| 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 | 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 readonly capacity: number |
| 27 | public size!: number |
| 28 | public maxSize!: number |
| 29 | |
| 30 | /** |
| 31 | * Constructs a fixed priority queue. |
| 32 | * |
| 33 | * @param size - Fixed priority queue size. @defaultValue defaultQueueSize |
| 34 | * @returns FixedPriorityQueue. |
| 35 | */ |
| 36 | constructor (size: number = defaultQueueSize) { |
| 37 | this.checkSize(size) |
| 38 | this.capacity = size |
| 39 | this.nodeArray = new Array<PriorityQueueNode<T>>(this.capacity) |
| 40 | this.clear() |
| 41 | } |
| 42 | |
| 43 | /** |
| 44 | * Checks if the fixed priority queue is empty. |
| 45 | * |
| 46 | * @returns `true` if the fixed priority queue is empty, `false` otherwise. |
| 47 | */ |
| 48 | public empty (): boolean { |
| 49 | return this.size === 0 |
| 50 | } |
| 51 | |
| 52 | /** |
| 53 | * Checks if the fixed priority queue is full. |
| 54 | * |
| 55 | * @returns `true` if the fixed priority queue is full, `false` otherwise. |
| 56 | */ |
| 57 | public full (): boolean { |
| 58 | return this.size === this.capacity |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * Enqueue data into the fixed priority queue. |
| 63 | * |
| 64 | * @param data - Data to enqueue. |
| 65 | * @param priority - Priority of the data. Lower values have higher priority. |
| 66 | * @returns The new size of the priority queue. |
| 67 | */ |
| 68 | public enqueue (data: T, priority?: number): number { |
| 69 | if (this.full()) { |
| 70 | throw new Error('Priority queue is full') |
| 71 | } |
| 72 | priority = priority ?? 0 |
| 73 | let index = this.start |
| 74 | let inserted = false |
| 75 | for (let i = 0; i < this.size; i++) { |
| 76 | if (this.nodeArray[index]?.priority > priority) { |
| 77 | this.nodeArray.splice(index, 0, { data, priority }) |
| 78 | inserted = true |
| 79 | break |
| 80 | } |
| 81 | ++index |
| 82 | if (index === this.capacity) { |
| 83 | index = 0 |
| 84 | } |
| 85 | } |
| 86 | this.nodeArray.length !== this.capacity && |
| 87 | (this.nodeArray.length = this.capacity) |
| 88 | if (!inserted) { |
| 89 | let index = this.start + this.size |
| 90 | if (index >= this.capacity) { |
| 91 | index -= this.capacity |
| 92 | } |
| 93 | this.nodeArray[index] = { data, priority } |
| 94 | } |
| 95 | return this.incrementSize() |
| 96 | } |
| 97 | |
| 98 | /** |
| 99 | * Dequeue data from the fixed priority queue. |
| 100 | * |
| 101 | * @returns The dequeued data or `undefined` if the priority queue is empty. |
| 102 | */ |
| 103 | public dequeue (): T | undefined { |
| 104 | if (this.empty()) { |
| 105 | return undefined |
| 106 | } |
| 107 | const index = this.start |
| 108 | --this.size |
| 109 | ++this.start |
| 110 | if (this.start === this.capacity) { |
| 111 | this.start = 0 |
| 112 | } |
| 113 | return this.nodeArray[index].data |
| 114 | } |
| 115 | |
| 116 | /** |
| 117 | * Clears the fixed priority queue. |
| 118 | */ |
| 119 | public clear (): void { |
| 120 | this.start = 0 |
| 121 | this.size = 0 |
| 122 | this.maxSize = 0 |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * Returns an iterator for the fixed priority queue. |
| 127 | * |
| 128 | * @returns An iterator for the fixed priority queue. |
| 129 | * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols |
| 130 | */ |
| 131 | public [Symbol.iterator] (): Iterator<T> { |
| 132 | let index = this.start |
| 133 | let i = 0 |
| 134 | return { |
| 135 | next: () => { |
| 136 | if (i >= this.size) { |
| 137 | return { |
| 138 | value: undefined, |
| 139 | done: true |
| 140 | } |
| 141 | } |
| 142 | const value = this.nodeArray[index].data |
| 143 | ++index |
| 144 | ++i |
| 145 | if (index === this.capacity) { |
| 146 | index = 0 |
| 147 | } |
| 148 | return { |
| 149 | value, |
| 150 | done: false |
| 151 | } |
| 152 | } |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * Increments the size of the fixed priority queue. |
| 158 | * |
| 159 | * @returns The new size of the fixed priority queue. |
| 160 | */ |
| 161 | private incrementSize (): number { |
| 162 | ++this.size |
| 163 | if (this.size > this.maxSize) { |
| 164 | this.maxSize = this.size |
| 165 | } |
| 166 | return this.size |
| 167 | } |
| 168 | |
| 169 | /** |
| 170 | * Checks the size. |
| 171 | * |
| 172 | * @param size - The size to check. |
| 173 | */ |
| 174 | private checkSize (size: number): void { |
| 175 | if (!Number.isSafeInteger(size)) { |
| 176 | throw new TypeError( |
| 177 | `Invalid fixed priority queue size: '${size}' is not an integer` |
| 178 | ) |
| 179 | } |
| 180 | if (size < 0) { |
| 181 | throw new RangeError(`Invalid fixed priority queue size: ${size} < 0`) |
| 182 | } |
| 183 | } |
| 184 | } |