Priority queue

Priority queue implemented with indirect binary heap. Implementation allows fast peek, enqueue, dequeue, update priority, delete from heap.

constructor(comparator = DEFAULT_COMPARATOR, arraylike?: [T,P][], buffer?: number[], offset?: number)

Creates new queue. By default uses comparator for minimal heap, i.e. item with the smallest priority will dequeue first. If arraylike is passed populate queue using batchEnqueue method

length

Property returning size of the queue

isEmpty

Yields true if length is zero and false otherwise

enqueue(element: T, priority: P): number

Enqueues element into the queue with specified priority. Returns descriptor which maps for efficent update and delete method. It's ok to enqueue already enqueued element, even with the same priority

batchEnqueue(arraylike: [T,P][], buffer?: number[], offset?: number): number[]

Enqueues list of elements using efficient Floyd's algorithm. It's effiecient if number of inserting elements is high compared to size of the heap. Ideal case is when heap is empty. If buffer is specifed populates it with descriptors (see enqueue. Also you can pass offset in this case populate buffer starting with passed index. Returns descriptors array if buffer is passed or default empty array

dequeue(): T | undefined

Dequeue element from queue. If queue is empty returns undefined

first(): T | undefined

Returns element with the highest priority or undefined if the queue is empty

firstPriority(): P | undefined

Returns highest priority of the queue or undefined if the queue is empty

has(element: T, descriptor?: number): boolean

Returns true if the element is in the queue and false otherwise. If descriptor is specified checks that element is mapped be descriptor, i.e. with wrong descriptor yields false even if element is in the queue. Without descriptor method is O(n)

descriptorOf(element: T): number

Returns descriptor of element. This is slow O(n) operation. If element is not in the queue returns -1

clear(): boolean

If queue has items clears them and returns true. Otherwise returns false

delete(element: T, descriptor?: number): boolean

If queue contains specified element then this function removes it from the queue and returns true. Otherwise returns false. If descriptor is passed this method is fast, otherwise it is slow O(n).

update(element: T, priority: P, descriptor?: number)

Updates element priority. This is the same as enqueue after delete. The only difference is that this method will not enqueue if element wasn't in the queue.

forEach( callback(element: T, priority: P, queue: PriorityQueue<T,P>), thisArg?: any )

Calls callback for each element and priority in the queue.