contrib/texi2pod.pl - gcc - Git at Google

 #! /usr/bin/perl -w

 #   Copyright (C) 1999-2014 Free Software Foundation, Inc.

 # This file is part of GCC.

 # GCC is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation; either version 3, or (at your option)
 # any later version.

 # GCC is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.

 # You should have received a copy of the GNU General Public License
 # along with GCC; see the file COPYING.  If not, write to
 # the Free Software Foundation, 51 Franklin Street, Fifth Floor,
 # Boston MA 02110-1301, USA.

 # This does trivial (and I mean _trivial_) conversion of Texinfo
 # markup to Perl POD format.  It's intended to be used to extract
 # something suitable for a manpage from a Texinfo document.

 $output = 0;
 $skipping = 0;
 %sects = ();
 $section = "";
 @icstack = ();
 @endwstack = ();
 @skstack = ();
 @instack = ();
 $shift = "";
 %defs = ();
 $fnno = 1;
 $inf = "";
 $ibase = "";
 @ipath = ();

 while ($_ = shift) {
     if (/^-D(.*)$/) {
 	if ($1 ne "") {
 	    $flag = $1;
 	} else {
 	    $flag = shift;
 	}
 	$value = "";
 	($flag, $value) = ($flag =~ /^([^=]+)(?:=(.+))?/);
 	die "no flag specified for -D\n"
 	    unless $flag ne "";
 	die "flags may only contain letters, digits, hyphens, dashes and underscores\n"
 	    unless $flag =~ /^[a-zA-Z0-9_-]+$/;
 	$defs{$flag} = $value;
     } elsif (/^-I(.*)$/) {
 	if ($1 ne "") {
 	    $flag = $1;
 	} else {
 	    $flag = shift;
 	}
         push (@ipath, $flag);
     } elsif (/^-/) {
 	usage();
     } else {
 	$in = $_, next unless defined $in;
 	$out = $_, next unless defined $out;
 	usage();
     }
 }

 if (defined $in) {
     $inf = gensym();
     open($inf, "<$in") or die "opening \"$in\": $!\n";
     $ibase = $1 if $in =~ m|^(.+)/[^/]+$|;
 } else {
     $inf = \*STDIN;
 }

 if (defined $out) {
     open(STDOUT, ">$out") or die "opening \"$out\": $!\n";
 }

 while(defined $inf) {
 while(<$inf>) {
     # Certain commands are discarded without further processing.
     /^\@(?:
 	 [a-z]+index		# @*index: useful only in complete manual
 	 |need			# @need: useful only in printed manual
 	 |(?:end\s+)?group	# @group .. @end group: ditto
 	 |page			# @page: ditto
 	 |node			# @node: useful only in .info file
 	 |(?:end\s+)?ifnottex   # @ifnottex .. @end ifnottex: use contents
 	)\b/x and next;

     chomp;

     # Look for filename and title markers.
     /^\@setfilename\s+([^.]+)/ and $fn = $1, next;
     /^\@settitle\s+([^.]+)/ and $tl = postprocess($1), next;

     # Identify a man title but keep only the one we are interested in.
     /^\@c\s+man\s+title\s+([A-Za-z0-9-]+)\s+(.+)/ and do {
 	if (exists $defs{$1}) {
 	    $fn = $1;
 	    $tl = postprocess($2);
 	}
 	next;
     };

     # Look for blocks surrounded by @c man begin SECTION ... @c man end.
     # This really oughta be @ifman ... @end ifman and the like, but such
     # would require rev'ing all other Texinfo translators.
     /^\@c\s+man\s+begin\s+([A-Z]+)\s+([A-Za-z0-9-]+)/ and do {
 	$output = 1 if exists $defs{$2};
         $sect = $1;
 	next;
     };
     /^\@c\s+man\s+begin\s+([A-Z]+)/ and $sect = $1, $output = 1, next;
     /^\@c\s+man\s+end/ and do {
 	$sects{$sect} = "" unless exists $sects{$sect};
 	$sects{$sect} .= postprocess($section);
 	$section = "";
 	$output = 0;
 	next;
     };

     # handle variables
     /^\@set\s+([a-zA-Z0-9_-]+)\s*(.*)$/ and do {
 	$defs{$1} = $2;
 	next;
     };
     /^\@clear\s+([a-zA-Z0-9_-]+)/ and do {
 	delete $defs{$1};
 	next;
     };

     next unless $output;

