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