escape ampersands in <pre> sections

[perl5.git] / lib / Pod / Html.pm

package Pod::Html;

use Pod::Functions;
use Getopt::Long;	# package for handling command-line parameters
use File::Spec::Unix;
require Exporter;
use vars qw($VERSION);
$VERSION = 1.02;
@ISA = Exporter;
@EXPORT = qw(pod2html htmlify);
use Cwd;

use Carp;

use locale;	# make \w work right in non-ASCII lands

use strict;

use Config;

=head1 NAME

Pod::Html - module to convert pod files to HTML

=head1 SYNOPSIS

    use Pod::Html;
    pod2html([options]);

=head1 DESCRIPTION

Converts files from pod format (see L<perlpod>) to HTML format.  It
can automatically generate indexes and cross-references, and it keeps
a cache of things it knows how to cross-reference.

=head1 ARGUMENTS

Pod::Html takes the following arguments:

=over 4

=item help

    --help

Displays the usage message.

=item htmldir

    --htmldir=name

Sets the directory in which the resulting HTML file is placed.  This
is used to generate relative links to other files. Not passing this
causes all links to be absolute, since this is the value that tells
Pod::Html the root of the documentation tree.

=item htmlroot

    --htmlroot=name

Sets the base URL for the HTML files.  When cross-references are made,
the HTML root is prepended to the URL.

=item infile

    --infile=name

Specify the pod file to convert.  Input is taken from STDIN if no
infile is specified.

=item outfile

    --outfile=name

Specify the HTML file to create.  Output goes to STDOUT if no outfile
is specified.

=item podroot

    --podroot=name

Specify the base directory for finding library pods.

=item podpath

    --podpath=name:...:name

Specify which subdirectories of the podroot contain pod files whose
HTML converted forms can be linked-to in cross-references.

=item libpods

    --libpods=name:...:name

List of page names (eg, "perlfunc") which contain linkable C<=item>s.

=item netscape

    --netscape

Use Netscape HTML directives when applicable.

=item nonetscape

    --nonetscape

Do not use Netscape HTML directives (default).

=item index

    --index

Generate an index at the top of the HTML file (default behaviour).

=item noindex

    --noindex

Do not generate an index at the top of the HTML file.


=item recurse

    --recurse

Recurse into subdirectories specified in podpath (default behaviour).

=item norecurse

    --norecurse

Do not recurse into subdirectories specified in podpath.

=item title

    --title=title

Specify the title of the resulting HTML file.

=item verbose

    --verbose

Display progress messages.

=back

=head1 EXAMPLE

    pod2html("pod2html",
	     "--podpath=lib:ext:pod:vms", 
	     "--podroot=/usr/src/perl",
	     "--htmlroot=/perl/nmanual",
	     "--libpods=perlfunc:perlguts:perlvar:perlrun:perlop",
	     "--recurse",
	     "--infile=foo.pod",
	     "--outfile=/perl/nmanual/foo.html");

=head1 AUTHOR

Tom Christiansen, E<lt>tchrist@perl.comE<gt>.

=head1 BUGS

Has trouble with C<> etc in = commands.

=head1 SEE ALSO

L<perlpod>

=head1 COPYRIGHT

This program is distributed under the Artistic License.

=cut

my $dircache = "pod2html-dircache";
my $itemcache = "pod2html-itemcache";

my @begin_stack = ();		# begin/end stack

my @libpods = ();	    	# files to search for links from C<> directives
my $htmlroot = "/";	    	# http-server base directory from which all
				#   relative paths in $podpath stem.
my $htmldir = "";		# The directory to which the html pages
				# will (eventually) be written.
my $htmlfile = "";		# write to stdout by default
my $htmlfileurl = "" ;		# The url that other files would use to
				# refer to this file.  This is only used
				# to make relative urls that point to
				# other files.
my $podfile = "";		# read from stdin by default
my @podpath = ();		# list of directories containing library pods.
my $podroot = ".";		# filesystem base directory from which all
				#   relative paths in $podpath stem.
my $recurse = 1;		# recurse on subdirectories in $podpath.
my $verbose = 0;		# not verbose by default
my $doindex = 1;   	    	# non-zero if we should generate an index
my $listlevel = 0;		# current list depth
my @listitem = ();		# stack of HTML commands to use when a =item is
				#   encountered.  the top of the stack is the
				#   current list.
my @listdata = ();		# similar to @listitem, but for the text after
				#   an =item
my @listend = ();		# similar to @listitem, but the text to use to
				#   end the list.
my $ignore = 1;			# whether or not to format text.  we don't
				#   format text until we hit our first pod
				#   directive.

my %items_named = ();		# for the multiples of the same item in perlfunc
my @items_seen = ();
my $netscape = 0;		# whether or not to use netscape directives.
my $title;			# title to give the pod(s)
my $top = 1;			# true if we are at the top of the doc.  used
				#   to prevent the first <HR> directive.
my $paragraph;			# which paragraph we're processing (used
				#   for error messages)
my %pages = ();			# associative array used to find the location
				#   of pages referenced by L<> links.
my %sections = ();		# sections within this page
my %items = ();			# associative array used to find the location
				#   of =item directives referenced by C<> links
my $Is83;                       # is dos with short filenames (8.3)

sub init_globals {
$dircache = "pod2html-dircache";
$itemcache = "pod2html-itemcache";

@begin_stack = ();		# begin/end stack

@libpods = ();	    	# files to search for links from C<> directives
$htmlroot = "/";	    	# http-server base directory from which all
				#   relative paths in $podpath stem.
$htmlfile = "";		# write to stdout by default
$podfile = "";		# read from stdin by default
@podpath = ();		# list of directories containing library pods.
$podroot = ".";		# filesystem base directory from which all
				#   relative paths in $podpath stem.
$recurse = 1;		# recurse on subdirectories in $podpath.
$verbose = 0;		# not verbose by default
$doindex = 1;   	    	# non-zero if we should generate an index
$listlevel = 0;		# current list depth
@listitem = ();		# stack of HTML commands to use when a =item is
				#   encountered.  the top of the stack is the
				#   current list.
@listdata = ();		# similar to @listitem, but for the text after
				#   an =item
@listend = ();		# similar to @listitem, but the text to use to
				#   end the list.
$ignore = 1;			# whether or not to format text.  we don't
				#   format text until we hit our first pod
				#   directive.

