delicate rain
So I have a small project where I want to use streams. But now I need two different transform streams on the same input
const file = await Deno.open(path);
const processingStream1 = file.pipeThrough(transform1);
for await (const line of processingStream1) console.log(line);
const processingStream2 = file.pipeThrough(transform2);
for await (const line of processingStream2) console.log(line);
What I want to try and do is let processingStream2 continue from where processStream1 left off
tranquil mica
a transform can only stop in the middle if it throws an error, otherwise it will consume all of its input
delicate rain
Even if .cancel() is used on the controller?
delicate rain
Cuz right now that is done, but the readable stream that feeds into the transformstream is still locked
Which means that I cannot reuse it :/
tranquil mica
I don't think you can do that. But I don't think that's a bad thing.
tranquil mica
To explain why, consider this implementation of TextLineStream:
new TransformStream({
lineSoFar: "",
transform(chunk, controller) {
chunk = this.lineSoFar + chunk;
const lines = chunk.split("\n");
this.lineSoFar = lines.pop();
for (const line of lines) {
controller.enqueue(line + "\n");
}
},
flush(controller) {
if (this.lineSoFar !== "") {
controller.enqueue(this.lineSoFar);
}
}
});
there's data coming from previous chunks that hasn't been enqueued yet
so if you could get back to the original stream, you'd lose that data
delicate rain
Hmmm. I guess I'll just use a reader and loop with that
It's just so annoying that a stream can't be reused or cloned from a certaint part
I guess I'll figure out another solution...
Cuz 1.5m nop fn calls are quite expensive...
Well thanks for the insight and help @tranquil mica. I'm going to bed thinking of how to do this