Markdown.pl: detail ability to "use" Markdown module

While the default mode of Markdown.pl remains that of a command
line utility, it's fairly simple to "use Markdown" and call the
functions directly.

Explain this usage in the help and make sure all of the auxiliary
functions that might be used for this appear in @EXPORT_OK.

Include an example that simulates `Markdown.pl --stub --wiki`.

Add a symbolic link from Markdown.pm to Markdown.pl to go
along with the new example.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>

Markdown.pl

@@ -35,7 +35,7 @@ use Scalar::Util qw(refaddr looks_like_number);
 my ($hasxml, $hasxml_err); BEGIN { ($hasxml, $hasxml_err) = (0, "") }
 my ($hasxmlp, $hasxmlp_err); BEGIN { ($hasxmlp, $hasxmlp_err) = (0, "") }
 @ISA = qw(Exporter);
-@EXPORT_OK = qw(Markdown);
+@EXPORT_OK = qw(Markdown ProcessRaw GenerateStyleSheet SetWikiOpts);
 $INC{__PACKAGE__.'.pm'} = $INC{basename(__FILE__)} unless exists $INC{__PACKAGE__.'.pm'};
 
 close(DATA) if fileno(DATA);
@@ -3769,6 +3769,116 @@ the usage and options are shown.
 =back
 
 
+=head1 PERL MODULE
+
+Markdown can be used as a Perl module and can be "use"d like so:
+
+ use Markdown qw(...);
+
+Or like so:
+
+ BEGIN {require "Markdown.pl" && Markdown->import(qw(...))}
+
+where the C<...> part is the list of desired imports.
+
+The Markdown module does not export any functions by default.
+
+The C<Markdown.pm> file is a symbolic link to C<Markdown.pl>.
+
+=head2 Markdown module functions
+
+Any of these functions may be imported, but none of them
+are imported by default.
+
+=over
+
+
+=item * $result = Markdown::Markdown($string[, options...])
+
+Converts Markdown-format C<$string> to UTF-8 encoded XHTML and
+returns it.
+
+The C<options...> may be either a single HASH ref or one or more
+pairs of C<< key => value >>.
+
+See the comments for the C<_SanitizeOpts> function for a list of
+possible option keys.
+
+
+=item * $result = Markdown::ProcessRaw($string[, options...])
+
+Converts raw XHTML in C<$string> to XHTML and returns it.
+
+The C<options...> may be either a single HASH ref or one or more
+pairs of C<< key => value >>.
+
+See the comments for the C<_SanitizeOpts> function for a list of
+possible option keys.
+
+This function provides the ability to apply the internal XML
+validation and sanitation functionality to arbitrary XHTML without
+performing any of the Markdown format interpretation.
+
+
+=item * $stylesheet = Markdown::GenerateStyleSheet([$prefix])
+
+Returns an XHTML style sheet that supports the fancy Markdown styles
+such as checkboxes and right parenthesis lists.
+
+All of the style class names have C<$prefix> prepended.
+
+If C<$prefix> is omitted or C<undef> then the default S<"_markdown-">
+prefix will be used which is the same default prefix that the
+C<Markdown> function uses.
+
+The returned string value consists of a C<< <style type="text/css"> >>
+tag, the contents of the style sheet and ends with a C<< </style> >> tag.
+
+
+=item * Markdown::SetWikiOpts($hashref, $wikioption)
+
+The value of C<$wikioption> should be the value of the C<wikipat> value
+from the B<--wiki> option.  Use the empty string S<""> to enable wiki
+links using the defaults and use C<undef> to disable wiki links.
+
+The C<wikipat> and C<wikiopt> keys in C<$hashref> will both be
+affected by this call and they should be passed in to the Markdown
+function as options to enable processing of wiki links.
+
+The simplest way to do this is simply to pass a HASH ref as the
+second argument to the Markdown function after having used this
+function on it to properly set the C<wikipat> and C<wikiopt>
+keys and values.
+
+
+=back
+
+
+=head2 Example
+
+This rudimentary example approximates running
+S<C<Markdown.pl --stub --wiki>>
+on the input (files if given, standard input if not).
+
+ use Markdown qw(Markdown SetWikiOpts GenerateStyleSheet);
+
+ # just enough XML escaping
+ sub escxml {local $_ = shift; s/&/&amp;/g; s/</&lt;/g; return $_}
+
+ my $string;
+ {local $/; $string = <>;}
+ my %opts = ( h1 => "default title" );
+ SetWikiOpts(\%opts, ""); # enable default --wiki processing
+ my $xhtml = Markdown($string, \%opts);
+ print "<html xmlns=\"http://www.w3.org/1999/xhtml\">\n",
+   "<head>\n<title>".escxml($opts{h1})."</title>\n",
+   GenerateStyleSheet(),"</head>\n",
+   "<body style=\"text-align:center\">\n",
+   "<div style=\"".
+   "display:inline-block;text-align:left;max-width:42pc\">\n",
+   $xhtml, "</div></body></html>\n";
+
+
 =head1 VERSION HISTORY
 
 Z<> See the F<README> file for detailed release notes for this version.

Markdown.pm

@@ -0,0 +1 @@
+Markdown.pl