Acme-URM

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INSTALL  view on Meta::CPAN

Any extra modules required for use:
Data::Dumper	- output in debug mode

The minimum version of Perl required:
?

If only works on certain operating systems:
Tested undef Linux but must work on any platform.

Installation:
$ perl Makefile.PL
$ make

lib/Acme/URM.pm  view on Meta::CPAN

our $VERSION	= '0.02';

use constant	LAST		=> -1;
use constant	THIS		=> -2;
use constant	MAX_STEPS	=> -3;

my $DEBUG   = 0;
sub import {
    foreach (@_) {
        if(/^debug$/) {
            $DEBUG  = 1;
        }
    }
}

sub new {
	my $class	= shift;
	my $self	= {@_};
	$self		= bless $self, $class;
	$self->_init();

lib/Acme/URM.pm  view on Meta::CPAN

sub run {
	my $self	= shift;
	$self->{instr_num}	= 0;
	$self->{steps_num}	= 0;
	my $run	= 1;
	do {
		my $step	= $self->_step();
		return	$step	if MAX_STEPS == $step;
		$run		= (scalar(@{$self->{program}}) > $step) ? 1 : 0;
	} while( $run );
	_debug( "program executed",
		   "registers: " . Dumper([$self->{registers}]),
		   "",
		  );
	$self->register(0)
}

sub _check_nreg {
	my $self	= shift;
	my $nreg	= shift;
	die "invalid register index: '$nreg'\n"	if $nreg !~ /^\s*\d+\s*$/ || $nreg < 0;
}

sub _step {
	my $self	= shift;
	my $cmd		= $self->{program}[ $self->{instr_num} ];
	_debug( "running instruction $self->{instr_num}: $cmd",
		   "registers: " . Dumper($self->{registers}),
		   "",
		  );
	my $instr_num_save	= $self->{instr_num};
	if( $cmd =~ /^\s*Z\s*\((.*)\)$/i ) {
		my $nreg	= $1;
		$self->_check_nreg( $nreg );
		$self->register( $nreg, 0 );
		$self->{instr_num}++;
	} elsif( $cmd =~ /^\s*S\s*\((.*)\)$/i ) {

lib/Acme/URM.pm  view on Meta::CPAN

		} else {
			$self->{instr_num}++;
		}
	} else {
		die "invalid instruction: '$cmd'\n";
	}
	$self->{steps_num}++;
	if( 0 < $self->{max_steps} && $self->{max_steps} < $self->{steps_num} ) {
		return	MAX_STEPS;
	}
	_debug( "after running instruction $instr_num_save: $cmd",
		   "registers: " . Dumper($self->{registers}),
		   "",
		  );
	$self->{instr_num}
}

sub max_steps {
	my $self	= shift;
	my $val		= shift;
	$self->{max_steps}	= $val	if defined $val;
	$self->{max_steps}
}

sub _debug {
	print join("\n",@_),"\n"	if $DEBUG;
}

1;

__END__

=head1 NAME

Acme::URM - URM (unlimited register machine) emulation

lib/Acme/URM.pm  view on Meta::CPAN

                         'S(3)',
                         'J(0,0,7)',
                         'T(1,0)',
                         );

  $urm->register( 0, 2, 3 );
  $urm->run() == 3;

=head1 DEBUG MODE

You can use this module in debug mode, like this:

  use Acme::URM qw/debug/;

Which will produce some output while running the program.

=head1 USEFULNESS

I coded this module while checking out TA (theory of algorithms) materials.

=head1 REFERENCES

Russian wiki link: