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lib/Forks/Super/LazyEval/BackgroundScalar.pm  view on Meta::CPAN

	$_[2] ? $_[1] cmp $_[0]->_fetch : $_[0]->_fetch cmp $_[1]
    },
    '-' => sub { $_[2] ? $_[1] - $_[0]->_fetch : $_[0]->_fetch - $_[1] },
    '/' => sub { $_[2] ? $_[1] / $_[0]->_fetch : $_[0]->_fetch / $_[1] },
    '%' => sub { $_[2] ? $_[1] % $_[0]->_fetch : $_[0]->_fetch % $_[1] },
    '**' => sub { $_[2] ? $_[1] ** $_[0]->_fetch : $_[0]->_fetch ** $_[1] },
    '<<' => sub { $_[2] ? $_[1] << $_[0]->_fetch : $_[0]->_fetch << $_[1] },
    '>>' => sub { $_[2] ? $_[1] >> $_[0]->_fetch : $_[0]->_fetch >> $_[1] },
    'x' => sub { $_[2] ? $_[1] x $_[0]->_fetch : $_[0]->_fetch x $_[1] },

# derefencing operators: should return a reference of the correct type.

    '${}' => sub { $_[0]->_fetch },
    '@{}' => sub { $_[0]->_fetch },
    '&{}' => sub { $_[0]->_fetch },
    '*{}' => sub { $_[0]->_fetch },

# A BackgroundScalar object is a HASH-type reference. Inside
# _fetch we must disable overloading of '%{}'
    '%{}' => sub { $_[0]->_fetch },

    'cos' => sub { cos $_[0]->_fetch },
    'sin' => sub { sin $_[0]->_fetch },
    'exp' => sub { exp $_[0]->_fetch },
    'log' => sub { log $_[0]->_fetch },
    'sqrt' => sub { sqrt $_[0]->_fetch },
    'int' => sub { int $_[0]->_fetch },
    'abs' => sub { abs $_[0]->_fetch },
    'atan2' => sub { $_[2] ? atan2($_[1], $_[0]->_fetch) 
		         : atan2($_[0]->_fetch, $_[1]) }
;

our $VERSION = '0.97';

# "protocols" for serializing data and the methods used
# to carry out the serialization

my %serialization_dispatch = (

    YAML => {
	require => sub { require YAML },
	encode => sub { return YAML::Dump($_[0]) },
	decode => sub { return YAML::Load($_[0]) }
    },

    'Data::Dumper' => {
	require => sub { require Data::Dumper },
	encode => sub { return Data::Dumper::Dumper($_[0]) },
	decode => sub {
	    my ($data,$job,$VAR1) = @_;
            if ($job->{untaint}) {
                ($data) = $data =~ /(.*)/s;
            } elsif (${^TAINT}) {
                carp 'Forks::Super::bg_eval/bg_qx(): ',
                        'Using Data::Dumper for serialization, which cannot ',
                        "operate on 'tainted' data. Use bg_eval {...} ",
                        '{untaint => 1} or bg_qx COMMAND, ',
                        "{untaint => 1} to retrieve the result.\n";
                return;
            }
	    my $decoded = eval "$data";    ## no critic (StringyEval)
	    return $decoded;
	}
    },

    );

# a scalar reference that is evaluated in a child process.
# when the value is dereferenced, retrieve the output from
# the child, waiting for the child to finish if necessary

sub new {
    my ($class, $style, $command_or_code, %other_options) = @_;
    my $self = { value_set => 0, style => $style };
    if ($style eq 'eval') {
	my $protocol = $other_options{'protocol'};
	$self->{code} = $command_or_code;
	$self->{job_id} = Forks::Super::fork { 
	    (%other_options,
	     child_fh => 'out',
	     sub => sub {
		 my $Result = $command_or_code->();
		 print STDOUT _encode($protocol, $Result);
	     }, 
	     _is_bg => 1,
	     _lazy_proto => $protocol )
	};

    } elsif ($style eq 'qx') {
	$self->{command} = $command_or_code;
	$self->{stdout} = '';
	$self->{job_id} = Forks::Super::fork { 
	    (%other_options, 
	     child_fh => 'out',
	     cmd => $command_or_code,
	     stdout => \$self->{stdout},
	     _is_bg => 1)
	};
        
    }
    $self->{job} = Forks::Super::Job::get($self->{job_id});
    ($Forks::Super::LAST_JOB, $Forks::Super::LAST_JOB_ID)
	= ($self->{job}, $self->{job_id});
    $self->{value} = undef;
    return bless $self, $class;
}

sub _encode {
    my ($protocol, $data) = @_;
    if (defined $serialization_dispatch{$protocol}) {
	$serialization_dispatch{$protocol}{'require'}->();
	return $serialization_dispatch{$protocol}{encode}->($data);
    } else {
	croak 'Forks::Super::LazyEval::BackgroundScalar: ',
	    'YAML or Data::Dumper required to use bg_eval';
    }
}

sub _decode {
    my ($protocol, $data, $job) = @_;
    if (defined $serialization_dispatch{$protocol}) {
	$serialization_dispatch{$protocol}{require}->();