001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.lang3.builder;
019
020import org.apache.commons.lang3.function.FailableSupplier;
021
022/**
023 * Abstracts supplying an instance of {@code T}. Use to implement the builder pattern.
024 *
025 * @param <T> The type of results supplied by this supplier.
026 * @param <B> the type of builder.
027 * @param <E> The kind of thrown exception or error.
028 * @since 3.14.0
029 */
030public abstract class AbstractSupplier<T, B extends AbstractSupplier<T, B, E>, E extends Throwable> implements FailableSupplier<T, E> {
031
032    /**
033     * Constructs a new instance.
034     */
035    public AbstractSupplier() {
036        // empty
037    }
038
039    /**
040     * Returns this instance typed as the subclass type {@code B}.
041     * <p>
042     * This is the same as the expression:
043     * </p>
044     * <pre>
045     * (B) this
046     * </pre>
047     *
048     * @return this instance typed as the subclass type {@code B}.
049     */
050    @SuppressWarnings("unchecked")
051    protected B asThis() {
052        return (B) this;
053    }
054
055}