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f8d5d8fd JB |
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 | ||
eadb37e2 JB |
17 | /** |
18 | * Fixed priority queue. | |
19 | * | |
20 | * @typeParam T - Type of fixed priority queue data. | |
21 | * @internal | |
22 | */ | |
f8d5d8fd JB |
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 | |
eadb37e2 | 48 | const nodeArrayLength = this.nodeArray.length |
f8d5d8fd | 49 | let inserted = false |
eadb37e2 | 50 | for (let index = this.start; index < nodeArrayLength; index++) { |
f8d5d8fd JB |
51 | if (this.nodeArray[index]?.priority > priority) { |
52 | this.nodeArray.splice(index, 0, { data, priority }) | |
53 | inserted = true | |
54 | break | |
55 | } | |
56 | } | |
eadb37e2 JB |
57 | this.nodeArray.length !== nodeArrayLength && |
58 | (this.nodeArray.length = nodeArrayLength) | |
f8d5d8fd JB |
59 | if (!inserted) { |
60 | let index = this.start + this.size | |
eadb37e2 JB |
61 | if (index >= nodeArrayLength) { |
62 | index -= nodeArrayLength | |
f8d5d8fd JB |
63 | } |
64 | this.nodeArray[index] = { data, priority } | |
65 | } | |
66 | return this.incrementSize() | |
67 | } | |
68 | ||
69 | public dequeue (): T | undefined { | |
70 | if (this.empty()) { | |
71 | return undefined | |
72 | } | |
73 | const index = this.start | |
74 | --this.size | |
75 | ++this.start | |
76 | if (this.start === this.nodeArray.length) { | |
77 | this.start = 0 | |
78 | } | |
79 | return this.nodeArray[index].data | |
80 | } | |
81 | ||
82 | /** | |
83 | * Clears the fixed priority queue. | |
84 | */ | |
85 | public clear (): void { | |
86 | this.start = 0 | |
87 | this.size = 0 | |
88 | this.maxSize = 0 | |
89 | } | |
90 | ||
91 | /** | |
92 | * Returns an iterator for the fixed priority queue. | |
93 | * | |
94 | * @returns An iterator for the fixed priority queue. | |
95 | * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols | |
96 | */ | |
97 | [Symbol.iterator] (): Iterator<T> { | |
98 | let i = this.start | |
99 | return { | |
100 | next: () => { | |
101 | if (i >= this.size) { | |
102 | return { | |
103 | value: undefined, | |
104 | done: true | |
105 | } | |
106 | } | |
107 | const value = this.nodeArray[i].data | |
108 | i++ | |
109 | return { | |
110 | value, | |
111 | done: false | |
112 | } | |
113 | } | |
114 | } | |
115 | } | |
116 | ||
117 | /** | |
118 | * Increments the size of the fixed priority queue. | |
119 | * | |
120 | * @returns The new size of the fixed priority queue. | |
121 | */ | |
122 | private incrementSize (): number { | |
123 | ++this.size | |
124 | if (this.size > this.maxSize) { | |
125 | this.maxSize = this.size | |
126 | } | |
127 | return this.size | |
128 | } | |
129 | ||
130 | private checkSize (size: number): void { | |
131 | if (!Number.isSafeInteger(size)) { | |
132 | throw new TypeError( | |
f45a8925 | 133 | `Invalid fixed priority queue size: '${size}' is not an integer` |
f8d5d8fd JB |
134 | ) |
135 | } | |
136 | if (size < 0) { | |
137 | throw new RangeError(`Invalid fixed priority queue size: ${size} < 0`) | |
138 | } | |
139 | } | |
140 | } |