RDF::Query rewriting ideas

gistfile1.pl

$query->rewrite_algebra( postfix => sub {
	my $visitor	= shift;
	my $algebra	= shift;
	
	if ($algebra->isa('RDF::Query::Algebra::BasicGraphPattern'))
		return $visitor->stop;	# stop traversal
	
	if ($algebra->isa('RDF::Query::Algebra::Filter')) {
		my $expr	= $algebra->expr;
		if ($expr->isa('RDF::Query::Expression::Function')) {
			if ($expr->uri eq 'sparql:regex') {
				# replace the algebra with a new one that's more efficient...
				return $new_algebra;
			}
		}
	}
	
	return;
} );


# Maybe there are better (DSL-like) ways to write the algebra pattern to match?
if ($algebra->matches('FILTER/FUNCTION[sparql:regex]')) { ... }