@items_seen = ();
%items_named = ();
$netscape = 0;		# whether or not to use netscape directives.
$title = '';			# title to give the pod(s)
$top = 1;			# true if we are at the top of the doc.  used
				#   to prevent the first <HR> directive.
$paragraph = '';			# which paragraph we're processing (used
				#   for error messages)
%sections = ();		# sections within this page

# These are not reinitialised here but are kept as a cache.
# See get_cache and related cache management code.
#%pages = ();			# associative array used to find the location
				#   of pages referenced by L<> links.
#%items = ();			# associative array used to find the location
				#   of =item directives referenced by C<> links
$Is83=$^O eq 'dos';
}

sub pod2html {
    local(@ARGV) = @_;
    local($/);
    local $_;

    init_globals();

    $Is83 = 0 if (defined (&Dos::UseLFN) && Dos::UseLFN());

    # cache of %pages and %items from last time we ran pod2html

    #undef $opt_help if defined $opt_help;

    # parse the command-line parameters
    parse_command_line();

    # set some variables to their default values if necessary
    local *POD;
    unless (@ARGV && $ARGV[0]) { 
	$podfile  = "-" unless $podfile;	# stdin
	open(POD, "<$podfile")
		|| die "$0: cannot open $podfile file for input: $!\n";
    } else {
	$podfile = $ARGV[0];  # XXX: might be more filenames
	*POD = *ARGV;
    } 
    $htmlfile = "-" unless $htmlfile;	# stdout
    $htmlroot = "" if $htmlroot eq "/";	# so we don't get a //
    $htmldir =~ s#/$## ;                # so we don't get a //
    if (  $htmlroot eq ''
       && defined( $htmldir ) 
       && $htmldir ne ''
       && substr( $htmlfile, 0, length( $htmldir ) ) eq $htmldir 
       ) 
    {
	# Set the 'base' url for this file, so that we can use it
	# as the location from which to calculate relative links 
	# to other files. If this is '', then absolute links will
	# be used throughout.
        $htmlfileurl= "$htmldir/" . substr( $htmlfile, length( $htmldir ) + 1);
    }

    # read the pod a paragraph at a time
    warn "Scanning for sections in input file(s)\n" if $verbose;
    $/ = "";
    my @poddata  = <POD>;
    close(POD);

    # scan the pod for =head[1-6] directives and build an index
    my $index = scan_headings(\%sections, @poddata);

    unless($index) {
	warn "No pod in $podfile\n" if $verbose;
	return;
    }

    # open the output file
    open(HTML, ">$htmlfile")
	    || die "$0: cannot open $htmlfile file for output: $!\n";

    # put a title in the HTML file if one wasn't specified
    if ($title eq '') {
	TITLE_SEARCH: {
	    for (my $i = 0; $i < @poddata; $i++) { 
		if ($poddata[$i] =~ /^=head1\s*NAME\b/m) {
		    for my $para ( @poddata[$i, $i+1] ) { 
			last TITLE_SEARCH
			    if ($title) = $para =~ /(\S+\s+-+.*\S)/s;
		    }
		} 

	    } 
	}
    }
    if (!$title and $podfile =~ /\.pod$/) {
	# probably a split pod so take first =head[12] as title
	for (my $i = 0; $i < @poddata; $i++) { 
	    last if ($title) = $poddata[$i] =~ /^=head[12]\s*(.*)/;
	} 
	warn "adopted '$title' as title for $podfile\n"
	    if $verbose and $title;
    } 
    if ($title) {
	$title =~ s/\s*\(.*\)//;
    } else {
	warn "$0: no title for $podfile";
	$podfile =~ /^(.*)(\.[^.\/]+)?$/;
	$title = ($podfile eq "-" ? 'No Title' : $1);
	warn "using $title" if $verbose;
    }
    print HTML <<END_OF_HEAD;
<HTML>
<HEAD>
<TITLE>$title</TITLE>
<LINK REV="made" HREF="mailto:$Config{perladmin}">
</HEAD>

<BODY>

END_OF_HEAD

    # load/reload/validate/cache %pages and %items
    get_cache($dircache, $itemcache, \@podpath, $podroot, $recurse);

    # scan the pod for =item directives
    scan_items("", \%items, @poddata);

    # put an index at the top of the file.  note, if $doindex is 0 we
    # still generate an index, but surround it with an html comment.
    # that way some other program can extract it if desired.
    $index =~ s/--+/-/g;
    print HTML "<!-- INDEX BEGIN -->\n";
    print HTML "<!--\n" unless $doindex;
    print HTML $index;
    print HTML "-->\n" unless $doindex;
    print HTML "<!-- INDEX END -->\n\n";
    print HTML "<HR>\n" if $doindex;

    # now convert this file
    warn "Converting input file\n" if $verbose;
    foreach my $i (0..$#poddata) {
	$_ = $poddata[$i];
	$paragraph = $i+1;
	if (/^(=.*)/s) {	# is it a pod directive?
	    $ignore = 0;
	    $_ = $1;
	    if (/^=begin\s+(\S+)\s*(.*)/si) {# =begin
		process_begin($1, $2);
	    } elsif (/^=end\s+(\S+)\s*(.*)/si) {# =end
		process_end($1, $2);
	    } elsif (/^=cut/) {			# =cut
		process_cut();
	    } elsif (/^=pod/) {			# =pod
		process_pod();
	    } else {
		next if @begin_stack && $begin_stack[-1] ne 'html';

		if (/^=(head[1-6])\s+(.*\S)/s) {	# =head[1-6] heading
		    process_head($1, $2);
		} elsif (/^=item\s*(.*\S)/sm) {	# =item text
		    process_item($1);
		} elsif (/^=over\s*(.*)/) {		# =over N
		    process_over();
		} elsif (/^=back/) {		# =back
		    process_back();
		} elsif (/^=for\s+(\S+)\s+(.*)/si) {# =for
		    process_for($1,$2);
		} else {
		    /^=(\S*)\s*/;
		    warn "$0: $podfile: unknown pod directive '$1' in "
		       . "paragraph $paragraph.  ignoring.\n";
		}
	    }
	    $top = 0;
	}
	else {
	    next if $ignore;
	    next if @begin_stack && $begin_stack[-1] ne 'html';
	    my $text = $_;
	    process_text(\$text, 1);
	    print HTML "<P>\n$text";
	}
    }

    # finish off any pending directives
    finish_list();
    print HTML <<END_OF_TAIL;
</BODY>

</HTML>
END_OF_TAIL

    # close the html file
    close(HTML);

    warn "Finished\n" if $verbose;
}

##############################################################################

my $usage;			# see below
sub usage {
    my $podfile = shift;
    warn "$0: $podfile: @_\n" if @_;
    die $usage;
}

$usage =<<END_OF_USAGE;
Usage:  $0 --help --htmlroot=<name> --infile=<name> --outfile=<name>
           --podpath=<name>:...:<name> --podroot=<name>
           --libpods=<name>:...:<name> --recurse --verbose --index
           --netscape --norecurse --noindex

  --flush      - flushes the item and directory caches.
  --help       - prints this message.
  --htmlroot   - http-server base directory from which all relative paths
                 in podpath stem (default is /).
  --index      - generate an index at the top of the resulting html
                 (default).
  --infile     - filename for the pod to convert (input taken from stdin
                 by default).
  --libpods    - colon-separated list of pages to search for =item pod
                 directives in as targets of C<> and implicit links (empty
                 by default).  note, these are not filenames, but rather
                 page names like those that appear in L<> links.
  --netscape   - will use netscape html directives when applicable.
  --nonetscape - will not use netscape directives (default).
  --outfile    - filename for the resulting html file (output sent to
                 stdout by default).
  --podpath    - colon-separated list of directories containing library
                 pods.  empty by default.
  --podroot    - filesystem base directory from which all relative paths
                 in podpath stem (default is .).
  --noindex    - don't generate an index at the top of the resulting html.
  --norecurse  - don't recurse on those subdirectories listed in podpath.
  --recurse    - recurse on those subdirectories listed in podpath
                 (default behavior).
  --title      - title that will appear in resulting html file.
  --verbose    - self-explanatory

