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lib: refactor PriorityQueue to use private field #43889

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Jul 23, 2022
Merged

lib: refactor PriorityQueue to use private field #43889

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lib: refactor PriorityQueue to use private field
F3n67u Jul 18, 2022
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F3n67u Jul 18, 2022
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54 changes: 22 additions & 32 deletions lib/internal/priority_queue.js
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Original file line number Diff line number Diff line change
@@ -1,14 +1,6 @@
'use strict';

const {
Array,
Symbol,
} = primordials;

const kCompare = Symbol('compare');
const kHeap = Symbol('heap');
const kSetPosition = Symbol('setPosition');
const kSize = Symbol('size');
const { Array } = primordials;
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// The PriorityQueue is a basic implementation of a binary heap that accepts
// a custom sorting function via its constructor. This function is passed
Expand All @@ -17,23 +9,21 @@ const kSize = Symbol('size');
// just a single criteria.

module.exports = class PriorityQueue {
#compare = (a, b) => a - b;
#heap = new Array(64);
#setPosition;
#size = 0;

constructor(comparator, setPosition) {
if (comparator !== undefined)
this[kCompare] = comparator;
this.#compare = comparator;
if (setPosition !== undefined)
this[kSetPosition] = setPosition;

this[kHeap] = new Array(64);
this[kSize] = 0;
}

[kCompare](a, b) {
return a - b;
this.#setPosition = setPosition;
}

insert(value) {
const heap = this[kHeap];
const pos = ++this[kSize];
const heap = this.#heap;
const pos = ++this.#size;
heap[pos] = value;

if (heap.length === pos)
Expand All @@ -43,14 +33,14 @@ module.exports = class PriorityQueue {
}

peek() {
return this[kHeap][1];
return this.#heap[1];
}

percolateDown(pos) {
const compare = this[kCompare];
const setPosition = this[kSetPosition];
const heap = this[kHeap];
const size = this[kSize];
const compare = this.#compare;
const setPosition = this.#setPosition;
const heap = this.#heap;
const size = this.#size;
const item = heap[pos];

while (pos * 2 <= size) {
Expand All @@ -71,9 +61,9 @@ module.exports = class PriorityQueue {
}

percolateUp(pos) {
const heap = this[kHeap];
const compare = this[kCompare];
const setPosition = this[kSetPosition];
const heap = this.#heap;
const compare = this.#compare;
const setPosition = this.#setPosition;
const item = heap[pos];

while (pos > 1) {
Expand All @@ -91,21 +81,21 @@ module.exports = class PriorityQueue {
}

removeAt(pos) {
const heap = this[kHeap];
const size = --this[kSize];
const heap = this.#heap;
const size = --this.#size;
heap[pos] = heap[size + 1];
heap[size + 1] = undefined;

if (size > 0 && pos <= size) {
if (pos > 1 && this[kCompare](heap[pos / 2 | 0], heap[pos]) > 0)
if (pos > 1 && this.#compare(heap[pos / 2 | 0], heap[pos]) > 0)
this.percolateUp(pos);
else
this.percolateDown(pos);
}
}

shift() {
const heap = this[kHeap];
const heap = this.#heap;
const value = heap[1];
if (value === undefined)
return;
Expand Down