my( $quote, $quoted, $end )=  $string =~
        /(['"])((?:\\.|[^'"\\]+|(?!\1)['"])*)(\1?)/;
    die "Unclosed quote: $quote$quoted\n"
        if  $quote  &&  ! $end;

##</code><code>##

     /(['"])((?:\\.|[^\1\\]+)*)(\1?)/

##</code><code>##

    /(['"])((?:(?:\\.)+|[^\1\\]+)*)(\1?)/

##</code><code>##

    /(['"])((?:(?:\\.)+|[^'"\\]+|(?!\1)['"])*)(\1?)/

##</code><code>##

    "'" . '\vv'x35_000 . "z'"

##</code><code>##

    my( $quote, $quoted );
    if(  $str =~ /(['"])/g  ) {
        my $beg= pos($str);
        $quote= $1;
        if(  $str !~ /(?<!\\)((?:\\\\)*)\Q$quote/g  ) {
            die "Unclosed quote: ", substr($str,$beg), $/;
        }
        my $end= pos($str);
        $quoted= substr( $str, $beg, $end-$beg-1 );
    }