END_OF_USAGE

sub parse_command_line {
    my ($opt_flush,$opt_help,$opt_htmldir,$opt_htmlroot,$opt_index,$opt_infile,$opt_libpods,$opt_netscape,$opt_outfile,$opt_podpath,$opt_podroot,$opt_norecurse,$opt_recurse,$opt_title,$opt_verbose);
    my $result = GetOptions(
			    'flush'      => \$opt_flush,
			    'help'       => \$opt_help,
			    'htmldir=s'  => \$opt_htmldir,
			    'htmlroot=s' => \$opt_htmlroot,
			    'index!'     => \$opt_index,
			    'infile=s'   => \$opt_infile,
			    'libpods=s'  => \$opt_libpods,
			    'netscape!'  => \$opt_netscape,
			    'outfile=s'  => \$opt_outfile,
			    'podpath=s'  => \$opt_podpath,
			    'podroot=s'  => \$opt_podroot,
			    'norecurse'  => \$opt_norecurse,
			    'recurse!'   => \$opt_recurse,
			    'title=s'    => \$opt_title,
			    'verbose'    => \$opt_verbose,
			   );
    usage("-", "invalid parameters") if not $result;

    usage("-") if defined $opt_help;	# see if the user asked for help
    $opt_help = "";			# just to make -w shut-up.

    $podfile  = $opt_infile if defined $opt_infile;
    $htmlfile = $opt_outfile if defined $opt_outfile;
    $htmldir  = $opt_htmldir if defined $opt_outfile;

    @podpath  = split(":", $opt_podpath) if defined $opt_podpath;
    @libpods  = split(":", $opt_libpods) if defined $opt_libpods;

    warn "Flushing item and directory caches\n"
	if $opt_verbose && defined $opt_flush;
    unlink($dircache, $itemcache) if defined $opt_flush;

    $htmlroot = $opt_htmlroot if defined $opt_htmlroot;
    $podroot  = $opt_podroot if defined $opt_podroot;

    $doindex  = $opt_index if defined $opt_index;
    $recurse  = $opt_recurse if defined $opt_recurse;
    $title    = $opt_title if defined $opt_title;
    $verbose  = defined $opt_verbose ? 1 : 0;
    $netscape = $opt_netscape if defined $opt_netscape;
}


my $saved_cache_key;

sub get_cache {
    my($dircache, $itemcache, $podpath, $podroot, $recurse) = @_;
    my @cache_key_args = @_;

    # A first-level cache:
    # Don't bother reading the cache files if they still apply
    # and haven't changed since we last read them.

    my $this_cache_key = cache_key(@cache_key_args);

    return if $saved_cache_key and $this_cache_key eq $saved_cache_key;

    # load the cache of %pages and %items if possible.  $tests will be
    # non-zero if successful.
    my $tests = 0;
    if (-f $dircache && -f $itemcache) {
	warn "scanning for item cache\n" if $verbose;
	$tests = load_cache($dircache, $itemcache, $podpath, $podroot);
    }

    # if we didn't succeed in loading the cache then we must (re)build
    #  %pages and %items.
    if (!$tests) {
	warn "scanning directories in pod-path\n" if $verbose;
	scan_podpath($podroot, $recurse, 0);
    }
    $saved_cache_key = cache_key(@cache_key_args);
}

sub cache_key {
    my($dircache, $itemcache, $podpath, $podroot, $recurse) = @_;
    return join('!', $dircache, $itemcache, $recurse,
	@$podpath, $podroot, stat($dircache), stat($itemcache));
}

#
# load_cache - tries to find if the caches stored in $dircache and $itemcache
#  are valid caches of %pages and %items.  if they are valid then it loads
#  them and returns a non-zero value.
#

sub load_cache {
    my($dircache, $itemcache, $podpath, $podroot) = @_;
    my($tests);
    local $_;

    $tests = 0;

    open(CACHE, "<$itemcache") ||
	die "$0: error opening $itemcache for reading: $!\n";
    $/ = "\n";

    # is it the same podpath?
    $_ = <CACHE>;
    chomp($_);
    $tests++ if (join(":", @$podpath) eq $_);

    # is it the same podroot?
    $_ = <CACHE>;
    chomp($_);
    $tests++ if ($podroot eq $_);

    # load the cache if its good
    if ($tests != 2) {
	close(CACHE);
	return 0;
    }

    warn "loading item cache\n" if $verbose;
    while (<CACHE>) {
	/(.*?) (.*)$/;
	$items{$1} = $2;
    }
    close(CACHE);

    warn "scanning for directory cache\n" if $verbose;
    open(CACHE, "<$dircache") ||
	die "$0: error opening $dircache for reading: $!\n";
    $/ = "\n";
    $tests = 0;

    # is it the same podpath?
    $_ = <CACHE>;
    chomp($_);
    $tests++ if (join(":", @$podpath) eq $_);

    # is it the same podroot?
    $_ = <CACHE>;
    chomp($_);
    $tests++ if ($podroot eq $_);

    # load the cache if its good
    if ($tests != 2) {
	close(CACHE);
	return 0;
    }

    warn "loading directory cache\n" if $verbose;
    while (<CACHE>) {
	/(.*?) (.*)$/;
	$pages{$1} = $2;
    }

    close(CACHE);

    return 1;
}

#
# scan_podpath - scans the directories specified in @podpath for directories,
#  .pod files, and .pm files.  it also scans the pod files specified in
#  @libpods for =item directives.
#
sub scan_podpath {
    my($podroot, $recurse, $append) = @_;
    my($pwd, $dir);
    my($libpod, $dirname, $pod, @files, @poddata);

    unless($append) {
	%items = ();
	%pages = ();
    }

    # scan each directory listed in @podpath
    $pwd = getcwd();
    chdir($podroot)
	|| die "$0: error changing to directory $podroot: $!\n";
    foreach $dir (@podpath) {
	scan_dir($dir, $recurse);
    }

    # scan the pods listed in @libpods for =item directives
    foreach $libpod (@libpods) {
	# if the page isn't defined then we won't know where to find it
	# on the system.
	next unless defined $pages{$libpod} && $pages{$libpod};

	# if there is a directory then use the .pod and .pm files within it.
	# NOTE: Only finds the first so-named directory in the tree.
#	if ($pages{$libpod} =~ /([^:]*[^(\.pod|\.pm)]):/) {
	if ($pages{$libpod} =~ /([^:]*(?<!\.pod)(?<!\.pm)):/) {
	    #  find all the .pod and .pm files within the directory
	    $dirname = $1;
	    opendir(DIR, $dirname) ||
		die "$0: error opening directory $dirname: $!\n";
	    @files = grep(/(\.pod|\.pm)$/ && ! -d $_, readdir(DIR));
	    closedir(DIR);

