/*
 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */
package java.util.function;

import java.util.Objects;

/**
 * An operation upon input objects. The operation may modify that object or
 * external state (other objects).
 *
 * <p>All block implementations are expected to: <ul>
 *
 * <li>When used for aggregate operations upon many elements blocks should not
 * assume that the {@code accept} operation will be called upon elements in any
 * specific order.</li>
 * </ul>
 *
 * @param <L> the type of input objects provided to {@code accept}.
 * @param <R> the type of input objects provided to {@code accept}.
 */
public interface BiBlock<L, R> {

    /**
     * Performs operations upon the provided object which may modify that object
     * and/or external state.
     *
     * @param l an input object
     */
    void accept(L l, R r);

    /**
     * Returns a Block which performs in sequence the {@code apply} methods of
     * multiple Blocks. This Block's {@code apply} method is performed followed
     * by the {@code apply} method of the specified Block operation.
     *
     * @param other an additional Block which will be chained after this Block
     * @return a Block which performs in sequence the {@code apply} method of
     * this Block and the {@code apply} method of the specified Block operation
     */
    public default BiBlock<L, R> chain(BiBlock<? super L, ? super R> other) {
        Objects.requireNonNull(other);

        return (l, r) -> {
            accept(l, r);
            other.accept(l, r);
        };
    }
}