modules/rdf/serializer/nquads.zzm

=encoding utf8

=head1 NAME

rdf/serializer/nquads - N-Quads serializer.

=head1 SYNOPSIS

  from rdf/serializer/nquads import NQuadsSerializer;
  
  let text := (new NQuadsSerializer()).serialize(quads);


=head1 DESCRIPTION

C<NQuadsSerializer> serializes RDF quads as RDF 1.1 N-Quads. Quads in the
default graph are emitted as three-term statements; named graph quads
include a fourth graph term. Term escaping and validation are shared with
the N-Triples serializer.

=head1 EXPORTS

=head2 Classes

=over

=item C<NQuadsSerializer>

=over

=item C<< line(quad) >>

Returns one N-Quads statement without a trailing newline.

=item C<< serialize_each(Array quads, Function emit) >>

Calls C<emit> once per serialized line, including the trailing newline.
Returns the serializer.

=item C<< serialize(Array quads) >>

Returns the complete serialized string, ending with a newline when there
is at least one quad.

=back

=back

=head1 COPYRIGHT AND LICENCE

B<< rdf/serializer/nquads >> is copyright Toby Inkster.

It is free software; you may redistribute it and/or modify it under
the terms of either the Artistic License 1.0 or the GNU General Public
License version 2.

=cut

from rdf/serializer import RdfSerializer;
from rdf/serializer/ntriples import _nt_term;
from rdf/term import RDFDefaultGraph;
from std/string import join;

class NQuadsSerializer with RdfSerializer {
	method line ( quad ) {
		let line := _nt_term(quad.get_subject()) _ " " _
			_nt_term(quad.get_predicate()) _ " " _
			_nt_term(quad.get_object());
		if ( not( quad.get_graph() instanceof RDFDefaultGraph ) ) {
			line _= " " _ _nt_term(quad.get_graph());
		}
		return line _ " .";
	}

	method serialize_each ( Array quads, Function emit ) {
		for ( let quad in quads ) {
			emit(self.line(quad) _ "\n");
		}
		return self;
	}

	method serialize ( Array quads ) {
		let lines := [];
		for ( let quad in quads ) {
			lines.push(self.line(quad));
		}
		return join( "\n", lines ) _ ( lines.length() > 0 ? "\n" : "" );
	}
}