@figliolia/data-structures/dist/cjs/PriorityQueue.js

Efficient data structures for every day programming

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.PriorityQueue = void 0;
/**
 * Priority Queue
 *
 * A bucket queue that sorts elements based on the priority level specified
 *
 * ```typescript
 * import { PriorityQueue } from "@figliolia/data-structures";
 *
 * const queue = new PriorityQueue<number>();
 * queue.push(1, 3);
 * queue.push(2, 2);
 * queue.push(3, 1);
 * queue.length // 3
 * // queue = [[3], [2], [1]]
 * while(!queue.isEmpty) {
 *   queue.pop() // 3, 2, 1
 * }
 * ```
 */
class PriorityQueue {
    constructor(max = Infinity) {
        this.buckets = [];
        this.priorities = {};
        this.maxPriority = max;
    }
    /**
     * Push
     *
     * Adds a new element to the queue at the specified priority level
     */
    push(priority, value) {
        if (priority > this.maxPriority) {
            throw new RangeError("Max Priority exceeded");
        }
        const bucket = this.buckets[priority] || [];
        bucket.push(value);
        this.buckets[priority] = bucket;
        this.priorities[priority] = true;
    }
    /**
     * Pop
     *
     * Removes the last element added to the highest available priority
     */
    pop() {
        for (const [p, bucket] of this) {
            const item = bucket.pop();
            if (!bucket.length) {
                delete this.priorities[p];
            }
            return item;
        }
    }
    /**
     * Poll
     *
     * Returns a reference to the last element added to the highest available priority
     */
    poll() {
        for (const [_, bucket] of this) {
            return bucket[bucket.length - 1];
        }
    }
    /**
     * Length
     *
     * Returns the total number of items in the queue
     */
    get length() {
        let length = 0;
        for (const [_, bucket] of this) {
            length += bucket.length;
        }
        return length;
    }
    /**
     * Is Empty
     *
     * Returns true if the queue contains no items
     */
    get isEmpty() {
        for (const _ of this) {
            return false;
        }
        return true;
    }
    *[Symbol.iterator]() {
        const keys = Object.keys(this.priorities);
        const { length } = keys;
        for (let i = 0; i < length; i++) {
            const key = parseInt(keys[i]);
            const bucket = this.buckets[key];
            if (bucket && bucket.length) {
                yield [key, bucket];
            }
        }
    }
}
exports.PriorityQueue = PriorityQueue;