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import { ILifetimeSlot } from "../typings/interfaces";
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import { isDestroyable } from "./traits";
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const _destroy = (item: unknown) => () => isDestroyable(item) && item.destroy();
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enum State {
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New,
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Initialized,
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Destroyed
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}
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export class LifetimeSlot<T> implements ILifetimeSlot<T> {
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private _value: NonNullable<T> | undefined = undefined;
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private _state = State.New;
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cleanup: () => void;
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readonly remove: () => void;
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constructor(remove: () => void) {
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this.remove = this._finalizer(remove);
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this.cleanup = this._finalizer(() => { });
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}
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has(): boolean {
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this._assertNotDisposed();
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return this._value !== undefined;
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}
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get(): NonNullable<T> {
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this._assertNotDisposed();
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if (this._value === undefined)
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throw new Error("The slot doesn't have a value");
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return this._value;
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}
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initialize(): boolean {
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return this._state === State.New ?
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(this._state = State.Initialized, true) :
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false;
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}
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store(item: NonNullable<T>, cleanup: ((item: NonNullable<T>) => void) | undefined = _destroy): void {
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this._assertNotDisposed();
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this._value = item;
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if (cleanup)
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this.cleanup = this._finalizer(() => cleanup(item));
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}
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private _finalizer(cb: () => void) {
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return () => this._state !== State.Destroyed ? (this._state = State.Destroyed, cb()) : void (0);
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}
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private _assertNotDisposed() {
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if (this._state === State.Destroyed)
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throw new Error("The slot is disposed");
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}
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}
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