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michaelficarramichaelficarra
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split zip into two methods
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‎demo/index.html

+3-3
Original file line numberDiff line numberDiff line change
@@ -27,16 +27,16 @@
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<h1>Joint Iteration</h1>
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<p>This proposal is at Stage 2 of the TC39 process.</p>
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<p>Open the console to try it out. Here are some examples:</p>
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<pre><code>Array.from(Iterator.zip([
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<pre><code>Array.from(Iterator.zipToArrays([
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[0, 1, 2],
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[3, 4, 5],
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]))</code></pre>
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<pre><code>Array.from(Iterator.zip({
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<pre><code>Array.from(Iterator.zipToArrays({
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a: [0, 1, 2],
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b: [3, 4, 5, 6],
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c: [7, 8, 9],
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}))</code></pre>
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<pre><code>Array.from(Iterator.zip({
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<pre><code>Array.from(Iterator.zipToArrays({
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a: [0, 1, 2],
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b: [3, 4, 5, 6],
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c: [7, 8, 9],

‎spec.emu

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Original file line numberDiff line numberDiff line change
@@ -9,8 +9,8 @@ location: https://tc39.es/proposal-joint-iteration/
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copyright: false
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</pre>
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<emu-clause id="sec-iterator.zip">
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<h1>Iterator.zip ( _iterables_ [ , _options_ ] )</h1>
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<emu-clause id="sec-iterator.ziptoarrays">
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<h1>Iterator.zipToArrays ( _iterables_ [ , _options_ ] )</h1>
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<p>This method performs the following steps when called:</p>
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<emu-alg>
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1. If _iterables_ is not an Object, throw a *TypeError* exception.
@@ -27,77 +27,117 @@ copyright: false
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1. Let _iters_ be a new empty List.
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1. Let _openIters_ be a new empty List.
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1. Let _padding_ be a new empty List.
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1. If ? HasProperty(_iterables_, %Symbol.iterator%) is *true*, then
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1. Let _inputIter_ be ? GetIterator(_iterables_, ~sync~).
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1. Let _next_ be ~not-started~.
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1. Repeat, while _next_ is not ~done~,
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1. Set _next_ to Completion(IteratorStepValue(_inputIter_)).
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1. IfAbruptCloseIterators(_next_, _openIters_).
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1. If _next_ is not ~done~, then
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1. Let _iter_ be Completion(GetIteratorFlattenable(_next_, ~iterate-strings~)).
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1. IfAbruptCloseIterators(_iter_, the list-concatenation of « _inputIter_ » and _openIters_).
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1. Append _iter_ to _iters_.
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1. Append _iter_ to _openIters_.
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1. Let _iterCount_ be the number of elements in _iters_.
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1. If _mode_ is ~longest~, then
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1. If _paddingOption_ is *undefined*, then
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1. Perform the following steps _iterCount_ times:
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1. Append *undefined* to _padding_.
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1. Else,
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1. Let _paddingIter_ be Completion(GetIterator(_paddingOption_, ~sync~)).
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1. IfAbruptCloseIterators(_paddingIter_, _openIters_).
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1. Let _usingIterator_ be *true*.
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1. Perform the following steps _iterCount_ times:
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1. If _usingIterator_ is *true*, then
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1. Set _next_ to Completion(IteratorStepValue(_paddingIter_)).
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1. IfAbruptCloseIterators(_next_, _openIters_).
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1. If _next_ is ~done~, then
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1. Set _usingIterator_ to *false*.
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1. Else,
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1. Append _next_ to _padding_.
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1. If _usingIterator_ is *false*, append *undefined* to _padding_.
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1. Let _inputIter_ be ? GetIterator(_iterables_, ~sync~).
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1. Let _next_ be ~not-started~.
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1. Repeat, while _next_ is not ~done~,
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1. Set _next_ to Completion(IteratorStepValue(_inputIter_)).
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1. IfAbruptCloseIterators(_next_, _openIters_).
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1. If _next_ is not ~done~, then
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1. Let _iter_ be Completion(GetIteratorFlattenable(_next_, ~iterate-strings~)).
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1. IfAbruptCloseIterators(_iter_, the list-concatenation of « _inputIter_ » and _openIters_).
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1. Append _iter_ to _iters_.
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1. Append _iter_ to _openIters_.
