NAME

CommonMark::Massage - Manipulate CommonMark AST

SYNOPSIS

    use CommonMark qw(:node :event);
    use CommonMark::Massage;

    my $parser = CommonMark::Parser->new;
    $parser->feed("Hello world");
    my $doc = $parser->finish;

    # Apply function to text nodes.
    my $doc->massage ( { NODE_TEXT => sub { ... } } } );
    $doc->render_html;

DESCRIPTION

The massage function can be used to manipulate the AST as produced by the CommonMark parsers.

METHODS

The methods are defined in the CommonMark::Node namespace, so they can be applied to the result of parsing.

massage

One argument: a hash ref of node names, to a subroutine. For example:

    { NODE_TEXT => \&fixit }

The subroutine is called with three arguments, the doc tree, the node, and a boolean indicating whether the call is upon an EVENT_ENTER (true) or EVENT_EXIT (false).

It is free to do whatever it wants, but caveat emptor.

See EXAMPLES and the example directory for some example routines.

reveal

This method dumps the AST nodes/events for entertainment and debugging.

The result is returned as a string.

EXAMPLES

This example manipulates links. Normally a link is rendered as

    <a href="uri">text</a>

After massaging with

    $doc->massage( { NODE_LINK => { EVENT_EXIT => \&fixlink } } )

this will become for non-local links:

    <a href="http://www.example.com" target="_blank">text</a>

This is the subroutine

    sub fixlink {
        my ( $doc, $node ) = @_;
        # Get the link and title.
        my $link = $node->get_url // "";
        my $title = $node->get_title // "";

        # Create a new custom node.
        my $n = CommonMark::Node->new(NODE_CUSTOM_INLINE);

        # The replacement 'enter' text.
        my $enter = "<a href=\"$link\"";
        $enter .= " title=\"$title\"" if $title;
        $enter .= " target=\"_blank\"" if $link =~ /^\w+:\/\//;
        $enter .= ">";
        $n->set_on_enter($enter);

        # The 'exit' text.
        $n->set_on_exit("</a>" );

        # NODE_LINK has a single child, copy it to the new node.
        my $t = $node->first_child;
        $n->append_child($t);
        $t->unlink;

        # Replace the LINK node by the CUSTOM node.
        $node->replace($n);
    }

AUTHOR

Johan Vromans, <JV at cpan.org>

SUPPORT AND DOCUMENTATION

Development of this module takes place on GitHub: https://github.com/sciurius/perl-CommonMark-Massage.

You can find documentation for this module with the perldoc command.

    perldoc CommonMark::Massage

Please report any bugs or feature requests using the issue tracker on GitHub.

SEE ALSO

CommonMark

COPYRIGHT & LICENSE

Copyright 2020 Johan Vromans, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

cpanm CommonMark::Massage

perl -MCPAN -e shell
install CommonMark::Massage