     # Discard comments.  (Can't do it above, because then we'd never see
     # @c man lines.)
     /^\@c\b/ and next;

     # End-block handler goes up here because it needs to operate even
     # if we are skipping.
     /^\@end\s+([a-z]+)/ and do {
 	# Ignore @end foo, where foo is not an operation which may
 	# cause us to skip, if we are presently skipping.
 	my $ended = $1;
 	next if $skipping && $ended !~ /^(?:ifset|ifclear|ignore|menu|iftex|copying)$/;

 	die "\@end $ended without \@$ended at line $.\n" unless defined $endw;
 	die "\@$endw ended by \@end $ended at line $.\n" unless $ended eq $endw;

 	$endw = pop @endwstack;

 	if ($ended =~ /^(?:ifset|ifclear|ignore|menu|iftex)$/) {
 	    $skipping = pop @skstack;
 	    next;
 	} elsif ($ended =~ /^(?:example|smallexample|display)$/) {
 	    $shift = "";
 	    $_ = "";	# need a paragraph break
 	} elsif ($ended =~ /^(?:itemize|enumerate|[fv]?table)$/) {
 	    $_ = "\n=back\n";
 	    $ic = pop @icstack;
 	} elsif ($ended eq "multitable") {
 	    $_ = "\n=back\n";
 	} else {
 	    die "unknown command \@end $ended at line $.\n";
 	}
     };

     # We must handle commands which can cause skipping even while we
     # are skipping, otherwise we will not process nested conditionals
     # correctly.
     /^\@ifset\s+([a-zA-Z0-9_-]+)/ and do {
 	push @endwstack, $endw;
 	push @skstack, $skipping;
 	$endw = "ifset";
 	$skipping = 1 unless exists $defs{$1};
 	next;
     };

     /^\@ifclear\s+([a-zA-Z0-9_-]+)/ and do {
 	push @endwstack, $endw;
 	push @skstack, $skipping;
 	$endw = "ifclear";
 	$skipping = 1 if exists $defs{$1};
 	next;
     };

     /^\@(ignore|menu|iftex|copying)\b/ and do {
 	push @endwstack, $endw;
 	push @skstack, $skipping;
 	$endw = $1;
 	$skipping = 1;
 	next;
     };

     next if $skipping;

     # Character entities.  First the ones that can be replaced by raw text
     # or discarded outright:
     s/\@copyright\{\}/(c)/g;
     s/\@dots\{\}/.../g;
     s/\@enddots\{\}/..../g;
     s/\@([.!? ])/$1/g;
     s/\@[:-]//g;
     s/\@bullet(?:\{\})?/*/g;
     s/\@TeX\{\}/TeX/g;
     s/\@pounds\{\}/\#/g;
     s/\@minus(?:\{\})?/-/g;
     s/\\,/,/g;

     # Now the ones that have to be replaced by special escapes
     # (which will be turned back into text by unmunge())
     # Replace @@ before @{ and @} in order to parse @samp{@@} correctly.
     s/&/&amp;/g;
     s/\@\@/&at;/g;
     s/\@\{/&lbrace;/g;
     s/\@\}/&rbrace;/g;
     s/\@`\{(.)\}/&$1grave;/g;

     # Inside a verbatim block, handle @var, @samp and @url specially.
     if ($shift ne "") {
 	s/\@var\{([^\}]*)\}/<$1>/g;
 	s/\@samp\{([^\}]*)\}/"$1"/g;
 	s/\@url\{([^\}]*)\}/<$1>/g;
     }

     # POD doesn't interpret E<> inside a verbatim block.
     if ($shift eq "") {
 	s/</&lt;/g;
 	s/>/&gt;/g;
     } else {
 	s/</&LT;/g;
 	s/>/&GT;/g;
     }

     # Single line command handlers.

     /^\@include\s+(.+)$/ and do {
 	push @instack, $inf;
 	$inf = gensym();
 	$file = postprocess($1);

 	# Try cwd and $ibase, then explicit -I paths.
 	$done = 0;
 	foreach $path ("", $ibase, @ipath) {
 	    $mypath = $file;
 	    $mypath = $path . "/" . $mypath if ($path ne "");
 	    open($inf, "<" . $mypath) and ($done = 1, last);
 	}
 	die "cannot find $file" if !$done;
 	next;
     };