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1. Let _iterCount_ be the number of elements in _iters_.
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1. If _mode_ is ~longest~, then
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1. If _paddingOption_ is *undefined*, then
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1. Perform the following steps _iterCount_ times:
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1. Append *undefined* to _padding_.
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1. Else,
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1. Let _paddingIter_ be Completion(GetIterator(_paddingOption_, ~sync~)).
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1. IfAbruptCloseIterators(_paddingIter_, _openIters_).
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1. Let _usingIterator_ be *true*.
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1. Perform the following steps _iterCount_ times:
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1. If _usingIterator_ is *true*, then
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1. Let _completion_ be Completion(IteratorClose(_paddingIter_, NormalCompletion(~unused~))).
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1. IfAbruptCloseIterators(_completion_, _openIters_).
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1. Let _finishResults_ be a new Abstract Closure with parameters (_results_) that captures nothing and performs the following steps when called:
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1. Return CreateArrayFromList(_results_).
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1. Else,
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1. Let _allKeys_ be ? _iterables_.[[OwnPropertyKeys]]().
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1. Let _keys_ be a new empty List.
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1. For each element _key_ of _allKeys_, do
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1. Let _desc_ be ? _iterables_.[[GetOwnProperty]](_key_).
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1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
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1. Let _value_ be *undefined*.
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1. If IsDataDescriptor(_desc_) is *true*, then
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1. Set _value_ to _desc_.[[Value]].
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1. Else,
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1. Assert: IsAccessorDescriptor(_desc_) is *true*.
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1. Let _getter_ be _desc_.[[Get]].
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1. If _getter_ is not *undefined*, then
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1. Let _getterResult_ be Completion(Call(_getter_, _iterables_)).
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1. IfAbruptCloseIterators(_getterResult_, _openIters_).
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1. Set _value_ to _getterResult_.
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1. If _value_ is not *undefined*, then
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1. Append _key_ to _keys_.
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1. Let _iter_ be Completion(GetIteratorFlattenable(_value_, ~iterate-strings~)).
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1. IfAbruptCloseIterators(_iter_, _openIters_).
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1. Append _iter_ to _iters_.
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1. Append _iter_ to _openIters_.
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1. Let _iterCount_ be the number of elements in _iters_.
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1. If _mode_ is ~longest~, then
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1. If _paddingOption_ is *undefined*, then
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1. Perform the following steps _iterCount_ times:
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1. Append *undefined* to _padding_.
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1. Set _next_ to Completion(IteratorStepValue(_paddingIter_)).
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1. IfAbruptCloseIterators(_next_, _openIters_).
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1. If _next_ is ~done~, then
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1. Set _usingIterator_ to *false*.
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1. Else,
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1. Append _next_ to _padding_.
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1. If _usingIterator_ is *false*, append *undefined* to _padding_.
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1. If _usingIterator_ is *true*, then
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1. Let _completion_ be Completion(IteratorClose(_paddingIter_, NormalCompletion(~unused~))).
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1. IfAbruptCloseIterators(_completion_, _openIters_).
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1. Let _finishResults_ be a new Abstract Closure with parameters (_results_) that captures nothing and performs the following steps when called:
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1. Return CreateArrayFromList(_results_).
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1. Return IteratorZipCore(_iters_, _openIters_, _mode_, _padding_, _finishResults_).
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</emu-alg>
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</emu-clause>
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<emu-clause id="sec-iterator.ziptoobjects">
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<h1>Iterator.zipToObjects ( _iterables_ [ , _options_ ] )</h1>
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<p>This method performs the following steps when called:</p>
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<emu-alg>
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1. If _iterables_ is not an Object, throw a *TypeError* exception.
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1. Set _options_ to ? GetOptionsObject(_options_).
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1. Let _longest_ be ? GetOption(_options_, *"longest"*, ~boolean~, ~empty~, *false*).
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1. Let _strict_ be ? GetOption(_options_, *"strict"*, ~boolean~, ~empty~, *false*).
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1. If _longest_ is *true* and _strict_ is *true*, throw a *TypeError* exception.
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1. Let _mode_ be ~shortest~.
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1. Let _paddingOption_ be *undefined*.
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1. If _longest_ is *true*, then
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1. Set _mode_ to ~longest~.
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1. Set _paddingOption_ to ? Get(_options_, *"padding"*).
