@johngw/stream
Version:
Reactive programming tools using the WHATWG Streams API.
56 lines • 1.69 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.ForkableReplaySink = void 0;
const ForkableSink_1 = require("@johngw/stream/sinks/ForkableSink");
/**
* An extension to the {@link ForkableSink:class} that immediately
* queues the entire contents of whatever has been previously consumed.
*
* @group Sinks
* @see {@link ForkableReplayStream:class}
* @example
* ```
* const forkable = new ForkableReplayStream<number>()
* const writable = new WritableStream(forkable)
* await fromCollection([1, 2, 3, 4, 5, 6, 7]).pipeTo(writable)
* ```
*
* Now the stream has finished, if we fork from it we'll
* receive the entire events that were published to it.
*
* ```
* await forkable.fork().pipeTo(write(console.info))
* // 1
* // 2
* // 3
* // 4
* // 5
* // 6
* // 7
* ```
*/
class ForkableReplaySink extends ForkableSink_1.ForkableSink {
#chunks = [];
#maxReplaySize = Number.MAX_SAFE_INTEGER;
constructor(maxReplaySize = Number.MAX_SAFE_INTEGER) {
super();
this.#maxReplaySize = maxReplaySize;
}
write(chunk) {
if (this.#chunks.length === this.#maxReplaySize)
this.#chunks.shift();
this.#chunks.push(chunk);
return super.write(chunk);
}
_addController(underlyingSource, queuingStrategy) {
const [controller, stream] = super._addController(underlyingSource, queuingStrategy);
for (const chunk of this.#chunks)
controller.enqueue(chunk);
return [controller, stream];
}
clear() {
this.#chunks = [];
}
}
exports.ForkableReplaySink = ForkableReplaySink;
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