+#!/usr/bin/perl
+# Table Of Contents generator
+package IkiWiki::Plugin::toc;
+
+use warnings;
+use strict;
+use IkiWiki;
+use HTML::Parser;
+
+sub import { #{{{
+ IkiWiki::hook(type => "preprocess", id => "toc",
+ call => \&preprocess);
+ IkiWiki::hook(type => "format", id => "toc",
+ call => \&format);
+} # }}}
+
+my @tocs;
+
+sub preprocess (@) { #{{{
+ my %params=@_;
+
+ $params{levels}=1 unless exists $params{levels};
+
+ # It's too early to generate the toc here, so just record the
+ # info.
+ push @tocs, \%params;
+
+ return "\n[[toc $#tocs]]\n";
+} # }}}
+
+sub format ($) { #{{{
+ my $content=shift;
+
+ return $content unless @tocs && $content=~/\[\[toc (\d+)\]\]/ && $#tocs >= $1;
+ my $id=$1;
+ my %params=%{$tocs[$id]};
+
+ my $p=HTML::Parser->new(api_version => 3);
+ my $page="";
+ my $index="";
+ my %anchors;
+ my $curlevel;
+ my $startlevel=0;
+ my $liststarted=0;
+ my $indent=sub { "\t" x $curlevel };
+ $p->handler(start => sub {
+ my $tagname=shift;
+ my $text=shift;
+ if ($tagname =~ /^h(\d+)$/i) {
+ my $level=$1;
+ my $anchor="index".++$anchors{$level}."h$level";
+ $page.="$text<a name=\"$anchor\" />";
+
+ # Take the first header level seen as the topmost level,
+ # even if there are higher levels seen later on.
+ if (! $startlevel) {
+ $startlevel=$level;
+ $curlevel=$startlevel-1;
+ }
+ elsif ($level < $startlevel) {
+ $level=$startlevel;
+ }
+
+ return if $level - $startlevel >= $params{levels};
+
+ if ($level > $curlevel) {
+ while ($level > $curlevel + 1) {
+ $index.=&$indent."<ol>\n";
+ $curlevel++;
+ $index.=&$indent."<li class=\"L$curlevel\">\n";
+ }
+ $index.=&$indent."<ol>\n";
+ $curlevel=$level;
+ $liststarted=1;
+ }
+ elsif ($level < $curlevel) {
+ while ($level < $curlevel) {
+ $index.=&$indent."</li>\n" if $curlevel;
+ $curlevel--;
+ $index.=&$indent."</ol>\n";
+ }
+ $liststarted=0;
+ }
+
+ $p->handler(text => sub {
+ $page.=join("", @_);
+ $index.=&$indent."</li>\n" unless $liststarted;
+ $liststarted=0;
+ $index.=&$indent."<li class=\"L$curlevel\">".
+ "<a href=\"#$anchor\">".
+ join("", @_).
+ "</a>\n";
+ $p->handler(text => undef);
+ }, "dtext");
+ }
+ else {
+ $page.=$text;
+ }
+ }, "tagname, text");
+ $p->handler(default => sub { $page.=join("", @_) }, "text");
+ $p->parse($content);
+ $p->eof;
+
+ while ($startlevel && $curlevel >= $startlevel) {
+ $index.=&$indent."</li>\n" if $curlevel;
+ $curlevel--;
+ $index.=&$indent."</ol>\n";
+ }
+
+ # Ignore cruft around the toc marker, probably <p> tags added by
+ # markdown which shouldn't appear in a list anyway.
+ $page=~s/\n.*\[\[toc $id\]\].*\n/$index/;
+ return $page;
+}
+
+1