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1. If _strict_ is *true*, set _mode_ to ~strict~.
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1. Let _iters_ be a new empty List.
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1. Let _openIters_ be a new empty List.
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1. Let _padding_ be a new empty List.
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1. Let _allKeys_ be ? _iterables_.[[OwnPropertyKeys]]().
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1. Let _keys_ be a new empty List.
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1. For each element _key_ of _allKeys_, do
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1. Let _desc_ be ? _iterables_.[[GetOwnProperty]](_key_).
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1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
90+
1. Let _value_ be *undefined*.
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1. If IsDataDescriptor(_desc_) is *true*, then
92+
1. Set _value_ to _desc_.[[Value]].
9193
1. Else,
92-
1. For each element _key_ of _keys_, do
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1. Let _value_ be Completion(Get(_paddingOption_, _key_)).
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1. IfAbruptCloseIterators(_value_, _openIters_).
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1. Append _value_ to _padding_.
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1. Let _finishResults_ be a new Abstract Closure with parameters (_results_) that captures _keys_ and _iterCount_ and performs the following steps when called:
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1. Let _obj_ be OrdinaryObjectCreate(*null*).
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1. For each integer _i_ such that 0 ≤ _i_ &lt; _iterCount_, do
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1. Perform ! CreateDataPropertyOrThrow(_obj_, _keys_[_i_], _results_[_i_]).
100-
1. Return _obj_.
94+
1. Assert: IsAccessorDescriptor(_desc_) is *true*.
95+
1. Let _getter_ be _desc_.[[Get]].
96+
1. If _getter_ is not *undefined*, then
97+
1. Let _getterResult_ be Completion(Call(_getter_, _iterables_)).
98+
1. IfAbruptCloseIterators(_getterResult_, _openIters_).
99+
1. Set _value_ to _getterResult_.
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1. If _value_ is not *undefined*, then
101+
1. Append _key_ to _keys_.
102+
1. Let _iter_ be Completion(GetIteratorFlattenable(_value_, ~iterate-strings~)).
103+
1. IfAbruptCloseIterators(_iter_, _openIters_).
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1. Append _iter_ to _iters_.
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1. Append _iter_ to _openIters_.
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1. Let _iterCount_ be the number of elements in _iters_.
107+
1. If _mode_ is ~longest~, then
108+
1. If _paddingOption_ is *undefined*, then
109+
1. Perform the following steps _iterCount_ times:
110+
1. Append *undefined* to _padding_.
111+
1. Else,
112+
1. For each element _key_ of _keys_, do
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1. Let _value_ be Completion(Get(_paddingOption_, _key_)).
114+
1. IfAbruptCloseIterators(_value_, _openIters_).
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1. Append _value_ to _padding_.
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1. Let _finishResults_ be a new Abstract Closure with parameters (_results_) that captures _keys_ and _iterCount_ and performs the following steps when called:
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1. Let _obj_ be OrdinaryObjectCreate(*null*).
118+
1. For each integer _i_ such that 0 ≤ _i_ &lt; _iterCount_, do
119+
1. Perform ! CreateDataPropertyOrThrow(_obj_, _keys_[_i_], _results_[_i_]).
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1. Return _obj_.
121+
1. Return IteratorZipCore(_iters_, _openIters_, _mode_, _padding_, _finishResults_).
122+
</emu-alg>
123+
</emu-clause>
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125+
<emu-clause id="sec-IteratorZipCore" type="abstract operation">
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<h1>
127+
IteratorZipCore (
128+
_iters_: a List of Iterator Records,
129+
_openIters_: a List of Iterator Records,
130+
_mode_: either ~shortest~, ~longest~, or ~strict~,
131+
_padding_: a List of ECMAScript language values,
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_finishResults_: an Abstract Closure that takes a List of ECMAScript values and returns an ECMAScript value,
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): a Generator
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</h1>
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<dl class="header">
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<dt>description</dt>
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<dd>TODO</dd>
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</dl>
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<emu-alg>
140+
1. Let _iterCount_ be the number of elements in _iters_.
101141
1. Let _closure_ be a new Abstract Closure with no parameters that captures _iters_, _iterCount_, _openIters_, _mode_, _padding_, and _finishResults_, and performs the following steps when called:
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1. Repeat,
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1. Let _results_ be a new empty List.

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