001/* -*- mode: Java; c-basic-offset: 2; indent-tabs-mode: nil; coding: utf-8-unix -*-
002 *
003 * Copyright © 2022 microBean™.
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
014 * implied.  See the License for the specific language governing
015 * permissions and limitations under the License.
016 */
017package org.microbean.loader.spi;
018
019import java.util.ServiceLoader;
020
021/**
022 * An instantiator of {@link ServiceLoader.Provider} instances.
023 *
024 * @author <a href="https://about.me/lairdnelson"
025 * target="_parent">Laird Nelson</a>
026 */
027public interface ServiceProviderInstantiator {
028
029  /**
030   * Instantiates the supplied {@link ServiceLoader.Provider} and
031   * returns the resulting service provider.
032   *
033   * @param <T> the type of service provider to instantiate
034   *
035   * @param serviceLoaderProvider a {@link ServiceLoader.Provider};
036   * must not be {@code null}
037   *
038   * @return a service provider; never {@code null}
039   *
040   * @exception NullPointerException if {@code
041   * serviceLoaderProvider} is {@code null}
042   *
043   * @nullability This method does not, and its overrides must not,
044   * return {@code null}.
045   *
046   * @idempotency The idempotency and determinism of any
047   * implementation of this method is left undefined.
048   *
049   * @threadsafety This method and any override is not guaranteed to
050   * be safe for concurrent use by multiple threads.
051   */
052  public default <T> T instantiate(final ServiceLoader.Provider<? extends T> serviceLoaderProvider) {
053    return serviceLoaderProvider.get();
054  }
055    
056}