001/* -*- mode: Java; c-basic-offset: 2; indent-tabs-mode: nil; coding: utf-8-unix -*-
002 *
003 * Copyright © 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.bean;
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.Objects;
022import java.util.Optional;
023
024import org.microbean.constant.Constables;
025
026import static java.lang.constant.ConstantDescs.BSM_INVOKE;
027import static java.lang.constant.ConstantDescs.CD_Object;
028
029public final record Constant<I>(I singleton) implements Constable, Factory<I> {
030
031  public Constant {
032    Objects.requireNonNull(singleton, "singleton");
033  }
034
035  @Override // Factory<I>
036  public final I create(final Request<I> r) {
037    return this.singleton();
038  }
039
040  @Override // Factory<I>
041  public final boolean destroys() {
042    return this.singleton() instanceof AutoCloseable;
043  }
044
045  // Experimental
046  @Override // Factory<I>
047  public final void destroy(final I i, final Request<I> request) {
048    Factory.super.destroy(i, request);
049  }
050
051  @Override // Constable
052  public final Optional<DynamicConstantDesc<I>> describeConstable() {
053    return Constables.describeConstable(this.singleton())
054      .map(iDesc -> DynamicConstantDesc.of(BSM_INVOKE,
055                                           MethodHandleDesc.ofConstructor(ClassDesc.of(this.getClass().getName()),
056                                                                          CD_Object),
057                                           iDesc));
058  }
059
060
061}