Tag: commandline

I wanted a quick implementation of Conway’s Game of Life this evening to muck about with, with the boys. Whipped this up in simple Perl for running in a terminal / on the commandline. It’s not the fastest implementation on the planet but that’s most likely just the way I’ve coded it.

Throw some 1s and 0s in the DATA block at the end to modify the start state, change the $WIDTH and $HEIGHT of the area, or uncomment the random data line in init() and see what you see.

#!/usr/local/bin/perl
# -*- mode: cperl; tab-width: 8; indent-tabs-mode: nil; basic-offset: 2 -*-
# vim:ts=8:sw=2:et:sta:sts=2
#########
# Author:        rmp
# Created:       2012-10-12
# Last Modified: $Date: 2012-10-12 19:09:00 +0100 (Fri, 12 Oct 2012) $
# Id:            $Id$
# $HeadURL$
#
use strict;
use warnings;
use Time::HiRes qw(sleep);
use Readonly;
use English qw(-no_match_vars);
use Carp;

Readonly::Scalar my $WIDTH      => 78;
Readonly::Scalar my $HEIGHT     => 21;
Readonly::Scalar my $TURN_DELAY => 0.1;

our $VERSION = '0.01';

my $grid  = init();
my $turns = 0;
while(1) {
  render($grid);
  $grid = turn($grid);
  sleep $TURN_DELAY;
  $turns++;
}

sub init {
  #########
  # initialise with a manual input from the DATA block below
  #
  local $RS = undef;
  my $data  = <data>;
  my $out   = [
	       map { [split //smx, $_] }
	       map { split /\n/smx, $_ }
	       $data
	      ];

  #########
  # fill the matrix with space
  #
  for my $y (0..$HEIGHT-1) {
    for my $x (0..$WIDTH-1) {
      $out->[$y]->[$x] ||= 0;
#      $out->[$y]->[$x] = rand >= 0.2 ? 0 : 1; # initialise with some random data
    }
  }
  return $out;
}

#########
# draw to stdout/screen
#
sub render {
  my ($in) = @_;
  system $OSNAME eq 'MSWin32' ? 'cls' : 'clear';

  print q[+], q[-]x$WIDTH, "+\n" or croak qq[Error printing: $ERRNO];
  for my $y (@{$in}) {
    print q[|] or croak qq[Error printing: $ERRNO];
    print map { $_ ? q[O] : q[ ] } @{$y} or croak qq[Error printing: $ERRNO];
    print "|\r\n" or croak qq[Error printing: $ERRNO];
  }
  print q[+], q[-]x$WIDTH, "+\n" or croak qq[Error printing: $ERRNO];

  return 1;
}

#########
# the fundamental Game of Life rules
#
sub turn {
  my ($in) = @_;
  my $out  = [];

  for my $y (0..$HEIGHT-1) {
    for my $x (0..$WIDTH-1) {
      my $topedge    = $y-1;
      my $bottomedge = $y+1;
      my $leftedge   = $x-1;
      my $rightedge  = $x+1;

      my $checks = [
		    grep { $_->[0] >= 0 && $_->[0] < $HEIGHT } # Y boundary checking
		    grep { $_->[1] >= 0 && $_->[1] < $WIDTH }  # X boundary checking
		    [$topedge,    $leftedge],
		    [$topedge,    $x],
		    [$topedge,    $rightedge],
		    [$y,          $leftedge],
		    [$y,          $rightedge],
		    [$bottomedge, $leftedge],
		    [$bottomedge, $x],
		    [$bottomedge, $rightedge],
		   ];

      my $alive = scalar
	          grep { $_ }
	          map { $in->[$_->[0]]->[$_->[1]] }
		  @{$checks};

      $out->[$y]->[$x] = (($in->[$y]->[$x] && $alive == 2) ||
			  $alive == 3);
    }
  }
  return $out;
}

__DATA__
0
0
0
0
0
0
0000000010
0000000111
0000000101
0000000111
0000000010
</data>

p.s. WordPress is merrily swapping “DATA” for “data” on line 38 and adding an extra /data tag at the end of that code snippet. Fix line 38 and don’t copy & paste the close tag. Damn I hate WordPress :(