File Content: lru.js module.exports = function(size) { return new LruCache(size) } function LruCache(size) { this.capacity = size | 0 this.map = Object.create(null) this.list = new DoublyLinkedList() } LruCache.prototype.get = function(key) { var node = this.map[key] if (node == null) return undefined this.used(node) return node.val } LruCache.prototype.set = function(key, val) { var node = this.map[key] if (node != null) { node.val = val } else { if (!this.capacity) this.prune() if (!this.capacity) return false node = new DoublyLinkedNode(key, val) this.map[key] = node this.capacity-- } this.used(node) return true } LruCache.prototype.used = function(node) { this.list.moveToFront(node) } LruCache.prototype.prune = function() { var node = this.list.pop() if (node != null) { delete this.map[node.key] this.capacity++ } } function DoublyLinkedList() { this.firstNode = null this.lastNode = null } DoublyLinkedList.prototype.moveToFront = function(node) { if (this.firstNode == node) return this.remove(node) if (this.firstNode == null) { this.firstNode = node this.lastNode = node node.prev = null node.next = null } else { node.prev = null node.next = this.firstNode node.next.prev = node this.firstNode = node } } DoublyLinkedList.prototype.pop = function() { var lastNode = this.lastNode if (lastNode != null) { this.remove(lastNode) } return lastNode } DoublyLinkedList.prototype.remove = function(node) { if (this.firstNode == node) { this.firstNode = node.next } else if (node.prev != null) { node.prev.next = node.next } if (this.lastNode == node) { this.lastNode = node.prev } else if (node.next != null) { node.next.prev = node.prev } } function DoublyLinkedNode(key, val) { this.key = key this.val = val this.prev = null this.next = null } Submit