org.omnifaces.utils.stream.CombinedCollector Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of omniutils Show documentation
Java utility library
There is a newer version: 0.14
/*
 * Copyright 2021 OmniFaces
 *
 * 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
 *
 *     https://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.omnifaces.utils.stream;

import java.util.AbstractMap;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;

// TODO find proper pair option
class CombinedCollector implements Collector, Map.Entry> {

	private final Collector collector1;
	private final Collector collector2;

	CombinedCollector(Collector collector1, Collector collector2) {
		this.collector1 = collector1;
		this.collector2 = collector2;
	}

	@Override
	public Supplier> supplier() {
		return () -> new AbstractMap.SimpleEntry<>(collector1.supplier().get(), collector2.supplier().get());
	}

	@Override
	public BiConsumer, T> accumulator() {
		BiConsumer accumulator1 = collector1.accumulator();
		BiConsumer accumulator2 = collector2.accumulator();

		return (pair, element) -> {
			accumulator1.accept(pair.getKey(), element);
			accumulator2.accept(pair.getValue(), element);
		};
	}

	@Override
	public BinaryOperator> combiner() {
		BinaryOperator combiner1 = collector1.combiner();
		BinaryOperator combiner2 = collector2.combiner();

		return (pair1, pair2) -> {
			I1 i1 = combiner1.apply(pair1.getKey(), pair2.getKey());
			I2 i2 = combiner2.apply(pair1.getValue(), pair2.getValue());

			return new AbstractMap.SimpleEntry<>(i1, i2);
		};
	}

	@Override
	public Function, Map.Entry> finisher() {
		Function finisher1 = collector1.finisher();
		Function finisher2 = collector2.finisher();

		return (pair) -> {
			R1 r1 = finisher1.apply(pair.getKey());
			R2 r2 = finisher2.apply(pair.getValue());

			return new AbstractMap.SimpleEntry<>(r1, r2);
		};
	}

	@Override
	public Set characteristics() {
		// TODO correctly determine elements
		return Collections.emptySet();
	}
}