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refine usage of undefined
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@brainkim
brainkim committed Oct 13, 2019
1 parent 6c91902 commit 073b3ed
Showing 1 changed file with 38 additions and 38 deletions.
76 changes: 38 additions & 38 deletions packages/repeater/src/repeater.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -32,8 +32,7 @@ export type Push<T, TNext = any> = (
value: PromiseLike<T> | T,
) => Promise<TNext | undefined>;

export type Stop<TReturn = any> = Promise<TReturn | undefined> &
((error?: any) => void);
export type Stop<TReturn = any> = Promise<TReturn> & ((error?: any) => void);

export type RepeaterExecutor<T, TReturn = any, TNext = any> = (
push: Push<T, TNext>,
Expand Down Expand Up @@ -70,13 +69,12 @@ class RepeaterController<T, TReturn = any, TNext = any>
private pushQueue: PushOperation<T, TNext>[] = [];
private pullQueue: PullOperation<T, TReturn, TNext>[] = [];
private onnext?: (value?: PromiseLike<TNext> | TNext) => void;
// TODO: maybe rename to onreturn
private onstop?: (value?: PromiseLike<TReturn> | TReturn) => void;
private execution?: Promise<TReturn>;
private error?: any;
// pending is continuously reassigned as the repeater is iterated. We use
// this mechanism to make sure all iterations settle in order.
private pending?: Promise<IteratorResult<T, TReturn>>;
private execution?: Promise<TReturn>;
private error?: any;

constructor(
private executor: RepeaterExecutor<T, TReturn, TNext>,
Expand All @@ -94,20 +92,20 @@ class RepeaterController<T, TReturn = any, TNext = any>
}

this.state = RepeaterState.Started;
const push: Push<T> = this.push.bind(this);
const stop: Stop = this.stop.bind(this) as Stop<TReturn>;
const push: Push<T, TNext> = this.push.bind(this);
const stop: Stop<TReturn> = this.stop.bind(this) as Stop<TReturn>;
const stopP = new Promise<TReturn>((onstop) => (this.onstop = onstop));
stop.then = stopP.then.bind(stopP);
stop.catch = stopP.catch.bind(stopP);
stop.finally = stopP.finally.bind(stopP);
// Errors which occur in the executor take precedence over those passed to
// this.stop, so calling this.stop with the caught error would be redundant.
try {
this.execution = Promise.resolve(this.executor(push, stop));
} catch (err) {
this.execution = Promise.reject(err);
}

// Errors which occur in the executor take precedence over those passed to
// this.stop, so calling this.stop with the caught error would be redundant.
this.execution.catch(() => this.stop());
}

Expand All @@ -116,14 +114,16 @@ class RepeaterController<T, TReturn = any, TNext = any>
* Rejections which settle after stop are ignored. This behavior is useful
* when you have yielded a pending promise but want to finish instead.
*/
private async reject(err: any): Promise<IteratorResult<T, TReturn>> {
private reject(err: any): Promise<IteratorResult<T, TReturn>> {
if (this.state >= RepeaterState.Stopped) {
const value = await this.execution!;
return { value, done: true };
return Promise.resolve(this.execution!).then((value) => ({
value,
done: true,
}));
}

this.finish().catch(() => {});
throw err;
return Promise.reject(err);
}

/**
Expand All @@ -134,7 +134,7 @@ class RepeaterController<T, TReturn = any, TNext = any>
private unwrap(
value: PromiseLike<T> | T,
): Promise<IteratorResult<T, TReturn>> {
if (this.pending == null) {
if (this.pending === undefined) {
this.pending = Promise.resolve(value).then(
(value) => {
return { value, done: false };
Expand Down Expand Up @@ -174,6 +174,8 @@ class RepeaterController<T, TReturn = any, TNext = any>
private finish(): Promise<IteratorResult<T, TReturn>> {
const execution = Promise.resolve(this.execution!);
const error = this.error;
delete this.execution;
delete this.error;
if (this.state < RepeaterState.Finished) {
if (this.state < RepeaterState.Stopped) {
this.stop();
Expand All @@ -182,13 +184,11 @@ class RepeaterController<T, TReturn = any, TNext = any>
this.state = RepeaterState.Finished;
this.pushQueue = [];
this.buffer = new FixedBuffer(0);
delete this.error;
delete this.execution;
}

if (this.pending == null) {
if (this.pending === undefined) {
this.pending = execution.then((value) => {
if (error == null) {
if (error === undefined) {
return { value, done: true };
}

Expand All @@ -202,7 +202,7 @@ class RepeaterController<T, TReturn = any, TNext = any>
}

return execution.then((value) => {
if (error == null) {
if (error === undefined) {
return { value, done: true };
}

Expand All @@ -219,10 +219,10 @@ class RepeaterController<T, TReturn = any, TNext = any>
/**
* This method is bound and passed to the executor as `push`.
*/
private push(value: PromiseLike<T> | T): Promise<TNext | void> {
private push(value: PromiseLike<T> | T): Promise<TNext | undefined> {
Promise.resolve(value).catch(() => {});
if (this.state >= RepeaterState.Stopped) {
return Promise.resolve();
return Promise.resolve(undefined);
} else if (this.pullQueue.length) {
const pull = this.pullQueue.shift()!;
pull.resolve(this.unwrap(value));
Expand All @@ -233,7 +233,7 @@ class RepeaterController<T, TReturn = any, TNext = any>
return new Promise((resolve) => (this.onnext = resolve));
} else if (!this.buffer.full) {
this.buffer.add(value);
return Promise.resolve();
return Promise.resolve(undefined);
} else if (this.pushQueue.length >= MAX_QUEUE_LENGTH) {
throw new RepeaterOverflowError(
`No more than ${MAX_QUEUE_LENGTH} pending calls to push are allowed on a single repeater.`,
Expand Down Expand Up @@ -319,7 +319,7 @@ class RepeaterController<T, TReturn = any, TNext = any>
value?: PromiseLike<TReturn> | TReturn,
): Promise<IteratorResult<T, TReturn>> {
if (this.state >= RepeaterState.Finished) {
if (this.pending == null) {
if (this.pending === undefined) {
this.pending = Promise.resolve(value).then((value) => ({
value: value!,
done: true,
Expand All @@ -331,17 +331,18 @@ class RepeaterController<T, TReturn = any, TNext = any>
}