     /^\@(?:section|unnumbered|unnumberedsec|center|heading)\s+(.+)$/
 	and $_ = "\n=head2 $1\n";
     /^\@subsection\s+(.+)$/
 	and $_ = "\n=head3 $1\n";
     /^\@subsubsection\s+(.+)$/
 	and $_ = "\n=head4 $1\n";

     # Block command handlers:
     /^\@itemize(?:\s+(\@[a-z]+|\*|-))?/ and do {
 	push @endwstack, $endw;
 	push @icstack, $ic;
 	if (defined $1) {
 	    $ic = $1;
 	} else {
 	    $ic = '*';
 	}
 	$_ = "\n=over 4\n";
 	$endw = "itemize";
     };

     /^\@enumerate(?:\s+([a-zA-Z0-9]+))?/ and do {
 	push @endwstack, $endw;
 	push @icstack, $ic;
 	if (defined $1) {
 	    $ic = $1 . ".";
 	} else {
 	    $ic = "1.";
 	}
 	$_ = "\n=over 4\n";
 	$endw = "enumerate";
     };

     /^\@multitable\s.*/ and do {
 	push @endwstack, $endw;
 	$endw = "multitable";
 	$_ = "\n=over 4\n";
     };

     /^\@([fv]?table)\s+(\@[a-z]+)/ and do {
 	push @endwstack, $endw;
 	push @icstack, $ic;
 	$endw = $1;
 	$ic = $2;
 	$ic =~ s/\@(?:samp|strong|key|gcctabopt|env)/B/;
 	$ic =~ s/\@(?:code|kbd)/C/;
 	$ic =~ s/\@(?:dfn|var|emph|cite|i)/I/;
 	$ic =~ s/\@(?:file)/F/;
 	$ic =~ s/\@(?:asis)//;
 	$_ = "\n=over 4\n";
     };

     /^\@((?:small)?example|display)/ and do {
 	push @endwstack, $endw;
 	$endw = $1;
 	$shift = "\t";
 	$_ = "";	# need a paragraph break
     };

     /^\@item\s+(.*\S)\s*$/ and $endw eq "multitable" and do {
 	@columns = ();
 	for $column (split (/\s*\@tab\s*/, $1)) {
 	    # @strong{...} is used a @headitem work-alike
 	    $column =~ s/^\@strong\{(.*)\}$/$1/;
 	    push @columns, $column;
 	}
 	$_ = "\n=item ".join (" : ", @columns)."\n";
     };

     /^\@itemx?\s*(.+)?$/ and do {
 	if (defined $1) {
             if ($ic) {
 		if ($endw eq "enumerate") {
 		    $_ = "\n=item $ic $1\n";
 		    $ic =~ s/(\d+)/$1 + 1/eg;
 		} else {
 		    # Entity escapes prevent munging by the <>
 		    # processing below.
 		    $_ = "\n=item $ic\&LT;$1\&GT;\n";
 		}
             } else {
                 $_ = "\n=item $1\n";
             }
 	} else {
 	    $_ = "\n=item Z\&LT;\&GT;$ic\n";
 	    $ic =~ y/A-Ya-y/B-Zb-z/;
 	    $ic =~ s/(\d+)/$1 + 1/eg;
 	}
     };

     $section .= $shift.$_."\n";
 }
 # End of current file.
 close($inf);
 $inf = pop @instack;
 }

 die "No filename or title\n" unless defined $fn && defined $tl;

 $sects{NAME} = "$fn \- $tl\n";
 $sects{FOOTNOTES} .= "=back\n" if exists $sects{FOOTNOTES};

 for $sect (qw(NAME SYNOPSIS DESCRIPTION OPTIONS ENVIRONMENT FILES
 	      BUGS NOTES FOOTNOTES SEEALSO AUTHOR COPYRIGHT)) {
     if(exists $sects{$sect}) {
 	$head = $sect;
 	$head =~ s/SEEALSO/SEE ALSO/;
 	print "=head1 $head\n\n";
 	print scalar unmunge ($sects{$sect});
 	print "\n";
     }
 }

 sub usage
 {
     die "usage: $0 [-D toggle...] [infile [outfile]]\n";
 }

 sub postprocess
 {
     local $_ = $_[0];

     # @value{foo} is replaced by whatever 'foo' is defined as.
     while (m/(\@value\{([a-zA-Z0-9_-]+)\})/g) {
 	if (! exists $defs{$2}) {
 	    print STDERR "Option $2 not defined\n";
 	    s/\Q$1\E//;
 	} else {
 	    $value = $defs{$2};
 	    s/\Q$1\E/$value/;
 	}
     }

