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ReadableStream.prototype.text(), .blob(), and .bytes() #1311

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120 changes: 120 additions & 0 deletions index.bs
Original file line number Diff line number Diff line change
Expand Up @@ -508,6 +508,10 @@ interface ReadableStream {
Promise<undefined> pipeTo(WritableStream destination, optional StreamPipeOptions options = {});
sequence<ReadableStream> tee();

Promise<USVString> text(optional ConsumeBytesOptions options = {});
Promise<Uint8Array> bytes(optional ConsumeBytesOptions options = {});
Promise<Blob> blob(optional ConsumeBytesOptions options = {});

async iterable<any>(optional ReadableStreamIteratorOptions options = {});
};

Expand All @@ -534,6 +538,11 @@ dictionary StreamPipeOptions {
boolean preventCancel = false;
AbortSignal signal;
};

dictionary ConsumeBytesOptions {
AbortSignal signal;
USVString type = "";
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  1. This type is not super clear about what type it means, maybe blobType? Especially if we want to put more stream related options, because we already have type in UnderlyingSource.
  2. Blob uses DOMString instead of USVString: https://w3c.github.io/FileAPI/#ref-for-dfn-BPtype
  3. Should we have a separate dictionary without type for other non-blob methods?

};
</xmp>

<h4 id="rs-internal-slots">Internal slots</h4>
Expand Down Expand Up @@ -1014,6 +1023,24 @@ option. If {{UnderlyingSource/type}} is set to undefined (including via omission
</div>
</div>

<div algorithm>
The <dfn id="rs-text" method for="ReadableStream">text(options)</div> method steps are:

1. Return ? [$ReadableStreamConsumeAsText$]([=this=], |options|).
</div>

<div algorithm>
The <dfn id="rs-bytes" method for="ReadableStream">bytes(options)</div> method steps are:

1. Return ? [$ReadableStreamConsumeAsBytes$]([=this=], |options|).
</div>

<div algorithm>
The <dfn id="rs-blob" method for="ReadableStream">blob(options)</div> method steps are:

1. Return ? [$ReadableStreamConsumeAsBlob$]([=this=], |options|).
</div>

<h4 id="rs-asynciterator" oldids="rs-asynciterator-prototype,
default-reader-asynciterator-prototype-internal-slots">Asynchronous iteration</h4>

Expand Down Expand Up @@ -2661,6 +2688,99 @@ create them does not matter.
1. Return « |branch1|, |branch2| ».
</div>

<div algorithm>
To <dfn lt="fully read">fully read</dfn> a {{ReadableStream}} |stream|, given an algorithm |processBody|, and an algorithm |processBodyError|, run these steps. |processBody| must be an algorithm accepting a [=byte sequence=]. |processBodyError| must be an algorithm optionally accepting an exception.
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Do we need this lt? Same for other <dfn>s.


1. Let |successSteps| given a [=byte sequence=] |bytes| be to run |processBody| given |bytes|.
1. Let |errorSteps| optionally given an exception |exception| be to run |processBodyError| given |exception|.
1. Let |reader| be the result of getting a reader for |stream|. If that threw an exception, then run |errorSteps| with that exception and return.
1. [=read all bytes|Read all bytes=] from |reader|, given |successSteps| and |errorSteps|.
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I think Bikeshed can compensate for different capitalisation automatically.

</div>

<div algorithm>
The <dfn lt="consume fully with abort">consume fully with abort</dfn> algorithm, given a {{ReadableStream}} |stream|, an optional {{AbortSignal}} |signal|, and an algorithm that takes a [=byte sequence=] and returns a JavaScript or throws an exception |convertBytesToJSValue|, runs these steps:
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"consume fully" or "fully consume"? We already have "fully read", so maybe consistency?

And also "an algorithm |convertBytesToJSValue| that ..."


1. Let |promise| be [=a new promise=].
1. Let |errorSteps| given |error| to be [=reject=] |promise| with |error|.
1. Let |successSteps| given a [=byte sequence=] |data| be to [=resolve=] |promise| with the result of running |convertBytesToJSValue| with |data|. If that threw an exception, then run |errorSteps| with that exception.
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Perhaps you want to name them as processBody and processBodyError as that's what the parameters of "fully read" are? Or maybe "fully read" parameters should be success/errorSteps instead.

