use strict;
use warnings;
use feature 'say';
use Time::HiRes 'time';

if ( !@ARGV ) {
    say $^V;
    for my $size ( 5e5, 1e6, 5e6 ) {
        say "Array size: $size";
        for my $method ( 0, 1, 2 ) {
            for my $heat ( 0, 1 ) {
                system $^X, $0, $method, $heat, $size
            }
        }
    }
}
else {
    my ( $method, $preheat, $size ) = @ARGV;

    my $s = join ' ', 0 .. 9;
    $s .= "\n";
    $s x= $size;
    chomp $s;
    
    my $t = time;
    
    if ( $preheat ) {
        my @garbage = ( undef ) x $size
    }
    
    my @a;
    if ( $method == 0 ) {               # split
        @a = split /(?<=\n)/, $s
    }
    elsif ( $method == 1 ) {            # global match
        @a = $s =~ /(.*?\n|.+)/gs
    }
    elsif ( $method == 2 ) {            # IO (list context)
        open my $fh, '>', 'garbage.tmp';
        binmode $fh;
        print $fh $s;
        close $fh;
        open $fh, '<', 'garbage.tmp';
        binmode $fh;
        @a = <$fh>;
        close $fh;
    }
    
    printf "\t%s, %s:\t%.3f\n", 
        ( <split match io(list)> )[ $method ],
        ( $preheat ? 'pre-heat' : 'no pre-heat' ),
        time - $t
}