     # Formatting commands.
     # Temporary escape for @r.
     s/\@r\{([^\}]*)\}/R<$1>/g;
     s/\@sc\{([^\}]*)\}/\U$1/g;
     s/\@(?:dfn|var|emph|cite|i)\{([^\}]*)\}/I<$1>/g;
     s/\@(?:code|kbd)\{([^\}]*)\}/C<$1>/g;
     s/\@(?:samp|strong|key|option|env|command|b)\{([^\}]*)\}/B<$1>/g;
     s/\@acronym\{([^\}]*)\}/\U$1/g;
     s/\@file\{([^\}]*)\}/F<$1>/g;
     s/\@w\{([^\}]*)\}/S<$1>/g;
     s/\@(?:dmn|math)\{([^\}]*)\}/$1/g;
     s/\@\///g;
     s/\@t\{([^\}]*)\}/$1/g;

     # keep references of the form @ref{...}, print them bold
     s/\@(?:ref)\{([^\}]*)\}/B<$1>/g;

     # Change double single quotes to double quotes.
     s/''/"/g;
     s/``/"/g;

     # Cross references are thrown away, as are @noindent and @refill.
     # (@noindent is impossible in .pod, and @refill is unnecessary.)
     # @* is also impossible in .pod; we discard it and any newline that
     # follows it.  Similarly, our macro @gol must be discarded.

     s/\(?\@xref\{(?:[^\}]*)\}(?:[^.<]|(?:<[^<>]*>))*\.\)?//g;
     s/\s+\(\@pxref\{(?:[^\}]*)\}\)//g;
     s/;\s+\@pxref\{(?:[^\}]*)\}//g;
     s/\@noindent\s*//g;
     s/\@refill//g;
     s/\@gol//g;
     s/\@\*\s*\n?//g;

     # Anchors are thrown away
     s/\@anchor\{(?:[^\}]*)\}//g;

     # @uref can take one, two, or three arguments, with different
     # semantics each time.  @url and @email are just like @uref with
     # one argument, for our purposes.
     s/\@(?:uref|url|email)\{([^\},]*)\}/&lt;B<$1>&gt;/g;
     s/\@uref\{([^\},]*),([^\},]*)\}/$2 (C<$1>)/g;
     s/\@uref\{([^\},]*),([^\},]*),([^\},]*)\}/$3/g;

     # Handle gccoptlist here, so it can contain the above formatting
     # commands.
     s/\@gccoptlist\{([^\}]*)\}/B<$1>/g;

     # Un-escape <> at this point.
     s/&LT;/</g;
     s/&GT;/>/g;

     # Now un-nest all B<>, I<>, R<>.  Theoretically we could have
     # indefinitely deep nesting; in practice, one level suffices.
     1 while s/([BIR])<([^<>]*)([BIR])<([^<>]*)>/$1<$2>$3<$4>$1</g;

     # Replace R<...> with bare ...; eliminate empty markup, B<>;
     # shift white space at the ends of [BI]<...> expressions outside
     # the expression.
     s/R<([^<>]*)>/$1/g;
     s/[BI]<>//g;
     s/([BI])<(\s+)([^>]+)>/$2$1<$3>/g;
     s/([BI])<([^>]+?)(\s+)>/$1<$2>$3/g;

     # Extract footnotes.  This has to be done after all other
     # processing because otherwise the regexp will choke on formatting
     # inside @footnote.
     while (/\@footnote/g) {
 	s/\@footnote\{([^\}]+)\}/[$fnno]/;
 	add_footnote($1, $fnno);
 	$fnno++;
     }

     return $_;
 }

 sub unmunge
 {
     # Replace escaped symbols with their equivalents.
     local $_ = $_[0];

     s/&(.)grave;/E<$1grave>/g;
     s/&lt;/E<lt>/g;
     s/&gt;/E<gt>/g;
     s/&lbrace;/\{/g;
     s/&rbrace;/\}/g;
     s/&at;/\@/g;
     s/&amp;/&/g;
     return $_;
 }

 sub add_footnote
 {
     unless (exists $sects{FOOTNOTES}) {
 	$sects{FOOTNOTES} = "\n=over 4\n\n";
     }

     $sects{FOOTNOTES} .= "=item $fnno.\n\n"; $fnno++;
     $sects{FOOTNOTES} .= $_[0];
     $sects{FOOTNOTES} .= "\n\n";
 }

 # stolen from Symbol.pm
 {
     my $genseq = 0;
     sub gensym
     {
 	my $name = "GEN" . $genseq++;
 	my $ref = \*{$name};
 	delete $::{$name};
 	return $ref;
     }
 }
	#! /usr/bin/perl -w

	# Copyright (C) 1999-2014 Free Software Foundation, Inc.

	# This file is part of GCC.

	# GCC is free software; you can redistribute it and/or modify
	# it under the terms of the GNU General Public License as published by
	# the Free Software Foundation; either version 3, or (at your option)
	# any later version.

