com.github.sviperll.adt4j.examples.Optional Maven / Gradle / Ivy
/*
* Copyright (c) 2014, Victor Nazarov
* 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 extends OptionalValue {
@SuppressWarnings({"rawtypes", "unchecked"})
private final static Optional MISSING = new Optional(OptionalValue.missing());
@SuppressWarnings({"rawtypes", "unchecked"})
public static Optional missing() {
return MISSING;
}
public static Optional present(T value) {
return new Optional(OptionalValue.present(value));
}
private Optional(OptionalValue value) {
super(value);
}
//
// equals and hashCode are correctly inherited from OptionalValue
//
public Optional flatMap(final Function> function) {
return accept(new OptionalVisitor, RuntimeException>() {
@Override
public Optional missing() {
return Optional.missing();
}
@Override
public Optional present(T value) {
return function.apply(value);
}
});
}
}