phpq

Pairing Heap Priority Queue

Implementation of a Priority Queue based on a Pairing Heap.

Platform Support

Supports Node version (4.0.0) and the following browsers:

Android	Firefox	Chrome	IE	Opera	Safari
All	36	21	11	All	5.1

Usage

Install the package from NPM:

npm i -S phpq

Import the package and use it, see the API for details.

import { PriorityQueue } from 'phpq';
 
const queue = new PriorityQueue((a, b) => a - b);
queue.push(1);
queue.push(2);
queue.push(3);

API

new PriorityQueue(comparator)

Constructs a new PriorityQueue with the provided comparator function. The comparator function is in the form (a, b) => N, where:

• N < 0: a is higher priority than b, a comes first.
• N = 0: a is equal priority to b.
• N > 0: a is lower priority than b, b comes first.

const queue = new PriorityQueue((a, b) => a.priority - b.priority)

queue.push(it[, ..., itN])

Pushes the elements it through itN to the PriorityQueue and returns the updated length of the PriorityQueue.

queue.push({ key: 'A', priority: 10 })

queue.pop()

Returns and removes the highest priority element from the PriorityQueue.

console.log(queue.pop().key); // 'A'
console.log(queue.pop()); // undefined

queue.peek()

Returns the highest priority element from the PriorityQueue without removing it.

console.log(queue.peek().key); // 'A'
console.log(queue.peek().key); // 'A'

queue.length

The length or number of items on the PriorityQueue.

console.log(queue.length); // 0
queue.push({ key: 'A', priority: 10 });
console.log(queue.length); // 1

Benchmarks

The implementation has been optimized for performance but does not perform as well as binary heap implementations, this implementation should, in theory, outperform binary heap implementations for inserts but the extra structural complexity (i.e. a binary heap can be implemented as a single array, whereas pairing heap is implemented as nested arrays) and resultant object allocations handicaps overall performance.

The benchmarks compare operations against a fast implementation of a binary heap bhpq:

phpq push and pop number x 4,038 ops/sec ±1.92% (94 runs sampled)
phpq push and pop object x 2,791 ops/sec ±0.96% (92 runs sampled)
bhpq push and pop number x 13,979 ops/sec ±0.48% (96 runs sampled)
bhpq push and pop object x 3,448 ops/sec ±1.24% (92 runs sampled)