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 *      http://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.function;
019
020import java.util.Objects;
021import java.util.function.LongUnaryOperator;
022
023/**
024 * A functional interface like {@link LongUnaryOperator} that declares a {@code Throwable}.
025 *
026 * @param <E> Thrown exception.
027 * @since 3.11
028 */
029public interface FailableLongUnaryOperator<E extends Throwable> {
030
031    /** NOP singleton */
032    @SuppressWarnings("rawtypes")
033    FailableLongUnaryOperator NOP = t -> 0L;
034
035    /**
036     * Returns a unary operator that always returns its input argument.
037     *
038     * @param <E> Thrown exception.
039     * @return a unary operator that always returns its input argument
040     */
041    static <E extends Throwable> FailableLongUnaryOperator<E> identity() {
042        return t -> t;
043    }
044
045    /**
046     * Returns The NOP singleton.
047     *
048     * @param <E> Thrown exception.
049     * @return The NOP singleton.
050     */
051    static <E extends Throwable> FailableLongUnaryOperator<E> nop() {
052        return NOP;
053    }
054
055    /**
056     * Returns a composed {@code FailableDoubleUnaryOperator} like {@link LongUnaryOperator#andThen(LongUnaryOperator)}.
057     *
058     * @param after the operator to apply after this one.
059     * @return a composed {@code FailableLongUnaryOperator} like {@link LongUnaryOperator#andThen(LongUnaryOperator)}.
060     * @throws NullPointerException if after is null.
061     * @see #compose(FailableLongUnaryOperator)
062     */
063    default FailableLongUnaryOperator<E> andThen(final FailableLongUnaryOperator<E> after) {
064        Objects.requireNonNull(after);
065        return (final long t) -> after.applyAsLong(applyAsLong(t));
066    }
067
068    /**
069     * Applies this operator to the given operand.
070     *
071     * @param operand the operand
072     * @return the operator result
073     * @throws E Thrown when a consumer fails.
074     */
075    long applyAsLong(long operand) throws E;
076
077    /**
078     * Returns a composed {@code FailableLongUnaryOperator} like {@link LongUnaryOperator#compose(LongUnaryOperator)}.
079     *
080     * @param before the operator to apply before this one.
081     * @return a composed {@code FailableLongUnaryOperator} like {@link LongUnaryOperator#compose(LongUnaryOperator)}.
082     * @throws NullPointerException if before is null.
083     * @see #andThen(FailableLongUnaryOperator)
084     */
085    default FailableLongUnaryOperator<E> compose(final FailableLongUnaryOperator<E> before) {
086        Objects.requireNonNull(before);
087        return (final long v) -> applyAsLong(before.applyAsLong(v));
088    }
089}