Editorial: stop using promises in internal algorithms

They are not designed for that and don't work well (e.g., resolve expects a JS value).

Follows whatwg/streams#1250 and addresses the Fetch part of whatwg/streams#1178.

Closes #1568.

Co-authored-by: Domenic Denicola <[email protected]>
Co-authored-by: Anne van Kesteren <[email protected]>

Author: 3 people

fetch.bs

@@ -1465,32 +1465,19 @@ null), run these steps. <var>processBody</var> must be an algorithm accepting a
  <li><p>If <var>taskDestination</var> is null, then set <var>taskDestination</var> to the result of
  <a>starting a new parallel queue</a>.
 
- <li><p>Let <var>promise</var> be the result of <a>fully reading body as promise</a> given
- <var>body</var>.
-
- <li><p>Let <var>fulfilledSteps</var> given a <a>byte sequence</a> <var>bytes</var> be to
+ <li><p>Let <var>successSteps</var> given a <a>byte sequence</a> <var>bytes</var> be to
  <a>queue a fetch task</a> to run <var>processBody</var> given <var>bytes</var>, with
  <var>taskDestination</var>.
 
- <li><p>Let <var>rejectedSteps</var> be to <a>queue a fetch task</a> to run
+ <li><p>Let <var>errorSteps</var> be to <a>queue a fetch task</a> to run
  <var>processBodyError</var>, with <var>taskDestination</var>.
 
- <li><p><a for=promise>React</a> to <var>promise</var> with <var>fulfilledSteps</var> and
- <var>rejectedSteps</var>.
-</ol>
-</div>
-
-<div algorithm>
-<p>To <dfn export lt="fully reading body as promise">fully read body as promise</dfn>, given a
-<a for=/>body</a> <var>body</var>, run these steps:
-
-<ol>
  <li><p>Let <var>reader</var> be the result of <a for=ReadableStream>getting a reader</a> for
- <var>body</var>'s <a for=body>stream</a>. If that threw an exception, then return
- <a>a promise rejected with</a> that exception.
+ <var>body</var>'s <a for=body>stream</a>. If that threw an exception, then run
+ <var>errorSteps</var> with that exception and return.
 
- <li><p>Return the result of <a for=ReadableStreamDefaultReader>reading all bytes</a> from
- <var>reader</var>.
+ <li><p><a for=ReadableStreamDefaultReader>Read all bytes</a> from
+ <var>reader</var>, given <var>successSteps</var> and <var>errorSteps</var>.
 </ol>
 </div>
 
@@ -6886,38 +6873,78 @@ returns failure or a <a for=/>MIME type</a>.
 
 <hr>
 
+<div algorithm>
 <p>The <dfn attribute for=Body><code>body</code></dfn> getter steps are to return null if
 <a>this</a>'s <a for=Body>body</a> is null; otherwise <a>this</a>'s <a for=Body>body</a>'s
 <a for=body>stream</a>.
+</div>
 
+<div algorithm>
 <p>The <dfn attribute for=Body><code>bodyUsed</code></dfn> getter steps are to return true if
 <a>this</a>'s <a for=Body>body</a> is non-null and <a>this</a>'s <a for=Body>body</a>'s
 <a for=body>stream</a> is <a for=ReadableStream>disturbed</a>; otherwise false.
+</div>
 
-<p>The <dfn id=concept-body-package-data for=Body>package data</dfn> algorithm, given
-<var>bytes</var>, <var>type</var>, and a <var>mimeType</var>, switches on <var>type</var>, and runs
-the associated steps:
+<div algorithm>
+<p id=concept-body-package-data>The <dfn id=concept-body-consume-body for=Body>consume body</dfn>
+algorithm, given an object that includes {{Body}} <var>object</var> and an algorithm that takes a
+<a for=/>byte sequence</a> and returns a JavaScript value or throws an exception
+<var>convertBytesToJSValue</var>, runs these steps:
 
-<dl class=switch>
- <dt><i>ArrayBuffer</i>
- <dd>
-  <p>Return a new {{ArrayBuffer}} whose contents are <var>bytes</var>.
+<ol>
+ <li><p>If <var>object</var> is <a for=Body>unusable</a>, then return <a>a promise rejected with</a>
+ a {{TypeError}}.
 
