67 lines
1.9 KiB
TypeScript
67 lines
1.9 KiB
TypeScript
/**
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* @author Martin Karkowski
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* @email m.karkowski@zema.de
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* @create date 2020-09-09 16:00:36
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* @modify date 2020-09-09 16:00:40
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* @desc [description]
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*/
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/**
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* Sometimes, the creation of an new Instance is very slow. Therefore this Lazy-Constructor could be used.
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* Instead of creating a new Instance, it looks for a not used and returns that Instance. By returning
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* the unused Instance it is marked as used. After the usage the instance could marked as unused again.
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* If there is no unused Instance available an new Instance is created.
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*
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* To utilize the Lazy-Constructor a specific create-instance method and a compare function is required.
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*
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* @export
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* @class LazyConstructor
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* @template T Args which are required to Construct an Instance
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* @template U Type of the Instance
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*/
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export class LazyConstructor<T> {
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private _inactive = new Set<T>();
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/**
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* Creates an instance of LazyConstructor.
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* @param {*} _ctor
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* @param {(a:T,b:t)=>boolean} _equals
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* @memberof LazyConstructor
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*/
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constructor(private _ctor: (...arggs) => T) {}
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/**
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* Creates a new Instance and tries to use an already existing
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* one if possible.
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*
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* @param {T} args An Object containing the args which are required to create an Instance
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* @returns {U} new Object
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* @memberof LazyConstructor
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*/
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public createInstance(...args): T {
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/** First Loop check whether there is a math in the Keys*/
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const _instance = this._inactive[Symbol.iterator]().next();
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if (!_instance.done) {
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/** Remove the Instance */
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this._inactive.delete(_instance.value);
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/** Return the Value. */
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return _instance.value;
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}
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return this._ctor(...args);
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}
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/**
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* Releases a used Instance. Thereby it could be
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* used again.
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*
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* @param {U} instance
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* @memberof LazyConstructor
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*/
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public releaseInstance(instance: T) {
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this._inactive.add(instance);
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}
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}
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