1 /*
   2  * Copyright (c) 2012, 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 /**
  28  * An operation on a single {@code double} operand yielding a {@code double}
  29  * result.
  30  *
  31  * <p>This is the primitive type specialization of {@link UnaryOperator} for
  32  * {@code double} and also may be used as a {@code UnaryOperator<Double>}. When
  33  * used as a {@code UnaryOperator} the default {@code operate} implementation
  34  * provided by this interface neither accepts null parameters nor does it return
  35  * null results.
  36  *
  37  * @since 1.8
  38  */
  39 public interface DoubleUnaryOperator extends UnaryOperator<Double> {
  40 
  41     /**
  42      * {@inheritDoc}
  43      *
  44      * @param operand {@inheritDoc}, must be non-null
  45      * @return {@inheritDoc}, always non-null
  46      */
  47     @Override
  48     public default Double operate(Double operand) {
  49         return operateAsDouble((double)operand);
  50     }
  51 
  52     /**
  53      * Returns the {@code double} result of the operation upon the
  54      * {@code double} operand.
  55      *
  56      * @param operand the operand value
  57      * @return the operation result value
  58      */
  59     public double operateAsDouble(double operand);
  60 }