modules/rdf/bnode.zzm

=encoding utf8

=head1 NAME

rdf/bnode - Blank node scope utilities.

=head1 SYNOPSIS

  from rdf/bnode import rdf_blank_scope;
  
  let scope := rdf_blank_scope("row");
  let a := scope.fresh();
  let b := scope.fresh();


=head1 DESCRIPTION

Blank node scopes generate deterministic labels with an isolated counter.
They are useful for parsers, builders, and tests that need fresh blank
nodes without sharing global state.

=head1 EXPORTS

=head2 Classes

=over

=item C<RDFBlankNodeScope>

=over

=item C<< fresh() >>

Returns a new C<RDFBlank> using the scope prefix and increments the
counter.

=item C<< reset() >>

Resets the counter to zero and returns the scope.

=back

=back

=head2 Functions

=over

=item C<< rdf_blank_scope(String prefix := "b") >>

Returns a new C<RDFBlankNodeScope>.

=back

=head1 COPYRIGHT AND LICENCE

B<< rdf/bnode >> 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/term import rdf_blank;

class RDFBlankNodeScope {
	let String prefix := "b";
	let Number counter := 0;

	method fresh () {
		counter++;
		return rdf_blank(prefix _ counter);
	}

	method reset () {
		counter := 0;
		return self;
	}
}

function rdf_blank_scope ( String prefix := "b" ) {
	return new RDFBlankNodeScope(prefix: prefix);
}