	    # scan each .pod and .pm file for =item directives
	    foreach $pod (@files) {
		open(POD, "<$dirname/$pod") ||
		    die "$0: error opening $dirname/$pod for input: $!\n";
		@poddata = <POD>;
		close(POD);

		scan_items("$dirname/$pod", @poddata);
	    }

	    # use the names of files as =item directives too.
	    foreach $pod (@files) {
		$pod =~ /^(.*)(\.pod|\.pm)$/;
		$items{$1} = "$dirname/$1.html" if $1;
	    }
	} elsif ($pages{$libpod} =~ /([^:]*\.pod):/ ||
		 $pages{$libpod} =~ /([^:]*\.pm):/) {
	    # scan the .pod or .pm file for =item directives
	    $pod = $1;
	    open(POD, "<$pod") ||
		die "$0: error opening $pod for input: $!\n";
	    @poddata = <POD>;
	    close(POD);

	    scan_items("$pod", @poddata);
	} else {
	    warn "$0: shouldn't be here (line ".__LINE__."\n";
	}
    }
    @poddata = ();	# clean-up a bit

    chdir($pwd)
	|| die "$0: error changing to directory $pwd: $!\n";

    # cache the item list for later use
    warn "caching items for later use\n" if $verbose;
    open(CACHE, ">$itemcache") ||
	die "$0: error open $itemcache for writing: $!\n";

    print CACHE join(":", @podpath) . "\n$podroot\n";
    foreach my $key (keys %items) {
	print CACHE "$key $items{$key}\n";
    }

    close(CACHE);

    # cache the directory list for later use
    warn "caching directories for later use\n" if $verbose;
    open(CACHE, ">$dircache") ||
	die "$0: error open $dircache for writing: $!\n";

    print CACHE join(":", @podpath) . "\n$podroot\n";
    foreach my $key (keys %pages) {
	print CACHE "$key $pages{$key}\n";
    }

    close(CACHE);
}

#
# scan_dir - scans the directory specified in $dir for subdirectories, .pod
#  files, and .pm files.  notes those that it finds.  this information will
#  be used later in order to figure out where the pages specified in L<>
#  links are on the filesystem.
#
sub scan_dir {
    my($dir, $recurse) = @_;
    my($t, @subdirs, @pods, $pod, $dirname, @dirs);
    local $_;

    @subdirs = ();
    @pods = ();

    opendir(DIR, $dir) ||
	die "$0: error opening directory $dir: $!\n";
    while (defined($_ = readdir(DIR))) {
	if (-d "$dir/$_" && $_ ne "." && $_ ne "..") {	    # directory
	    $pages{$_}  = "" unless defined $pages{$_};
	    $pages{$_} .= "$dir/$_:";
	    push(@subdirs, $_);
	} elsif (/\.pod$/) {	    	    	    	    # .pod
	    s/\.pod$//;
	    $pages{$_}  = "" unless defined $pages{$_};
	    $pages{$_} .= "$dir/$_.pod:";
	    push(@pods, "$dir/$_.pod");
	} elsif (/\.pm$/) { 	    	    	    	    # .pm
	    s/\.pm$//;
	    $pages{$_}  = "" unless defined $pages{$_};
	    $pages{$_} .= "$dir/$_.pm:";
	    push(@pods, "$dir/$_.pm");
	}
    }
    closedir(DIR);

    # recurse on the subdirectories if necessary
    if ($recurse) {
	foreach my $subdir (@subdirs) {
	    scan_dir("$dir/$subdir", $recurse);
	}
    }
}

#
# scan_headings - scan a pod file for head[1-6] tags, note the tags, and
#  build an index.
#
sub scan_headings {
    my($sections, @data) = @_;
    my($tag, $which_head, $title, $listdepth, $index);

    # here we need	local $ignore = 0;
    #  unfortunately, we can't have it, because $ignore is lexical
    $ignore = 0;

    $listdepth = 0;
    $index = "";

    # scan for =head directives, note their name, and build an index
    #  pointing to each of them.
    foreach my $line (@data) {
	if ($line =~ /^=(head)([1-6])\s+(.*)/) {
	    ($tag,$which_head, $title) = ($1,$2,$3);
	    chomp($title);
	    $$sections{htmlify(0,$title)} = 1;

	    while ($which_head != $listdepth) {
		if ($which_head > $listdepth) {
		    $index .= "\n" . ("\t" x $listdepth) . "<UL>\n";
		    $listdepth++;
		} elsif ($which_head < $listdepth) {
		    $listdepth--;
		    $index .= "\n" . ("\t" x $listdepth) . "</UL>\n";
		}
	    }

	    $index .= "\n" . ("\t" x $listdepth) . "<LI>" .
	              "<A HREF=\"#" . htmlify(0,$title) . "\">" .
		      html_escape(process_text(\$title, 0)) . "</A>";
	}
    }

    # finish off the lists
    while ($listdepth--) {
	$index .= "\n" . ("\t" x $listdepth) . "</UL>\n";
    }

    # get rid of bogus lists
    $index =~ s,\t*<UL>\s*</UL>\n,,g;

    $ignore = 1;	# restore old value;

    return $index;
}

#
# scan_items - scans the pod specified by $pod for =item directives.  we
#  will use this information later on in resolving C<> links.
#
sub scan_items {
    my($pod, @poddata) = @_;
    my($i, $item);
    local $_;

    $pod =~ s/\.pod$//;
    $pod .= ".html" if $pod;

    foreach $i (0..$#poddata) {
	$_ = $poddata[$i];

	# remove any formatting instructions
	s,[A-Z]<([^<>]*)>,$1,g;

	# figure out what kind of item it is and get the first word of
	#  it's name.
	if (/^=item\s+(\w*)\s*.*$/s) {
	    if ($1 eq "*") {		# bullet list
		/\A=item\s+\*\s*(.*?)\s*\Z/s;
		$item = $1;
	    } elsif ($1 =~ /^\d+/) {	# numbered list
		/\A=item\s+\d+\.?(.*?)\s*\Z/s;
		$item = $1;
	    } else {
#		/\A=item\s+(.*?)\s*\Z/s;
		/\A=item\s+(\w*)/s;
		$item = $1;
	    }

	    $items{$item} = "$pod" if $item;
	}
    }
}

#
# process_head - convert a pod head[1-6] tag and convert it to HTML format.
#
sub process_head {
    my($tag, $heading) = @_;
    my $firstword;

