PriorityQueue

A Priority Queue implementation in TypeScript that uses numeric priorities.
It is designed to focus on cleanliness and performance and allows for either a highest priority first or a lowest priority first queue based on the what is passed to the constructor.

Internal benchmarking shows this is faster than fastpriorityqueue. The speedup primarily comes from explicitly passing a numeric priority into the queue instead of using a comparator to sort items.

This is not currently feature rich, though requests on the github are welcome.

Features

- O(log n) insertion and removal.
- O(1) peek
- Supports negative and fractional priorities.
- Configurable for either highest or lowest priority first.

Installation

You can install the PriorityQueue module via npm:

``bash
npm install @grinstead/priority-queue
`

Usage

Here is a basic example of how to use the PriorityQueue:

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`typescript
import { PriorityQueue } from "@grinstead/priority-queue";
`

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By default, the priority queue returns the highest priority item first:

`typescript
const queue = new PriorityQueue();
`

You can create a priority queue that returns the lowest priority item first by passing true to the constructor:

`typescript
const queue = new PriorityQueue(true);
`

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You can add items to the queue using the add method, which takes a priority and the item:

`typescript
queue.add(1, "low priority item");
queue.add(10, "high priority item");
`

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The peek method returns the item with the highest priority without removing it from the queue:

`typescript
console.log(queue.peek()); // Outputs: 'high priority item'
`

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The peekPriority method returns the priority of the item with the highest priority without removing it from the queue:

`typescript
console.log(queue.peekPriority()); // Outputs: 10
`

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The poll method returns and removes the item with the highest priority:

`typescript
console.log(queue.poll()); // Outputs: 'high priority item'
console.log(queue.peek()); // Outputs: 'low priority item'
`

API

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- isLowestToHighest (optional): A boolean indicating whether the queue should prioritize lower values (true) or higher values (false). Defaults to false.

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Adds an item to the queue with the given priority.

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Returns the item with the highest priority without removing it from the queue. Returns undefined if the queue is empty.

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Returns the priority of the item with the highest priority without removing it from the queue. Returns undefined if the queue is empty.

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Returns and removes the item with the highest priority from the queue. Returns undefined` if the queue is empty.

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The number of items currently in the queue.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributing

Contributions are welcome! Please open an issue or submit a pull request for any bugs or feature requests.

Author

- Joe Grinstead