# comments refer to benchmark tests using ~/Documents/ and ~/etext/ dirs
sub want_file {
    my $filename = shift;
    if ( $check_type && -T $filename ) {
	# 15061 filenames in 0.692 sec
	return 1;
    } elsif ( $check_extensions ) {
	# 8857 filenames in . 0.794 sec with 
	# --extensions=txt,pl,html,htm 
	if ( ( grep { $filename =~ m(\.$_$) } @file_extensions ) && -e $filename) {
	    return 1;
	}
    } else {
	# this test finds 5066 files in ~/Documents and ~/etext 
	#  in 0.218 sec
	if ( $filename =~ m(\.txt$) &&  -e $filename  ) {
	    return 1;
	}
    }
    return 0;
}


sub recurse_dir {
    my $dirname = shift;

    local *D;
    opendir D, $dirname;

    my $fname;
    while ( $fname = readdir D ) {
	my $name = $dirname . "/" . $fname;
	if ( -d $name ) {
	    # don't recurse on . or .. or dotfiles generally
	    if ( $fname !~ /^\./ ) {
		print "$name is a dir\n"	if $debug >= 3;
		&recurse_dir( $name );
	    }
	} elsif ( &want_file( $name ) ) {
	    print "$name is a text file\n"	if $debug >= 3;
	    push @filenames, $name;
	} else {
	    print "skipping $name\n"	if $debug >= 3;
	}
	if ( $preload_paras and ((rand 100) < 1) ) {
	    print "preload mode so printing something while still gathering filenames (" . (scalar @filenames) . " read so far)\n"	if $debug;
	    if ( scalar @filenames ) {
		&add_paras;
		&slow_print( int rand scalar @paras );
	    } else {
		print "...but there are no usable files yet\n" 	if $debug;
	    }
	}
    }
    closedir D;
}