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x/evt/lib/Evt.ts

­čĺžEventEmitter's typesafe replacement
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import type { LightMap } from "../tools/minimal-polyfills/LightMap.ts";import { importProxy } from "./importProxy.ts";import { create } from "./Evt.create.ts";import { getCtxFactory } from "./Evt.getCtx.ts";import { factorize } from "./Evt.factorize.ts";import { merge } from "./Evt.merge.ts";import { from } from "./Evt.from.ts";import { asPostable } from "./Evt.asPostable.ts";import { asyncPipe } from "./Evt.asyncPipe.ts";import { asNonPostable } from "./Evt.asNonPostable.ts";import { parsePropsFromArgs, matchAll } from "./Evt.parsePropsFromArgs.ts";import { newCtx } from "./Evt.newCtx.ts";import { LazyEvt } from "./LazyEvt.ts";import * as runExclusive from "https://deno.land/x/run_exclusive@v2.2.18/mod.ts";import { overwriteReadonlyProp } from "https://deno.land/x/tsafe@v1.4.1/lab/overwriteReadonlyProp.ts";import { typeGuard } from "https://deno.land/x/tsafe@v1.4.1/typeGuard.ts";import { Deferred } from "../tools/Deferred.ts";import { loosenType } from "./Evt.loosenType.ts";import { safeClearTimeout, safeSetTimeout, Timer } from "../tools/safeSetTimeout.ts";import { isPromiseLike } from "https://deno.land/x/tsafe@v1.4.1/isPromiseLike.ts";import { DetachedEvtError, TimeoutEvtError } from "./types/EvtError.ts";import * as nsCtxLike from "./types/interfaces/CtxLike.ts";import type { Handler, Operator, NonPostableEvt, StatefulEvt, NonPostableEvtLike, CtxLike } from "./types/index.ts";import { convertOperatorToStatelessF╬╗ } from "./util/convertOperatorToStatelessFLambda.ts";import type { AsyncIterableEvt } from "./types/AsyncIterableEvt.ts";
const runSideEffect = (sideEffect: () => void) => sideEffect();
// NOTE: For compat with --no-check // https://github.com/asos-craigmorten/opine/issues/97#issuecomment-751806014const { CtxLike: CtxLikeAsValue } = nsCtxLike;
/** https://docs.evt.land/api/evt */export type Evt<T> = import("./types/interfaces/Evt.ts").Evt<T>;

class EvtImpl<T> implements Evt<T> {
static readonly create = create;
static readonly newCtx = newCtx;
static readonly merge = merge;
static readonly from = from;
static readonly getCtx = getCtxFactory();
static readonly loosenType = loosenType;
static readonly factorize = factorize;
static readonly asPostable = asPostable;
static readonly asyncPipe = asyncPipe;
static readonly asNonPostable = asNonPostable;
private static __defaultMaxHandlers = 25;
static setDefaultMaxHandlers(n: number): void { this.__defaultMaxHandlers = isFinite(n) ? n : 0; }
toStateful(p1: any, p2?: CtxLike): StatefulEvt<any> {
const isP1Ctx = CtxLikeAsValue.match(p1);
const initialValue: any = isP1Ctx ? undefined : p1; const ctx = p2 || (isP1Ctx ? p1 : undefined);
const out = new importProxy.StatefulEvt<any>(initialValue);
const callback = (data: T) => out.post(data);
if (!!ctx) { this.attach(ctx, callback); } else { this.attach(callback); }
return out;
}
get evtAttach(): Evt<Handler<T, any>> { return this.lazyEvtAttach.evt; }
get evtDetach(): Evt<Handler<T, any>> { return this.lazyEvtDetach.evt; }
private readonly lazyEvtAttach = new LazyEvt<Handler<T, any>>(); private readonly lazyEvtDetach = new LazyEvt<Handler<T, any>>();

