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}