# RDF::Trine::Serializer::NTriples
# -----------------------------------------------------------------------------

=head1 NAME

RDF::Trine::Serializer::NTriples - N-Triples Serializer

=head1 VERSION

This document describes RDF::Trine::Serializer::NTriples version 1.012

=head1 SYNOPSIS

 use RDF::Trine::Serializer::NTriples;
 my $serializer	= RDF::Trine::Serializer::NTriples->new();

=head1 DESCRIPTION

The RDF::Trine::Serializer::NTriples class provides an API for serializing RDF
graphs to the N-Triples syntax.

=head1 METHODS

Beyond the methods documented below, this class inherits methods from the
L<RDF::Trine::Serializer> class.

=over 4

=cut

package RDF::Trine::Serializer::NTriples;

use strict;
use warnings;
use base qw(RDF::Trine::Serializer);

use URI;
use Carp;
use Data::Dumper;
use Scalar::Util qw(blessed);

use RDF::Trine::Node;
use RDF::Trine::Statement;
use RDF::Trine::Error qw(:try);

######################################################################

our ($VERSION);
BEGIN {
	$VERSION	= '1.012';
	$RDF::Trine::Serializer::serializer_names{ 'ntriples' }	= __PACKAGE__;
	$RDF::Trine::Serializer::format_uris{ 'http://www.w3.org/ns/formats/N-Triples' }	= __PACKAGE__;
	foreach my $type (qw(text/plain)) {
		$RDF::Trine::Serializer::media_types{ $type }	= __PACKAGE__;
	}
}

######################################################################

=item C<< new >>

Returns a new N-Triples serializer object.

=cut

sub new {
	my $class	= shift;
	my %args	= @_;
	my $self = bless( {}, $class);
	return $self;
}

=item C<< serialize_model_to_file ( $fh, $model ) >>

Serializes the C<$model> to N-Triples, printing the results to the supplied
filehandle C<<$fh>>.

=cut

sub serialize_model_to_file {
	my $self	= shift;
	my $file	= shift;
	my $model	= shift;
	my $st		= RDF::Trine::Statement->new( map { RDF::Trine::Node::Variable->new($_) } qw(s p o) );
	my $pat		= RDF::Trine::Pattern->new( $st );
	my $stream	= $model->get_pattern( $pat, undef, orderby => [ qw(s ASC p ASC o ASC) ] );
	my $iter	= $stream->as_statements( qw(s p o) );
	while (my $st = $iter->next) {
		print {$file} $self->statement_as_string( $st );
	}
}

=item C<< serialize_model_to_string ( $model ) >>

Serializes the C<$model> to N-Triples, returning the result as a string.

=cut

sub serialize_model_to_string {
	my $self	= shift;
	my $model	= shift;
	my $st		= RDF::Trine::Statement->new( map { RDF::Trine::Node::Variable->new($_) } qw(s p o) );
	my $pat		= RDF::Trine::Pattern->new( $st );
	my $stream	= $model->get_pattern( $pat, undef, orderby => [ qw(s ASC p ASC o ASC) ] );
	my $iter	= $stream->as_statements( qw(s p o) );
	
	my $string	= '';
	while (my $st = $iter->next) {
		my @nodes	= $st->nodes;
		$string		.= $self->statement_as_string( $st );
	}
	return $string;
}

=item C<< serialize_iterator_to_file ( $file, $iter ) >>

Serializes the iterator to N-Triples, printing the results to the supplied
filehandle C<<$fh>>.

=cut

sub serialize_iterator_to_file {
	my $self	= shift;
	my $file	= shift;
	my $iter	= shift;
	while (my $st = $iter->next) {
		print {$file} $self->statement_as_string( $st );
	}
}

=item C<< serialize_iterator_to_string ( $iter ) >>

Serializes the iterator to N-Triples, returning the result as a string.

=cut

sub serialize_iterator_to_string {
	my $self	= shift;
	my $iter	= shift;
	my $string	= '';
	while (my $st = $iter->next) {
		my @nodes	= $st->nodes;
		$string		.= $self->statement_as_string( $st );
	}
	return $string;
}

sub _serialize_bounded_description {
	my $self	= shift;
	my $model	= shift;
	my $node	= shift;
	my $seen	= shift || {};
	return '' if ($seen->{ $node->sse }++);
	my $iter	= $model->get_statements( $node, undef, undef );
	my $string	= '';
	while (my $st = $iter->next) {
		my @nodes	= $st->nodes;
		$string		.= $self->statement_as_string( $st );
		if ($nodes[2]->isa('RDF::Trine::Node::Blank')) {
			$string	.= $self->_serialize_bounded_description( $model, $nodes[2], $seen );
		}
	}
	return $string;
}

=item C<< statement_as_string ( $st ) >>

Returns a string with the supplied RDF::Trine::Statement object serialized as
N-Triples, ending in a DOT and newline.

=cut

sub statement_as_string {
	my $self	= shift;
	my $st		= shift;
	my @nodes	= $st->nodes;
	return join(' ', map { $_->as_ntriples } @nodes[0..2]) . " .\n";
}

=item C<< serialize_node ( $node ) >>

Returns a string containing the N-Triples serialization of C<< $node >>.

=cut

sub serialize_node {
	my $self	= shift;
	my $node	= shift;
	return $node->as_ntriples;
}

1;

__END__

=back

=head1 NOTES

As described in L<RDF::Trine::Node::Resource/as_ntriples>, N-Triples serialization will
decode any L<punycode|http://www.ietf.org/rfc/rfc3492.txt> that is included in the IRI,
and serialize it using unicode codepoint escapes.

=head1 BUGS

Please report any bugs or feature requests to through the GitHub web interface
at L<https://github.com/kasei/perlrdf/issues>.

=head1 SEE ALSO

L<http://www.w3.org/TR/rdf-testcases/#ntriples>

=head1 AUTHOR

Gregory Todd Williams  C<< <gwilliams@cpan.org> >>

=head1 COPYRIGHT

Copyright (c) 2006-2012 Gregory Todd Williams. This
program is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.

=cut