net.openhft.chronicle.testframework.Combination Maven / Gradle / Ivy
/*
*
* Copyright (c) 2006-2020, Speedment, Inc. 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 net.openhft.chronicle.testframework;
import net.openhft.chronicle.testframework.internal.CombinationUtil;
import org.jetbrains.annotations.NotNull;
import java.util.Collection;
import java.util.Set;
import java.util.stream.Stream;
import static java.util.Objects.requireNonNull;
/**
* Utility class that provides functionality to generate all possible combinations
* of a given set of elements. The class eagerly calculates the combinations.
*
* This class cannot be instantiated.
*
* @author Per Minborg
*/
public final class Combination {
// Suppresses default constructor, ensuring non-instantiability.
private Combination() {
}
/**
* Creates and returns a stream of all possible combinations of the given elements.
*
* The order of the combinations in the stream is unspecified.
*
* @param element type
* @param items the array of items to combine
* @return a stream of sets containing all possible combinations of the given elements
* @throws NullPointerException if the provided {@code items} array is {@code null}.
*/
@SafeVarargs
@SuppressWarnings("varargs") // Creating a Set from an array is safe
public static Stream> of(@NotNull final T... items) {
requireNonNull(items);
return CombinationUtil.of(items);
}
/**
* Creates and returns a stream of all possible combinations of the given elements.
*
* The order of the combinations in the stream is unspecified.
*
* @param element type
* @param items a collection of items to combine
* @return a stream of sets containing all possible combinations of the given elements
* @throws NullPointerException if the provided {@code items} collection is {@code null}.
*/
public static Stream> of(@NotNull final Collection items) {
requireNonNull(items);
return CombinationUtil.of(items);
}
/**
* Creates and returns a stream of all possible combinations of the given elements.
*
* The order of the combinations in the stream is unspecified.
*
* It is unspecified if the method lazily consumes the provided stream before providing
* the result or not.
*
* @param element type
* @param items a stream of items to combine
* @return a stream of sets containing all possible combinations of the given elements
* @throws NullPointerException if the provided {@code items} stream is {@code null}.
*/
public static Stream> of(@NotNull final Stream items) {
requireNonNull(items);
return CombinationUtil.of(items);
}
}