#!/usr/bin/env perl

use 5.010;
use strict;
use warnings;

use Benchmark 'cmpthese';

use constant STRING => 'X';
use constant CONST_RE => qr{^X$};

my    $my_re          = qr{^X$};
state $state_re       = qr{^X$};
our   $our_re         = qr{^X$};
local $main::local_re = qr{^X$};

cmpthese 0 => {
    re_str        => sub { STRING =~ '^X$'              }, 
    re_re         => sub { STRING =~ /^X$/              }, 
    re_re_o       => sub { STRING =~ /^X$/o             }, 
    re_qr         => sub { STRING =~ qr{^X$}            }, 
    re_qr_o       => sub { STRING =~ qr{^X$}o           }, 
    qr_my         => sub { STRING =~ $my_re             }, 
    qr_my_re      => sub { STRING =~ /$my_re/           }, 
    qr_my_re_o    => sub { STRING =~ /$my_re/o          }, 
    qr_state      => sub { STRING =~ $state_re          }, 
    qr_state_re   => sub { STRING =~ /$state_re/        }, 
    qr_state_re_o => sub { STRING =~ /$state_re/o       }, 
    qr_our        => sub { STRING =~ $our_re            }, 
    qr_our_re     => sub { STRING =~ /$our_re/          }, 
    qr_our_re_o   => sub { STRING =~ /$our_re/o         }, 
    qr_const      => sub { STRING =~ CONST_RE           }, 
    qr_const_re   => sub { STRING =~ /${\CONST_RE()}/   }, 
    qr_const_re_o => sub { STRING =~ /${\CONST_RE()}/o  }, 
    qr_local      => sub { STRING =~ $main::local_re    }, 
    qr_local_re   => sub { STRING =~ /$main::local_re/  }, 
    qr_local_re_o => sub { STRING =~ /$main::local_re/o }, 
};