1 /*

     2  * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 package java.util.function;

    26 

    27 import java.util.Objects;

    28 

    29 /**

    30  * Represents an operation on a single {@code long}-valued operand that produces

    31  * a {@code long}-valued result.  This is the primitive type specialization of

    32  * {@link UnaryOperator} for {@code long}.

    33  *

    34  * <p>This is a <a href="package-summary.html">functional interface</a>

    35  * whose functional method is {@link #applyAsLong(long)}.

    36  *

    37  * @see UnaryOperator

    38  * @since 1.8

    39  */

    40 @FunctionalInterface

    41 public interface LongUnaryOperator {

    42 

    43     /**

    44      * Applies this operator to the given operand.

    45      *

    46      * @param operand the operand

    47      * @return the operator result

    48      */

    49     long applyAsLong(long operand);

    50 

    51     /**

    52      * Returns a composed operator that first applies the {@code before}

    53      * operator to its input, and then applies this operator to the result.

    54      * If evaluation of either operator throws an exception, it is relayed to

    55      * the caller of the composed operator.

    56      *

    57      * @param before the operator to apply before this operator is applied

    58      * @return a composed operator that first applies the {@code before}

    59      * operator and then applies this operator

    60      * @throws NullPointerException if before is null

    61      *

    62      * @see #andThen(LongUnaryOperator)

    63      */

    64     default LongUnaryOperator compose(LongUnaryOperator before) {

    65         Objects.requireNonNull(before);

    66         return (long v) -> applyAsLong(before.applyAsLong(v));

    67     }

    68 

    69     /**

    70      * Returns a composed operator that first applies this operator to

    71      * its input, and then applies the {@code after} operator to the result.

    72      * If evaluation of either operator throws an exception, it is relayed to

    73      * the caller of the composed operator.

    74      *

    75      * @param after the operator to apply after this operator is applied

    76      * @return a composed operator that first applies this operator and then

    77      * applies the {@code after} operator

    78      * @throws NullPointerException if after is null

    79      *

    80      * @see #compose(LongUnaryOperator)

    81      */

    82     default LongUnaryOperator andThen(LongUnaryOperator after) {

    83         Objects.requireNonNull(after);

    84         return (long t) -> after.applyAsLong(applyAsLong(t));

    85     }

    86 

    87     /**

    88      * Returns a unary operator that always returns its input argument.

    89      *

    90      * @return a unary operator that always returns its input argument

    91      */

    92     static LongUnaryOperator identity() {

    93         return t -> t;

    94     }

    95 }