    # figure out the level of the =head
    $tag =~ /head([1-6])/;
    my $level = $1;

    # can't have a heading full of spaces and speechmarks and so on
    $firstword = $heading; $firstword =~ s/\s*(\w+)\s.*/$1/;

    print HTML "<P>\n" unless $listlevel;
    print HTML "<HR>\n" unless $listlevel || $top;
    print HTML "<H$level>"; # unless $listlevel;
    #print HTML "<H$level>" unless $listlevel;
    my $convert = $heading; process_text(\$convert, 0);
    $convert = html_escape($convert);
    print HTML '<A NAME="' . htmlify(0,$heading) . "\">$convert</A>";
    print HTML "</H$level>"; # unless $listlevel;
    print HTML "\n";
}

#
# process_item - convert a pod item tag and convert it to HTML format.
#
sub process_item {
    my $text = $_[0];
    my($i, $quote, $name);

    my $need_preamble = 0;
    my $this_entry;


    # lots of documents start a list without doing an =over.  this is
    # bad!  but, the proper thing to do seems to be to just assume
    # they did do an =over.  so warn them once and then continue.
    warn "$0: $podfile: unexpected =item directive in paragraph $paragraph.  ignoring.\n"
	unless $listlevel;
    process_over() unless $listlevel;

    return unless $listlevel;

    # remove formatting instructions from the text
    1 while $text =~ s/[A-Z]<([^<>]*)>/$1/g;
    pre_escape(\$text);

    $need_preamble = $items_seen[$listlevel]++ == 0;

    # check if this is the first =item after an =over
    $i = $listlevel - 1;
    my $need_new = $listlevel >= @listitem;

    if ($text =~ /\A\*/) {		# bullet

	if ($need_preamble) {
	    push(@listend,  "</UL>");
	    print HTML "<UL>\n";
	}

	print HTML '<LI>';
	if ($text =~ /\A\*\s*(.+)\Z/s) {
	    print HTML '<STRONG>';
	    if ($items_named{$1}++) {
		print HTML html_escape($1);
	    } else {
		my $name = 'item_' . htmlify(1,$1);
		print HTML qq(<A NAME="$name">), html_escape($1), '</A>';
	    }
	    print HTML '</STRONG>';
	}

    } elsif ($text =~ /\A[\d#]+/) {	# numbered list

	if ($need_preamble) {
	    push(@listend,  "</OL>");
	    print HTML "<OL>\n";
	}

	print HTML '<LI>';
	if ($text =~ /\A\d+\.?\s*(.+)\Z/s) {
	    print HTML '<STRONG>';
	    if ($items_named{$1}++) {
		print HTML html_escape($1);
	    } else {
		my $name = 'item_' . htmlify(0,$1);
		print HTML qq(<A NAME="$name">), html_escape($1), '</A>';
	    }
	    print HTML '</STRONG>';
	}

    } else {			# all others

	if ($need_preamble) {
	    push(@listend,  '</DL>');
	    print HTML "<DL>\n";
	}

	print HTML '<DT>';
	if ($text =~ /(\S+)/) {
	    print HTML '<STRONG>';
	    if ($items_named{$1}++) {
		print HTML html_escape($text);
	    } else {
		my $name = 'item_' . htmlify(1,$text);
		print HTML qq(<A NAME="$name">), html_escape($text), '</A>';
	    }
	    print HTML '</STRONG>';
	}
       print HTML '<DD>';
    }

    print HTML "\n";
}

#
# process_over - process a pod over tag and start a corresponding HTML
# list.
#
sub process_over {
    # start a new list
    $listlevel++;
}

#
# process_back - process a pod back tag and convert it to HTML format.
#
sub process_back {
    warn "$0: $podfile: unexpected =back directive in paragraph $paragraph.  ignoring.\n"
	unless $listlevel;
    return unless $listlevel;

    # close off the list.  note, I check to see if $listend[$listlevel] is
    # defined because an =item directive may have never appeared and thus
    # $listend[$listlevel] may have never been initialized.
    $listlevel--;
    print HTML $listend[$listlevel] if defined $listend[$listlevel];
    print HTML "\n";

    # don't need the corresponding perl code anymore
    pop(@listitem);
    pop(@listdata);
    pop(@listend);

    pop(@items_seen);
}

#
# process_cut - process a pod cut tag, thus stop ignoring pod directives.
#
sub process_cut {
    $ignore = 1;
}

#
# process_pod - process a pod pod tag, thus ignore pod directives until we see a
# corresponding cut.
#
sub process_pod {
    # no need to set $ignore to 0 cause the main loop did it
}

#
# process_for - process a =for pod tag.  if it's for html, split
# it out verbatim, if illustration, center it, otherwise ignore it.
#
sub process_for {
    my($whom, $text) = @_;
    if ( $whom =~ /^(pod2)?html$/i) {
	print HTML $text;
    } elsif ($whom =~ /^illustration$/i) {
        1 while chomp $text;
	for my $ext (qw[.png .gif .jpeg .jpg .tga .pcl .bmp]) {
	  $text .= $ext, last if -r "$text$ext";
	}
        print HTML qq{<p align = "center"><img src = "$text" alt = "$text illustration"></p>};
    }
}

#
# process_begin - process a =begin pod tag.  this pushes
# whom we're beginning on the begin stack.  if there's a
# begin stack, we only print if it us.
#
sub process_begin {
    my($whom, $text) = @_;
    $whom = lc($whom);
    push (@begin_stack, $whom);
    if ( $whom =~ /^(pod2)?html$/) {
	print HTML $text if $text;
    }
}

#
# process_end - process a =end pod tag.  pop the
# begin stack.  die if we're mismatched.
#
sub process_end {
    my($whom, $text) = @_;
    $whom = lc($whom);
    if ($begin_stack[-1] ne $whom ) {
	die "Unmatched begin/end at chunk $paragraph\n"
    } 
    pop @begin_stack;
}

#
# process_text - handles plaintext that appears in the input pod file.
# there may be pod commands embedded within the text so those must be
# converted to html commands.
#
sub process_text {
    my($text, $escapeQuotes) = @_;
    my($result, $rest, $s1, $s2, $s3, $s4, $match, $bf);
    my($podcommand, $params, $tag, $quote);

    return if $ignore;

    $quote  = 0;    	    	# status of double-quote conversion
    $result = "";
    $rest = $$text;

    if ($rest =~ /^\s+/) {	# preformatted text, no pod directives
	$rest =~ s/\n+\Z//;
	$rest =~ s#.*#
	    my $line = $&;
	    1 while $line =~ s/\t+/' ' x (length($&) * 8 - length($`) % 8)/e;
	    $line;
	#eg;

	$rest   =~ s/&/&amp;/g;
	$rest   =~ s/</&lt;/g;
	$rest   =~ s/>/&gt;/g;
	$rest   =~ s/"/&quot;/g;

