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fixes #229: flatMap supports returning both iterables and iterators (#…
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michaelficarra authored Oct 19, 2022
1 parent 45b0598 commit 462cd66
Showing 1 changed file with 43 additions and 25 deletions.
68 changes: 43 additions & 25 deletions spec.html
Original file line number Diff line number Diff line change
Expand Up @@ -248,6 +248,39 @@ <h1>
1. Return _iteratorRecord_.
</emu-alg>
</emu-clause>

<emu-clause id="sec-getiteratorflattenable" type="abstract operation">
<h1>
GetIteratorFlattenable (
_obj_: an ECMAScript language value,
_hint_: ~sync~ or ~async~,
): either a normal completion containing an Iterator Record or a throw completion
</h1>
<dl class="header">
</dl>
<emu-alg>
1. If _obj_ is not an Object, throw a *TypeError* exception.
1. Let _alreadyAsync_ be *false*.
1. Let _method_ be *undefined*.
1. If _hint_ is ~async~, then
1. Set _method_ to ? Get(_obj_, @@asyncIterator).
1. Set _alreadyAsync_ to *true*.
1. If IsCallable(_method_) is *false*, then
1. Set _method_ to ? Get(_obj_, @@iterator).
1. Set _alreadyAsync_ to *false*.
1. If IsCallable(_method_) is *false*, then
1. Let _iterator_ be _obj_.
1. Set _alreadyAsync_ to *true*.
1. Else,
1. Let _iterator_ be ? Call(_method_, _obj_).
1. Let _nextMethod_ be ? GetV(_iterator_, *"next"*).
1. If IsCallable(_nextMethod_) is *false*, throw a *TypeError* exception.
1. Let _iteratorRecord_ be the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: _nextMethod_, [[Done]]: *false* }.
1. If _hint_ is ~async~ and _alreadyAsync_ is *false*, then
1. Return CreateAsyncFromSyncIterator(_iteratorRecord_).
1. Return _iteratorRecord_.
</emu-alg>
</emu-clause>
</emu-clause>
</emu-clause>

Expand Down Expand Up @@ -310,14 +343,10 @@ <h1>Iterator.prototype</h1>
<emu-clause id="sec-iterator.from">
<h1>Iterator.from ( _O_ )</h1>
<emu-alg>
1. Let _usingIterator_ be ? GetMethod(_O_, @@iterator).
1. If _usingIterator_ is not *undefined*, then
1. Let _iteratorRecord_ be ? GetIterator(_O_, ~sync~, _usingIterator_).
1. If IsCallable(_iteratorRecord_.[[NextMethod]]) is *false*, throw a *TypeError* exception.
1. Let _hasInstance_ be ? OrdinaryHasInstance(%Iterator%, _iteratorRecord_.[[Iterator]]).
1. If _hasInstance_ is *true*, then
1. Return _iteratorRecord_.[[Iterator]].
1. Else, Let _iteratorRecord_ be ? GetIteratorDirect(_O_).
1. Let _iteratorRecord_ be ? GetIteratorFlattenable(_O_, ~sync~).
1. Let _hasInstance_ be ? OrdinaryHasInstance(%Iterator%, _iteratorRecord_.[[Iterator]]).
1. If _hasInstance_ is *true*, then
1. Return _iteratorRecord_.[[Iterator]].
1. Let _wrapper_ be OrdinaryObjectCreate(%WrapForValidIteratorPrototype%, « [[Iterated]] »).
1. Set _wrapper_.[[Iterated]] to _iteratorRecord_.
1. Return _wrapper_.
Expand Down Expand Up @@ -392,21 +421,10 @@ <h1>AsyncIterator.prototype</h1>
<emu-clause id="sec-asynciterator.from">
<h1>AsyncIterator.from ( _O_ )</h1>
<emu-alg>
1. Let _usingIterator_ be ? GetMethod(_O_, @@asyncIterator).
1. Let _iteratorRecord_ be *undefined*.
1. If _usingIterator_ is not *undefined*, then
1. Set _iteratorRecord_ to ? GetIterator(_O_, ~async~, _usingIterator_).
1. If IsCallable(_iteratorRecord_.[[NextMethod]]) is *false*, throw a *TypeError* exception.
1. Let _hasInstance_ be ? OrdinaryHasInstance(%AsyncIterator%, _iteratorRecord_.[[Iterator]]).
1. If _hasInstance_ is *true*, then
1. Return _iteratorRecord_.[[Iterator]].
1. If _iteratorRecord_ is *undefined*, then
1. Set _usingIterator_ to ? GetMethod(_O_, @@iterator).
1. If _usingIterator_ is not *undefined*, then
1. Let _syncIteratorRecord_ be ? GetIterator(_O_, ~sync~, _usingIterator_).
1. If IsCallable(_syncIteratorRecord_.[[NextMethod]]) is *false*, throw a *TypeError* exception.
1. Set _iteratorRecord_ to CreateAsyncFromSyncIterator(_syncIteratorRecord_).
1. If _iteratorRecord_ is *undefined*, set _iteratorRecord_ to ? GetIteratorDirect(_O_).
1. Let _iteratorRecord_ be ? GetIteratorFlattenable(_O_, ~async~).
1. Let _hasInstance_ be ? OrdinaryHasInstance(%AsyncIterator%, _iteratorRecord_.[[Iterator]]).
1. If _hasInstance_ is *true*, then
1. Return _iteratorRecord_.[[Iterator]].
1. Let _wrapper_ be OrdinaryObjectCreate(%WrapForValidAsyncIteratorPrototype%, « [[AsyncIterated]] »).
1. Set _wrapper_.[[AsyncIterated]] to _iteratorRecord_.
1. Return _wrapper_.
Expand Down Expand Up @@ -651,7 +669,7 @@ <h1>Iterator.prototype.flatMap ( _mapper_ )</h1>
1. Let _value_ be ? IteratorValue(_next_).
1. Let _mapped_ be Completion(Call(_mapper_, *undefined*, « _value_, 𝔽(_counter_) »)).
1. IfAbruptCloseIterator(_mapped_, _iterated_).
1. Let _innerIterator_ be Completion(GetIterator(_mapped_, ~sync~)).
1. Let _innerIterator_ be Completion(GetIteratorFlattenable(_mapped_, ~sync~)).
1. IfAbruptCloseIterator(_innerIterator_, _iterated_).
1. Let _innerAlive_ be *true*.
1. Repeat, while _innerAlive_ is *true*,
Expand Down Expand Up @@ -928,7 +946,7 @@ <h1>AsyncIterator.prototype.flatMap ( _mapper_ )</h1>
1. IfAbruptCloseAsyncIterator(_mapped_, _iterated_).
1. Set _mapped_ to Completion(Await(_mapped_)).
1. IfAbruptCloseAsyncIterator(_mapped_, _iterated_).
1. Let _innerIterator_ be Completion(GetIterator(_mapped_, ~async~)).
1. Let _innerIterator_ be Completion(GetIteratorFlattenable(_mapped_, ~async~)).
1. IfAbruptCloseAsyncIterator(_innerIterator_, _iterated_).
1. Let _innerAlive_ be *true*.
1. Repeat, while _innerAlive_ is *true*,
Expand Down

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