001package com.hfg.util;
002
003import java.util.Objects;
004import java.util.function.Function;
005
006
007//------------------------------------------------------------------------------
008/**
009 * Represents a function that accepts three arguments and produces a result.
010 * This is the three-arity specialization of {@link Function}.
011 *
012 * <p>This is a <a href="package-summary.html">functional interface</a>
013 * whose functional method is {@link #apply(Object, Object, Object)}.
014 *
015 * @param <A> the type of the first argument to the function
016 * @param <B> the type of the second argument to the function
017 * @param <C> the type of the third argument to the function
018 * @param <R> the type of the result of the function
019 *
020 <div>
021  @author J. Alex Taylor, hairyfatguy.com
022 </div>
023 */
024//------------------------------------------------------------------------------
025// com.hfg XML/HTML Coding Library
026//
027// This library is free software; you can redistribute it and/or
028// modify it under the terms of the GNU Lesser General Public
029// License as published by the Free Software Foundation; either
030// version 2.1 of the License, or (at your option) any later version.
031//
032// This library is distributed in the hope that it will be useful,
033// but WITHOUT ANY WARRANTY; without even the implied warranty of
034// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
035// Lesser General Public License for more details.
036//
037// You should have received a copy of the GNU Lesser General Public
038// License along with this library; if not, write to the Free Software
039// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
040//
041// J. Alex Taylor, President, Founder, CEO, COO, CFO, OOPS hairyfatguy.com
042// jataylor@hairyfatguy.com
043//------------------------------------------------------------------------------
044
045@FunctionalInterface
046public interface TriFunction<A, B, C, R>
047{
048    /**
049     * Applies this function to the given arguments.
050     *
051     * @param a the first function argument
052     * @param b the second function argument
053     * @param c the third function argument
054     * @return the function result
055     */
056    R apply(A a, B b, C c);
057
058    /**
059     * Returns a composed function that first applies this function to
060     * its input, and then applies the {@code after} function to the result.
061     * If evaluation of either function throws an exception, it is relayed to
062     * the caller of the composed function.
063     *
064     * @param <V> the type of output of the {@code after} function, and of the
065     *           composed function
066     * @param after the function to apply after this function is applied
067     * @return a composed function that first applies this function and then
068     * applies the {@code after} function
069     * @throws NullPointerException if after is null
070     */
071    default <V> TriFunction<A, B, C, V> andThen(Function<? super R, ? extends V> after)
072    {
073        Objects.requireNonNull(after);
074        return (A a, B b, C c) -> after.apply(apply(a, b, c));
075    }
076}