	# GCC is distributed in the hope that it will be useful,
	# but WITHOUT ANY WARRANTY; without even the implied warranty of
	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	# GNU General Public License for more details.

	# You should have received a copy of the GNU General Public License
	# along with GCC; see the file COPYING. If not, write to
	# the Free Software Foundation, 51 Franklin Street, Fifth Floor,
	# Boston MA 02110-1301, USA.

	# This does trivial (and I mean _trivial_) conversion of Texinfo
	# markup to Perl POD format. It's intended to be used to extract
	# something suitable for a manpage from a Texinfo document.

	$output = 0;
	$skipping = 0;
	%sects = ();
	$section = "";
	@icstack = ();
	@endwstack = ();
	@skstack = ();
	@instack = ();
	$shift = "";
	%defs = ();
	$fnno = 1;
	$inf = "";
	$ibase = "";
	@ipath = ();

	while ($_ = shift) {
	if (/^-D(.*)$/) {
	if ($1 ne "") {
	$flag = $1;
	} else {
	$flag = shift;
	}
	$value = "";
	($flag, $value) = ($flag =~ /^([^=]+)(?:=(.+))?/);
	die "no flag specified for -D\n"
	unless $flag ne "";
	die "flags may only contain letters, digits, hyphens, dashes and underscores\n"
	unless $flag =~ /^[a-zA-Z0-9_-]+$/;
	$defs{$flag} = $value;
	} elsif (/^-I(.*)$/) {
	if ($1 ne "") {
	$flag = $1;
	} else {
	$flag = shift;
	}
	push (@ipath, $flag);
	} elsif (/^-/) {
	usage();
	} else {
	$in = $_, next unless defined $in;
	$out = $_, next unless defined $out;
	usage();
	}
	}

	if (defined $in) {
	$inf = gensym();
	open($inf, "<$in") or die "opening \"$in\": $!\n";
	$ibase = $1 if $in =~ m\|^(.+)/[^/]+$\|;
	} else {
	$inf = \*STDIN;
	}

	if (defined $out) {
	open(STDOUT, ">$out") or die "opening \"$out\": $!\n";
	}

	while(defined $inf) {
	while(<$inf>) {
	# Certain commands are discarded without further processing.
	/^\@(?:
	[a-z]+index # @*index: useful only in complete manual
	\|need # @need: useful only in printed manual
	\|(?:end\s+)?group # @group .. @end group: ditto
	\|page # @page: ditto
	\|node # @node: useful only in .info file
	\|(?:end\s+)?ifnottex # @ifnottex .. @end ifnottex: use contents
	)\b/x and next;

	chomp;

	# Look for filename and title markers.
	/^\@setfilename\s+([^.]+)/ and $fn = $1, next;
	/^\@settitle\s+([^.]+)/ and $tl = postprocess($1), next;

	# Identify a man title but keep only the one we are interested in.
	/^\@c\s+man\s+title\s+([A-Za-z0-9-]+)\s+(.+)/ and do {
	if (exists $defs{$1}) {
	$fn = $1;
	$tl = postprocess($2);
	}
	next;
	};

	# Look for blocks surrounded by @c man begin SECTION ... @c man end.
	# This really oughta be @ifman ... @end ifman and the like, but such
	# would require rev'ing all other Texinfo translators.
	/^\@c\s+man\s+begin\s+([A-Z]+)\s+([A-Za-z0-9-]+)/ and do {
	$output = 1 if exists $defs{$2};
	$sect = $1;
	next;
	};
	/^\@c\s+man\s+begin\s+([A-Z]+)/ and $sect = $1, $output = 1, next;
	/^\@c\s+man\s+end/ and do {
	$sects{$sect} = "" unless exists $sects{$sect};
	$sects{$sect} .= postprocess($section);
	$section = "";
	$output = 0;
	next;
	};

