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/*
* Copyright 2021 Google LLC
*
* 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.auto.common;
import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.toList;
import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Collectors;
/**
* A utility class that provides Android compatible alternatives to Guava's streaming APIs.
*
* <p>This is useful when the Android flavor of Guava somehow finds its way onto the processor
* classpath.
*/
public final class MoreStreams {
/** Returns a collector for an {@link ImmutableList}. */
public static <T> Collector<T, ?, ImmutableList<T>> toImmutableList() {
return collectingAndThen(toList(), ImmutableList::copyOf);
}
/** Returns a collector for an {@link ImmutableSet}. */
public static <T> Collector<T, ?, ImmutableSet<T>> toImmutableSet() {
return collectingAndThen(toList(), ImmutableSet::copyOf);
}
/** Returns a collector for an {@link ImmutableMap}. */
public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
Function<? super T, K> keyMapper, Function<? super T, V> valueMapper) {
return Collectors.mapping(
value -> Maps.immutableEntry(keyMapper.apply(value), valueMapper.apply(value)),
Collector.of(
ImmutableMap::builder,
(ImmutableMap.Builder<K, V> builder, Map.Entry<K, V> entry) -> builder.put(entry),
(left, right) -> left.putAll(right.build()),
ImmutableMap.Builder::build));
}
/** Returns a collector for an {@link ImmutableBiMap}. */
public static <T, K, V> Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
Function<? super T, K> keyMapper, Function<? super T, V> valueMapper) {
return Collectors.mapping(
value -> Maps.immutableEntry(keyMapper.apply(value), valueMapper.apply(value)),
Collector.of(
ImmutableBiMap::builder,
(ImmutableBiMap.Builder<K, V> builder, Map.Entry<K, V> entry) -> builder.put(entry),
(left, right) -> left.putAll(right.build()),
ImmutableBiMap.Builder::build));
}
private MoreStreams() {}
}
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