private __maxHandlers: undefined | number = undefined;
setMaxHandlers(n: number): this { this.__maxHandlers = isFinite(n) ? n : 0; return this; }
readonly postCount: number = 0;
private traceId: string | null = null; private traceFormatter!: (data: T) => string; private log!: Exclude<Parameters<NonPostableEvt<any>["enableTrace"]>[0]["log"], false>;
enableTrace( params: { id: string, formatter?: (data: T) => string, log?: ((message?: any, ...optionalParams: any[]) => void) | false } //NOTE: Not typeof console.log as we don't want to expose types from node ): void {
const { id, formatter, log } = params;
this.traceId = id;
this.traceFormatter = formatter || ( data => { try { return JSON.stringify(data, null, 2); } catch { return `${data}`; } } );
this.log = log === undefined ? ((...inputs) => console.log(...inputs)) : log === false ? undefined : log ;
}
disableTrace(): this { this.traceId = null; return this; }
private readonly handlers: Handler<T, any>[] = [];
private readonly handlerTriggers: LightMap< Handler<T, any>, (opResult: readonly [any]) => PromiseLike<void> | undefined > = new Map();

//NOTE: An async handler ( attached with waitFor ) is only eligible to handle a post if the post //occurred after the handler was set. We don't want to waitFor event from the past. //private readonly asyncHandlerChronologyMark = new WeakMap<ImplicitParams.Async, number>(); private get asyncHandlerChronologyMark(): WeakMap< Handler.PropsFromMethodName.Async, number > { return ((this as any)["~internal"] ??= {})["asyncHandlerChronologyMark"] ??= new WeakMap<any, any>(); }
//NOTE: There is an exception to the above rule, we want to allow async waitFor loop //do so we have to handle the case where multiple event would be posted synchronously. private get asyncHandlerChronologyExceptionRange(): WeakMap< Handler.PropsFromMethodName.Async, { lowerMark: number; upperMark: number; } > { return ((this as any)["~internal"] ??= {})["asyncHandlerChronologyExceptionRange"] ??= new WeakMap<any, any>(); }

private get invocableOpByOp(): WeakMap< Operator<T, any>, Operator.f╬╗.Stateless<T, any> > { return ((this as any)["~internal"] ??= {})["invocableOpByOp"] ??= new WeakMap<any, any>(); }
getInvocableOp<U>(op: Operator<T, U>): Operator.f╬╗.Stateless<T, U> {
const invocableOp = this.invocableOpByOp.get(op);
if (invocableOp === undefined) { throw new Error([ "Provided operator isn't the operator of any handler", "currently attached to the Evt instance" ].join(" ")); }
return invocableOp;
}
/* NOTE: Used as Date.now() would be used to compare if an event is anterior or posterior to an other. We don't use Date.now() because two call within less than a ms will return the same value unlike this function. */ private __currentChronologyMark = 0; private getChronologyMark() { return this.__currentChronologyMark++; }

private asyncHandlerCount: number = 0;
private detachHandler( handler: Handler<T, any>, wTimer: [Timer | undefined], rejectPr: (error: DetachedEvtError) => void ) {
const index = this.handlers.indexOf(handler);
if (index < 0) { return false; }
if (typeGuard<Handler<T, any, CtxLike<any>>>(handler, !!handler.ctx)) { handler.ctx.zz__removeHandler(handler); }

this.handlers.splice(index, 1);
if (handler.async) { this.asyncHandlerCount--; }
this.handlerTriggers.delete(handler);
if (wTimer[0] !== undefined) {
safeClearTimeout(wTimer[0]);
rejectPr(new DetachedEvtError());
}
this.lazyEvtDetach.post(handler);
return true;
}

