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import {Pipe, PipeFunction, PipeObject} from "./types/pipes"; |
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export class Pipeline<T> { |
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private passable: T | null = null; |
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private pipes: Pipe<T>[] = []; |
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/** |
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* Set the object being sent through the pipeline. |
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* @param passable The data to be passed through the pipeline. |
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* @returns {Pipeline<T>} The pipeline instance. |
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*/ |
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send(passable: T): this { |
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this.passable = passable; |
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return this; |
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} |
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/** |
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* Set the array of pipes. |
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* @param pipes The pipes to process the passable object. |
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* @returns {Pipeline<T>} The pipeline instance. |
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*/ |
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through(pipes: Pipe<T>[] | Pipe<T>): this { |
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this.pipes = Array.isArray(pipes) ? pipes : [pipes]; |
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return this; |
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} |
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/** |
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* Execute the pipeline and resolve the final result. |
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* @param destination The final operation after all pipes. |
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* @returns {Promise<T>} The final processed result. |
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*/ |
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async then(destination: (value: T) => Promise<T>): Promise<T> { |
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if (this.passable === null) { |
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throw new Error('No passable object provided to the pipeline.'); |
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} |
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if (!this.pipes.length) { |
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return destination(this.passable); |
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} |
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// Reduce the pipes into a single composed function |
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const pipeline = this.pipes.reduceRight( |
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(next: (value: T) => Promise<T>, pipe: Pipe<T>) => { |
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return async (passable: T): Promise<T> => { |
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if (this.isPipeFunction(pipe)) { |
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return pipe(passable, next); |
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} |
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if (this.isPipeObject(pipe)) { |
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return pipe.handle(passable, next); |
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} |
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throw new Error('Pipe must be a function or an object with a "handle" method.'); |
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}; |
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}, |
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destination |
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); |
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return pipeline(this.passable); |
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} |
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/** |
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* Type guard to check if the pipe is a function. |
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* @param pipe The pipe to check. |
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* @returns {pipe is PipeFunction<T>} Whether the pipe is a function. |
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*/ |
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private isPipeFunction(pipe: Pipe<T>): pipe is PipeFunction<T> { |
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return typeof pipe === 'function'; |
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} |
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/** |
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* Type guard to check if the pipe is an object with a handle method. |
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* @param pipe The pipe to check. |
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* @returns {pipe is PipeObject<T>} Whether the pipe is an object with a handle method. |
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*/ |
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private isPipeObject(pipe: Pipe<T>): pipe is PipeObject<T> { |
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return typeof (pipe as PipeObject<T>).handle === 'function'; |
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} |
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} |
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bytesfield /
sweet-pipeline