	# handle variables
	/^\@set\s+([a-zA-Z0-9_-]+)\s(.)$/ and do {
	$defs{$1} = $2;
	next;
	};
	/^\@clear\s+([a-zA-Z0-9_-]+)/ and do {
	delete $defs{$1};
	next;
	};

	next unless $output;

	# Discard comments. (Can't do it above, because then we'd never see
	# @c man lines.)
	/^\@c\b/ and next;

	# End-block handler goes up here because it needs to operate even
	# if we are skipping.
	/^\@end\s+([a-z]+)/ and do {
	# Ignore @end foo, where foo is not an operation which may
	# cause us to skip, if we are presently skipping.
	my $ended = $1;
	next if $skipping && $ended !~ /^(?:ifset\|ifclear\|ignore\|menu\|iftex\|copying)$/;

	die "\@end $ended without \@$ended at line $.\n" unless defined $endw;
	die "\@$endw ended by \@end $ended at line $.\n" unless $ended eq $endw;

	$endw = pop @endwstack;

	if ($ended =~ /^(?:ifset\|ifclear\|ignore\|menu\|iftex)$/) {
	$skipping = pop @skstack;
	next;
	} elsif ($ended =~ /^(?:example\|smallexample\|display)$/) {
	$shift = "";
	$_ = ""; # need a paragraph break
	} elsif ($ended =~ /^(?:itemize\|enumerate\|[fv]?table)$/) {
	$_ = "\n=back\n";
	$ic = pop @icstack;
	} elsif ($ended eq "multitable") {
	$_ = "\n=back\n";
	} else {
	die "unknown command \@end $ended at line $.\n";
	}
	};

	# We must handle commands which can cause skipping even while we
	# are skipping, otherwise we will not process nested conditionals
	# correctly.
	/^\@ifset\s+([a-zA-Z0-9_-]+)/ and do {
	push @endwstack, $endw;
	push @skstack, $skipping;
	$endw = "ifset";
	$skipping = 1 unless exists $defs{$1};
	next;
	};

	/^\@ifclear\s+([a-zA-Z0-9_-]+)/ and do {
	push @endwstack, $endw;
	push @skstack, $skipping;
	$endw = "ifclear";
	$skipping = 1 if exists $defs{$1};
	next;
	};

	/^\@(ignore\|menu\|iftex\|copying)\b/ and do {
	push @endwstack, $endw;
	push @skstack, $skipping;
	$endw = $1;
	$skipping = 1;
	next;
	};

	next if $skipping;

	# Character entities. First the ones that can be replaced by raw text
	# or discarded outright:
	s/\@copyright\{\}/(c)/g;
	s/\@dots\{\}/.../g;
	s/\@enddots\{\}/..../g;
	s/\@([.!? ])/$1/g;
	s/\@[:-]//g;
	s/\@bullet(?:\{\})?/*/g;
	s/\@TeX\{\}/TeX/g;
	s/\@pounds\{\}/\#/g;
	s/\@minus(?:\{\})?/-/g;
	s/\\,/,/g;

	# Now the ones that have to be replaced by special escapes
	# (which will be turned back into text by unmunge())
	# Replace @@ before @{ and @} in order to parse @samp{@@} correctly.
	s/&/&/g;
	s/\@\@/&at;/g;
	s/\@\{/{/g;
	s/\@\}/}/g;
	s/\@`\{(.)\}/&$1grave;/g;

	# Inside a verbatim block, handle @var, @samp and @url specially.
	if ($shift ne "") {
	s/\@var\{([^\}]*)\}/<$1>/g;
	s/\@samp\{([^\}]*)\}/"$1"/g;
	s/\@url\{([^\}]*)\}/<$1>/g;
	}

	# POD doesn't interpret E<> inside a verbatim block.
	if ($shift eq "") {
	s/</</g;
	s/>/>/g;
	} else {
	s/</&LT;/g;
	s/>/&GT;/g;
	}

	# Single line command handlers.

	/^\@include\s+(.+)$/ and do {
	push @instack, $inf;
	$inf = gensym();
	$file = postprocess($1);

	# Try cwd and $ibase, then explicit -I paths.
	$done = 0;
	foreach $path ("", $ibase, @ipath) {
	$mypath = $file;
	$mypath = $path . "/" . $mypath if ($path ne "");
	open($inf, "<" . $mypath) and ($done = 1, last);
	}
	die "cannot find $file" if !$done;
	next;
	};

