| // Copyright 2014 The Bazel Authors. All rights reserved. |
| // |
| // Licensed 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 com.google.devtools.build.xcode.util; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| import com.google.common.collect.Multimap; |
| |
| import java.util.Collection; |
| import java.util.Map; |
| |
| /** |
| * Provides methods that make checking for the presence of an item in a collection type-safe. For |
| * instance, in {@code foo.containsKey(bar)}, where {@code foo} is a {@code Map<K, V>}, {@code bar} |
| * can be a type other than {@code K} and may be {@code null}, in which case the method will just |
| * return false (collections that allow null references may of course return true in the latter |
| * case). |
| * <p> |
| * The methods in this class, such as {@link #key(Map, Object)}, will cause a compiler error if you |
| * use the wrong type and throw a {@link NullPointerException} if you pass {@code null} for the |
| * object whose presence to check. In the case where you want to check for {@code null} in a |
| * collection, add a new method to this class, use the methods in the plain Collections API |
| * (such as {@link Collection#contains(Object)}), or use the {@code Optional} type as the element of |
| * the collection. |
| * <p> |
| * TODO(bazel-team): This class should either be simplified or eliminated when the |
| * CollectionIncompatibleType feature is available: |
| * https://code.google.com/p/error-prone/wiki/CollectionIncompatibleType |
| */ |
| public class Containing { |
| private Containing() { |
| throw new UnsupportedOperationException("static-only"); |
| } |
| |
| public static <K> boolean key(Map<K, ?> map, K key) { |
| checkNotNull(key); |
| return map.containsKey(key); |
| } |
| |
| public static <K> boolean key(Multimap<K, ?> map, K key) { |
| checkNotNull(key); |
| return map.containsKey(key); |
| } |
| |
| public static <E> boolean item(Collection<E> collection, E item) { |
| checkNotNull(item); |
| return collection.contains(item); |
| } |
| |
| public static <V> boolean value(Map<?, V> map, V value) { |
| checkNotNull(value); |
| return map.containsValue(value); |
| } |
| |
| public static <V> boolean value(Multimap<?, V> map, V value) { |
| checkNotNull(value); |
| return map.containsValue(value); |
| } |
| } |