| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.rya.indexing.external.matching; |
| |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import org.eclipse.rdf4j.query.algebra.evaluation.impl.ExternalSet; |
| |
| /** |
| * Interface for extracting {@link ExternalSet}s from specified {@link QuerySegment}s. |
| * |
| * @param <T> - Extension of ExternalSet class |
| */ |
| public interface ExternalSetProvider<T extends ExternalSet> { |
| |
| /** |
| * Extract all {@link ExternalSet}s from specified QuerySegment. |
| * |
| * @param segment |
| * @return - List of ExternalSets |
| */ |
| public List<T> getExternalSets(QuerySegment<T> segment); |
| |
| /** |
| * Extract an Iterator over Lists of ExternalSets. This allows an ExtenalSetProvider to pass back |
| * different combinations of ExternalSets for the purposes of query optimization. |
| * |
| * @param segment |
| * @return - Iterator over different combinations of ExternalSets |
| */ |
| public Iterator<List<T>> getExternalSetCombos(QuerySegment<T> segment); |
| |
| } |