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/*
 * de.unkrig.commons - A general-purpose Java class library
 *
 * Copyright (c) 2015, Arno Unkrig
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
 * following conditions are met:
 *
 *    1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
 *       following disclaimer.
 *    2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
 *       following disclaimer in the documentation and/or other materials provided with the distribution.
 *    3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
 *       products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package de.unkrig.commons.lang.protocol;

import de.unkrig.commons.nullanalysis.Nullable;

/**
 * An entity that transforms an "input value" (which may be {@code null}) into an "output value" (which may also be
 * {@code null}).
 *
 * IMPORTANT NOTICE:
 * 
 *   When using this type in a variable, parameter or field declaration, never write
 * 
 * FunctionEhichThrows<
 *    input-type,
 *    output-type,
 *    thrown-exception
 *>
 * 
 *   , but always
 * 
 * FunctionEhichThrows<
 *    ? super input-type,
 *    ? extends output-type,
 *    ? extends thrown-exception
 *>
 * 
 *   .
 * 
 *
 * @param                   The type of the parameter of {@link #call(Object)}
 * @param                   The return type of {@link #call(Object)}
 * @param                  The exception type that {@link #call(Object)} is allowed to throw; use {@link
 *                             NoException} to indicate that {@link #call(Object)} does not declare any checked
 *                             exceptions
 * @see                        #call(Object)
 * @see TransformerWhichThrows {@code TransformerWhichThrows} -- similar to this interface, but transforms only
 *                             non-null values into non-null values
 */
public
interface FunctionWhichThrows {

    /**
     * Calculates a value of type O from an argument of type I.
     */
    @Nullable O
    call(@Nullable I argument) throws EX;
}