private triggerHandler<U>( handler: Handler<T, U>, wTimer: [Timer | undefined], resolvePr: ((transformedData: any) => void) | undefined, opResult: readonly [U] //TODO: Or readonly [ any ] ?? ): PromiseLike<void> | undefined {
const { callback, once } = handler;
if (wTimer[0] !== undefined) { safeClearTimeout(wTimer[0]); wTimer[0] = undefined; }
if (once) { handler.detach(); }
const [transformedData] = opResult;
const prOrValue = callback?.call( this, transformedData );
resolvePr?.(transformedData);
return isPromiseLike(prOrValue) ? prOrValue : undefined;
}
private addHandler<U>( propsFromArgs: Handler.PropsFromArgs<T, U>, propsFromMethodName: Handler.PropsFromMethodName ): Handler<T, U> {
this.invocableOpByOp.set( propsFromArgs.op, convertOperatorToStatelessF╬╗(propsFromArgs.op) );
const d = new Deferred<U>();
const wTimer: [Timer | undefined] = [undefined];
const handler: Handler<T, U> = { ...propsFromArgs, ...propsFromMethodName, "detach": () => this.detachHandler(handler, wTimer, d.reject), "promise": d.pr };
if (typeof handler.timeout === "number") {
wTimer[0] = safeSetTimeout(() => {
wTimer[0] = undefined;
handler.detach();
d.reject(new TimeoutEvtError(handler.timeout!));
}, handler.timeout);
}
const handlerTrigger: (opResult: readonly [U]) => PromiseLike<void> | undefined = opResult => this.triggerHandler( handler, wTimer, d.isPending ? d.resolve : undefined, opResult );
this.handlerTriggers.set( handler, handlerTrigger );
if (handler.async) {
this.asyncHandlerChronologyMark.set( handler, this.getChronologyMark() );
}
if (handler.prepend) {
let i: number;
for (i = 0; i < this.handlers.length; i++) {
if (this.handlers[i].extract) { continue; }
break;
}
this.handlers.splice(i, 0, handler);
} else {
this.handlers.push(handler);
}
if (handler.async) { this.asyncHandlerCount++; }
this.checkForPotentialMemoryLeak();
if (typeGuard<Handler<T, U, CtxLike<any>>>(handler, !!handler.ctx)) { handler.ctx.zz__addHandler(handler, this); }
onAddHandlerByEvt.get(this)?.(handler, handlerTrigger);
//NOTE: Can happen for example if this is a StatefulEvt //and the handler is "once" and the matcher match the state //We don't want to post an attach if the handler is already detached. if (this.handlerTriggers.has(handler)) {
this.lazyEvtAttach.post(handler);
}
return handler;
}


private checkForPotentialMemoryLeak(): void {
const maxHandlers = this.__maxHandlers !== undefined ? this.__maxHandlers : EvtImpl.__defaultMaxHandlers ;

if ( maxHandlers === 0 || this.handlers.length % (maxHandlers + 1) !== 0) { return; }
let message = [ `MaxHandlersExceededWarning: Possible Evt memory leak detected.`, `${this.handlers.length} handlers attached${this.traceId ? ` to "${this.traceId}"` : ""}.\n`, `Use Evt.prototype.setMaxHandlers(n) to increase limit on a specific Evt.\n`, `Use Evt.setDefaultMaxHandlers(n) to change the default limit currently set to ${EvtImpl.__defaultMaxHandlers}.\n`, ].join("");
const map = new Map<string, number>();
this.getHandlers() .map(({ ctx, async, once, prepend, extract, op, callback }) => ({ "hasCtx": !!ctx, once, prepend, extract, "isWaitFor": async, ...(op === matchAll ? {} : { "op": op.toString() }), ...(!callback ? {} : { "callback": callback.toString() }) })) .map(obj => "{\n" + Object.keys(obj) .map(key => ` ${key}: ${(obj as any)[key]}`) .join(",\n") + "\n}" ) .forEach(str => map.set(str, (map.has(str) ? map.get(str)! : 0) + 1)) ;
message += "\n" + Array.from(map.keys()) .map(str => `${map.get(str)} handler${map.get(str) === 1 ? "" : "s"} like:\n${str}`) .join("\n") + "\n";
if (this.traceId === null) {
message += "\n" + [ `To validate the identify of the Evt instance that is triggering this warning you can call`, `Evt.prototype.enableTrace({ "id": "My evt id", "log": false }) on the Evt that you suspect.\n` ].join(" ");
}
try { console.warn(message); } catch { }
}
isHandledByOp<U>(op: Operator<T, U>, data: T): boolean {
let hasSideEffect = false;
let invocableOp: Operator.f╬╗.Stateless<T, U>;
try {
invocableOp = this.getInvocableOp(op);
} catch {
return false;
}
const opResult = invocableOp( data, () => hasSideEffect = true );
return opResult !== null || hasSideEffect;
}