	/^\@(?:section\|unnumbered\|unnumberedsec\|center\|heading)\s+(.+)$/
	and $_ = "\n=head2 $1\n";
	/^\@subsection\s+(.+)$/
	and $_ = "\n=head3 $1\n";
	/^\@subsubsection\s+(.+)$/
	and $_ = "\n=head4 $1\n";

	# Block command handlers:
	/^\@itemize(?:\s+(\@[a-z]+\|\*\|-))?/ and do {
	push @endwstack, $endw;
	push @icstack, $ic;
	if (defined $1) {
	$ic = $1;
	} else {
	$ic = '*';
	}
	$_ = "\n=over 4\n";
	$endw = "itemize";
	};

	/^\@enumerate(?:\s+([a-zA-Z0-9]+))?/ and do {
	push @endwstack, $endw;
	push @icstack, $ic;
	if (defined $1) {
	$ic = $1 . ".";
	} else {
	$ic = "1.";
	}
	$_ = "\n=over 4\n";
	$endw = "enumerate";
	};

	/^\@multitable\s.*/ and do {
	push @endwstack, $endw;
	$endw = "multitable";
	$_ = "\n=over 4\n";
	};

	/^\@([fv]?table)\s+(\@[a-z]+)/ and do {
	push @endwstack, $endw;
	push @icstack, $ic;
	$endw = $1;
	$ic = $2;
	$ic =~ s/\@(?:samp\|strong\|key\|gcctabopt\|env)/B/;
	$ic =~ s/\@(?:code\|kbd)/C/;
	$ic =~ s/\@(?:dfn\|var\|emph\|cite\|i)/I/;
	$ic =~ s/\@(?:file)/F/;
	$ic =~ s/\@(?:asis)//;
	$_ = "\n=over 4\n";
	};

	/^\@((?:small)?example\|display)/ and do {
	push @endwstack, $endw;
	$endw = $1;
	$shift = "\t";
	$_ = ""; # need a paragraph break
	};

	/^\@item\s+(.\S)\s$/ and $endw eq "multitable" and do {
	@columns = ();
	for $column (split (/\s\@tab\s/, $1)) {
	# @strong{...} is used a @headitem work-alike
	$column =~ s/^\@strong\{(.*)\}$/$1/;
	push @columns, $column;
	}
	$_ = "\n=item ".join (" : ", @columns)."\n";
	};

	/^\@itemx?\s*(.+)?$/ and do {
	if (defined $1) {
	if ($ic) {
	if ($endw eq "enumerate") {
	$_ = "\n=item $ic $1\n";
	$ic =~ s/(\d+)/$1 + 1/eg;
	} else {
	# Entity escapes prevent munging by the <>
	# processing below.
	$_ = "\n=item $ic\&LT;$1\&GT;\n";
	}
	} else {
	$_ = "\n=item $1\n";
	}
	} else {
	$_ = "\n=item Z\&LT;\&GT;$ic\n";
	$ic =~ y/A-Ya-y/B-Zb-z/;
	$ic =~ s/(\d+)/$1 + 1/eg;
	}
	};

	$section .= $shift.$_."\n";
	}
	# End of current file.
	close($inf);
	$inf = pop @instack;
	}

	die "No filename or title\n" unless defined $fn && defined $tl;

	$sects{NAME} = "$fn \- $tl\n";
	$sects{FOOTNOTES} .= "=back\n" if exists $sects{FOOTNOTES};

	for $sect (qw(NAME SYNOPSIS DESCRIPTION OPTIONS ENVIRONMENT FILES
	BUGS NOTES FOOTNOTES SEEALSO AUTHOR COPYRIGHT)) {
	if(exists $sects{$sect}) {
	$head = $sect;
	$head =~ s/SEEALSO/SEE ALSO/;
	print "=head1 $head\n\n";
	print scalar unmunge ($sects{$sect});
	print "\n";
	}
	}

	sub usage
	{
	die "usage: $0 [-D toggle...] [infile [outfile]]\n";
	}

	sub postprocess
	{
	local $_ = $_[0];

	# @value{foo} is replaced by whatever 'foo' is defined as.
	while (m/(\@value\{([a-zA-Z0-9_-]+)\})/g) {
	if (! exists $defs{$2}) {
	print STDERR "Option $2 not defined\n";
	s/\Q$1\E//;
	} else {
	$value = $defs{$2};
	s/\Q$1\E/$value/;
	}
	}

