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| 1 | +/* |
| 2 | + * Copyright 2021 Google LLC |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + */ |
| 16 | + |
| 17 | +package com.google.auto.common; |
| 18 | + |
| 19 | +import static java.util.stream.Collectors.collectingAndThen; |
| 20 | +import static java.util.stream.Collectors.toList; |
| 21 | + |
| 22 | +import com.google.common.collect.ImmutableBiMap; |
| 23 | +import com.google.common.collect.ImmutableList; |
| 24 | +import com.google.common.collect.ImmutableMap; |
| 25 | +import com.google.common.collect.ImmutableSet; |
| 26 | +import com.google.common.collect.Maps; |
| 27 | +import java.util.Map; |
| 28 | +import java.util.function.Function; |
| 29 | +import java.util.stream.Collector; |
| 30 | +import java.util.stream.Collectors; |
| 31 | + |
| 32 | +/** |
| 33 | + * A utility class that provides Android compatible alternatives to Guava's streaming APIs. |
| 34 | + * |
| 35 | + * <p>This is useful when the Android flavor of Guava somehow finds its way onto the processor |
| 36 | + * classpath. |
| 37 | + */ |
| 38 | +public final class MoreStreams { |
| 39 | + |
| 40 | + /** Returns a collector for an {@link ImmutableList}. */ |
| 41 | + public static <T> Collector<T, ?, ImmutableList<T>> toImmutableList() { |
| 42 | + return collectingAndThen(toList(), ImmutableList::copyOf); |
| 43 | + } |
| 44 | + |
| 45 | + /** Returns a collector for an {@link ImmutableSet}. */ |
| 46 | + public static <T> Collector<T, ?, ImmutableSet<T>> toImmutableSet() { |
| 47 | + return collectingAndThen(toList(), ImmutableSet::copyOf); |
| 48 | + } |
| 49 | + |
| 50 | + /** Returns a collector for an {@link ImmutableMap}. */ |
| 51 | + public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap( |
| 52 | + Function<? super T, K> keyMapper, Function<? super T, V> valueMapper) { |
| 53 | + return Collectors.mapping( |
| 54 | + value -> Maps.immutableEntry(keyMapper.apply(value), valueMapper.apply(value)), |
| 55 | + Collector.of( |
| 56 | + ImmutableMap::builder, |
| 57 | + (ImmutableMap.Builder<K, V> builder, Map.Entry<K, V> entry) -> builder.put(entry), |
| 58 | + (left, right) -> left.putAll(right.build()), |
| 59 | + ImmutableMap.Builder::build)); |
| 60 | + } |
| 61 | + |
| 62 | + /** Returns a collector for an {@link ImmutableBiMap}. */ |
| 63 | + public static <T, K, V> Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap( |
| 64 | + Function<? super T, K> keyMapper, Function<? super T, V> valueMapper) { |
| 65 | + return Collectors.mapping( |
| 66 | + value -> Maps.immutableEntry(keyMapper.apply(value), valueMapper.apply(value)), |
| 67 | + Collector.of( |
| 68 | + ImmutableBiMap::builder, |
| 69 | + (ImmutableBiMap.Builder<K, V> builder, Map.Entry<K, V> entry) -> builder.put(entry), |
| 70 | + (left, right) -> left.putAll(right.build()), |
| 71 | + ImmutableBiMap.Builder::build)); |
| 72 | + } |
| 73 | + |
| 74 | + private MoreStreams() {} |
| 75 | +} |
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