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Edit File: DoublyLinkedList.js

"use strict";

Object.defineProperty(exports, "__esModule", {
    value: true
});
// Simple doubly linked list (https://en.wikipedia.org/wiki/Doubly_linked_list) implementation
// used for queues. This implementation assumes that the node provided by the user can be modified
// to adjust the next and last properties. We implement only the minimal functionality
// for queue support.
class DLL {
    constructor() {
        this.head = this.tail = null;
        this.length = 0;
    }

removeLink(node) {
        if (node.prev) node.prev.next = node.next;else this.head = node.next;
        if (node.next) node.next.prev = node.prev;else this.tail = node.prev;

node.prev = node.next = null;
        this.length -= 1;
        return node;
    }

empty() {
        while (this.head) this.shift();
        return this;
    }

insertAfter(node, newNode) {
        newNode.prev = node;
        newNode.next = node.next;
        if (node.next) node.next.prev = newNode;else this.tail = newNode;
        node.next = newNode;
        this.length += 1;
    }

insertBefore(node, newNode) {
        newNode.prev = node.prev;
        newNode.next = node;
        if (node.prev) node.prev.next = newNode;else this.head = newNode;
        node.prev = newNode;
        this.length += 1;
    }

unshift(node) {
        if (this.head) this.insertBefore(this.head, node);else setInitial(this, node);
    }

push(node) {
        if (this.tail) this.insertAfter(this.tail, node);else setInitial(this, node);
    }

shift() {
        return this.head && this.removeLink(this.head);
    }

pop() {
        return this.tail && this.removeLink(this.tail);
    }

toArray() {
        return [...this];
    }

*[Symbol.iterator]() {
        var cur = this.head;
        while (cur) {
            yield cur.data;
            cur = cur.next;
        }
    }

remove(testFn) {
        var curr = this.head;
        while (curr) {
            var { next } = curr;
            if (testFn(curr)) {
                this.removeLink(curr);
            }
            curr = next;
        }
        return this;
    }
}

exports.default = DLL;
function setInitial(dll, node) {
    dll.length = 1;
    dll.head = dll.tail = node;
}
module.exports = exports.default;

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