	# try and create links for all occurrences of perl.* within
	# the preformatted text.
	$rest =~ s{
		    (\s*)(perl\w+)
		  }{
		    if (defined $pages{$2}) {	# is a link
			qq($1<A HREF="$htmlroot/$pages{$2}">$2</A>);
		    } elsif (defined $pages{dosify($2)}) {	# is a link
			qq($1<A HREF="$htmlroot/$pages{dosify($2)}">$2</A>);
		    } else {
			"$1$2";
		    }
		  }xeg;
#	$rest =~ s/(<A HREF=)([^>:]*:)?([^>:]*)\.pod:([^>:]*:)?/$1$3.html/g;
	$rest =~ s{
		    (<A\ HREF="?) ([^>:]*:)? ([^>:]*) \.pod: ([^>:]*:)?
                  }{
                    my $url ;
                    if ( $htmlfileurl ne '' ) {
			# Here, we take advantage of the knowledge 
			# that $htmlfileurl ne '' implies $htmlroot eq ''.
			# Since $htmlroot eq '', we need to prepend $htmldir
			# on the fron of the link to get the absolute path
			# of the link's target. We check for a leading '/'
			# to avoid corrupting links that are #, file:, etc.
			my $old_url = $3 ;
			$old_url = "$htmldir$old_url"
			    if ( $old_url =~ m{^\/} ) ;
			$url = relativize_url( "$old_url.html", $htmlfileurl );
# print( "  a: [$old_url.html,$htmlfileurl,$url]\n" ) ;
		    }
		    else {
			$url = "$3.html" ;
		    }
		    "$1$url" ;
		  }xeg;

  # Look for embedded URLs and make them in to links.  We don't
  # relativize them since they are best left as the author intended.
  my $urls = '(' . join ('|', qw{
                http
                telnet
		mailto
		news
                gopher
                file
                wais
                ftp
            } ) 
        . ')';
  
  my $ltrs = '\w';
  my $gunk = '/#~:.?+=&%@!\-';
  my $punc = '.:?\-';
  my $any  = "${ltrs}${gunk}${punc}";

  $rest =~ s{
        \b                          # start at word boundary
        (                           # begin $1  {
          $urls     :               # need resource and a colon
	  (?!:)                     # Ignore File::, among others.
          [$any] +?                 # followed by on or more
                                    #  of any valid character, but
                                    #  be conservative and take only
                                    #  what you need to....
        )                           # end   $1  }
        (?=                         # look-ahead non-consumptive assertion
                [$punc]*            # either 0 or more puntuation
                [^$any]             #   followed by a non-url char
            |                       # or else
                $                   #   then end of the string
        )
      }{<A HREF="$1">$1</A>}igox;

	$result =   "<PRE>"	# text should be as it is (verbatim)
		  . "$rest\n"
		  . "</PRE>\n";
    } else {			# formatted text
	# parse through the string, stopping each time we find a
	# pod-escape.  once the string has been throughly processed
	# we can output it.
	while (length $rest) {
	    # check to see if there are any possible pod directives in
	    # the remaining part of the text.
	    if ($rest =~ m/[BCEIFLSZ]</) {
		warn "\$rest\t= $rest\n" unless
		    $rest =~ /\A
			   ([^<]*?)
			   ([BCEIFLSZ]?)
			   <
			   (.*)\Z/xs;

		$s1 = $1;	# pure text
		$s2 = $2;	# the type of pod-escape that follows
		$s3 = '<';	# '<'
		$s4 = $3;	# the rest of the string
	    } else {
		$s1 = $rest;
		$s2 = "";
		$s3 = "";
		$s4 = "";
	    }

	    if ($s3 eq '<' && $s2) {	# a pod-escape
		$result    .= ($escapeQuotes ? process_puretext($s1, \$quote) : $s1);
		$podcommand = "$s2<";
		$rest       = $s4;

		# find the matching '>'
		$match = 1;
		$bf = 0;
		while ($match && !$bf) {
		    $bf = 1;
		    if ($rest =~ /\A([^<>]*[BCEIFLSZ]<)(.*)\Z/s) {
			$bf = 0;
			$match++;
			$podcommand .= $1;
			$rest        = $2;
		    } elsif ($rest =~ /\A([^>]*>)(.*)\Z/s) {
			$bf = 0;
			$match--;
			$podcommand .= $1;
			$rest        = $2;
		    }
		}

		if ($match != 0) {
		    warn <<WARN;
$0: $podfile: cannot find matching > for $s2 in paragraph $paragraph.
WARN
		    $result .= substr $podcommand, 0, 2;
		    $rest = substr($podcommand, 2) . $rest;
		    next;
		}

		# pull out the parameters to the pod-escape
		$podcommand =~ /^([BCFEILSZ]?)<(.*)>$/s;
		$tag    = $1;
		$params = $2;

		# process the text within the pod-escape so that any escapes
		# which must occur do.
		process_text(\$params, 0) unless $tag eq 'L';

		$s1 = $params;
		if (!$tag || $tag eq " ") {	#  <> : no tag
		    $s1 = "&lt;$params&gt;";
		} elsif ($tag eq "L") {		# L<> : link 
		    $s1 = process_L($params);
		} elsif ($tag eq "I" ||		# I<> : italicize text
			 $tag eq "B" ||		# B<> : bold text
			 $tag eq "F") {		# F<> : file specification
		    $s1 = process_BFI($tag, $params);
		} elsif ($tag eq "C") {		# C<> : literal code
		    $s1 = process_C($params, 1);
		} elsif ($tag eq "E") {		# E<> : escape
		    $s1 = process_E($params);
		} elsif ($tag eq "Z") {		# Z<> : zero-width character
		    $s1 = process_Z($params);
		} elsif ($tag eq "S") {		# S<> : non-breaking space
		    $s1 = process_S($params);
		} elsif ($tag eq "X") {		# S<> : non-breaking space
		    $s1 = process_X($params);
		} else {
		    warn "$0: $podfile: unhandled tag '$tag' in paragraph $paragraph\n";
		}

		$result .= "$s1";
	    } else {
		# for pure text we must deal with implicit links and
		# double-quotes among other things.
		$result .= ($escapeQuotes ? process_puretext("$s1$s2$s3", \$quote) : "$s1$s2$s3");
		$rest    = $s4;
	    }
	}
    }
    $$text = $result;
}

sub html_escape {
    my $rest = $_[0];
    $rest   =~ s/&(?!\w+;|#)/&amp;/g;	# XXX not bulletproof
    $rest   =~ s/</&lt;/g;
    $rest   =~ s/>/&gt;/g;
    $rest   =~ s/"/&quot;/g;
    return $rest;
} 

#
# process_puretext - process pure text (without pod-escapes) converting
#  double-quotes and handling implicit C<> links.
#
sub process_puretext {
    my($text, $quote) = @_;
    my(@words, $result, $rest, $lead, $trail);

    # convert double-quotes to single-quotes
    $text =~ s/\A([^"]*)"/$1''/s if $$quote;
    while ($text =~ s/\A([^"]*)["]([^"]*)["]/$1``$2''/sg) {}

    $$quote = ($text =~ m/"/ ? 1 : 0);
    $text =~ s/\A([^"]*)"/$1``/s if $$quote;

    # keep track of leading and trailing white-space
    $lead  = ($text =~ /\A(\s*)/s ? $1 : "");
    $trail = ($text =~ /(\s*)\Z/s ? $1 : "");

