Add comments to Queue class.

This commit is contained in:
Oleksii Trekhleb 2018-08-17 18:00:20 +03:00
parent 5eea37837f
commit 5a57c5f018

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@ -2,6 +2,10 @@ import LinkedList from '../linked-list/LinkedList';
export default class Queue {
constructor() {
// We're going to implement Queue based on LinkedList since this
// structures a quite similar. Namely they both operates mostly with
// with theirs beginning and the end. Compare enqueue/de-queue
// operations of the Queue with append/prepend operations of LinkedList.
this.linkedList = new LinkedList();
}
@ -9,6 +13,7 @@ export default class Queue {
* @return {boolean}
*/
isEmpty() {
// The queue is empty in case if its linked list don't have tail.
return !this.linkedList.tail;
}
@ -17,9 +22,11 @@ export default class Queue {
*/
peek() {
if (!this.linkedList.head) {
// If linked list is empty then there is nothing to peek from.
return null;
}
// Just read the value from the end of linked list without deleting it.
return this.linkedList.head.value;
}
@ -27,6 +34,9 @@ export default class Queue {
* @param {*} value
*/
enqueue(value) {
// Enqueueing means to stand in the line. Therefore let's just add
// new value at the beginning of the linked list. It will need to wait
// until all previous nodes will be processed.
this.linkedList.append(value);
}
@ -34,6 +44,8 @@ export default class Queue {
* @return {*}
*/
dequeue() {
// Let's try to delete the last node from linked list (the tail).
// If there is no tail in linked list (it is empty) just return null.
const removedHead = this.linkedList.deleteHead();
return removedHead ? removedHead.value : null;
}
@ -43,6 +55,7 @@ export default class Queue {
* @return {string}
*/
toString(callback) {
// Return string representation of the queue's linked list.
return this.linkedList.toString(callback);
}
}