110 lines
3 KiB
TypeScript
110 lines
3 KiB
TypeScript
/* eslint-disable @typescript-eslint/no-explicit-any */
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// ^^ because of performance reasons
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import Long from 'long'
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import { LongSet } from './long-utils'
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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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* 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 SessionConnection}
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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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export class LruSet<T extends string | number | Long> {
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private _capacity: number
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private _first?: OneWayLinkedList<T>
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private _last?: OneWayLinkedList<T>
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private _set?: Set<T> | LongSet
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private _obj?: object
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private _objSize?: number
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constructor(capacity: number, useObject = false, forLong = false) {
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this._capacity = capacity
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if (!forLong && (typeof Set === 'undefined' || useObject)) {
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this._obj = Object.create(null)
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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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this.clear = this._clearForObj.bind(this)
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} else {
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this._set = forLong ? new LongSet(useObject) : 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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this.clear = this._clearForSet.bind(this)
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}
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}
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readonly add: (val: T) => void
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readonly has: (val: T) => boolean
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readonly clear: () => void
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private _clearForSet() {
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this._first = this._last = undefined
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this._set!.clear()
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}
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private _clearForObj() {
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this._first = this._last = undefined
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this._obj = {}
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this._objSize = 0
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}
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private _addForSet(val: T) {
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if (this._set!.has(val as any)) return
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if (!this._first) this._first = { v: val }
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if (!this._last) this._last = this._first
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else {
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this._last.n = { v: val }
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this._last = this._last.n
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}
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this._set!.add(val as any)
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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 as any)
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this._first = this._first.n
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}
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}
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private _hasForSet(val: T) {
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return this._set!.has(val as any)
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}
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private _addForObj(val: T) {
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if ((val as any) in this._obj!) return
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if (!this._first) this._first = { v: val }
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if (!this._last) this._last = this._first
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else {
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this._last.n = { v: val }
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this._last = this._last.n
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}
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(this._obj as any)[val] = 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 as any)[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(val: T) {
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return (val as any) in this._obj!
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}
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}
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