#! /usr/bin/perl -w
use strict;
use Benchmark;
use Algorithm::Loops qw(NestedLoops);

use vars qw(@chars $loop_cnt $printit);
$loop_cnt = 3;
@chars = map chr, 0x21 .. 0x7e;
# @chars = ("a" .. "c");

sub printit {
   print @_ if $printit;
}

#------------------------------------------------

sub doit4 {
   my $x = 1;
   while ($x <= $loop_cnt) {
      NestedLoops(
         [ map \@chars, 1 .. $x++ ],
         sub { printit join "", @_, "\n" }
      );
   }
}

#------------------------------------------------

sub ret_iter3 {
   my $accum = shift;
   my $range = shift;
   if ($range) { ret_iter3( [@$accum, $_], @_ ) for @$range }
   else        { printit join "", @$accum, "\n" }
}

sub nested_for3 {
   ret_iter3 [], @_;
}

sub doit3 {
   my $x = 1;
   while ($x <= $loop_cnt) {
      nested_for3 map \@chars, 1 .. $x++;
   }
}

#------------------------------------------------

sub ret_iter2 {
   my $accum = shift;
   my $range = shift;
   if (@_) {
      for (@$range) {
         push @$accum, $_;
         ret_iter2($accum, @_);
         pop @$accum;
      }
   } else {
      printit join "", @$accum, $_, "\n" for @$range;
   }
}

sub nested_for2 {
   ret_iter2 [], @_;
}

sub doit2 {
   my $x = 1;
   while ($x <= $loop_cnt) {
      nested_for2 map \@chars, 1 .. $x++;
   }
}

#------------------------------------------------

sub doit1 {
   my $x = 0;
   while (++$x <= $loop_cnt) {
      nested_for1(
         sub {printit join "", @_, "\n";}
       , map \@chars, 1..$x
      );
#     nested_for1(
#        sub {printit join "", reverse(@_), "\n";}
#      , reverse(map \@chars, 1..$x)
#     );
   }
}

sub nested_for1 {
   ret_iter(@_)->();
}

sub ret_iter {
   my $fn = shift;
   my $range = shift;
   my $sub = sub {$fn->($_, @_) for @$range};
   return @_ ? ret_iter($sub, @_) : $sub;
}

#------------------------------------------------

# $printit = 1;
# doit1;
# doit2;
# doit3;
# doit4;
# exit;

timethese (-10, {
   doit1 => 'doit1',
   doit2 => 'doit2',
   doit3 => 'doit3',
   doit4 => 'doit4',
});