Acme::Brainfuck - Embed Brainfuck in your perl code


Acme-Brainfuck documentation Contained in the Acme-Brainfuck distribution.

Index


Code Index:

NAME

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Acme::Brainfuck - Embed Brainfuck in your perl code

SYNOPSIS

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 #!/usr/bin/env perl
 use Acme::Brainfuck;

 print 'Hello world!', chr ++++++++++. ; 

DESCRIPTION

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Brainfuck is about the tiniest Turing-complete programming language you can get. A language is Turing-complete if it can model the operations of a Turing machine--an abstract model of a computer defined by the British mathematician Alan Turing in 1936. A Turing machine consists only of an endless sequence of memory cells and a pointer to one particular memory cell. Yet it is theoretically capable of performing any computation. With this module, you can embed Brainfuck instructions delimited by whitespace into your perl code. It will be translated into Perl as parsed. Brainfuck has just just 8 instructions (well more in this implementation, see "Extensions to ANSI Brainfuck" below.) which are as follows

Instructions

+ Increment

Increase the value of the current memory cell by one.

- Decrement

Decrease the value of the current memory cell by one.

> Forward

Move the pointer to the next memory cell.

< Back

Move the pointer to the previous memory cell.

, Input

Read a byte from Standard Input and store it in the current memory cell.

. Output

Write the value of the current memory cell to standard output.

[ Loop

If the value of the current memory cell is 0, continue to the cell after the next ']'.

] Next

Go back to the last previous '['.

Extensions to ANSI Brainfuck

This implementation has extra instructions available. In order to avoid such terrible bloat, they are only available if you use the verbose pragma like so:

use Acme::Brainfuck qw/verbose/;

The extra instructions are:

~ Reset

Resets the pointer to the first memory cell and clear all memory cells.

# Peek

Prints the values of the memory pointer and the current memory cell to STDERR. See also "Debugging" below.

Debugging

By using the debug pragma like this:

use Acme::Brainfuck qw/debug/;

you can dump out the generated perl code. (Caution: it is not pretty.) The key to understanding it is that the memory pointer is represented by $p, and the memory array by @m Therefore the value of the current memory cell is $m[$p].

RETURN VALUE

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Each sequence of Brainfuck instructions becomes a Perl block and returns the value of the current memory cell.

EXAMPLES

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JABH

 #!/usr/bin/env perl
 use Acme::Brainfuck;
 print "Just another ";
 ++++++[>++++++++++++++++<-]>
 ++.--
 >+++[<++++++>-]<.>[-]+++[<------>-]<
 +.-
 +++++++++.---------
 ++++++++++++++.--------------
 ++++++.------
 >+++[<+++++++>-]<.>[-]+++[<------->-]<
 +++.---
 +++++++++++.-----------
 print " hacker.\n";

Countdown

 #!/usr/bin/env perl
 use strict;
 use Acme::Brainfuck qw/verbose/;

 print "Countdown commencing...\n";
 ++++++++++[>+>+<<-]
 >>+++++++++++++++++++++++++++++++++++++++++++++++<<
 ++++++++++[>>.-<.<-]
 print "We have liftoff!\n";

Reverse

 #!/usr/bin/env perl
 use Acme::Brainfuck qw/verbose/;

 while(1)
 {
   print "Say something to Backwards Man and then press enter: ";
   +[->,----------]<
   print 'Backwards Man says, "';
   [+++++++++++.<]<
   print "\" to you too.\n";
   ~
 }

Math

 #!/usr/bin/env perl
 use Acme::Brainfuck;
 use strict;
 use warnings;

 my $answer = +++[>++++++<-]> ;

 print "3 * 6 = $answer \n";

VERSION

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 1.1.1 Apr 06, 2004

AUTHOR

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 Jaldhar H. Vyas E<lt>jaldhar@braincells.comE<gt>

THANKS

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Urban Mueller - The inventor of Brainfuck.

Damian Conway - For twisting perl to hitherto unimaginable heights of weirdness.

Marco Nippula <http://www.hut.fi/~mnippula/> - Some code in this module comes from his brainfuck.pl

Mr. Rock - Who has a nice Brainfuck tutorial at http://www.cydathria.com/bf/. Some of the example code comes from there.

COPYRIGHT AND LICENSE

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Acme-Brainfuck documentation Contained in the Acme-Brainfuck distribution.

#
# See POD documentation below for description, copyright and licensing info.
#
# $Id: Brainfuck.pm,v 1.5 2002/09/23 02:26:31 jaldhar Exp $
#
package Acme::Brainfuck;
use Filter::Simple;
use strict;
use warnings;

#remember to change this in the POD too.
our $VERSION = '1.1.1';
 
# The memory pointer and memory cells of our Turing machine. 
our $p = 0;
our @m = (); 

# The basic Brainfuck instructions.  Extras will be added in import().
our $ops = '+-<>,.[]'; 

# Whether or not we accept extra instructions.
our $verbose = 0;

# print out filtered text?
our $debug = 0;

sub import()
{
    shift;
    foreach (@_)
    {
	if (/^verbose$/)
	{
	    $ops .= '~#';
	    $verbose = 1;
	}
	if (/^debug$/)
	{
	    $debug = 1;
	}
    }
}

FILTER_ONLY code => sub
{
    my $ret = $_;
    while ($ret =~ /\s ([\Q$ops\E]+) \s/gsx)
    {
	my $code = $1;
	my $len = length($1);
	my $at = pos($ret) - ($len + 1);

	$code =~ s/^/do { /g;
	$code =~ s/$/P; }; /g;
	$code =~ s/(\++)/"P += ".length($1).";" /eg;
	$code =~ s/(\-+)/"P -= ".length($1).";" /eg;
	$code =~ s/(<+)/"\$Acme::Brainfuck::p -= ".length($1).";" /eg; 
	$code =~ s/(>+)/"\$Acme::Brainfuck::p += ".length($1).";" /eg;
	$code =~ s/\./print chr P; /g;
	$code =~ s/,/P = ord getc;/g;
	$code =~ s/\[/while(P){/g;
	$code =~ s/\]/}; /g;
	if ($verbose)
	{
	    $code =~
		s/~/\$Acme::Brainfuck::p = 0;\@Acme::Brainfuck::m = (); /g;
	    $code =~
		s/\#/print STDERR sprintf\('\$p = %d \$m[\$p]= %d', \$Acme::Brainfuck::p, P\), "\\n"; /g;
	}
	$code =~ s/P/\$Acme::Brainfuck::m\[\$Acme::Brainfuck::p\]/g;
	substr($ret, $at, $len, $code);
    }
    $_ = $ret;
    print $_ if $debug;
};

1;

__END__