ringBuffer.ts87 lines · main

1	export class RingBuffer<T> {
2	private readonly capacity: number
3	private readonly buffer: (T | undefined)[]
4	private head = 0
5	private tail = 0
6	private size = 0
7
8	constructor(capacity: number) {
9	if (!Number.isInteger(capacity) || capacity <= 0) {
10	throw new Error('RingBuffer capacity must be a positive integer')
11	}
12
13	this.capacity = capacity
14	this.buffer = new Array<T | undefined>(capacity).fill(undefined)
15	}
16
17	get length(): number {
18	return this.size
19	}
20
21	pushBack(value: T): void {
22	this.buffer[this.tail] = value
23
24	if (this.size === this.capacity) {
25	this.head = (this.head + 1) % this.capacity
26	} else {
27	this.size += 1
28	}
29
30	this.tail = (this.tail + 1) % this.capacity
31	}
32
33	popFront(): T | undefined {
34	if (this.size === 0) {
35	return undefined
36	}
37
38	const value = this.buffer[this.head]
39	this.buffer[this.head] = undefined
40	this.head = (this.head + 1) % this.capacity
41	this.size -= 1
42
43	return value
44	}
45
46	popBack(): T | undefined {
47	if (this.size === 0) {
48	return undefined
49	}
50
51	const index = (this.tail - 1 + this.capacity) % this.capacity
52	const value = this.buffer[index]
53	this.buffer[index] = undefined
54	this.tail = index
55	this.size -= 1
56
57	return value
58	}
59
60	toArray(start?: number, end?: number): T[] {
61	const len = this.size
62
63	let startIndex = start === undefined ? 0 : Math.trunc(start)
64	if (startIndex < 0) {
65	startIndex = Math.max(len + startIndex, 0)
66	} else {
67	startIndex = Math.min(startIndex, len)
68	}
69
70	let endIndex = end === undefined ? len : Math.trunc(end)
71	if (endIndex < 0) {
72	endIndex = Math.max(len + endIndex, 0)
73	} else {
74	endIndex = Math.min(endIndex, len)
75	}
76
77	const sliceLength = Math.max(endIndex - startIndex, 0)
78	const result = new Array<T>(sliceLength)
79
80	for (let offset = 0; offset < sliceLength; offset += 1) {
81	const physicalIndex = (this.head + startIndex + offset) % this.capacity
82	result[offset] = this.buffer[physicalIndex] as T
83	}
84
85	return result
86	}
87	}