1. If |signal| is not undefined,
1. Let |abortAlgorithm| be the following steps:
1. Let |error| be |signal|'s [=AbortSignal/abort reason=].
1. Run |errorSteps| with |error|.
1. Let |actions| be an empty [=ordered set=].
1. If |stream|.[=ReadableStream/[[state]]=] is "`readable`", [=set/append=] the following action action to |actions|:
1. return ! [$ReadableStreamCancel$](|stream|, |error|).
1. Otherwise, return [=a promise resolved with=] undefined.
1. [=Shutdown with an action=] consisting of [=getting a promise to wait for all=] of the actions
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This is pipeTo specific, maybe we can simply call ReadableStreamCancel?

in |actions|, and with |error|.
1. If |signal| is [=AbortSignal/aborted=], perform the following steps:
1. perform |abortAlgorithm|.
1. return |promise|.
1. [=AbortSignal/Add=] |abortAlgorithm| to |signal|.
1. [=fully read=] |stream| given |successSteps|, |errorSteps|, and |stream|’s relevant global object.
1. Return promise.
</div>

<div algorithm>
<dfn abstract-op lt="ReadableStreamConsumeAsText" id="ReadableStreamConsumeAsText">ReadableStreamConsumeAsText(|stream|, |options|})</dfn> will
consume all bytes produced by a given readable stream and return a promise that resolves with a string containing the UTF-8-decoded text.

It performs the following steps:

1. Assert: |stream| [=implements=] {{ReadableStream}}.
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Maybe we could have a PrepareToConsume abstract op to encapsulate these common steps?

1. If ! [$IsReadableStreamLocked$]([=stream=]) is true, return [=a promise rejected with=] a
{{TypeError}} exception.
1. If ! |stream|.[=ReadableStream/[[disturbed]]=] is true, return [=a promise rejected with=] a
{{TypeError}} exception.
1. Let |signal| be |options|["{{ConsumeBytesOptions/signal}}"] if it [=map/exists=], or undefined
otherwise.
1. Assert: either |signal| is undefined, or |signal| [=implements=] {{AbortSignal}}.
1. Return the result of running [=consume fully with abort=] with |stream|, |signal|, and <a>UTF-8 decode</a>.
</div>

<div algorithm>
<dfn abstract-op lt="ReadableStreamConsumeAsBytes" id="ReadableStreamConsumeAsBytes">ReadableStreamConsumeAsBytes(|stream|, |options|})</dfn> will
consume all bytes produced by a given readable stream and return a promise that resolves with a single Uint8Array containing the read bytes.

It performs the following steps:

1. Assert: |stream| [=implements=] {{ReadableStream}}.
1. If ! [$IsReadableStreamLocked$]([=stream=]) is true, return [=a promise rejected with=] a
{{TypeError}} exception.
1. If ! |stream|.[=ReadableStream/[[disturbed]]=] is true, return [=a promise rejected with=] a
{{TypeError}} exception.
1. Let |signal| be |options|["{{ConsumeBytesOptions/signal}}"] if it [=map/exists=], or undefined
otherwise.
1. Assert: either |signal| is undefined, or |signal| [=implements=] {{AbortSignal}}.
1. Let |decode as Uint8Array| be an algorithm that takes a [=byte sequence=] |bytes| and runs the steps:
1. Let |arrayBuffer| be a new {{ArrayBuffer}} whose contents are |bytes|.
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This is a faithful copy of the text in fetch, but fetch has a bug which is copied here. It doesn't necessarily need to be fixed here, just gotta make sure it gets fixed here as well when fixed upstream.

1. Let |view| be the result of [=ArrayBufferView/create|creating=] a {{Uint8Array}} from |arrayBuffer|.
1. Return |view|.
1. Return the result of running [=consume fully with abort=] with |stream|, |signal|, and |decode as Uint8Array|.
</div>

<div algorithm>
<dfn abstract-op lt="ReadableStreamConsumeAsBlob" id="ReadableStreamConsumeAsBlob">ReadableStreamConsumeAsBlob(|stream|, |options|})</dfn> will
consume all bytes produced by a given readable stream and return a promise that resolves with a Blob.

It performs the following steps:

1. Assert: |stream| [=implements=] {{ReadableStream}}.
1. If ! [$IsReadableStreamLocked$]([=stream=]) is true, return [=a promise rejected with=] a
{{TypeError}} exception.
1. If ! |stream|.[=ReadableStream/[[disturbed]]=] is true, return [=a promise rejected with=] a
{{TypeError}} exception.
1. Let |signal| be |options|["{{ConsumeBytesOptions/signal}}"] if it [=map/exists=], or undefined
otherwise.
1. Let |type| be |options|["{{ConsumeBytesOptions/type}}"] if it [=map/exists=], or an empty string
otherwise.
1. Assert: either |signal| is undefined, or |signal| [=implements=] {{AbortSignal}}.
1. Let |decode as Blob| be an algorithm that takes a [=byte sequence=] |bytes| and a string |type| and runs the steps:
1. Let |blob| be a new {{Blob}} whose contents are |bytes| and whose {{Blob/type}} attribute is |type|.
1. Return |blob|.
1. Return the result of running [=consume fully with abort=] with |stream|, |signal|, and |decode as Blob|.
</div>

<h4 id="rs-abstract-ops-used-by-controllers">Interfacing with controllers</h4>

In terms of specification factoring, the way that the {{ReadableStream}} class encapsulates the
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