/*
 * Copyright (c) 2014, Victor Nazarov <asviraspossible@gmail.com>
 * 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 com.github.sviperll.adt4j.examples;

public class Optional<T> extends OptionalValue<T> {
    @SuppressWarnings({"rawtypes", "unchecked"})
    private final static Optional MISSING = new Optional(OptionalValue.missing());

    @SuppressWarnings({"rawtypes", "unchecked"})
    public static <T> Optional<T> missing() {
        return MISSING;
    }

    public static <T> Optional<T> present(T value) {
        return new Optional<T>(OptionalValue.present(value));
    }

    private Optional(OptionalValue<T> value) {
        super(value);
    }

    //
    // equals and hashCode are correctly inherited from OptionalValue
    //

    public <U> Optional<U> flatMap(final Function<T, Optional<U>> function) {
        return accept(new OptionalVisitor<T, Optional<U>, RuntimeException>() {
            @Override
            public Optional<U> missing() {
                return Optional.missing();
            }

            @Override
            public Optional<U> present(T value) {
                return function.apply(value);
            }
        });
    }
}
