Remove TypedArrayFrom abstraction

bterlson · Dec 28, 2015 · eadbf0b · eadbf0b
1 parent a8cd700
commit eadbf0b
Showing 1 changed file with 34 additions and 53 deletions.
diff --git a/spec.html b/spec.html
@@ -30945,28 +30945,30 @@ <h1>%TypedArray%.from ( _source_ [ , _mapfn_ [ , _thisArg_ ] ] )</h1>
         <emu-alg>
           1. Let _C_ be the *this* value.
           1. If IsConstructor(_C_) is *false*, throw a *TypeError* exception.
-          1. If _mapfn_ was supplied, let _f_ be _mapfn_; otherwise let _f_ be *undefined*.
-          1. If _f_ is not *undefined*, then
-            1. If IsCallable(_f_) is *false*, throw a *TypeError* exception.
-          1. If _thisArg_ was supplied, let _t_ be _thisArg_; else let _t_ be *undefined*.
-          1. Return ? TypedArrayFrom(*undefined*, _C_, _source_, _f_, _t_).
+          1. If _mapfn_ was supplied and _mapfn_ is not *undefined*, then
+            1. If IsCallable(_mapfn_) is *false*, throw a *TypeError* exception.
+            1. Let _mapping_ be *true*.
+          1. Else, let _mapping_ be *false*.
+          1. If _thisArg_ was supplied, let _T_ be _thisArg_; else let _T_ be *undefined*.
+          1. Let _arrayLike_ be ? IterableToArrayLike(_source_).
+          1. Let _len_ be ? ToLength(? Get(_arrayLike_, `"length"`)).
+          1. Let _targetObj_ be ? TypedArrayCreate(_C_, &laquo;_len_&raquo;).
+          1. Let _k_ be 0.
+          1. Repeat, while _k_ &lt; _len_
+            1. Let _Pk_ be ! ToString(_k_).
+            1. Let _kValue_ be ? Get(_arrayLike_, _Pk_).
+            1. If _mapping_ is *true*, then
+              1. Let _mappedValue_ be ? Call(_mapfn_, _T_, &laquo; _kValue_, _k_ &raquo;).
+            1. Else, let _mappedValue_ be _kValue_.
+            1. Perform ? Set(_targetObj_, _Pk_, _mappedValue_, *true*).
+            1. Increase _k_ by 1.
+          1. Return _targetObj_.
         </emu-alg>
 
-        <!-- es6num="22.2.2.1.1" -->
-        <emu-clause id="sec-typedarrayfrom" aoid="TypedArrayFrom">
-          <h1>Runtime Semantics: TypedArrayFrom( _O_, _constructor_, _items_, _mapfn_, _thisArg_ )</h1>
-          <p>When the TypedArrayFrom abstract operation is called with arguments _O_, _constructor_, _items_, _mapfn_, and _thisArg_, the following steps are taken:</p>
+        <emu-clause id="sec-iterabletoarraylike" aoid="IterableToArrayLike">
+          <h1>Runtime Semantics: IterableToArrayLike( _items_ )</h1>
+          <p>The abstract operation IterableToArrayLike performs the following steps:</p>
           <emu-alg>
-            1. Let _C_ be _constructor_.
-            1. If _O_ is not *undefined*, then
-              1. Assert: _O_ is an Object that has a [[ViewedArrayBuffer]] internal slot.
-            1. Else,
-              1. Assert: IsConstructor(_C_) is *true*.
-            1. Assert: _mapfn_ is either a callable Object or *undefined*.
-            1. If _mapfn_ is *undefined*, let _mapping_ be *false*.
-            1. Else,
-              1. Let _T_ be _thisArg_.
-              1. Let _mapping_ be *true*.
             1. Let _usingIterator_ be ? GetMethod(_items_, @@iterator).
             1. If _usingIterator_ is not *undefined*, then
               1. Let _iterator_ be ? GetIterator(_items_, _usingIterator_).
@@ -30977,39 +30979,9 @@ <h1>Runtime Semantics: TypedArrayFrom( _O_, _constructor_, _items_, _mapfn_, _th
                 1. If _next_ is not *false*, then
                   1. Let _nextValue_ be ? IteratorValue(_next_).
                   1. Append _nextValue_ to the end of the List _values_.
-              1. Let _len_ be the number of elements in _values_.
