// Copyright Jerome Benoit. 2023. All Rights Reserved.
-class Node<T> {
- public value: T
+/**
+ * Node.
+ *
+ * @typeParam T - Type of node data.
+ * @internal
+ */
+export class Node<T> {
+ public data: T
public next?: Node<T>
public prev?: Node<T>
- public constructor (value: T) {
- this.value = value
+ public constructor (data: T) {
+ this.data = data
}
}
* Deque.
* Implemented with a doubly linked list.
*
- * @typeParam T - Type of deque values.
+ * @typeParam T - Type of deque data.
+ * @internal
*/
export class Deque<T> {
private head?: Node<T>
}
/**
- * Appends a value to the deque.
+ * Appends data to the deque.
*
- * @param value - Value to append.
+ * @param data - Data to append.
* @returns The new size of the queue.
*/
- public push (value: T): number {
- const node = new Node(value)
+ public push (data: T): number {
+ const node = new Node(data)
if (this.tail == null) {
this.head = this.tail = node
} else {
}
/**
- * Prepends a value to the deque.
+ * Prepends data to the deque.
*
- * @param value - Value to prepend.
+ * @param data - Data to prepend.
* @returns The new size of the queue.
*/
- public unshift (value: T): number {
- const node = new Node(value)
+ public unshift (data: T): number {
+ const node = new Node(data)
if (this.head == null) {
this.head = this.tail = node
} else {
}
/**
- * Pops a value from the deque.
+ * Pops data from the deque.
+ *
+ * @returns The popped data or `undefined` if the deque is empty.
*/
public pop (): T | undefined {
if (this.head == null) {
this.tail.next = undefined
}
--this.size
- return tail?.value
+ return tail?.data
}
/**
- * Shifts a value from the deque.
+ * Shifts data from the deque.
*
- * @returns The shifted value or `undefined` if the deque is empty.
+ * @returns The shifted data or `undefined` if the deque is empty.
*/
public shift (): T | undefined {
if (this.head == null) {
this.head.prev = undefined
}
--this.size
- return head?.value
+ return head?.data
}
/**
- * Peeks at the first value.
- * @returns The first value or `undefined` if the queue is empty.
+ * Peeks at the first data.
+ * @returns The first data or `undefined` if the deque is empty.
*/
public peekFirst (): T | undefined {
- return this.head?.value
+ return this.head?.data
}
/**
- * Peeks at the last value.
- * @returns The last value or `undefined` if the queue is empty.
+ * Peeks at the last data.
+ * @returns The last data or `undefined` if the deque is empty.
*/
public peekLast (): T | undefined {
- return this.tail?.value
+ return this.tail?.data
}
/**
}
}
const ret = {
- value: node.value,
+ value: node.data,
done: false
}
node = node.next as Node<T>
}
}
+ /**
+ * Returns an backward iterator for the deque.
+ *
+ * @returns An backward iterator for the deque.
+ * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
+ */
+ backward (): Iterable<T> {
+ return {
+ [Symbol.iterator]: (): Iterator<T> => {
+ let node = this.tail
+ return {
+ next: () => {
+ if (node == null) {
+ return {
+ value: undefined,
+ done: true
+ }
+ }
+ const ret = {
+ value: node.data,
+ done: false
+ }
+ node = node.prev as Node<T>
+ return ret
+ }
+ }
+ }
+ }
+ }
+
private incrementSize (): number {
++this.size
if (this.size > this.maxSize) {