use 5.020;
use Regexp::Grammars;
my $input = <<'...';
input abc10;

output wireax;

checkinst_0(
.port1(wireY),
.port2(wireZ),
.port3(wireX),
.port4(port711),
.port10
);

checkinst_2(
.port5(wireYx),
.port6(wireZ),
.port7(wireaX),
.port8(abc10),
.port11
);

checkinst_3(
.port100(wireYd),
.port101(wireZS),
.port102(wireXW),
.port103(port10),
.port12
);
...

my $parser = qr{
    <start>
    <rule: start>           <input> <output> <[checkinst]>+
    <rule: input>           input <identifier> ;
    <rule: output>          output <identifier> ;
    <rule: checkinst>       <checkinstid> [(] <ports> [)];
    <rule: ports>           <[port]>+ % ,
    <rule: port>            <portid> <parens>?
    <rule: parens>          [(] <identifier> [)]
    <token: identifier>     \w+\d*
    <token: checkinstid>    checkinst_ \d+
    <token: portid>         [.]port \d+
}msx;

if ($input =~ $parser) {
    my %r;
    {
        my $i = $/{start}{input}{identifier};
        my $o = $/{start}{output}{identifier};
        $r{top} = {
            source => [$i, $o],
            dest => [$i, $o],
        };
    }
    {
        my @implicit;
        for my $checkinst ($/{start}{checkinst}->@*) {
            for my $port ($checkinst->{ports}{port}->@*) {
                if ($port->{parens}) {
                    push $r{$checkinst->{checkinstid}}{dest}->@*,
                        $port->{parens}{identifier};
                    push $r{$checkinst->{checkinstid}}{source}->@*,
                        $port->{portid} =~ s/^\.//r;
                } else {
                    push @implicit, $port->{portid} =~ s/^\.//r;
                }
            }
        }
        $r{Implicit} = {
            source  => \@implicit,
            dest => \@implicit,
        };
    }
}
__END__
%r = (
    checkinst_0 => {
        dest   => [qw(wireY wireZ wireX port711)],
        source => [qw(port1 port2 port3 port4)],
    },
    checkinst_2 => {
        dest   => [qw(wireYx wireZ wireaX abc10)],
        source => [qw(port5 port6 port7 port8)],
    },
    checkinst_3 => {
        dest   => [qw(wireYd wireZS wireXW port10)],
        source => [qw(port100 port101 port102 port103)],
    },
    Implicit => {
        dest   => [qw(port10 port11 port12)],
        source => [qw(port10 port11 port12)],
    },
    top => {
        dest   => [qw(abc10 wireax)],
        source => [qw(abc10 wireax)]
    },
)