@johngw/stream/dist/sources/CachableSource.d.ts

Reactive programming tools using the WHATWG Streams API.

import { StorageCache } from '../storages/StorageCache.js';
import type { Clearable } from '../types/Clearable.js';
import type { UnderlyingDefaultSource } from 'node:stream/web';
/**
 * Describes a function to pull data.
 *
 * @group Sources
 */
export interface CachePuller<T> {
    (): CachePullerResult<T> | Promise<CachePullerResult<T>>;
}
/**
 * The result of a CachableStream pull.
 *
 * @group Sources
 */
export type CachePullerResult<T> = IteratorResult<T>;
/**
 * The source of a `ReadableStream` that queues items
 * only when a timed cache becomes invalid.
 *
 * @group Sources
 * @see {@link StorageCache}
 * @see {@link CachableStream:class}
 * @example
 * Caching for 30 minutes.
 *
 * ```
 * const cache = new StorageCache(
 *   localStorage,
 *   'my-cache',
 *   30 * 60_000
 * )
 *
 * let i = 0
 * const stream = new ReadableStream(
 *   new CachableSource<number>(
 *     cache,
 *     ['numbers'],
 *     () => ++i
 *   )
 * )
 *
 * stream.pipeTo(write(console.info))
 * // 1
 *
 * await setTimeout(30 * 60_000))
 * // 2
 * ```
 * @example
 * Manually clearing cache.
 *
 * ```
 * const cache = new StorageCache(
 *   localStorage,
 *   'my-cache',
 *   30 * 60_000
 * )
 *
 * let i = 0
 * const source = new CachableSource<number>(
 *   cache,
 *   ['numbers'],
 *   () => ++i
 * )
 *
 * const stream = new ReadableStream(source)
 *
 * stream.pipeTo(write(console.info))
 * // 1
 *
 * source.clear()
 * // 2
 * ```
 */
export declare class CachableSource<T> implements UnderlyingDefaultSource<T>, Clearable {
    #private;
    constructor(cache: StorageCache, path: string[], pullResult: CachePuller<T>, ms?: number);
    pull(controller: ReadableStreamDefaultController<T>): Promise<void>;
    cancel(reason: unknown): void;
    clear(): void;
    get sourceHasFinished(): boolean;
}
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