-  <p class=note>Allocating an {{ArrayBuffer}} can throw a {{RangeError}}.
+ <li><p>Let <var>promise</var> be <a>a new promise</a>.
 
- <dt><i>Blob</i>
- <dd><p>Return a {{Blob}} whose contents are <var>bytes</var> and {{Blob/type}} attribute is
- <var>mimeType</var>.
+ <li>Let <var>errorSteps</var> given <var>error</var> be to <a>reject</a> <var>promise</var> with
+ <var>error</var>.
 
- <dt><i>FormData</i>
- <dd>
-  <p>If <var>mimeType</var>'s <a for="MIME type">essence</a> is "<code>multipart/form-data</code>",
-  then:
+ <li>Let <var>successSteps</var> given a <a for=/>byte sequence</a> <var>data</var> be to
+ <a for=/>resolve</a> <var>promise</var> with the result of running <var>convertBytesToJSValue</var>
+ with <var>data</var>. If that threw an exception, then run <var>errorSteps</var> with that
+ exception.
+
+ <li><p>If <var>object</var>'s <a for=Body>body</a> is null, then run <var>successSteps</var>
+ with an empty <a for=/>byte sequence</a>.
+
+ <li><p>Otherwise, <a for=body>fully read</a> <var>object</var>'s <a for=Body>body</a> given
+ <var>successSteps</var>, <var>errorSteps</var>, and <var>object</var>'s
+ <a>relevant global object</a>.
+
+ <li><p>Return <var>promise</var>.
+</ol>
+</div>
+
+<div algorithm>
+<p>The <dfn method for=Body><code>arrayBuffer()</code></dfn> method steps are to return the result
+of running <a for=Body>consume body</a> with <a>this</a> and the following step given a
+<a for=/>byte sequence</a> <var>bytes</var>: return a new {{ArrayBuffer}} whose contents are
+<var>bytes</var>.
+
+<p class="note">The above method can reject with a {{RangeError}}.
+</div>
 
+<div algorithm>
+<p>The <dfn method for=Body><code>blob()</code></dfn> method steps are to return the result
+of running <a for=Body>consume body</a> with <a>this</a> and the following step given a
+<a for=/>byte sequence</a> <var>bytes</var>: return a {{Blob}} whose contents are <var>bytes</var>
+and whose {{Blob/type}} attribute is <a>this</a>'s <a for=Body>MIME type</a>.
+</div>
+
+<div algorithm>
+<p>The <dfn method for=Body><code>formData()</code></dfn> method steps are to return the result of
+running <a for=Body>consume body</a> with <a>this</a> and the following step given a
+<a for=/>byte sequence</a> <var>bytes</var>: switch on <a>this</a>'s <a for=Body>MIME type</a>'s
+<a for="MIME type">essence</a> and run the corresponding steps:
+
+<dl class=switch>
+ <dt>"<code>multipart/form-data</code>",
+ <dd>
   <ol>
    <li>
     <p>Parse <var>bytes</var>, using the value of the `<code>boundary</code>` parameter from
-    <var>mimeType</var>, per the rules set forth in
+    <a>this</a>'s <a for=Body>MIME type</a>, per the rules set forth in
     <cite>Returning Values from Forms: multipart/form-data</cite>. [[!RFC7578]]</p>
 
     <p>Each part whose `<code>Content-Disposition</code>` header contains a `<code>filename</code>`
@@ -6950,62 +6977,34 @@ the associated steps:
   `<code>multipart/form-data</code>`, a more detailed parsing specification is to be
   written. Volunteers welcome.
 
