Function pullWithBYOBReader

examples/io/streams/modules/streams.js:1177–1252

(view, forBranch2)

		ReadableStreamDefaultReaderRead(reader, readRequest);
	}
	function pullWithBYOBReader(view, forBranch2) {
		if (ReadableStreamDefaultReaderBrand.has(reader.self)) {
			assert(reader.readRequests.length === 0);
			ReadableStreamDefaultReaderRelease(reader);
			reader = AcquireReadableStreamBYOBReader(stream);
			forwardReaderError(reader);
		}
		const byobBranch = forBranch2 ? branch2 : branch1;
		const otherBranch = forBranch2 ? branch1 : branch2;
		const readIntoRequest = {
			chunkSteps: chunk => {
				// This needs to be delayed a microtask because it takes at least a microtask to detect errors (using
				// reader.closedPromise below), and we want errors in stream to error both branches immediately. We cannot let
				// successful synchronously-available reads get ahead of asynchronously-available errors.
				queueMicrotask(() => {
					readAgainForBranch1 = false;
					readAgainForBranch2 = false;
					const byobCanceled = forBranch2 ? canceled2 : canceled1;
					const otherCanceled = forBranch2 ? canceled1 : canceled2;
					if (otherCanceled === false) {
						let clonedChunk;
						try {
							clonedChunk = CloneAsUint8Array(chunk);
						} 
						catch (e) {
							ReadableByteStreamControllerError(byobBranch.controller, e);
							ReadableByteStreamControllerError(otherBranch.controller, e);
							cancelPromise.resolvePromise(ReadableStreamCancel(stream, e));
							return;
						}
						if (byobCanceled === false) {
							ReadableByteStreamControllerRespondWithNewView(byobBranch.controller, chunk);
						}
						ReadableByteStreamControllerEnqueue(otherBranch.controller, clonedChunk);
					}
					else if (byobCanceled === false) {
						ReadableByteStreamControllerRespondWithNewView(byobBranch.controller, chunk);
					}
					reading = false;
					if (readAgainForBranch1 === true) {
						pull1Algorithm();
					}
					else if (readAgainForBranch2 === true) {
						pull2Algorithm();
					}
				});
			},
			closeSteps: chunk => {
				reading = false;
				const byobCanceled = forBranch2 ? canceled2 : canceled1;
				const otherCanceled = forBranch2 ? canceled1 : canceled2;
				if (byobCanceled === false) {
					ReadableByteStreamControllerClose(byobBranch.controller);
				}
				if (otherCanceled === false) {
					ReadableByteStreamControllerClose(otherBranch.controller);
				}
				if (chunk !== undefined) {