001/*
002 * Portions of this software was developed by employees of the National Institute
003 * of Standards and Technology (NIST), an agency of the Federal Government and is
004 * being made available as a public service. Pursuant to title 17 United States
005 * Code Section 105, works of NIST employees are not subject to copyright
006 * protection in the United States. This software may be subject to foreign
007 * copyright. Permission in the United States and in foreign countries, to the
008 * extent that NIST may hold copyright, to use, copy, modify, create derivative
009 * works, and distribute this software and its documentation without fee is hereby
010 * granted on a non-exclusive basis, provided that this notice and disclaimer
011 * of warranty appears in all copies.
012 *
013 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
014 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
015 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
016 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
017 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
018 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
019 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
020 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
021 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
022 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
023 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
024 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
025 */
026
027package gov.nist.secauto.metaschema.cli.processor.command;
028
029import java.util.List;
030import java.util.ServiceLoader;
031import java.util.ServiceLoader.Provider;
032import java.util.stream.Collectors;
033
034import edu.umd.cs.findbugs.annotations.NonNull;
035import nl.talsmasoftware.lazy4j.Lazy;
036
037public final class CommandService {
038  private static final Lazy<CommandService> INSTANCE = Lazy.lazy(() -> new CommandService());
039  @NonNull
040  private final ServiceLoader<ICommand> loader;
041
042  /**
043   * Get the singleton instance of the function service.
044   *
045   * @return the service instance
046   */
047  public static CommandService getInstance() {
048    return INSTANCE.get();
049  }
050
051  public CommandService() {
052    ServiceLoader<ICommand> loader = ServiceLoader.load(ICommand.class);
053    assert loader != null;
054    this.loader = loader;
055  }
056
057  /**
058   * Get the function service loader instance.
059   *
060   * @return the service loader instance.
061   */
062  @NonNull
063  private ServiceLoader<ICommand> getLoader() {
064    return loader;
065  }
066
067  @SuppressWarnings("null")
068  @NonNull
069  public List<ICommand> getCommands() {
070    return getLoader().stream()
071        .map(Provider<ICommand>::get)
072        .collect(Collectors.toUnmodifiableList());
073  }
074}