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DoublyLinkedList.js
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DoublyLinkedList.js
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import defined from "./defined.js";
/**
* @private
*/
function DoublyLinkedList() {
this.head = undefined;
this.tail = undefined;
this._length = 0;
}
Object.defineProperties(DoublyLinkedList.prototype, {
length: {
get: function () {
return this._length;
},
},
});
/**
* @private
*/
function DoublyLinkedListNode(item, previous, next) {
this.item = item;
this.previous = previous;
this.next = next;
}
/**
* Adds the item to the end of the list
* @param {*} [item]
* @return {DoublyLinkedListNode}
*/
DoublyLinkedList.prototype.add = function (item) {
const node = new DoublyLinkedListNode(item, this.tail, undefined);
if (defined(this.tail)) {
this.tail.next = node;
this.tail = node;
} else {
this.head = node;
this.tail = node;
}
++this._length;
return node;
};
function remove(list, node) {
if (defined(node.previous) && defined(node.next)) {
node.previous.next = node.next;
node.next.previous = node.previous;
} else if (defined(node.previous)) {
// Remove last node
node.previous.next = undefined;
list.tail = node.previous;
} else if (defined(node.next)) {
// Remove first node
node.next.previous = undefined;
list.head = node.next;
} else {
// Remove last node in the linked list
list.head = undefined;
list.tail = undefined;
}
node.next = undefined;
node.previous = undefined;
}
/**
* Removes the given node from the list
* @param {DoublyLinkedListNode} node
*/
DoublyLinkedList.prototype.remove = function (node) {
if (!defined(node)) {
return;
}
remove(this, node);
--this._length;
};
/**
* Moves nextNode after node
* @param {DoublyLinkedListNode} node
* @param {DoublyLinkedListNode} nextNode
*/
DoublyLinkedList.prototype.splice = function (node, nextNode) {
if (node === nextNode) {
return;
}
// Remove nextNode, then insert after node
remove(this, nextNode);
const oldNodeNext = node.next;
node.next = nextNode;
// nextNode is the new tail
if (this.tail === node) {
this.tail = nextNode;
} else {
oldNodeNext.previous = nextNode;
}
nextNode.next = oldNodeNext;
nextNode.previous = node;
};
export default DoublyLinkedList;