private trace(data: T) {
if (this.traceId === null) { return; }
let message = `(${this.traceId}) `;
const isExtracted = !!this.handlers.find( ({ extract, op }) => ( extract && this.isHandledByOp(op, data) ) );
if (isExtracted) {
message += "extracted ";
} else {
const handlerCount = this.handlers .filter( ({ extract, op }) => !extract && this.isHandledByOp(op, data) ) .length;
message += `${handlerCount} handler${(handlerCount > 1) ? "s" : ""}, `;
}
this.log?.(message + this.traceFormatter(data));
}
/** Return [ isExtracted, prAllHandlerCallbacksResolved ] */ private postSync(data: T): readonly [boolean, Promise<void>] {
const prAllHandlerCallbacksResolved: PromiseLike<void>[] = [];
const getReturnValue = (isExtracted: boolean) => [ isExtracted, Promise.all(prAllHandlerCallbacksResolved).then(() => { }) ] as const;

for (const handler of [...this.handlers]) {
const { async, op, extract } = handler;
if (async) { continue; }
//NOTE: If detached while executing the operator //we still want to trigger the handler. const handlerTrigger = this.handlerTriggers.get(handler);
const opResult = this.getInvocableOp(op)( data, runSideEffect );
if (opResult === null) { continue; }
//NOTE: Possible if detached while in the loop. if (!handlerTrigger) { continue; }
const prOrUndefined = handlerTrigger(opResult);
if (prOrUndefined !== undefined) { prAllHandlerCallbacksResolved.push(prOrUndefined); }
if (extract) { return getReturnValue(true); }
}
return getReturnValue(false);
}
private postAsyncFactory() { return runExclusive.buildMethodCb( (data: T, postChronologyMark: number, releaseLock?) => {
if (this.asyncHandlerCount === 0) { releaseLock(); return; }
const promises: Promise<void>[] = [];
let chronologyMarkStartResolveTick: number;
//NOTE: Must be before handlerTrigger call. Promise.resolve().then( () => chronologyMarkStartResolveTick = this.getChronologyMark() );

for (const handler of [...this.handlers]) {
if (!handler.async) { continue; }
const opResult = this.getInvocableOp(handler.op)( data, runSideEffect );
if (opResult === null) { continue; }
const handlerTrigger = this.handlerTriggers.get(handler);
if (!handlerTrigger) { continue; }
const shouldCallHandlerTrigger = (() => {
const handlerMark = this.asyncHandlerChronologyMark.get(handler)!;
if (postChronologyMark > handlerMark) { return true; }
const exceptionRange = this.asyncHandlerChronologyExceptionRange.get(handler);
return ( exceptionRange !== undefined && exceptionRange.lowerMark < postChronologyMark && postChronologyMark < exceptionRange.upperMark && handlerMark > exceptionRange.upperMark );
})();
if (!shouldCallHandlerTrigger) { continue; }
promises.push( new Promise<void>( resolve => handler.promise .then(() => resolve()) .catch(() => resolve()) ) );
handlerTrigger(opResult);

