| 1 | /** |
| 2 | * Default buffer size. |
| 3 | */ |
| 4 | export const defaultQueueSize = 2048 |
| 5 | |
| 6 | /** |
| 7 | * Priority queue node. |
| 8 | * |
| 9 | * @typeParam T - Type of priority queue node data. |
| 10 | * @internal |
| 11 | */ |
| 12 | export interface PriorityQueueNode<T> { |
| 13 | data: T |
| 14 | priority: number |
| 15 | } |
| 16 | |
| 17 | /** |
| 18 | * Fixed priority queue. |
| 19 | * |
| 20 | * @typeParam T - Type of fixed priority queue data. |
| 21 | * @internal |
| 22 | */ |
| 23 | export class FixedPriorityQueue<T> { |
| 24 | private start!: number |
| 25 | private readonly nodeArray: Array<PriorityQueueNode<T>> |
| 26 | public size!: number |
| 27 | public maxSize!: number |
| 28 | |
| 29 | constructor (size: number = defaultQueueSize) { |
| 30 | this.checkSize(size) |
| 31 | this.nodeArray = new Array<PriorityQueueNode<T>>(size) |
| 32 | this.clear() |
| 33 | } |
| 34 | |
| 35 | public empty (): boolean { |
| 36 | return this.size === 0 |
| 37 | } |
| 38 | |
| 39 | public full (): boolean { |
| 40 | return this.size === this.nodeArray.length |
| 41 | } |
| 42 | |
| 43 | public enqueue (data: T, priority?: number): number { |
| 44 | if (this.full()) { |
| 45 | throw new Error('Priority queue is full') |
| 46 | } |
| 47 | priority = priority ?? 0 |
| 48 | const nodeArrayLength = this.nodeArray.length |
| 49 | let index = this.start |
| 50 | let inserted = false |
| 51 | for (let i = 0; i < this.size; i++) { |
| 52 | if (this.nodeArray[index]?.priority > priority) { |
| 53 | this.nodeArray.splice(index, 0, { data, priority }) |
| 54 | inserted = true |
| 55 | break |
| 56 | } |
| 57 | ++index |
| 58 | if (index === nodeArrayLength) { |
| 59 | index = 0 |
| 60 | } |
| 61 | } |
| 62 | this.nodeArray.length !== nodeArrayLength && |
| 63 | (this.nodeArray.length = nodeArrayLength) |
| 64 | if (!inserted) { |
| 65 | let index = this.start + this.size |
| 66 | if (index >= nodeArrayLength) { |
| 67 | index -= nodeArrayLength |
| 68 | } |
| 69 | this.nodeArray[index] = { data, priority } |
| 70 | } |
| 71 | return this.incrementSize() |
| 72 | } |
| 73 | |
| 74 | public dequeue (): T | undefined { |
| 75 | if (this.empty()) { |
| 76 | return undefined |
| 77 | } |
| 78 | const index = this.start |
| 79 | --this.size |
| 80 | ++this.start |
| 81 | if (this.start === this.nodeArray.length) { |
| 82 | this.start = 0 |
| 83 | } |
| 84 | return this.nodeArray[index].data |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * Clears the fixed priority queue. |
| 89 | */ |
| 90 | public clear (): void { |
| 91 | this.start = 0 |
| 92 | this.size = 0 |
| 93 | this.maxSize = 0 |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Returns an iterator for the fixed priority queue. |
| 98 | * |
| 99 | * @returns An iterator for the fixed priority queue. |
| 100 | * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols |
| 101 | */ |
| 102 | [Symbol.iterator] (): Iterator<T> { |
| 103 | let index = this.start |
| 104 | let i = 0 |
| 105 | return { |
| 106 | next: () => { |
| 107 | if (i >= this.size) { |
| 108 | return { |
| 109 | value: undefined, |
| 110 | done: true |
| 111 | } |
| 112 | } |
| 113 | const value = this.nodeArray[index].data |
| 114 | ++index |
| 115 | ++i |
| 116 | if (index === this.nodeArray.length) { |
| 117 | index = 0 |
| 118 | } |
| 119 | return { |
| 120 | value, |
| 121 | done: false |
| 122 | } |
| 123 | } |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * Increments the size of the fixed priority queue. |
| 129 | * |
| 130 | * @returns The new size of the fixed priority queue. |
| 131 | */ |
| 132 | private incrementSize (): number { |
| 133 | ++this.size |
| 134 | if (this.size > this.maxSize) { |
| 135 | this.maxSize = this.size |
| 136 | } |
| 137 | return this.size |
| 138 | } |
| 139 | |
| 140 | private checkSize (size: number): void { |
| 141 | if (!Number.isSafeInteger(size)) { |
| 142 | throw new TypeError( |
| 143 | `Invalid fixed priority queue size: '${size}' is not an integer` |
| 144 | ) |
| 145 | } |
| 146 | if (size < 0) { |
| 147 | throw new RangeError(`Invalid fixed priority queue size: ${size} < 0`) |
| 148 | } |
| 149 | } |
| 150 | } |