path: root/IkiWiki/Plugin/toc.pm

#!/usr/bin/perl
# Table Of Contents generator
package IkiWiki::Plugin::toc;

use warnings;
use strict;
use IkiWiki 2.00;
use HTML::Parser;

sub import {
    hook(type => "getsetup", id => "toc", call => \&getsetup);
    hook(type => "preprocess", id => "toc", call => \&preprocess);
    hook(type => "format", id => "toc", call => \&format);
}

sub getsetup () {
    return
        plugin => {
            safe => 1,
            rebuild => undef,
        },
}

my %tocpages;

sub preprocess (@) {
    my %params=@_;

    if ($params{page} eq $params{destpage}) {
        $params{levels}=1 unless exists $params{levels};

        # It's too early to generate the toc here, so just record the
        # info.
        $tocpages{$params{destpage}}=\%params;

        return "\n<div class=\"toc\"></div>\n";
    }
    else {
        # Don't generate toc in an inlined page, doesn't work
        # right.
        return "";
    }
}

sub format (@) {
    my %params=@_;
    my $content=$params{content};
    
    return $content unless exists $tocpages{$params{page}};
    %params=%{$tocpages{$params{page}}};

    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\"></a>";
    
            # 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;
            }
                
            $index.=&$indent."</li>\n" unless $liststarted;
            $liststarted=0;
            $index.=&$indent."<li class=\"L$curlevel\">".
                "<a href=\"#$anchor\">";
    
            $p->handler(text => sub {
                $page.=join("", @_);
                $index.=join("", @_);
            }, "dtext");
            $p->handler(end => sub {
                my $tagname=shift;
                if ($tagname =~ /^h(\d+)$/i) {
                    $p->handler(text => undef);
                    $p->handler(end => undef);
                    $index.="</a>\n";
                }
                $page.=join("", @_);
            }, "tagname, text");
        }
        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";
    }

    $page=~s/(<div class=\"toc\">)/$1\n$index/;
    return $page;
}

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