-  <p>Otherwise, if <var>mimeType</var>'s <a for="MIME type">essence</a> is
-  "<code>application/x-www-form-urlencoded</code>", then:
-
+ <dt>"<code>application/x-www-form-urlencoded</code>",
+ <dd>
   <ol>
-   <li><p>Let <var>entries</var> be the result of
-   <a lt="urlencoded parser">parsing</a> <var>bytes</var>.
+   <li><p>Let <var>entries</var> be the result of  <a lt="urlencoded parser">parsing</a>
+   <var>bytes</var>.
 
    <li><p>If <var>entries</var> is failure, then <a>throw</a> a {{TypeError}}.
 
    <li><p>Return a new {{FormData}} object whose <a for=FormData>entry list</a> is
    <var>entries</var>.
   </ol>
 
-  <p>Otherwise, <a>throw</a> a {{TypeError}}.
-
- <dt><i>JSON</i>
- <dd><p>Return the result of running <a>parse JSON from bytes</a> on <var>bytes</var>.
-
- <dt><i>text</i>
- <dd><p>Return the result of running <a>UTF-8 decode</a> on
- <var>bytes</var>.
+ <dt>Otherwise
+ <dd><p><a>Throw</a> a {{TypeError}}.
 </dl>
+</div>
 
-<p>The <dfn id=concept-body-consume-body for=Body>consume body</dfn> algorithm, given an
-<var>object</var> and <var>type</var>, runs these steps:
-
-<ol>
- <li><p>If <var>object</var> is <a for=Body>unusable</a>, then return <a>a promise rejected with</a>
- a {{TypeError}}.
-
- <li><p>Let <var>promise</var> be <a>a promise resolved with</a> an empty
- <a for=/>byte sequence</a>.
-
- <li><p>If <var>object</var>'s <a for=Body>body</a> is non-null, then set <var>promise</var> to the
- result of <a>fully reading body as promise</a> given <var>object</var>'s <a for=Body>body</a>.
-
- <li><p>Let <var>steps</var> be to return the result of <a>package data</a> with the first argument
- given, <var>type</var>, and <var>object</var>'s <a for=Body>MIME type</a>.
-
- <li><p>Return the result of <a>upon fulfillment</a> of <var>promise</var> given <var>steps</var>.
-</ol>
-
-<p>The <dfn method for=Body><code>arrayBuffer()</code></dfn> method steps are to return the result
-of running <a for=Body>consume body</a> with <a>this</a> and <i>ArrayBuffer</i>.
-
-<p>The <dfn method for=Body><code>blob()</code></dfn> method steps are to return the result of
-running <a for=Body>consume body</a> with <a>this</a> and <i>Blob</i>.
-
-<p>The <dfn method for=Body><code>formData()</code></dfn> method steps are to return the result of
-running <a for=Body>consume body</a> with <a>this</a> and <i>FormData</i>.
+<div algorithm>
+<p>The <dfn method for=Body><code>json()</code></dfn> method steps are to return the result
+of running <a for=Body>consume body</a> with <a>this</a> and <a>parse JSON from bytes</a>.
 
-<p>The <dfn method for=Body><code>json()</code></dfn> method steps are to return the result of
-running <a for=Body>consume body</a> with <a>this</a> and <i>JSON</i>.
+<p class="note">The above method can reject with a {{SyntaxError}}.
+</div>
 
-<p>The <dfn method for=Body><code>text()</code></dfn> method steps are to return the result of
-running <a for=Body>consume body</a> with <a>this</a> and <i>text</i>.
+<div algorithm>
+<p>The <dfn method for=Body><code>text()</code></dfn> method steps are to return the result
+of running <a for=Body>consume body</a> with <a>this</a> and <a>UTF-8 decode</a>.
+</div>
 
 
 <h3 id=request-class>Request class</h3>