queueable/dist/adapters/Channel.d.ts

Convert push-based streams to pull-based async iterables

/// <reference types="node" />
import Deferred from '../Deferred';
import Buffer from '../Buffer';
import { PushAdapter } from '../common';
/**
 * Async iterable iterator with a non-optional return method.
 */
export interface WrappedBalancer<A> extends AsyncIterableIterator<A> {
    return(value?: A): Promise<IteratorResult<A>>;
    throw?: undefined;
}
export interface Unpushed<A> {
    result: IteratorResult<A>;
    defer: Deferred<IteratorResult<A>>;
}
/**
 * Balances a push queue with a pull queue, also known as a
 * dropping-buffer channel, since the queues are FIFO and
 * can be set to be bounded, i.e., to drop the oldest enqueued
 * values if the limit is exceeded. The channel is unbounded
 * by default.
 */
export default class Channel<A> implements PushAdapter<A> {
    /** Pushed results waiting for pulls to resolve */
    readonly pushBuffer: Buffer<Unpushed<A>>;
    /** Unresolved pulls waiting for results to be pushed */
    readonly pullBuffer: Buffer<Deferred<IteratorResult<A>>>;
    /** Determines whether new values can be pushed or pulled */
    private closed;
    static fromDom: (type: keyof GlobalEventHandlersEventMap, target: import("../fromDom").Target<keyof GlobalEventHandlersEventMap, import("../fromDom").Listener<keyof GlobalEventHandlersEventMap>, boolean | AddEventListenerOptions>, options?: boolean | AddEventListenerOptions | undefined) => AsyncIterableIterator<UIEvent | Event | AnimationEvent | MouseEvent | InputEvent | FocusEvent | CompositionEvent | DragEvent | ErrorEvent | FormDataEvent | PointerEvent | KeyboardEvent | ProgressEvent<EventTarget> | SecurityPolicyViolationEvent | SubmitEvent | TouchEvent | TransitionEvent | WheelEvent>;
    static fromEmitter: (type: string | symbol, emitter: NodeJS.EventEmitter) => AsyncIterableIterator<any>;
    constructor(
    /** Limit (bounds) after which the oldest buffered value is dropped. */
    limit?: number);
    /**
     * Pull a promise of the next result.
     */
    next(): Promise<IteratorResult<A>>;
    /**
     * Push the next result value.
     *
     * @param value - Result
     * @param done - If true, closes the balancer when this result is resolved
     * @throws Throws if the balancer is already closed
     */
    push(value: A, done?: boolean): Promise<IteratorResult<A>>;
    /**
     * Returns itself, since {@link Channel} already implements the iterator protocol.
     */
    [Symbol.asyncIterator](): this;
    /**
     * Closes the balancer; clears the queues and makes {@link Channel#next} only
     * return `doneResult`.
     *
     * @param value - The result value to be returned
     */
    return(value?: A): Promise<IteratorResult<A>>;
    close(): void;
    /**
     * Convert {@link Channel} to a generic async iterable iterator to hide implementation details.
     *
     * @param onReturn - Optional callback for when the iterator is closed with {@link Channel#return}
     * @throws Throws if called when closed
     */
    wrap(onReturn?: () => void): WrappedBalancer<A>;
}