    # collapse all white space into a single space
    $text =~ s/\s+/ /g;
    @words = split(" ", $text);

    # process each word individually
    foreach my $word (@words) {
	# see if we can infer a link
	if ($word =~ /^\w+\(/) {
	    # has parenthesis so should have been a C<> ref
	    $word = process_C($word);
#	    $word =~ /^[^()]*]\(/;
#	    if (defined $items{$1} && $items{$1}) {
#		$word =   "\n<CODE><A HREF=\"$htmlroot/$items{$1}#item_"
#			. htmlify(0,$word)
#			. "\">$word</A></CODE>";
#	    } elsif (defined $items{$word} && $items{$word}) {
#		$word =   "\n<CODE><A HREF=\"$htmlroot/$items{$word}#item_"
#			. htmlify(0,$word)
#			. "\">$word</A></CODE>";
#	    } else {
#		$word =   "\n<CODE><A HREF=\"#item_"
#			. htmlify(0,$word)
#			. "\">$word</A></CODE>";
#	    }
	} elsif ($word =~ /^[\$\@%&*]+\w+$/) {
	    # perl variables, should be a C<> ref
	    $word = process_C($word, 1);
	} elsif ($word =~ m,^\w+://\w,) {
	    # looks like a URL
            # Don't relativize it: leave it as the author intended
	    $word = qq(<A HREF="$word">$word</A>);
	} elsif ($word =~ /[\w.-]+\@[\w-]+\.\w/) {
	    # looks like an e-mail address
	    my ($w1, $w2, $w3) = ("", $word, "");
	    ($w1, $w2, $w3) = ("(", $1, ")$2") if $word =~ /^\((.*?)\)(,?)/;
	    ($w1, $w2, $w3) = ("&lt;", $1, "&gt;$2") if $word =~ /^<(.*?)>(,?)/;
	    $word = qq($w1<A HREF="mailto:$w2">$w2</A>$w3);
	} elsif ($word !~ /[a-z]/ && $word =~ /[A-Z]/) {  # all uppercase?
	    $word = html_escape($word) if $word =~ /["&<>]/;
	    $word = "\n<FONT SIZE=-1>$word</FONT>" if $netscape;
	} else { 
	    $word = html_escape($word) if $word =~ /["&<>]/;
	}
    }

    # build a new string based upon our conversion
    $result = "";
    $rest   = join(" ", @words);
    while (length($rest) > 75) {
	if ( $rest =~ m/^(.{0,75})\s(.*?)$/o ||
	     $rest =~ m/^(\S*)\s(.*?)$/o) {

	    $result .= "$1\n";
	    $rest    = $2;
	} else {
	    $result .= "$rest\n";
	    $rest    = "";
	}
    }
    $result .= $rest if $rest;

    # restore the leading and trailing white-space
    $result = "$lead$result$trail";

    return $result;
}

#
# pre_escape - convert & in text to $amp;
#
sub pre_escape {
    my($str) = @_;
    $$str =~ s/&(?!\w+;|#)/&amp;/g;	# XXX not bulletproof
}

#
# dosify - convert filenames to 8.3
#
sub dosify {
    my($str) = @_;
    if ($Is83) {
        $str = lc $str;
        $str =~ s/(\.\w+)/substr ($1,0,4)/ge;
        $str =~ s/(\w+)/substr ($1,0,8)/ge;
    }
    return $str;
}

#
# process_L - convert a pod L<> directive to a corresponding HTML link.
#  most of the links made are inferred rather than known about directly
#  (i.e it's not known whether the =head\d section exists in the target file,
#   or whether a .pod file exists in the case of split files).  however, the
#  guessing usually works.
#
# Unlike the other directives, this should be called with an unprocessed
# string, else tags in the link won't be matched.
#
sub process_L {
    my($str) = @_;
    my($s1, $s2, $linktext, $page, $page83, $section, $link);	# work strings

    $str =~ s/\n/ /g;			# undo word-wrapped tags
    $s1 = $str;
    for ($s1) {
	# LREF: a la HREF L<show this text|man/section>
	$linktext = $1 if s:^([^|]+)\|::;

	# make sure sections start with a /
	s,^",/",g;
	s,^,/,g if (!m,/, && / /);

	# check if there's a section specified
	if (m,^(.*?)/"?(.*?)"?$,) {	# yes
	    ($page, $section) = ($1, $2);
	} else {			# no
	    ($page, $section) = ($str, "");
	}

	# check if we know that this is a section in this page
	if (!defined $pages{$page} && defined $sections{$page}) {
	    $section = $page;
	    $page = "";
	}

	# remove trailing punctuation, like ()
	$section =~ s/\W*$// ;
    }

    $page83=dosify($page);
    $page=$page83 if (defined $pages{$page83});
    if ($page eq "") {
	$link = "#" . htmlify(0,$section);
	$linktext = $section unless defined($linktext);
    } elsif ( $page =~ /::/ ) {
	$linktext  = ($section ? "$section" : "$page");
	$page =~ s,::,/,g;
	# Search page cache for an entry keyed under the html page name,
	# then look to see what directory that page might be in.  NOTE:
	# this will only find one page. A better solution might be to produce
	# an intermediate page that is an index to all such pages.
	my $page_name = $page ;
	$page_name =~ s,^.*/,, ;
	if ( defined( $pages{ $page_name } ) && 
	     $pages{ $page_name } =~ /([^:]*$page)\.(?:pod|pm):/ 
	   ) {
	    $page = $1 ;
	}
	else {
	    # NOTE: This branch assumes that all A::B pages are located in
	    # $htmlroot/A/B.html . This is often incorrect, since they are
	    # often in $htmlroot/lib/A/B.html or such like. Perhaps we could
	    # analyze the contents of %pages and figure out where any
	    # cousins of A::B are, then assume that.  So, if A::B isn't found,
	    # but A::C is found in lib/A/C.pm, then A::B is assumed to be in
	    # lib/A/B.pm. This is also limited, but it's an improvement.
	    # Maybe a hints file so that the links point to the correct places
	    # non-theless?
	    # Also, maybe put a warn "$0: cannot resolve..." here.
	}
	$link = "$htmlroot/$page.html";
	$link .= "#" . htmlify(0,$section) if ($section);
    } elsif (!defined $pages{$page}) {
	warn "$0: $podfile: cannot resolve L<$str> in paragraph $paragraph: no such page '$page'\n";
	$link = "";
	$linktext = $page unless defined($linktext);
    } else {
	$linktext  = ($section ? "$section" : "the $page manpage") unless defined($linktext);
	$section = htmlify(0,$section) if $section ne "";

	# if there is a directory by the name of the page, then assume that an
	# appropriate section will exist in the subdirectory
#	if ($section ne "" && $pages{$page} =~ /([^:]*[^(\.pod|\.pm)]):/) {
	if ($section ne "" && $pages{$page} =~ /([^:]*(?<!\.pod)(?<!\.pm)):/) {
	    $link = "$htmlroot/$1/$section.html";