return this.pending;
} else if (this.onstop != null) {
}

if (this.onstop !== undefined) {
this.onstop(value);
}

this.stop();
return this.finish();
}

throw(error: any): Promise<IteratorResult<T, TReturn>> {
if (this.state >= RepeaterState.Finished) {
if (this.pending == null) {
if (this.pending === undefined) {
this.pending = Promise.reject(error);
} else {
this.pending = this.pending.then(
Expand Down Expand Up @@ -383,7 +384,7 @@ export class Repeater<T, TReturn = any, TNext = any> {

next(value?: PromiseLike<TNext> | TNext): Promise<IteratorResult<T>> {
const controller = controllers.get(this);
if (controller == null) {
if (controller === undefined) {
throw new Error("RepeaterController missing from controllers WeakMap");
}

Expand All @@ -392,7 +393,7 @@ export class Repeater<T, TReturn = any, TNext = any> {

return(value?: PromiseLike<TReturn> | TReturn): Promise<IteratorResult<T>> {
const controller = controllers.get(this);
if (controller == null) {
if (controller === undefined) {
throw new Error("RepeaterController missing from controllers WeakMap");
}

Expand All @@ -401,7 +402,7 @@ export class Repeater<T, TReturn = any, TNext = any> {

throw(error?: any): Promise<IteratorResult<T>> {
const controller = controllers.get(this);
if (controller == null) {
if (controller === undefined) {
throw new Error("RepeaterController missing from controllers WeakMap");
}

Expand All @@ -419,7 +420,7 @@ export class Repeater<T, TReturn = any, TNext = any> {
}

// TODO: parameterize TReturn
type Contender<T> = AsyncIterable<T> | Iterable<T> | PromiseLike<any> | any;
type Contender<T> = AsyncIterable<T> | Iterable<T> | PromiseLike<any>;

function iterators<T>(
contenders: Iterable<Contender<T>>,
Expand All @@ -432,7 +433,6 @@ function iterators<T>(
iters.push((contender as Iterable<T>)[Symbol.iterator]());
} else {
iters.push(
// eslint-disable-next-line @typescript-eslint/no-use-before-define
new Repeater((_, stop) => (stop(), contender)),
);
}
Expand Down Expand Up @@ -489,7 +489,7 @@ function race<T>(contenders: Iterable<Contender<T>>): Repeater<T> {
for (const result1 of results) {
Promise.resolve(result1)
.then((result1) => {
if (result1.done && result == null) {
if (result === undefined && result1.done) {
stop();
result = result1;
}
Expand All @@ -499,7 +499,7 @@ function race<T>(contenders: Iterable<Contender<T>>): Repeater<T> {

results.unshift(finish);
const result1 = await Promise.race(results);
if (result1.done && result == null) {
if (result === undefined && result1.done) {
result = result1;
break;
}
Expand Down Expand Up @@ -541,7 +541,7 @@ function merge<T1, T2, T3, T4, T5, T6, T7, T8, T9>(contenders: [Contender<T1>, C
function merge<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(contenders: [Contender<T1>, Contender<T2>, Contender<T3>, Contender<T4>, Contender<T5>, Contender<T6>, Contender<T7>, Contender<T8>, Contender<T9>, Contender<T10>]): Repeater<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10>;
function merge<T>(contenders: Iterable<Contender<T>>): Repeater<T> {
// need to pass type parameter here for some reason
const iters = iterators<T>(contenders);
const iters = iterators(contenders);
return new Repeater<T>(async (push, stop) => {
if (!iters.length) {
stop();
Expand Down Expand Up @@ -574,7 +574,7 @@ function merge<T>(contenders: Iterable<Contender<T>>): Repeater<T> {
} catch (err) {
stop(err);
} finally {
if (iter.return != null) {
if (iter.return) {
await iter.return(returned);
}
}
Expand Down Expand Up @@ -626,7 +626,7 @@ function zip<T>(contenders: Iterable<Contender<T>>): Repeater<T[]> {
if (stopped) {
return Promise.all(
iters.map(async (iter) => {
if (iter.return == null) {
if (iter.return === undefined) {
return returned;
}
return (await iter.return(returned)).value;
Expand Down Expand Up @@ -695,7 +695,7 @@ function latest<T>(contenders: Iterable<Contender<T>>): Repeater<T[]> {
if (stopped) {
return Promise.all(
iters.map(async (iter) => {
if (iter.return == null) {
if (iter.return === undefined) {
return returned;
}
return (await iter.return(returned)).value;
Expand Down Expand Up @@ -728,7 +728,7 @@ function latest<T>(contenders: Iterable<Contender<T>>): Repeater<T[]> {
} catch (err) {
stop(err);
} finally {
if (iter.return != null) {
if (iter.return) {
await iter.return(returned);
}
}
Expand Down

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