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