}
if (promises.length === 0) { releaseLock(); return; }
const handlersDump = [...this.handlers];
Promise.all(promises).then(() => {
for (const handler of this.handlers) {
if (!handler.async) { continue; }
if (handlersDump.indexOf(handler) >= 0) { continue; }
this.asyncHandlerChronologyExceptionRange.set( handler, { "lowerMark": postChronologyMark, "upperMark": chronologyMarkStartResolveTick } );
}
releaseLock();
});
} ); }
declare private postAsync: ( ( data: T, postChronologyMark: number ) => void ) | undefined;
private static readonly propsFormMethodNames: Record< "waitFor" | "attach" | "attachExtract" | "attachPrepend" | "attachOnce" | "attachOncePrepend" | "attachOnceExtract" , Handler.PropsFromMethodName > = { "waitFor": { "async": true, "extract": false, "once": true, "prepend": false }, "attach": { "async": false, "extract": false, "once": false, "prepend": false }, "attachExtract": { "async": false, "extract": true, "once": false, "prepend": true }, "attachPrepend": { "async": false, "extract": false, "once": false, "prepend": true }, "attachOnce": { "async": false, "extract": false, "once": true, "prepend": false }, "attachOncePrepend": { "async": false, "extract": false, "once": true, "prepend": true }, "attachOnceExtract": { "async": false, "extract": true, "once": true, "prepend": true } };
isHandled(data: T): boolean { return !!this.getHandlers() .find(({ op }) => this.isHandledByOp(op, data)) ; }
getHandlers(): Handler<T, any>[] { return [...this.handlers]; }
detach(ctx?: CtxLike<any>): Handler<T, any, any>[] {
const detachedHandlers: Handler<T, any>[] = [];
for (const handler of this.getHandlers()) {
if (ctx !== undefined && handler.ctx !== ctx) { continue; }
const wasStillAttached = handler.detach();
//NOTE: It should not be possible. if (!wasStillAttached) { continue; }
detachedHandlers.push(handler);
}
return detachedHandlers;
}
pipe(...args: any[]): Evt<any> {
const evtDelegate = new EvtImpl<any>();
this.addHandler( { ...parsePropsFromArgs<T>(args, "pipe"), "callback": (transformedData: any) => evtDelegate.post(transformedData) }, EvtImpl.propsFormMethodNames.attach );
return evtDelegate;
}
waitFor(...args: any[]): Promise<any> { return this.addHandler( parsePropsFromArgs<T>(args, "waitFor"), EvtImpl.propsFormMethodNames.waitFor ).promise; }
[Symbol.asyncIterator]() { return this.iter()[Symbol.asyncIterator](); }
iter(...args: any[]): AsyncIterableEvt<any, any> {
const props = parsePropsFromArgs<T>(args, "waitFor");
const ctx = (props.ctx ?? newCtx()) as ReturnType<typeof newCtx>;
const self = this;
return { ctx, [Symbol.asyncIterator]() {
const previousDonePostCount = ctx.evtDoneOrAborted.postCount;
const timerWrap = (() => {
const { timeout } = props;
if (timeout === undefined) { return undefined; }
const setTimeoutCallback = () => { const error = new TimeoutEvtError(timeout); ctx.abort(error); };
const timer = setTimeout(setTimeoutCallback, timeout);
return { timeout, setTimeoutCallback, timer };
})();
const evtProxy = self .pipe(ctx, props.op) .pipe((data, registerSideEffect) => {
if (timerWrap !== undefined) {
registerSideEffect(() => {
clearTimeout(timerWrap.timer);
timerWrap.timer = setTimeout(timerWrap.setTimeoutCallback, timerWrap.timeout); });
}
return [data]; });
const events: [T][] = [];
evtProxy.attach(event => events.push([event]));
if (timerWrap !== undefined) {
const { timer } = timerWrap;
ctx.evtDoneOrAborted.attachOnce( event => event.type === "DONE", () => clearTimeout(timer) );
}
return { async next() {
let eventWrap = events.shift();
if (eventWrap === undefined) {
const dEventWrap = new Deferred<[T] | undefined>();
if (previousDonePostCount < ctx.evtDoneOrAborted.postCount) { return { "done": true }; }
const ctx2 = newCtx();
ctx.evtDoneOrAborted.attachOnce( ctx2, () => dEventWrap.resolve(undefined) );
evtProxy.attachOnceExtract(ctx2, event => { ctx2.done(); dEventWrap.resolve([event]) });
eventWrap = await dEventWrap.pr;
if (eventWrap === undefined) { return { "done": true }; }
}
const out = { "done": false, "value": eventWrap[0] } as any;
return out;
}, return() {
self.detach(ctx);
return { "done": true } as any; }, }; }
};

