Add support for parametric containers that subtype ArrayRef or HashRef

[gitmo/Moose.git] / lib / Moose / Meta / TypeConstraint / Parameterized.pm

package Moose::Meta::TypeConstraint::Parameterized;

use strict;
use warnings;
use metaclass;

use Scalar::Util 'blessed';
use Carp         'confess';

our $VERSION   = '0.01';
our $AUTHORITY = 'cpan:STEVAN';

use base 'Moose::Meta::TypeConstraint';

__PACKAGE__->meta->add_attribute('type_parameter' => (
    accessor  => 'type_parameter',
    predicate => 'has_type_parameter',
));

sub compile_type_constraint {
    my $self = shift;
    
    ($self->has_type_parameter)
        || confess "You cannot create a Higher Order type without a type parameter";
        
    my $type_parameter = $self->type_parameter;
    
    (blessed $type_parameter && $type_parameter->isa('Moose::Meta::TypeConstraint'))
        || confess "The type parameter must be a Moose meta type";
    
    my $constraint;
    
    my $array_constraint = sub {
        foreach my $x (@$_) {
            ($type_parameter->check($x)) || return
        } 1;
    };

    my $hash_constraint = sub {
        foreach my $x (values %$_) {
            ($type_parameter->check($x)) || return
        } 1;
    };

    if ($self->is_subtype_of('ArrayRef')) {
        $constraint = $array_constraint;
    }
    elsif ($self->is_subtype_of('HashRef')) {
        $constraint = $hash_constraint;
    }
    else {
        confess "The " . $self->name . " constraint cannot be used, because " . $self->parent->name . " doesn't subtype ArrayRef or HashRef.";
    }
    
    $self->_set_constraint($constraint);
    
    $self->SUPER::compile_type_constraint;
}

1;

__END__


=pod

=head1 NAME

Moose::Meta::TypeConstraint::Parameterized - Higher Order type constraints for Moose

=head1 DESCRIPTION

=head1 METHODS

=over 4

=item B<compile_type_constraint>

=item B<type_parameter>

=item B<has_type_parameter>

=item B<meta>

=back

=head1 BUGS

All complex software has bugs lurking in it, and this module is no 
exception. If you find a bug please either email me, or add the bug
to cpan-RT.

=head1 AUTHOR

Stevan Little E<lt>stevan@iinteractive.comE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright 2006, 2007 by Infinity Interactive, Inc.

L<http://www.iinteractive.com>

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=cut