Text::Tokenizer::ClassでS式計算機

あんまり構文エラーとかチェックしてない

use Text::Tokenizer::Class;
use Scalar::Util qw(looks_like_number);
use Perl6::Say;


my $parser = Text::Tokenizer::Class->new(parse_type => 'handler');
$parser->ignored_chars(qr/\s/);

$parser->add_pattern(
    qr/[+\-*\/]/ => sub { shift->step }
);
$parser->add_pattern(
    sub { looks_like_number($_) } => sub { shift->step }
);
$parser->add_pattern(
    '(' => sub {
        my $self = shift;
        my $proc = $self->parse(post_stop_if_found => 1);
        my @nums;
        while (1) {
            my $n = $self->parse(post_stop_if_found => 1);
            last    unless defined $n;
            push @nums, $n;
        }
        eval join $proc, @nums;
    }
);
$parser->add_pattern(
    ')' => sub { undef }
);


$parser->string("(+ 1 1)");
say $parser->parse();    # => 2