Editorial: Better align %TypedArray%.prototype.set with other mutating methods

Author: gibson042

spec.emu

@@ -287,95 +287,23 @@ contributors: Mark S. Miller, Richard Gibson
 
       <emu-clause id="sec-%typedarray%.prototype.set" oldids="sec-%typedarray%.prototype.set-overloaded-offset" number="26">
         <h1>%TypedArray%.prototype.set ( _source_ [ , _offset_ ] )</h1>
-
-        <emu-clause id="sec-settypedarrayfromtypedarray" type="abstract operation" oldids="sec-%typedarray%.prototype.set-typedarray-offset">
-          <h1>
-            SetTypedArrayFromTypedArray (
-              _target_: a TypedArray,
-              _targetOffset_: a non-negative integer or +&infin;,
-              _source_: a TypedArray,
-            ): either a normal completion containing ~unused~ or a throw completion
-          </h1>
-          <dl class="header">
-            <dt>description</dt>
-            <dd>It sets multiple values in _target_, starting at index _targetOffset_, reading the values from _source_.</dd>
-          </dl>
-          <emu-alg>
-            1. Let _targetBuffer_ be _target_.[[ViewedArrayBuffer]].
-            1. Let _targetRecord_ be MakeTypedArrayWithBufferWitnessRecord(_target_, ~seq-cst~).
-            1. If IsTypedArrayOutOfBounds(_targetRecord_) is *true*, throw a *TypeError* exception.
-            1. <ins>If IsImmutableBuffer(_target_.[[ViewedArrayBuffer]]) is *true*, throw a *TypeError* exception.</ins>
-            1. Let _targetLength_ be TypedArrayLength(_targetRecord_).
-            1. Let _srcBuffer_ be _source_.[[ViewedArrayBuffer]].
-            1. Let _srcRecord_ be MakeTypedArrayWithBufferWitnessRecord(_source_, ~seq-cst~).
-            1. If IsTypedArrayOutOfBounds(_srcRecord_) is *true*, throw a *TypeError* exception.
-            1. Let _srcLength_ be TypedArrayLength(_srcRecord_).
-            1. Let _targetType_ be TypedArrayElementType(_target_).
-            1. Let _targetElementSize_ be TypedArrayElementSize(_target_).
-            1. Let _targetByteOffset_ be _target_.[[ByteOffset]].
-            1. Let _srcType_ be TypedArrayElementType(_source_).
-            1. Let _srcElementSize_ be TypedArrayElementSize(_source_).
-            1. Let _srcByteOffset_ be _source_.[[ByteOffset]].
-            1. If _targetOffset_ = +∞, throw a *RangeError* exception.
-            1. If _srcLength_ + _targetOffset_ > _targetLength_, throw a *RangeError* exception.
-            1. If _target_.[[ContentType]] is not _source_.[[ContentType]], throw a *TypeError* exception.
-            1. If IsSharedArrayBuffer(_srcBuffer_) is *true*, IsSharedArrayBuffer(_targetBuffer_) is *true*, and _srcBuffer_.[[ArrayBufferData]] is _targetBuffer_.[[ArrayBufferData]], let _sameSharedArrayBuffer_ be *true*; otherwise, let _sameSharedArrayBuffer_ be *false*.
-            1. If SameValue(_srcBuffer_, _targetBuffer_) is *true* or _sameSharedArrayBuffer_ is *true*, then
-              1. Let _srcByteLength_ be TypedArrayByteLength(_srcRecord_).
-              1. Set _srcBuffer_ to ? CloneArrayBuffer(_srcBuffer_, _srcByteOffset_, _srcByteLength_).
-              1. Let _srcByteIndex_ be 0.
-            1. Else,
-              1. Let _srcByteIndex_ be _srcByteOffset_.
-            1. Let _targetByteIndex_ be (_targetOffset_ × _targetElementSize_) + _targetByteOffset_.
-            1. Let _limit_ be _targetByteIndex_ + (_targetElementSize_ × _srcLength_).
-            1. If _srcType_ is _targetType_, then
-              1. NOTE: The transfer must be performed in a manner that preserves the bit-level encoding of the source data.
-              1. Repeat, while _targetByteIndex_ &lt; _limit_,
-                1. Let _value_ be GetValueFromBuffer(_srcBuffer_, _srcByteIndex_, ~uint8~, *true*, ~unordered~).
-                1. Perform SetValueInBuffer(_targetBuffer_, _targetByteIndex_, ~uint8~, _value_, *true*, ~unordered~).
-                1. Set _srcByteIndex_ to _srcByteIndex_ + 1.
-                1. Set _targetByteIndex_ to _targetByteIndex_ + 1.
-            1. Else,
