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.reference;
015
016import java.util.function.BooleanSupplier;
017import java.util.function.Supplier;
018
019import org.microbean.bean.Bean;
020import org.microbean.bean.Id;
021import org.microbean.bean.Creation;
022import org.microbean.bean.ReferencesSelector;
023
024/**
025 * A factory for {@link Supplier}s of contextual instances.
026 *
027 * <p>{@link Instances} instances are used by {@link Request} instances.</p>
028 *
029 * @author <a href="https://about.me/lairdnelson" target="_top">Laird Nelson</a>
030 *
031 * @see #supplier(Bean, Creation)
032 *
033 * @see Request
034 */
035public interface Instances {
036
037  /**
038   * Returns {@code true} if and only if it is possible for a client proxy to be created for contextual instances
039   * described by the supplied {@link Id}.
040   *
041   * @param id an {@link Id}; must not be {@code null}
042   *
043   * @return {@code true} if and only if it is possible for a client proxy to be created for contextual instances
044   * described by the supplied {@link Id}; {@code false} otherwise
045   *
046   * @exception NullPointerException if {@code id} is {@code null}
047   */
048  public boolean proxiable(final Id id);
049
050  /**
051   * Returns a {@link Supplier} of contextual instances appropriate for the given {@link Creation}.
052   *
053   * @param <I> the type of the contextual instance being requested
054   *
055   * @param bean the {@link Bean} whose {@link Bean#factory() Factory} will create any contextual instances; must not be
056   * {@code null}
057   *
058   * @param creation a {@link Creation}; may be {@code null}
059   *
060   * @return a non-{@code null} {@link Supplier} of contextual instances of the appropriate type
061   */
062  public <I> Supplier<? extends I> supplier(final Bean<I> bean, final Creation<I> creation);
063
064}