-              1. If _O_ is not *undefined*, then
-                1. Let _targetObj_ be ? AllocateTypedArrayBuffer(_O_, _len_).
-              1. Else,
-                1. Let _targetObj_ be ? TypedArrayCreate(_C_, &laquo;_len_&raquo;).
-              1. Let _k_ be 0.
-              1. Repeat, while _k_ &lt; _len_
-                1. Let _Pk_ be ! ToString(_k_).
-                1. Let _kValue_ be the first element of _values_ and remove that element from _values_.
-                1. If _mapping_ is *true*, then
-                  1. Let _mappedValue_ be ? Call(_mapfn_, _T_, &laquo; _kValue_, _k_ &raquo;).
-                1. Else, let _mappedValue_ be _kValue_.
-                1. Perform ? Set(_targetObj_, _Pk_, _mappedValue_, *true*).
-                1. Increase _k_ by 1.
-              1. Assert: _values_ is now an empty List.
-              1. Return _targetObj_.
-            1. Assert: _items_ is not an Iterable so assume it is an array-like object.
-            1. Let _arrayLike_ be ? ToObject(_items_).
-            1. Let _len_ be ? ToLength(? Get(_arrayLike_, `"length"`)).
-            1. If _O_ is not *undefined*, then
-              1. Let _targetObj_ be ? AllocateTypedArrayBuffer(_O_, _len_).
-            1. Else,
-              1. Let _targetObj_ be ? TypedArrayCreate(_C_, &laquo;_len_&raquo;).
-            1. Let _k_ be 0.
-            1. Repeat, while _k_ &lt; _len_
-              1. Let _Pk_ be ! ToString(_k_).
-              1. Let _kValue_ be ? Get(_arrayLike_, _Pk_).
-              1. If _mapping_ is *true*, then
-                1. Let _mappedValue_ be ? Call(_mapfn_, _T_, &laquo; _kValue_, _k_ &raquo;).
-              1. Else, let _mappedValue_ be _kValue_.
-              1. Perform ? Set(_targetObj_, _Pk_, _mappedValue_, *true*).
-              1. Increase _k_ by 1.
-            1. Return _targetObj_.
+              1. Return CreateArrayFromList(_values_).
+            1. Assert: _items_ is not an Iterable so assume it is already an array-like object.
+            1. Return ? ToObject(_items_).
           </emu-alg>
         </emu-clause>
       </emu-clause>
@@ -31702,7 +31674,16 @@ <h1>_TypedArray_ ( _object_ )</h1>
           1. Assert: Type(_object_) is Object and _object_ does not have either a [[TypedArrayName]] or an [[ArrayBufferData]] internal slot.
           1. If NewTarget is *undefined*, throw a *TypeError* exception.
           1. Let _O_ be ? AllocateTypedArray(_TypedArray_.[[TypedArrayConstructorName]], NewTarget, <code>"%<var>TypedArray</var>Prototype%"</code>).
-          1. Return ? TypedArrayFrom(_O_, *undefined*, _object_, *undefined*, *undefined*).
+          1. Let _arrayLike_ be ? IterableToArrayLike(_object_).
+          1. Let _len_ be ? ToLength(? Get(_arrayLike_, `"length"`)).
+          1. Perform ? AllocateTypedArrayBuffer(_O_, _len_).
+          1. Let _k_ be 0.
+          1. Repeat, while _k_ &lt; _len_
+            1. Let _Pk_ be ! ToString(_k_).
+            1. Let _kValue_ be ? Get(_arrayLike_, _Pk_).
+            1. Perform ? Set(_O_, _Pk_, _kValue_, *true*).
+            1. Increase _k_ by 1.
+          1. Return _O_.
         </emu-alg>
       </emu-clause>