
+    my ($class, $value) = @_;
+    $debug = $value;
+    walkoptree_debug($value);
+}
+
+sub class {
+    my $obj = shift;
+    my $name = ref $obj;
+    $name =~ s/^.*:://;
+    return $name;
+}
+
+sub parents { \@parents }
+
+# For debugging
+sub peekop {
+    my $op = shift;
+    return sprintf("%s (0x%x) %s", class($op), $$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 $op->can($method);
+    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'
+	&& ref($op->pmreplroot)
+	&& ${$op->pmreplroot}
+	&& $op->pmreplroot->isa( 'B::OP' ))
+    {
+	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), $$op));
+	$op->$method($level);
+	$ppname = $op->name;
+	if ($ppname =~
+	    /^(d?or(assign)?|and(assign)?|mapwhile|grepwhile|entertry|range|cond_expr)$/)
+	{
+	    print $prefix, uc($1), " => {\n";
+	    walkoptree_exec($op->other, $method, $level + 1);
+	    print $prefix, "}\n";
+	} elsif ($ppname eq "match" || $ppname eq "subst") {
+	    my $pmreplstart = $op->pmreplstart;
+	    if ($$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 . $sym;
+	    if (svref_2object(\*$sym)->NAME 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
+
+The C<B> 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<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.
+
+=head2 Functions Returning C<B::SV>, C<B::AV>, C<B::HV>, and C<B::CV> objects
+
+For descriptions of the class hierarchy 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<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 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<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.
+
+The returned object will only be valid as long as the underlying OPs
+and SVs continue to exist. Do not attempt to use the object after the
+underlying structures are freed.
+
+=item amagic_generation
+
+Returns the SV object corresponding to the C variable C<amagic_generation>.
+
+=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 unitcheck_av
+
+Returns the AV object (i.e. in class B::AV) representing UNITCHECK 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<B::OP> objects or for walking op trees
+
+For descriptions of the class hierarchy 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<walkoptree_debug> (see below) 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.
+
+=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
+
+=head2 Exported utility variabiles
+
+=over 4
+
+=item @optype
+
+  my $op_type = $optype[$op_type_num];
+
+A simple mapping of the op type number to its type (like 'COP' or 'BINOP').
+
+=item @specialsv_name
+
+  my $sv_name = $specialsv_name[$sv_index];
+
+Certain SV types are considered 'special'.  They're represented by
+B::SPECIAL and are referred to by a number from the specialsv_list.
+This array maps that number back to the name of the SV (like 'Nullsv'
+or '&PL_sv_undef').
+
+=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<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. Also, note that the B::OP and B::SV objects created
+by this module are only valid for as long as the underlying objects
+exist; their creation doesn't increase the reference counts of the
+underlying objects. Trying to access the fields of a freed object will
+give incomprehensible results, or worse.
+
+=head2 SV-RELATED CLASSES
+
+B::IV, B::NV, B::RV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::BM (5.9.5 and
+earlier), 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". For the
+5.10.x branch, (I<ie> 5.10.0, 5.10.1 I<etc>) this is:
+
+                           B::SV
+                             |
+                +------------+------------+------------+
+                |            |            |            |
+              B::PV        B::IV        B::NV        B::RV
+                  \         /           /
+                   \       /           /
+                    B::PVIV           /
+                         \           /
+                          \         /
+                           \       /
+                            B::PVNV
+                               |
+                               |
+                            B::PVMG
+                               |
+                   +-----+-----+-----+-----+
+                   |     |     |     |     |
+                 B::AV B::GV B::HV B::CV B::IO
+                         |           |
+                         |           |
+                      B::PVLV      B::FM
+
+For 5.9.0 and earlier, PVLV is a direct subclass of PVMG, and BM is still
+present as a distinct type, so the base of this diagram is
+
+
+                               |
+                               |
+                            B::PVMG
+                               |
+            +------+-----+-----+-----+-----+-----+
+            |      |     |     |     |     |     |
+         B::PVLV B::BM B::AV B::GV B::HV B::CV B::IO
+                                           |
+                                           |
+                                         B::FM
+
+For 5.11.0 and later, B::RV is abolished, and IVs can be used to store
+references, and a new type B::REGEXP is introduced, giving this structure:
+
+                           B::SV
+                             |
+                +------------+------------+
+                |            |            |
+              B::PV        B::IV        B::NV
+                  \         /           /
+                   \       /           /
+                    B::PVIV           /
+                         \           /
+                          \         /
+                           \       /
+                            B::PVNV
+                               |
+                               |
+                            B::PVMG
+                               |
+           +-------+-------+---+---+-------+-------+
+           |       |       |       |       |       |
+         B::AV   B::GV   B::HV   B::CV   B::IO B::REGEXP
+                   |               |
+                   |               |
+                B::PVLV          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<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
+
+=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<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 ARRAY
+
+=item ARRAYelt
+
+Like C<ARRAY>, but takes an index as an argument to get only one element,
+rather than a list of all of them.
+
+=item OFF
+
+This method is deprecated if running under Perl 5.8, and is no longer present
+if running under Perl 5.9
+
+=item AvFLAGS
+
+This method returns the AV specific flags. In Perl 5.9 these are now stored
+in with the main SV flags, so this method is no longer present.
+
+=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 ARRAY
+
+=item PMROOT
+
+This method is not present if running under Perl 5.9, as the PMROOT
+information is no longer stored directly in the hash.
+
+=back
+
+=head2 OP-RELATED CLASSES
+
+C<B::OP>, C<B::UNOP>, C<B::BINOP>, C<B::LOGOP>, C<B::LISTOP>, C<B::PMOP>,
+C<B::SVOP>, C<B::PADOP>, C<B::PVOP>, C<B::LOOP>, C<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":
+
+                                 B::OP
+                                   |
+                   +---------------+--------+--------+-------+
+                   |               |        |        |       |
+                B::UNOP          B::SVOP B::PADOP  B::COP  B::PVOP
+                 ,'  `-.
+                /       `--.
+           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
+
+These methods get the values of similarly named fields within the OP
+data structure.  See top of C<op.h> for more info.
+
+=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 opt
+
+=item flags
+
+=item private
+
+=item spare
+
+=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
+
+Only up to Perl 5.9.4
+
+=item pmregexp
+
+=item pmflags
+
+=item extflags
+
+Since Perl 5.9.5
+
+=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
+
+=item hints
+
+=item hints_hash
+
+=back
+
+
+=head1 AUTHOR
+
+Malcolm Beattie, C<mbeattie@sable.ox.ac.uk>
+
+=cut