91 lines
2.3 KiB
TypeScript
91 lines
2.3 KiB
TypeScript
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interface OneWayLinkedList<T> {
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v: T
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n?: OneWayLinkedList<T>
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}
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/**
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* Simple class implementing LRU-like behaviour for a set
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* of strings, falling back to objects when `Set` is not available.
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*
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* Used to store recently received message IDs in {@link TelegramConnection}
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*
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* Uses one-way linked list internally to keep track of insertion order
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*
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* @internal
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*/
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export class LruStringSet {
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private _capacity: number
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private _first?: OneWayLinkedList<string>
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private _last?: OneWayLinkedList<string>
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private _set?: Set<string>
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private _obj?: Record<string, true>
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private _objSize?: number
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constructor(capacity: number, useObject = false) {
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this._capacity = capacity
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if (typeof Set === 'undefined' || useObject) {
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this._obj = {}
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this._objSize = 0
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this.add = this._addForObj.bind(this)
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this.has = this._hasForObj.bind(this)
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} else {
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this._set = new Set()
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this.add = this._addForSet.bind(this)
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this.has = this._hasForSet.bind(this)
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}
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}
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add: (str: string) => void
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has: (str: string) => boolean
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private _addForSet(str: string) {
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if (this._set!.has(str)) return
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if (!this._first) this._first = { v: str }
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if (!this._last) this._last = this._first
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else {
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this._last.n = { v: str }
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this._last = this._last.n
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}
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this._set!.add(str)
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if (this._set!.size > this._capacity && this._first) {
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// remove least recently used
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this._set!.delete(this._first.v)
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this._first = this._first.n
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}
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}
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private _hasForSet(str: string) {
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return this._set!.has(str)
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}
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private _addForObj(str: string) {
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if (str in this._obj!) return
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if (!this._first) this._first = { v: str }
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if (!this._last) this._last = this._first
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else {
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this._last.n = { v: str }
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this._last = this._last.n
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}
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this._obj![str] = true
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if (this._objSize === this._capacity) {
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// remove least recently used
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delete this._obj![this._first.v]
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this._first = this._first.n
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} else {
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this._objSize! += 1
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}
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}
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private _hasForObj(str: string) {
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return str in this._obj!
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}
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}
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