001/**
002 * The MIT License (MIT)
003 *
004 * Copyright (c) 2018 nobark (tools4j), Marco Terzer, Anton Anufriev
005 *
006 * Permission is hereby granted, free of charge, to any person obtaining a copy
007 * of this software and associated documentation files (the "Software"), to deal
008 * in the Software without restriction, including without limitation the rights
009 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
010 * copies of the Software, and to permit persons to whom the Software is
011 * furnished to do so, subject to the following conditions:
012 *
013 * The above copyright notice and this permission notice shall be included in all
014 * copies or substantial portions of the Software.
015 *
016 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
017 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
018 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
019 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
020 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
021 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
022 * SOFTWARE.
023 */
024package org.tools4j.nobark.queue;
025
026import java.util.Map;
027import java.util.Queue;
028import java.util.function.Supplier;
029
030/**
031 * Helper class dealing with unsafe casts necessary for factories of objects whose generic types are not known to the
032 * factory provider.
033 */
034final class Factories {
035
036    /**
037     * Encapsulates the unsafe cast necessary when creating a queue with a factory that is unaware of the value type of
038     * the queue.
039     *
040     * @param factory the queue factory
041     * @param <V> the queue value type
042     * @return a typed queue
043     */
044    static <V> Queue<V> createQueue(final Supplier<? extends Queue<Object>> factory) {
045        //NOTE: casting a queue that takes objects to a specific typed queue is fine as long as we only add those typed
046        //      values to the queue
047        @SuppressWarnings({"unchecked"})
048        final Queue<V> typed = (Queue<V>)factory.get();
049        return typed;
050    }
051
052    /**
053     * Encapsulates the unsafe cast necessary when creating a map with a factory that is unaware of the key/value types
054     * of the map.
055     *
056     * @param factory the map factory
057     * @param <K> the map key type
058     * @param <V> the map value type
059     * @return a typed map
060     */
061    static <K,V> Map<K,V> createMap(final Supplier<? extends Map<Object,Object>> factory) {
062        //NOTE: casting a map that takes object keys/values to a specific typed map is fine as long as we only put those
063        //      typed keys and values to the map
064        @SuppressWarnings({"unchecked"})
065        final Map<K,V> typed = (Map<K,V>)factory.get();
066        return typed;
067    }
068
069    private Factories() {
070        throw new RuntimeException("No Factories for you!");
071    }
072}