@thi.ng/heaps/priority-queue.js

Various heap implementations for arbitrary values and with customizable ordering

import { compareNumDesc } from "@thi.ng/compare/numeric";
import { equiv } from "@thi.ng/equiv";
import { Heap } from "./heap.js";
const defPriorityQueue = (values, opts) => new PriorityQueue(values, opts);
class PriorityQueue {
  constructor(values, opts = {}) {
    this.opts = opts;
    const compare = opts.compare || compareNumDesc;
    this.heap = new Heap(null, {
      compare: (a, b) => compare(a[0], b[0])
    });
    this.equiv = opts.equiv || equiv;
    values && this.into(values);
  }
  heap;
  equiv;
  get length() {
    return this.heap.length;
  }
  *[Symbol.iterator]() {
    yield* this.heap;
  }
  clear() {
    this.heap.clear();
  }
  copy() {
    return new PriorityQueue(this.heap, this.opts);
  }
  empty() {
    return new PriorityQueue(null, this.opts);
  }
  push(val, priority) {
    this.heap.push([priority, val]);
    return this;
  }
  pushPop(val, priority) {
    return this.heap.pushPop([priority, val]);
  }
  pop() {
    const res = this.heap.pop();
    return res ? res[1] : void 0;
  }
  peek() {
    const res = this.heap.peek();
    return res ? res[1] : void 0;
  }
  peekPriority() {
    const res = this.heap.peek();
    return res ? res[0] : void 0;
  }
  remove(val) {
    const item = this.find(val);
    return item ? this.heap.remove(item) : false;
  }
  find(val) {
    return this.heap.findWith((x) => this.equiv(x[1], val));
  }
  findWith(fn) {
    return this.heap.findWith(fn);
  }
  has(val) {
    return !!this.find(val);
  }
  into(values) {
    this.heap.into(values);
    return this;
  }
  reprioritize(val, priority) {
    const { heap, equiv: equiv2 } = this;
    const item = heap.findWith((x) => equiv2(x[1], val));
    if (item) {
      item[0] = priority;
      heap.heapify();
      return true;
    }
    return false;
  }
}
export {
  PriorityQueue,
  defPriorityQueue
};