Intermediate Perl (Alpaca Book), exercise 10.4

recursion.pl

#/usr/bin/perl
use strict;
use warnings;
use 5.010;

my $path = shift // '.';
my $data = data_for_path($path);

#use Data::Dumper;
#print Dumper \$data;
dump_data_for_path( $path, $data );

sub data_for_path {
    my $path = shift;

    if ( -f $path or -l $path ) {
        return undef;
    }

    if ( -d $path ) {
        opendir PATH, $path or die $!;
        my @names = readdir PATH;
        close PATH;
        my %directory;
        foreach my $name (@names) {
            next if $name eq '.' or $name eq '..';
            $directory{$name} = data_for_path("$path/$name");
        }
        return \%directory;
    }

    warn "$path of neither a file nor a directory\n";
    return undef;
}

sub dump_data_for_path {
    my $path  = shift;
    my $data  = shift;
    my $level = shift // 0;

    print ' ' x $level, $path;

    if ( not defined $data ) {    # plain file
        print "\n";
        return;
    }

    if ( keys %$data ) {
        print ", with contents:\n";
        foreach ( sort keys %$data ) {
            dump_data_for_path( "$path/$_", $data->{$_}, $level + 1 );
        }
    } else {
        print ", an empty directory\n";
    }
}