package IMPL::ORM::Schema;
use strict;
use warnings;

use base qw(IMPL::DOM::Document);
use IMPL::Class::Property;

BEGIN {
    public property mapValueTypes => prop_get | owner_set;
    public property mapReferenceTypes => prop_get | owner_set;
}

sub CTOR {
    my ($this ) = @_;
    $this->mapValueTypes({});
    $this->mapReferenceTypes({});
}

# return an entity for the specified typename
# makes forward declaration if nesessary
sub resolveType {
    my ($this,$typeName) = @_;
    
    $this = ref $this ? $this : $this->instance;
    
    if (my $entity = $this->mapReferenceTypes->{$typeName}) {
        return $entity;
    } elsif (UNIVERSAL::isa($typeName,'IMPL::ORM::Object')) {
        return $this->declareReferenceType($typeName);
    } else {
        return undef;
    }
}

# returns valuetype name
sub isValueType {
    my ($this,$typeName) = @_;
    
    $this = ref $this ? $this : $this->instance;
    
    return $this->mapValueTypes->{$typeName};
}

my %instances;
sub instance {
    my ($class) = @_;
    
    return ($instances{$class} || ($instances{$class} = $class->new));
}

1;

__END__

=pod

=head1 DESCRIPTION

Схема данных, представляет собой DOM документ, элементами которой
являются сущности.

Каждый узел - это описание сущности.

=cut