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// Flags: --expose-internals
'use strict';
require('../common');
const assert = require('assert');
const PriorityQueue = require('internal/priority_queue');
{
// Checks that the queue is fundamentally correct.
const queue = new PriorityQueue();
for (let i = 15; i > 0; i--)
queue.insert(i);
for (let i = 1; i < 16; i++) {
assert.strictEqual(queue.peek(), i);
assert.strictEqual(queue.shift(), i);
}
assert.strictEqual(queue.shift(), undefined);
// Reverse the order.
for (let i = 1; i < 16; i++)
queue.insert(i);
for (let i = 1; i < 16; i++) {
assert.strictEqual(queue.shift(), i);
}
assert.strictEqual(queue.shift(), undefined);
}
{
// Checks that the queue is capable of resizing and fitting more elements.
const queue = new PriorityQueue();
for (let i = 2048; i > 0; i--)
queue.insert(i);
for (let i = 1; i < 2049; i++) {
assert.strictEqual(queue.shift(), i);
}
assert.strictEqual(queue.shift(), undefined);
}
{
// Checks that remove works as expected.
const queue = new PriorityQueue();
for (let i = 16; i > 0; i--)
queue.insert(i);
const removed = [5, 10, 15];
for (const id of removed)
assert(queue.remove(id));
assert(!queue.remove(100));
assert(!queue.remove(-100));
for (let i = 1; i < 17; i++) {
if (removed.indexOf(i) < 0)
assert.strictEqual(queue.shift(), i);
}
assert.strictEqual(queue.shift(), undefined);
}
{
// Make a max heap with a custom sort function.
const queue = new PriorityQueue((a, b) => b - a);
for (let i = 1; i < 17; i++)
queue.insert(i);
for (let i = 16; i > 0; i--) {
assert.strictEqual(queue.shift(), i);
}
assert.strictEqual(queue.shift(), undefined);
}
{
// Make a min heap that accepts objects as values, which necessitates
// a custom sorting function. In addition, add a setPosition function
// as 2nd param which provides a reference to the node in the heap
// and allows speedy deletions.
const queue = new PriorityQueue((a, b) => {
return a.value - b.value;
}, (node, pos) => (node.position = pos));
for (let i = 1; i < 17; i++)
queue.insert({ value: i, position: null });
for (let i = 1; i < 17; i++) {
assert.strictEqual(queue.peek().value, i);
queue.removeAt(queue.peek().position);
}
assert.strictEqual(queue.peek(), undefined);
}
{
const queue = new PriorityQueue((a, b) => {
return a.value - b.value;
}, (node, pos) => (node.position = pos));
queue.insert({ value: 1, position: null });
queue.insert({ value: 2, position: null });
queue.insert({ value: 3, position: null });
queue.insert({ value: 4, position: null });
queue.insert({ value: 5, position: null });
queue.insert({ value: 2, position: null });
const secondLargest = { value: 10, position: null };
queue.insert(secondLargest);
const largest = { value: 15, position: null };
queue.insert(largest);
queue.removeAt(5);
assert.strictEqual(largest.position, 5);
// Check that removing 2nd to last item works fine
queue.removeAt(6);
assert.strictEqual(secondLargest.position, 6);
// Check that removing the last item doesn't throw
queue.removeAt(6);
assert.strictEqual(queue.shift().value, 1);
assert.strictEqual(queue.shift().value, 2);
assert.strictEqual(queue.shift().value, 2);
assert.strictEqual(queue.shift().value, 4);
assert.strictEqual(queue.shift().value, 15);
assert.strictEqual(queue.shift(), undefined);
}
{
// Checks that removeAt respects binary heap properties
const queue = new PriorityQueue((a, b) => {
return a.value - b.value;
}, (node, pos) => (node.position = pos));
const i3 = { value: 3, position: null };
const i7 = { value: 7, position: null };
const i8 = { value: 8, position: null };
queue.insert({ value: 1, position: null });
queue.insert({ value: 6, position: null });
queue.insert({ value: 2, position: null });
queue.insert(i7);
queue.insert(i8);
queue.insert(i3);
assert.strictEqual(i7.position, 4);
queue.removeAt(4);
// 3 should percolate up to swap with 6 (up)
assert.strictEqual(i3.position, 2);
queue.removeAt(2);
// 8 should swap places with 6 (down)
assert.strictEqual(i8.position, 4);
}
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