/*
 * Copyright (C) 2003-2017 Paolo Boldi and Sebastiano Vigna
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package PACKAGE;

import java.util.NoSuchElementException;

import it.unimi.dsi.fastutil.PriorityQueue;

/** A type-specific {@link PriorityQueue}; provides some additional methods that use polymorphism to avoid (un)boxing.
 *
 * <p>Additionally, this interface strengthens {@link #comparator()}.
 */

public interface PRIORITY_QUEUE extends PriorityQueue<KEY_CLASS> {

	/** Enqueues a new element.
	 * @see PriorityQueue#enqueue(Object)
	 * @param x the element to enqueue.
	 */

	void enqueue(KEY_GENERIC_TYPE x);

	/** Dequeues the {@linkplain #first() first} element from the queue.
	 * @see #dequeue()
	 * @return the dequeued element.
	 * @throws NoSuchElementException if the queue is empty.
	 */

	KEY_GENERIC_TYPE DEQUEUE();

	/** Returns the first element of the queue.
	 * @see #first()
	 * @return the first element.
	 * @throws NoSuchElementException if the queue is empty.
	 */

	KEY_GENERIC_TYPE FIRST();

	/** Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).
	 * <p>This default implementation just throws an {@link UnsupportedOperationException}.
	 * @see #last()
	 * @return the last element.
	 * @throws NoSuchElementException if the queue is empty.
	 */

	default KEY_GENERIC_TYPE LAST() { throw new UnsupportedOperationException(); }

	/** Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.
	 *
	 * <p>Note that this specification strengthens the one given in {@link PriorityQueue#comparator()}.
	 * @see PriorityQueue#comparator()
	 * @return the comparator associated with this priority queue.
	 */
	@Override
	KEY_COMPARATOR comparator();

	/** {@inheritDoc}
	 * <p>This default implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	default void enqueue(final KEY_GENERIC_CLASS x) { enqueue(x.KEY_VALUE()); }

	/** {@inheritDoc}
	 * <p>This default implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	default KEY_GENERIC_CLASS dequeue() { return KEY2OBJ(DEQUEUE()); }

	/** {@inheritDoc}
	 * <p>This default implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	default KEY_GENERIC_CLASS first() { return KEY2OBJ(FIRST()); }

	/** {@inheritDoc}
	 * <p>This default implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	default KEY_GENERIC_CLASS last() { return KEY2OBJ(LAST()); }
}
