/**
* @license
* Copyright Larry Diamond 2018 All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://github.com/larrydiamond/typescriptcollectionsframework/blob/master/LICENSE
*/
import { Queue } from "./Queue";
/**
 * A linear collection that supports element insertion and removal at both ends.
 * The name deque is short for "double ended queue" and is usually pronounced "deck".
 *
 * This interface extends the Queue interface. When a deque is used as a queue, FIFO (First-In-First-Out) behavior results.
 * Elements are added at the end of the deque and removed from the beginning.
 *
 * This interface defines methods to access the elements at both ends of the deque. Methods are provided to insert, remove, and examine the element.
 *
 * Deques can also be used as LIFO (Last-In-First-Out) stacks. When a deque is used as a stack, elements are pushed and popped from the beginning of the deque.
 *
 * This interface provides two methods to remove interior elements, removeFirstOccurrence and removeLastOccurrence.
 *
 * This interface corresponds to java.util.Deque
 */
export interface Deque<K> extends Queue<K> {
    /**
    * Inserts the specified element at the front of this deque
    * @param {K} k element to add
    * @return {boolean} true if this collection changed as a result of the call
    */
    addFirst(k: K): boolean;
    /**
    * Inserts the specified element at the end of this deque
    * @param {K} k element to add
    * @return {boolean} true if this collection changed as a result of the call
    */
    addLast(k: K): boolean;
    /**
    * Inserts the specified element at the front of this deque
    * @param {K} k element to add
    * @return {boolean} true if this collection changed as a result of the call
    */
    offerFirst(k: K): boolean;
    /**
    * Inserts the specified element at the end of this deque
    * @param {K} k element to add
    * @return {boolean} true if this collection changed as a result of the call
    */
    offerLast(k: K): boolean;
    /**
    * Retrieves and removes the head of this queue. This method differs from poll only in that it returns undefined if this queue is empty
    * @return {K} the element at the head of the queue or undefined if empty
    */
    removeFirst(): K;
    /**
    * Retrieves and removes the element at the end of this queue. This method differs from poll only in that it returns undefined if this queue is empty
    * @return {K} the element at the end of the queue or undefined if empty
    */
    removeLast(): K;
    /**
    * Retrieves and removes the head of this queue, or returns null if this queue is empty.
    * @return {K} the element at the head of the queue or null if empty
    */
    pollFirst(): K;
    /**
    * Retrieves and removes the element at the end of this queue, or returns null if this queue is empty.
    * @return {K} the element at the head of the queue or null if empty
    */
    pollLast(): K;
    /**
    * Retrieves, but does not remove, the head of this queue. This method differs from peek only in that it returns undefined if this queue is empty.
    * @return {K} the element at the head of the queue or undefined if empty
    */
    getFirst(): K;
    /**
    * Retrieves, but does not remove, the last element of this queue. This method differs from peek only in that it returns undefined if this queue is empty.
    * @return {K} the element at the tail of the queue or undefined if empty
    */
    getLast(): K;
    /**
    * Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
    * @return {K} the element at the head of the queue or null if empty
    */
    peekFirst(): K;
    /**
    * Retrieves, but does not remove, the last element of this queue, or returns null if this queue is empty.
    * @return {K} the element at the head of the queue or null if empty
    */
    peekLast(): K;
}