use strict;
use warnings;

use 5.014;

use Benchmark qw{ cmpthese };

my $n = 4;

my $str = q{x} x 50;
substr $str, $_, 4, q{fred} for 4, 9, 20, 24, 31, 40;
say qq{String: $str\n};

my $rcMovePos = sub {
   my $raMatches;
   while ( $str =~ m{\G(?:.{$n})*?(?=(fred.*))}g )
   {
       push @{ $raMatches }, [ pos( $str ), $1 ];
       pos $str += $n;
   }
   return $raMatches;
   };

my $rcNoDups = sub {
   my $rhMatches;
   $rhMatches->{ pos( $str ) } = $1 while
      $str =~ m{\G(?:.{$n})*?(?=(fred.*))}g;
   return $rhMatches;
   };

my $rcWithDups = sub {
   my $raMatches;
   push @{ $raMatches }, [ pos( $str ), $1 ] while
      $str =~ m{\G(?:.{$n})*?(?=(fred.*))}g;
   return $raMatches;
   };

my $raRes = $rcMovePos->();
say  q{Using $rcMovePos};
say qq{  Matched $_->[ 1 ] at position $_->[ 0 ]} for @{ $raRes };

my $rhRes = $rcNoDups->();
say  q{Using $rcNoDups};
say qq{  Matched $rhRes->{ $_ } at position $_} for
   sort { $a <=> $b } keys %{ $rhRes };

$raRes = $rcWithDups->();
say  q{Using $rcWithDups};
say qq{  Matched $_->[ 1 ] at position $_->[ 0 ]} for @{ $raRes };

srand 1234567890;

$str = q{x} x 10000;
substr $str, int rand 9997, 4, q{fred} for 1 .. 50;

say q{};
cmpthese(
   -5,
   {
       movePos  => $rcMovePos,
       noDups   => $rcNoDups,
       withDups => $rcWithDups,
   } );