	# Formatting commands.
	# Temporary escape for @r.
	s/\@r\{([^\}]*)\}/R<$1>/g;
	s/\@sc\{([^\}]*)\}/\U$1/g;
	s/\@(?:dfn\|var\|emph\|cite\|i)\{([^\}]*)\}/I<$1>/g;
	s/\@(?:code\|kbd)\{([^\}]*)\}/C<$1>/g;
	s/\@(?:samp\|strong\|key\|option\|env\|command\|b)\{([^\}]*)\}/B<$1>/g;
	s/\@acronym\{([^\}]*)\}/\U$1/g;
	s/\@file\{([^\}]*)\}/F<$1>/g;
	s/\@w\{([^\}]*)\}/S<$1>/g;
	s/\@(?:dmn\|math)\{([^\}]*)\}/$1/g;
	s/\@\///g;
	s/\@t\{([^\}]*)\}/$1/g;

	# keep references of the form @ref{...}, print them bold
	s/\@(?:ref)\{([^\}]*)\}/B<$1>/g;

	# Change double single quotes to double quotes.
	s/''/"/g;
	s/``/"/g;

	# Cross references are thrown away, as are @noindent and @refill.
	# (@noindent is impossible in .pod, and @refill is unnecessary.)
	# @* is also impossible in .pod; we discard it and any newline that
	# follows it. Similarly, our macro @gol must be discarded.

	s/\(?\@xref\{(?:[^\}])\}(?:[^.<]\|(?:<[^<>]>))*\.\)?//g;
	s/\s+\(\@pxref\{(?:[^\}]*)\}\)//g;
	s/;\s+\@pxref\{(?:[^\}]*)\}//g;
	s/\@noindent\s*//g;
	s/\@refill//g;
	s/\@gol//g;
	s/\@\\s\n?//g;

	# Anchors are thrown away
	s/\@anchor\{(?:[^\}]*)\}//g;

	# @uref can take one, two, or three arguments, with different
	# semantics each time. @url and @email are just like @uref with
	# one argument, for our purposes.
	s/\@(?:uref\|url\|email)\{([^\},]*)\}/<B<$1>>/g;
	s/\@uref\{([^\},]),([^\},])\}/$2 (C<$1>)/g;
	s/\@uref\{([^\},]),([^\},]),([^\},]*)\}/$3/g;

	# Handle gccoptlist here, so it can contain the above formatting
	# commands.
	s/\@gccoptlist\{([^\}]*)\}/B<$1>/g;

	# Un-escape <> at this point.
	s/&LT;/</g;
	s/&GT;/>/g;

	# Now un-nest all B<>, I<>, R<>. Theoretically we could have
	# indefinitely deep nesting; in practice, one level suffices.
	1 while s/([BIR])<([^<>])([BIR])<([^<>])>/$1<$2>$3<$4>$1</g;

	# Replace R<...> with bare ...; eliminate empty markup, B<>;
	# shift white space at the ends of [BI]<...> expressions outside
	# the expression.
	s/R<([^<>]*)>/$1/g;
	s/[BI]<>//g;
	s/([BI])<(\s+)([^>]+)>/$2$1<$3>/g;
	s/([BI])<([^>]+?)(\s+)>/$1<$2>$3/g;

	# Extract footnotes. This has to be done after all other
	# processing because otherwise the regexp will choke on formatting
	# inside @footnote.
	while (/\@footnote/g) {
	s/\@footnote\{([^\}]+)\}/[$fnno]/;
	add_footnote($1, $fnno);
	$fnno++;
	}

	return $_;
	}

	sub unmunge
	{
	# Replace escaped symbols with their equivalents.
	local $_ = $_[0];

	s/&(.)grave;/E<$1grave>/g;
	s/</E<lt>/g;
	s/>/E<gt>/g;
	s/{/\{/g;
	s/}/\}/g;
	s/&at;/\@/g;
	s/&/&/g;
	return $_;
	}

	sub add_footnote
	{
	unless (exists $sects{FOOTNOTES}) {
	$sects{FOOTNOTES} = "\n=over 4\n\n";
	}

	$sects{FOOTNOTES} .= "=item $fnno.\n\n"; $fnno++;
	$sects{FOOTNOTES} .= $_[0];
	$sects{FOOTNOTES} .= "\n\n";
	}

	# stolen from Symbol.pm
	{
	my $genseq = 0;
	sub gensym
	{
	my $name = "GEN" . $genseq++;
	my $ref = \*{$name};
	delete $::{$name};
	return $ref;
	}
	}