001/* -*- mode: Java; c-basic-offset: 2; indent-tabs-mode: nil; coding: utf-8-unix -*-
002 *
003 * Copyright © 2025 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.bean;
015
016import java.lang.constant.ClassDesc;
017import java.lang.constant.Constable;
018import java.lang.constant.ConstantDesc;
019import java.lang.constant.DynamicConstantDesc;
020import java.lang.constant.MethodHandleDesc;
021
022import java.util.Objects;
023import java.util.Optional;
024import java.util.SequencedSet;
025
026import java.util.function.Function;
027
028import org.microbean.assign.Aggregate;
029import org.microbean.assign.Assignment;
030import org.microbean.assign.AttributedElement;
031import org.microbean.assign.AttributedType;
032
033import static java.lang.constant.ConstantDescs.BSM_INVOKE;
034
035/**
036 * A ({@link Constable}) pairing of an {@link Id} with a {@link Factory}.
037 *
038 * @param <I> the type of the contextual instances the associated {@link Factory} creates
039 *
040 * @param id the {@link Id}; must not be {@code null}
041 *
042 * @param factory the {@link Factory}; must not be {@code null}
043 *
044 * @author <a href="https://about.me/lairdnelson" target="_top">Laird Nelson</a>
045 *
046 * @see Factory
047 *
048 * @see Id
049 */
050public final record Bean<I>(Id id, Factory<I> factory) implements Aggregate, Constable, Ranked {
051
052  /**
053   * Creates a new {@link Bean}.
054   *
055   * @param id the {@link Id}; must not be {@code null}
056   *
057   * @param factory the {@link Factory}; must not be {@code null}
058   *
059   * @exception NullPointerException if either argument is {@code null}
060   */
061  public Bean {
062    Objects.requireNonNull(id, "id");
063    Objects.requireNonNull(factory, "factory");
064  }
065
066  @Override // Ranked
067  public final boolean alternate() {
068    return this.id().alternate();
069  }
070
071  @Override // Aggregate
072  public final SequencedSet<? extends Assignment<?>> assign(final Function<? super AttributedType, ?> r) {
073    return this.factory().assign(r);
074  }
075
076  /**
077   * Returns this {@link Bean}, forcibly cast appropriately.
078   *
079   * @param <X> the type of contextual instances this {@link Bean} creates
080   *
081   * @return this {@link Bean}
082   *
083   * @exception ClassCastException if the cast is inappropriate
084   */
085  @SuppressWarnings("unchecked")
086  public final <X> Bean<X> cast() {
087    return (Bean<X>)this;
088  }
089
090  @Override // Aggregate
091  public final SequencedSet<AttributedElement> dependencies() {
092    return this.factory().dependencies();
093  }
094
095  @Override // Constable
096  public final Optional<DynamicConstantDesc<Bean<I>>> describeConstable() {
097    return (this.factory() instanceof Constable c ? c.describeConstable() : Optional.<ConstantDesc>empty())
098      .flatMap(factoryDesc -> this.id().describeConstable()
099               .map(idDesc -> DynamicConstantDesc.of(BSM_INVOKE,
100                                                     MethodHandleDesc.ofConstructor(ClassDesc.of(Bean.class.getName()),
101                                                                                    ClassDesc.of(Id.class.getName()),
102                                                                                    ClassDesc.of(Factory.class.getName())),
103                                                     idDesc,
104                                                     factoryDesc)));
105  }
106
107  @Override // Record (Object)
108  public final boolean equals(final Object other) {
109    return this == other || other != null && this.getClass() == other.getClass() && this.id().equals(((Bean<?>)other).id());
110  }
111
112  @Override // Record (Object)
113  public final int hashCode() {
114    return this.id().hashCode();
115  }
116
117  @Override // Ranked
118  public final int rank() {
119    return this.id().rank();
120  }
121
122}