-              1. Repeat, while _targetByteIndex_ &lt; _limit_,
-                1. Let _value_ be GetValueFromBuffer(_srcBuffer_, _srcByteIndex_, _srcType_, *true*, ~unordered~).
-                1. Perform SetValueInBuffer(_targetBuffer_, _targetByteIndex_, _targetType_, _value_, *true*, ~unordered~).
-                1. Set _srcByteIndex_ to _srcByteIndex_ + _srcElementSize_.
-                1. Set _targetByteIndex_ to _targetByteIndex_ + _targetElementSize_.
-            1. Return ~unused~.
-          </emu-alg>
-        </emu-clause>
-
-        <emu-clause id="sec-settypedarrayfromarraylike" type="abstract operation" oldids="sec-%typedarray%.prototype.set-array-offset">
-          <h1>
-            SetTypedArrayFromArrayLike (
-              _target_: a TypedArray,
-              _targetOffset_: a non-negative integer or +&infin;,
-              _source_: an ECMAScript language value, but not a TypedArray,
-            ): either a normal completion containing ~unused~ or a throw completion
-          </h1>
-          <dl class="header">
-            <dt>description</dt>
-            <dd>It sets multiple values in _target_, starting at index _targetOffset_, reading the values from _source_.</dd>
-          </dl>
-          <emu-alg>
-            1. Let _targetRecord_ be MakeTypedArrayWithBufferWitnessRecord(_target_, ~seq-cst~).
-            1. If IsTypedArrayOutOfBounds(_targetRecord_) is *true*, throw a *TypeError* exception.
-            1. <ins>If IsImmutableBuffer(_target_.[[ViewedArrayBuffer]]) is *true*, throw a *TypeError* exception.</ins>
-            1. Let _targetLength_ be TypedArrayLength(_targetRecord_).
-            1. Let _src_ be ? ToObject(_source_).
-            1. Let _srcLength_ be ? LengthOfArrayLike(_src_).
-            1. If _targetOffset_ = +∞, throw a *RangeError* exception.
-            1. If _srcLength_ + _targetOffset_ > _targetLength_, throw a *RangeError* exception.
-            1. Let _k_ be 0.
-            1. Repeat, while _k_ &lt; _srcLength_,
-              1. Let _Pk_ be ! ToString(𝔽(_k_)).
-              1. Let _value_ be ? Get(_src_, _Pk_).
-              1. Let _targetIndex_ be 𝔽(_targetOffset_ + _k_).
-              1. Perform ? TypedArraySetElement(_target_, _targetIndex_, _value_).
-              1. Set _k_ to _k_ + 1.
-            1. Return ~unused~.
-          </emu-alg>
-        </emu-clause>
+        <p>This method sets multiple values in this _TypedArray_, reading the values from _source_. The details differ based upon the type of _source_. The optional _offset_ value indicates the first element index in this _TypedArray_ where values are written. If omitted, it is assumed to be 0.</p>
+        <p>It performs the following steps when called:</p>
+        <emu-alg>
+          1. Let _target_ be the *this* value.
+          1. <ins>NOTE: `Let _taRecord_ be ? ValidateTypedArray(_O_, ~seq-cst~<ins>, ~write~</ins>).` here would observably change the observable calls into user code and thrown error when IsTypedArrayOutOfBounds returns *true* and _offset_ is negative. Such a change should be pursued.</ins>
+          1. Perform ? RequireInternalSlot(_target_, [[TypedArrayName]]).
+          1. Assert: _target_ has a [[ViewedArrayBuffer]] internal slot.
+          1. <ins>If IsImmutableBuffer(_target_.[[ViewedArrayBuffer]]) is *true*, throw a *TypeError* exception.</ins>
+          1. Let _targetOffset_ be ? ToIntegerOrInfinity(_offset_).
+          1. If _targetOffset_ &lt; 0, throw a *RangeError* exception.
+          1. If _source_ is an Object that has a [[TypedArrayName]] internal slot, then
+            1. Perform ? SetTypedArrayFromTypedArray(_target_, _targetOffset_, _source_).
+          1. Else,
+            1. Perform ? SetTypedArrayFromArrayLike(_target_, _targetOffset_, _source_).
+          1. Return *undefined*.
+        </emu-alg>
+        <p>This method is not generic. The *this* value must be an object with a [[TypedArrayName]] internal slot.</p>
       </emu-clause>
 
       <emu-clause id="sec-%typedarray%.prototype.sort" oldids="sec-typedarraysortcompare" number="29">