my @parsed;
my $line = 1;

while ($asp =~ /\G((?: [^<]+ | <(?!%) )*) (?: <%(.*?)%> | ((?=<%)) )?/gsx) {

    $1 and push @parsed, [ $line, html => $1 ];
    $line += $1 =~ tr/\n//;

    $2 and push @parsed, [ $line, asp  => $1 ];
    $line += $2 =~ tr/\n//;

    defined $3 and die "Unclosed ASP code block starting on line $line near '",
        $asp =~ /\G(<%\s*\n?.*)/g, "'.\n";
}