use strict;
use warnings;
use Benchmark qw(cmpthese);

($_) = <DATA>;
chomp;
my @data = split /:/;

cmpthese(100_000, {

'for-ind-eq' => sub {
my @copy = @data;
for (0..$#copy) { $copy[$_] = undef if $copy[$_] eq ''; }
},

'for-ind-match' => sub {
my @copy = @data;
for (0..$#copy) { $copy[$_] = undef if $copy[$_] =~ /^$/; }
},

'foreach-eq' => sub{
my @copy = @data;
foreach (@copy) { $_ = undef if $_ eq ''; }
},

'foreach-match' => sub {
my @copy = @data;
foreach (@copy) { $_ = undef if /^$/; }
},

'map-eq' => sub {
my @copy = @data;
map { $_ = $_ eq '' ? undef : $_ } @copy;
},

'map-match' => sub {
my @copy = @data;
map { $_ = /^$/ ? undef : $_ } @copy;
},

});
__DATA__
4479:5509:7721:1743:7821::9119::9532::7095::5028:6179:2693:2133::4158:7256:7960:::8094:1458:5739:7570:::5059:4926:4933:7378:3066:7916:6062:::7671:399::::1010::3938:2278:8571:::2286::4740::4133::::2712::::2507::1579::4503:3889:1892:7667::::5676::::::8371:2258:372::2795:4126:2156:6580:5798:::8138::4545:7843:2231:4414:5792::6187::3488