}



$attach(...args: any[]) { return this.attach(...args); }
attach(...args: any[]) { return this.__attachX(args, "attach"); }
$attachOnce(...args: any[]) { return this.attachOnce(...args); }
attachOnce(...args: any[]) { return this.__attachX(args, "attachOnce"); }
$attachExtract(...args: any[]) { return this.attachExtract(...args); }
attachExtract(...args: any[]) { return this.__attachX(args, "attachExtract"); }
$attachPrepend(...args: any[]) { return (this.attachPrepend as any)(...args); }
attachPrepend(...args: any[]) { return this.__attachX(args, "attachPrepend"); }
$attachOncePrepend(...args: any[]) { return this.attachOncePrepend(...args); }
attachOncePrepend(...args: any[]) { return this.__attachX(args, "attachOncePrepend"); }
$attachOnceExtract(...args: any[]) { return this.attachOnceExtract(...args); }
attachOnceExtract(...args: any[]) { return this.__attachX(args, "attachOnceExtract"); }
private __attachX( args: any[], methodName: keyof typeof EvtImpl.propsFormMethodNames ): any {
const propsFromArgs = parsePropsFromArgs<T>(args, "attach*");
const handler = this.addHandler( propsFromArgs, EvtImpl.propsFormMethodNames[methodName] );
return propsFromArgs.timeout === undefined ? this : handler.promise ;
}
postAsyncOnceHandled(data: T): number | Promise<number> {
if (this.isHandled(data)) { return this.post(data); }
const d = new Deferred<number>();
this.evtAttach.attachOnce( ({ op }) => this.isHandledByOp(op, data), () => Promise.resolve().then(() => d.resolve(this.post(data))) );
return d.pr;
}
private postOrPostAndWait(data: T, wait: false): number; private postOrPostAndWait(data: T, wait: true): Promise<void>; private postOrPostAndWait(data: T, wait: boolean): number | Promise<void> {
this.trace(data);
overwriteReadonlyProp(this, "postCount", this.postCount + 1);
//NOTE: Must be before postSync. const postChronologyMark = this.getChronologyMark();
const [isExtracted, prAllHandlerCallbacksResolved] = this.postSync(data);
const getReturnValue = wait ? () => prAllHandlerCallbacksResolved : () => this.postCount;
if (isExtracted) { return getReturnValue(); }
if (this.postAsync === undefined) {
if (this.asyncHandlerCount === 0) { return getReturnValue(); }
this.postAsync = this.postAsyncFactory();
}
this.postAsync(data, postChronologyMark);
return getReturnValue();
}
post(data: T) { return this.postOrPostAndWait(data, false); }
postAndWait(data: T) { return this.postOrPostAndWait(data, true); }
}
/** * Can be seen as a protected method that can be * optionally be implemented by class extending Evt. * * Should only be accessible from within the module. * Basically it is for allowing StatefulEvt to execute * the callback on attach. */export const onAddHandlerByEvt = new WeakMap< NonPostableEvtLike<any>, ( handler: Handler<any, any>, handlerTrigger: (opResult: readonly [any]) => PromiseLike<void> | undefined ) => void>();

export const Evt: { new <T>(): Evt<T>; readonly prototype: Evt<any>;
readonly create: typeof create;
readonly newCtx: typeof newCtx;
readonly merge: typeof merge;
readonly from: typeof from;
readonly getCtx: ReturnType<typeof getCtxFactory>;
readonly loosenType: typeof loosenType;
readonly factorize: typeof factorize;
readonly asPostable: typeof asPostable;
readonly asyncPipe: typeof asyncPipe;
readonly asNonPostable: typeof asNonPostable;
/** https://docs.evt.land/api/evt/setdefaultmaxhandlers */ setDefaultMaxHandlers(n: number): void;
} = EvtImpl;
try { overwriteReadonlyProp(Evt as any, "name", "Evt"); } catch { }
importProxy.Evt = Evt;