sub parse_value {
    if( peek( qr{['"]} ) ) {
        parse_string();
    ...

sub parse_string {
    my $start = get_pos();  # now a seek position, not a string offset
    my $str = '';
    if( eat("'") ) {
        # Inside '...', '' is a literal ', all else is just literal:
        while( ! peek("'(?!')",1) ) {
            #                  ^ keep leading whitespace
            if( eat("''",1) ) {
                $str .= "'";
            } else {
                swallow("[^']+",1,\$str,1); # fatal if no match
                # Can match to $Buf end ^
            }
        }
        swallow("'",1);
    } else {
        swallow('"');
        while( peek('[^"]',1) ) {
            while( peek('\\',1) ) {
                $str .= parse_escape();
            }
            eat( qr{[^\\"]*}, 1, \$str, 1 );
        }
        swallow('"',1,'',0,'Unclosed string',$start);
    }
    return $str;
}