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

use Benchmark qw( timethese cmpthese );

my $template = 1 x 200;

cmpthese timethese -5 => {
	end_end => sub {
		my $from = $template;
		my $to = '';
		for ( 0 .. 100 ) {
			substr $to, length $to, 0, substr $from, -1, 1, '' while length $from;
			substr $from, length $from, 0, substr $to, -1, 1, '' while length $to;
		}
	},
	start_end => sub {
		my $from = $template;
		my $to = '';
		for ( 0 .. 100 ) {
			substr $to, length $to && 0, 0, substr $from, -1, 1, '' while length $from;
			substr $from, length $from && 0, 0, substr $to, -1, 1, '' while length $to;
		}
	},
	end_start => sub {
		my $from = $template;
		my $to = '';
		for ( 0 .. 100 ) {
			substr $to, length $to, 0, substr $from, 0, 1, '' while length $from;
			substr $from, length $from, 0, substr $to, 0, 1, '' while length $to;
		}
	},
	start_start => sub {
		my $from = $template;
		my $to = '';
		for ( 0 .. 100 ) {
			substr $to, length $to && 0, 0, substr $from, 0, 1, '' while length $from;
			substr $from, length $from && 0, 0, substr $to, 0, 1, '' while length $to;
		}
	},
};

__END__
Benchmark: running end_end, end_start, start_end, start_start for at least 5 CPU seconds...
   end_end:  6 wallclock secs ( 5.28 usr +  0.01 sys =  5.29 CPU) @ 34.22/s (n=181)
 end_start:  5 wallclock secs ( 5.33 usr +  0.01 sys =  5.34 CPU) @ 33.33/s (n=178)
 start_end:  6 wallclock secs ( 5.25 usr +  0.00 sys =  5.25 CPU) @ 25.90/s (n=136)
start_start:  5 wallclock secs ( 5.22 usr +  0.01 sys =  5.23 CPU) @ 25.43/s (n=133)
              Rate start_start   start_end   end_start     end_end
start_start 25.4/s          --         -2%        -24%        -26%
start_end   25.9/s          2%          --        -22%        -24%
end_start   33.3/s         31%         29%          --         -3%
end_end     34.2/s         35%         32%          3%          --