| /* |
| * 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.beam.runners.core; |
| |
| import java.util.Collections; |
| import java.util.Set; |
| import org.apache.beam.sdk.transforms.windowing.BoundedWindow; |
| import org.apache.beam.sdk.values.PCollectionView; |
| import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.Sets; |
| |
| /** |
| * A {@link SideInputReader} representing a well-defined set of views, but not storing any values |
| * for them. Used to check if a side input is present when the data itself comes from elsewhere. |
| */ |
| public class NullSideInputReader implements SideInputReader { |
| |
| private Set<PCollectionView<?>> views; |
| |
| public static NullSideInputReader empty() { |
| return new NullSideInputReader(Collections.emptySet()); |
| } |
| |
| public static NullSideInputReader of(Iterable<? extends PCollectionView<?>> views) { |
| return new NullSideInputReader(views); |
| } |
| |
| private NullSideInputReader(Iterable<? extends PCollectionView<?>> views) { |
| this.views = Sets.newHashSet(views); |
| } |
| |
| @Override |
| public <T> T get(PCollectionView<T> view, BoundedWindow window) { |
| throw new IllegalArgumentException("cannot call NullSideInputReader.get()"); |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| return views.isEmpty(); |
| } |
| |
| @Override |
| public <T> boolean contains(PCollectionView<T> view) { |
| return views.contains(view); |
| } |
| } |