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1 | // Copyright Jerome Benoit. 2024. All Rights Reserved. |
2 | ||
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3 | import { FixedPriorityQueue } from './fixed-priority-queue.js' |
4 | ||
5 | /** | |
6 | * Default bucket size. | |
7 | */ | |
8 | export const defaultBucketSize = 2048 | |
9 | ||
bcfb06ce | 10 | /** |
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11 | * Priority queue node. |
12 | * | |
13 | * @typeParam T - Type of priority queue node data. | |
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14 | * @internal |
15 | */ | |
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16 | export interface PriorityQueueNode<T> extends FixedPriorityQueue<T> { |
17 | next?: FixedPriorityQueue<T> | |
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18 | } |
19 | ||
20 | /** | |
95d1a734 | 21 | * Priority queue. |
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22 | * |
23 | * @typeParam T - Type of priority queue data. | |
24 | * @internal | |
25 | */ | |
26 | export class PriorityQueue<T> { | |
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27 | private head!: PriorityQueueNode<T> |
28 | private tail!: PriorityQueueNode<T> | |
2107bc57 | 29 | private readonly bucketSize: number |
13ed544a | 30 | /** The priority queue maximum size. */ |
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31 | public maxSize!: number |
32 | ||
bd8b441c | 33 | /** |
95d1a734 | 34 | * Constructs a priority queue. |
bd8b441c | 35 | * |
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36 | * @param bucketSize - Prioritized bucket size. @defaultValue defaultBucketSize |
37 | * @returns PriorityQueue. | |
bd8b441c | 38 | */ |
9df282a0 | 39 | public constructor (bucketSize: number = defaultBucketSize) { |
e75373e6 | 40 | if (!Number.isSafeInteger(bucketSize)) { |
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41 | throw new TypeError( |
42 | `Invalid bucket size: '${bucketSize}' is not an integer` | |
43 | ) | |
e75373e6 | 44 | } |
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45 | if (bucketSize < 0) { |
46 | throw new RangeError(`Invalid bucket size: ${bucketSize} < 0`) | |
e75373e6 | 47 | } |
2107bc57 | 48 | this.bucketSize = bucketSize |
e41b0271 | 49 | this.clear() |
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50 | } |
51 | ||
e75373e6 | 52 | /** |
13ed544a | 53 | * The priority queue size. |
e75373e6 | 54 | */ |
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55 | public get size (): number { |
56 | let node: PriorityQueueNode<T> | undefined = this.tail | |
57 | let size = 0 | |
58 | while (node != null) { | |
59 | size += node.size | |
60 | node = node.next | |
61 | } | |
62 | return size | |
63 | } | |
64 | ||
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65 | /** |
66 | * The number of filled prioritized buckets. | |
67 | */ | |
68 | public get buckets (): number { | |
69 | return Math.trunc(this.size / this.bucketSize) | |
70 | } | |
71 | ||
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72 | /** |
73 | * Enqueue data into the priority queue. | |
74 | * | |
75 | * @param data - Data to enqueue. | |
76 | * @param priority - Priority of the data. Lower values have higher priority. | |
77 | * @returns The new size of the priority queue. | |
78 | */ | |
79 | public enqueue (data: T, priority?: number): number { | |
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80 | if (this.head.full()) { |
81 | this.head = this.head.next = new FixedPriorityQueue(this.bucketSize) | |
bcfb06ce | 82 | } |
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83 | this.head.enqueue(data, priority) |
84 | const size = this.size | |
85 | if (size > this.maxSize) { | |
86 | this.maxSize = size | |
bcfb06ce | 87 | } |
9df282a0 | 88 | return size |
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89 | } |
90 | ||
91 | /** | |
92 | * Dequeue data from the priority queue. | |
93 | * | |
9df282a0 | 94 | * @param bucket - The prioritized bucket to dequeue from. |
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95 | * @returns The dequeued data or `undefined` if the priority queue is empty. |
96 | */ | |
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97 | public dequeue (bucket?: number): T | undefined { |
98 | let tail: PriorityQueueNode<T> | undefined = this.tail | |
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99 | let tailChanged = false |
100 | if (bucket != null && bucket > 0) { | |
101 | let currentBucket = 1 | |
9df282a0 | 102 | while (tail != null) { |
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103 | if (currentBucket === bucket) { |
104 | break | |
95d1a734 | 105 | } |
1d98bad2 | 106 | ++currentBucket |
9df282a0 | 107 | tail = tail.next |
1d98bad2 | 108 | tailChanged = true |
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109 | } |
110 | } | |
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111 | // eslint-disable-next-line @typescript-eslint/no-non-null-assertion |
112 | const data = tail!.dequeue() | |
113 | // eslint-disable-next-line @typescript-eslint/no-non-null-assertion | |
114 | if (tail!.empty() && tail!.next != null) { | |
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115 | if (!tailChanged) { |
116 | // eslint-disable-next-line @typescript-eslint/no-non-null-assertion | |
117 | this.tail = tail!.next | |
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118 | } else { |
119 | let node: PriorityQueueNode<T> | undefined = this.tail | |
120 | while (node != null) { | |
121 | if (node.next === tail) { | |
122 | // eslint-disable-next-line @typescript-eslint/no-non-null-assertion | |
123 | node.next = tail!.next | |
124 | break | |
125 | } | |
126 | node = node.next | |
127 | } | |
128 | } | |
129 | // eslint-disable-next-line @typescript-eslint/no-non-null-assertion | |
130 | delete tail!.next | |
131 | } | |
132 | return data | |
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133 | } |
134 | ||
135 | /** | |
136 | * Clears the priority queue. | |
137 | */ | |
138 | public clear (): void { | |
9df282a0 | 139 | this.head = this.tail = new FixedPriorityQueue(this.bucketSize) |
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140 | this.maxSize = 0 |
141 | } | |
142 | ||
143 | /** | |
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144 | * Returns an iterator for the priority queue. |
145 | * | |
2be9b405 | 146 | * @returns An iterator for the priority queue. |
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147 | * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols |
148 | */ | |
9df282a0 | 149 | public [Symbol.iterator] (): Iterator<T> { |
1d98bad2 | 150 | let index = 0 |
9df282a0 | 151 | let node = this.tail |
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152 | return { |
153 | next: () => { | |
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154 | const value = node.get(index) as T |
155 | if (value == null) { | |
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156 | return { |
157 | value: undefined, | |
158 | done: true | |
159 | } | |
160 | } | |
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161 | ++index |
162 | if (index === node.capacity && node.next != null) { | |
9df282a0 | 163 | node = node.next |
1d98bad2 | 164 | index = 0 |
9df282a0 | 165 | } |
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166 | return { |
167 | value, | |
168 | done: false | |
169 | } | |
170 | } | |
171 | } | |
172 | } | |
bcfb06ce | 173 | } |