001/* -*- mode: Java; c-basic-offset: 2; indent-tabs-mode: nil; coding: utf-8-unix -*-
002 *
003 * Copyright © 2023–2024 microBean™.
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
006 * the License.  You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
011 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the
012 * specific language governing permissions and limitations under the License.
013 */
014package org.microbean.scopelet;
015
016import java.lang.constant.ClassDesc;
017import java.lang.constant.Constable;
018import java.lang.constant.DynamicConstantDesc;
019import java.lang.constant.MethodHandleDesc;
020
021import java.util.List;
022import java.util.Optional;
023
024import org.microbean.bean.AutoCloseableRegistry;
025import org.microbean.bean.Creation;
026import org.microbean.bean.DisposableReference;
027import org.microbean.bean.Factory;
028import org.microbean.bean.Id;
029import org.microbean.bean.ReferenceSelector;
030
031import static java.lang.constant.ConstantDescs.BSM_INVOKE;
032
033import static org.microbean.bean.Qualifiers.anyQualifier;
034
035import static org.microbean.lang.Lang.declaredType;
036import static org.microbean.lang.Lang.typeElement;
037
038import static org.microbean.scope.Scope.NONE_ID;
039import static org.microbean.scope.Scope.SINGLETON_ID;
040
041public final class NoneScopelet extends Scopelet<NoneScopelet> implements Constable {
042
043  public static final Id ID =
044    new Id(List.of(declaredType(NoneScopelet.class),
045                   declaredType(null,
046                                typeElement(Scopelet.class),
047                                declaredType(NoneScopelet.class))),
048           List.of(NONE_ID, anyQualifier()), // qualifiers
049           SINGLETON_ID); // the scope we belong to
050
051  private static final ClassDesc CD_NoneScopelet = ClassDesc.of(NoneScopelet.class.getName());
052
053  private static final boolean useDisposableReferences =
054    Boolean.parseBoolean(System.getProperty("useDisposableReferences", "false"));
055
056  public NoneScopelet() {
057    super(NONE_ID); // the scope we implement
058  }
059
060  @Override // Scopelet<NoneScopelet>
061  public final Id id() {
062    return ID;
063  }
064
065  @Override // Scopelet<NoneScopelet>
066  public final <I> I get(final Object beanId) {
067    if (!this.active()) {
068      throw new InactiveScopeletException();
069    }
070    return null;
071  }
072
073  @Override // Scopelet<NoneScopelet>
074  public final <I> I instance(final Object beanId,
075                              final Factory<I> factory,
076                              final Creation<I> c,
077                              final ReferenceSelector r) {
078    if (!this.active()) {
079      throw new InactiveScopeletException();
080    } else if (factory == null) {
081      return null;
082    }
083    final I returnValue = factory.create(c, r);
084    if (factory.destroys()) {
085      if (useDisposableReferences) {
086        new DisposableReference<>(returnValue, referent -> factory.destroy(referent, c, c, r));
087      } else if (c instanceof AutoCloseableRegistry acr) {
088        acr.register(new Instance<>(returnValue, factory::destroy, c, r));
089      }
090    }
091    return returnValue;
092  }
093
094  @Override // Scopelet<NoneScopelet>
095  public final boolean remove(final Object id) {
096    if (!this.active()) {
097      throw new InactiveScopeletException();
098    }
099    return false;
100  }
101
102  @Override // Constable
103  public final Optional<DynamicConstantDesc<NoneScopelet>> describeConstable() {
104    return Optional.of(DynamicConstantDesc.of(BSM_INVOKE, MethodHandleDesc.ofConstructor(CD_NoneScopelet)));
105  }
106
107}