	# since there is no directory by the name of the page, the section will
	# have to exist within a .html of the same name.  thus, make sure there
	# is a .pod or .pm that might become that .html
	} else {
	    $section = "#$section";
	    # check if there is a .pod with the page name
	    if ($pages{$page} =~ /([^:]*)\.pod:/) {
		$link = "$htmlroot/$1.html$section";
	    } elsif ($pages{$page} =~ /([^:]*)\.pm:/) {
		$link = "$htmlroot/$1.html$section";
	    } else {
		warn "$0: $podfile: cannot resolve L$str in paragraph $paragraph: ".
			     "no .pod or .pm found\n";
		$link = "";
		$linktext = $section unless defined($linktext);
	    }
	}
    }

    process_text(\$linktext, 0);
    if ($link) {
	# Here, we take advantage of the knowledge that $htmlfileurl ne ''
	# implies $htmlroot eq ''. This means that the link in question
	# needs a prefix of $htmldir if it begins with '/'. The test for
	# the initial '/' is done to avoid '#'-only links, and to allow
	# for other kinds of links, like file:, ftp:, etc.
        my $url ;
        if (  $htmlfileurl ne '' ) {
            $link = "$htmldir$link"
		if ( $link =~ m{^/} ) ;
            
            $url = relativize_url( $link, $htmlfileurl ) ;
# print( "  b: [$link,$htmlfileurl,$url]\n" ) ;
	}
	else {
            $url = $link ;
	}

	$s1 = "<A HREF=\"$url\">$linktext</A>";
    } else {
	$s1 = "<EM>$linktext</EM>";
    }
    return $s1;
}

#
# relativize_url - convert an absolute URL to one relative to a base URL.
# Assumes both end in a filename.
#
sub relativize_url {
    my ($dest,$source) = @_ ;

    my ($dest_volume,$dest_directory,$dest_file) = 
        File::Spec::Unix->splitpath( $dest ) ;
    $dest = File::Spec::Unix->catpath( $dest_volume, $dest_directory, '' ) ;

    my ($source_volume,$source_directory,$source_file) = 
        File::Spec::Unix->splitpath( $source ) ;
    $source = File::Spec::Unix->catpath( $source_volume, $source_directory, '' ) ;

    my $rel_path = '' ;
    if ( $dest ne '' ) {
       $rel_path = File::Spec::Unix->abs2rel( $dest, $source ) ;
    }

    if ( $rel_path ne ''                && 
         substr( $rel_path, -1 ) ne '/' &&
         substr( $dest_file, 0, 1 ) ne '#' 
        ) {
        $rel_path .= "/$dest_file" ;
    }
    else {
        $rel_path .= "$dest_file" ;
    }

    return $rel_path ;
}

#
# process_BFI - process any of the B<>, F<>, or I<> pod-escapes and
# convert them to corresponding HTML directives.
#
sub process_BFI {
    my($tag, $str) = @_;
    my($s1);			# work string
    my(%repltext) = (	'B' => 'STRONG',
			'F' => 'EM',
			'I' => 'EM');

    # extract the modified text and convert to HTML
    $s1 = "<$repltext{$tag}>$str</$repltext{$tag}>";
    return $s1;
}

#
# process_C - process the C<> pod-escape.
#
sub process_C {
    my($str, $doref) = @_;
    my($s1, $s2);

    $s1 = $str;
    $s1 =~ s/\([^()]*\)//g;	# delete parentheses
    $s2 = $s1;
    $s1 =~ s/\W//g;		# delete bogus characters
    $str = html_escape($str);

    # if there was a pod file that we found earlier with an appropriate
    # =item directive, then create a link to that page.
    if ($doref && defined $items{$s1}) {
        if ( $items{$s1} ) {
            my $link = "$htmlroot/$items{$s1}#item_" . htmlify(0,$s2) ;
	    # Here, we take advantage of the knowledge that $htmlfileurl ne ''
	    # implies $htmlroot eq ''.
            my $url ;
            if (  $htmlfileurl ne '' ) {
                $link = "$htmldir$link" ;
                $url = relativize_url( $link, $htmlfileurl ) ;
	    }
	    else {
                $url = $link ;
	    }
	    $s1 = "<A HREF=\"$url\">$str</A>" ;
        }
        else {
	    $s1 = "<A HREF=\"#item_" . htmlify(0,$s2) .  "\">$str</A>" ;
        }
	$s1 =~ s,(perl\w+/(\S+)\.html)#item_\2\b,$1,; 
	confess "s1 has space: $s1" if $s1 =~ /HREF="[^"]*\s[^"]*"/;
    } else {
	$s1 = "<CODE>$str</CODE>";
	# warn "$0: $podfile: cannot resolve C<$str> in paragraph $paragraph\n" if $verbose
    }


    return $s1;
}

#
# process_E - process the E<> pod directive which seems to escape a character.
#
sub process_E {
    my($str) = @_;

    for ($str) {
	s,([^/].*),\&$1\;,g;
    }

    return $str;
}

#
# process_Z - process the Z<> pod directive which really just amounts to
# ignoring it.  this allows someone to start a paragraph with an =
#
sub process_Z {
    my($str) = @_;

    # there is no equivalent in HTML for this so just ignore it.
    $str = "";
    return $str;
}

#
# process_S - process the S<> pod directive which means to convert all
# spaces in the string to non-breaking spaces (in HTML-eze).
#
sub process_S {
    my($str) = @_;

    # convert all spaces in the text to non-breaking spaces in HTML.
    $str =~ s/ /&nbsp;/g;
    return $str;
}

#
# process_X - this is supposed to make an index entry.  we'll just 
# ignore it.
#
sub process_X {
    return '';
}


#
# Adapted from Nick Ing-Simmons' PodToHtml package.
sub relative_url {
    my $source_file = shift ;
    my $destination_file = shift;

    my $source = URI::file->new_abs($source_file);
    my $uo = URI::file->new($destination_file,$source)->abs;
    return $uo->rel->as_string;
}


#
# finish_list - finish off any pending HTML lists.  this should be called
# after the entire pod file has been read and converted.
#
sub finish_list {
    while ($listlevel > 0) {
	print HTML "</DL>\n";
	$listlevel--;
    }
}

#
# htmlify - converts a pod section specification to a suitable section
# specification for HTML.  if first arg is 1, only takes 1st word.
#
sub htmlify {
    my($compact, $heading) = @_;

    if ($compact) {
      $heading =~ /^(\w+)/;
      $heading = $1;
    } 

  # $heading = lc($heading);
  $heading =~ s/[^\w\s]/_/g;
  $heading =~ s/(\s+)/ /g;
  $heading =~ s/^\s*(.*?)\s*$/$1/s;
  $heading =~ s/ /_/g;
  $heading =~ s/\A(.{32}).*\Z/$1/s;
  $heading =~ s/\s+\Z//;
  $heading =~ s/_{2,}/_/g;

  return $heading;
}

BEGIN {
}

1;