pandoc-emphasis



#!/usr/bin/perl

# emphasis + doublequote means technical or foreign term.
# doublequote + emphasis means title.

use Moops -strict;

use feature qw(switch);
no if $] >= 5.018, warnings => "experimental::smartmatch";

use Pandoc::Filter 0.06;
use Pandoc::Elements;

use Log::Any qw($log);
use Log::Any::Adapter ( 'ScreenColoredLevel',
    use_color => ! -t *STDERR );

class Window {
    use Pandoc::Filter;

    has view => {
        is => 'rw',
        isa => Object,
    };
    has ledge => {
        is => 'rw',
        isa => Maybe[Object],
    };
    method set_view ( Object $object ) {
        $self->view($object);
    }
    method peek_at_ledge () {
        return
            unless ( $self->ledge );
        my $value = stringify( $self->ledge );
        $value = $self->ledge->content;
        return $value;
    }
    method clear_ledge () {
        $self->ledge(undef);
    }
    method my $recall_from_ledge () {
        my $oldview = $self->ledge;
        $self->clear_ledge;
        return $oldview;
    }
    method describe_view () {
        return [ $self->$recall_from_ledge, $self->view ]
            if ( $self->ledge );
        return;
    }
    method interpret_view ( Object $interpretation ) {
        return [ $self->$recall_from_ledge, $interpretation ]
            if ( $self->$recall_from_ledge );
        return [ $interpretation ];
    }
    method suppress_view () {
        return [ $self->$recall_from_ledge ]
            if ( $self->ledge );
        return [];
    }
    method postpone_view () {
        $self->ledge( $self->view );
        return [];
    }
}

my $window = Window->new;

my ($title, $foreign);

pandoc_filter(
    \&emphasis,
);

sub emphasis {
    my $self = shift;
    return unless ( $self->name =~ /Str|Emph/ );
    if ( $self->name eq 'Emph' ) {
        $window->set_view($self);
        given ( stringify($self) ) {
            when ( $self->content->[0]->name eq 'Str' ) {
                if ( $window->peek_at_ledge() eq '"' ) {
                    $window->clear_ledge();
                    $title++;
                    $log->infof( 'emphasis: %s+Emph→title: %s',
                        '"',
                        $_ );
                    return $window->interpret_view(
                        Quoted( DoubleQuote,
                        $self->content ));
                }
            }
            when ( $self->content->[0]->name eq 'Quoted' ) {
                $log->infof( 'emphasis: Emph+Quoted→foreign: %s',
                    $_ );
                # FIXME: LaTeX-encode text
                return $window->interpret_view(
                    RawInline( 'latex',
                    '\\foreign{' . $_ . '}' ));
            }
        }
        return $window->describe_view();
    }
    if ( $self->name eq 'Str' ) {
        $window->set_view($self);
        given ( $self->content ) {
            when ('"') {
                if ($title) {
                    $title--;
                    return $window->suppress_view();
                };
                return $window->postpone_view();
            }
        }
        $window->clear_ledge();
        if ($title) {
            $log->warnf( "emphasis: odd title end markup." );
            $title--;
        }
        return $window->describe_view();
    }
    return;
}