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import {b64DataURL} from "./base64.ts";import {u8Encode} from "./text.ts";
interface TaskMessage<T extends unknown>{    message: T;    transfers?: Transferable[];}
/*** Content of processing run by worker thread.*/export type TaskAction<T extends unknown, K extends unknown> = (message:T) => TaskMessage<K> | Promise<TaskMessage<K>>;
/*** Run registered `TaskAction` in worker thread.*/export type TaskContext<T extends unknown, K extends unknown> = (message:T, transfers?:Transferable[]) => Promise<K>;
/*** Register `TaskAction` and return reusable task execution context.* `Worker` instance is created and destroyed each time they run `TaskContext`.* `import` can only use "syntax", not "declaration".* @example* ```ts* const task = createTask<number, number>(async(data)=>{*     const {delay} = await import("https://deno.land/std/async/mod.ts");*     await delay(data);*     return {*         message: data * 2*     };* });* const result1 = await task(10);* const result2 = await task(20);* ```*/export function createTask<T extends unknown, K extends unknown>(task:TaskAction<T, K>):TaskContext<T, K>{    const script = /*js*/`        globalThis.onmessage = async({data})=>{            const {message, transfers} = await(${task.toString()})(data);            globalThis.postMessage(message, {                transfer: transfers            });        };    `;
    return (message, transfers)=>{        return new Promise<K>((res, rej)=>{            const worker = new Worker(b64DataURL(u8Encode(script), "text/javascript"), {                type: "module"            });
            worker.onmessage = ({data})=>{                res(data);                worker.terminate();            };
            worker.onerror = (e)=>{                rej(e);                worker.terminate();            };
            worker.onmessageerror = (e)=>{                rej(e);                worker.terminate();            };
            worker.postMessage(message, {                transfer: transfers            });        });    };}