LibJS: Add spec comments to %TypedArray%.prototype.set

Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp

@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2020-2021, Linus Groh <[email protected]>
  * Copyright (c) 2021, Luke Wilde <[email protected]>
- * Copyright (c) 2021, Idan Horowitz <[email protected]>
+ * Copyright (c) 2021-2022, Idan Horowitz <[email protected]>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -610,124 +610,226 @@ JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::to_string_tag_getter)
 // 23.2.3.24 %TypedArray%.prototype.set ( source [ , offset ] ), https://tc39.es/ecma262/#sec-%typedarray%.prototype.set
 JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::set)
 {
+ auto source = vm.argument(0);
+
+ // 1. Let target be the this value.
+ // 2. Perform ? RequireInternalSlot(target, [[TypedArrayName]]).
  auto* typed_array = TRY(typed_array_from_this(global_object));
 
- auto source = vm.argument(0);
+ // 3. Assert: target has a [[ViewedArrayBuffer]] internal slot.
 
+ // 4. Let targetOffset be ? ToIntegerOrInfinity(offset).
  auto target_offset = TRY(vm.argument(1).to_integer_or_infinity(global_object));
+
+ // 5. If targetOffset < 0, throw a RangeError exception.
  if (target_offset < 0)
- return vm.throw_completion<JS::RangeError>(global_object, "Invalid target offset");
+ return vm.throw_completion<RangeError>(global_object, "Invalid target offset");
 
+ // 6. If source is an Object that has a [[TypedArrayName]] internal slot, then
  if (source.is_object() && is<TypedArrayBase>(source.as_object())) {
- auto& source_typed_array = static_cast<TypedArrayBase&>(source.as_object());
+ // a. Perform ? SetTypedArrayFromTypedArray(target, targetOffset, source).
+
  // 23.2.3.23.1 SetTypedArrayFromTypedArray ( target, targetOffset, source ), https://tc39.es/ecma262/#sec-settypedarrayfromtypedarray
- auto target_buffer = typed_array->viewed_array_buffer();
+
+ auto& source_typed_array = static_cast<TypedArrayBase&>(source.as_object());
+
+ // 1. Let targetBuffer be target.[[ViewedArrayBuffer]].
+ auto* target_buffer = typed_array->viewed_array_buffer();
+
+ // 2. If IsDetachedBuffer(targetBuffer) is true, throw a TypeError exception.
  if (target_buffer->is_detached())
- return vm.throw_completion<JS::TypeError>(global_object, ErrorType::DetachedArrayBuffer);
+ return vm.throw_completion<TypeError>(global_object, ErrorType::DetachedArrayBuffer);
+
+ // 3. Let targetLength be target.[[ArrayLength]].
  auto target_length = typed_array->array_length();
- auto target_byte_offset = typed_array->byte_offset();
 
- auto source_buffer = source_typed_array.viewed_array_buffer();
+ // 4. Let srcBuffer be source.[[ViewedArrayBuffer]].
+ auto* source_buffer = source_typed_array.viewed_array_buffer();
+
+ // 5. If IsDetachedBuffer(srcBuffer) is true, throw a TypeError exception.
  if (source_buffer->is_detached())
- return vm.throw_completion<JS::TypeError>(global_object, ErrorType::DetachedArrayBuffer);
+ return vm.throw_completion<TypeError>(global_object, ErrorType::DetachedArrayBuffer);
+
+ // 6. Let targetName be the String value of target.[[TypedArrayName]].
+ // 7. Let targetType be the Element Type value in Table 69 for targetName.
+ // 8. Let targetElementSize be the Element Size value specified in Table 69 for targetName.
+ auto target_element_size = typed_array->element_size();
+
+ // 9. Let targetByteOffset be target.[[ByteOffset]].
+ auto target_byte_offset = typed_array->byte_offset();
+
+ // 10. Let srcName be the String value of source.[[TypedArrayName]].
+ // 11. Let srcType be the Element Type value in Table 69 for srcName.
+ // 12. Let srcElementSize be the Element Size value specified in Table 69 for srcName.
+ auto source_element_size = source_typed_array.element_size();
+
+ // 13. Let srcLength be source.[[ArrayLength]].
  auto source_length = source_typed_array.array_length();
+
+ // 14. Let srcByteOffset be source.[[ByteOffset]].
  auto source_byte_offset = source_typed_array.byte_offset();
 
+ // 15. If targetOffset is +∞, throw a RangeError exception.
  if (isinf(target_offset))
- return vm.throw_completion<JS::RangeError>(global_object, "Invalid target offset");
+ return vm.throw_completion<RangeError>(global_object, "Invalid target offset");
 
+ // 16. If srcLength + targetOffset > targetLength, throw a RangeError exception.
  Checked<size_t> checked = source_length;
  checked += static_cast<u32>(target_offset);
  if (checked.has_overflow() || checked.value() > target_length)
- return vm.throw_completion<JS::RangeError>(global_object, "Overflow or out of bounds in target length");
+ return vm.throw_completion<RangeError>(global_object, "Overflow or out of bounds in target length");
 
+ // 17. If target.[[ContentType]] ≠ source.[[ContentType]], throw a TypeError exception.
  if (typed_array->content_type() != source_typed_array.content_type())
- return vm.throw_completion<JS::TypeError>(global_object, "Copy between arrays of different content types is prohibited");
+ return vm.throw_completion<TypeError>(global_object, "Copy between arrays of different content types is prohibited");
+
+ // FIXME: 18. If both IsSharedArrayBuffer(srcBuffer) and IsSharedArrayBuffer(targetBuffer) are true, then
+ // FIXME: a. If srcBuffer.[[ArrayBufferData]] and targetBuffer.[[ArrayBufferData]] are the same Shared Data Block values, let same be true; else let same be false.
+
+ // 19. Else, let same be SameValue(srcBuffer, targetBuffer).
+ auto same = same_value(source_buffer, target_buffer);
 
  size_t source_byte_index;
- bool same = false;
- // FIXME: Step 19: If both IsSharedArrayBuffer(srcBuffer) and IsSharedArrayBuffer(targetBuffer) are true...
- same = same_value(source_buffer, target_buffer);
+
+ // 20. If same is true, then
  if (same) {
- // FIXME: Implement this: Step 21
+ // a. Let srcByteLength be source.[[ByteLength]].
+ // b. Set srcBuffer to ? CloneArrayBuffer(srcBuffer, srcByteOffset, srcByteLength, %ArrayBuffer%).
+ // c. NOTE: %ArrayBuffer% is used to clone srcBuffer because is it known to not have any observable side-effects.
+ // d. Let srcByteIndex be 0.
  TODO();
  } else {
+ // 21. Else, let srcByteIndex be srcByteOffset.
  source_byte_index = source_byte_offset;
  }
+
+ // 22. Let targetByteIndex be targetOffset × targetElementSize + targetByteOffset.
  Checked<size_t> checked_target_byte_index(static_cast<size_t>(target_offset));
- checked_target_byte_index *= typed_array->element_size();
+ checked_target_byte_index *= target_element_size;
  checked_target_byte_index += target_byte_offset;
  if (checked_target_byte_index.has_overflow())
- return vm.throw_completion<JS::RangeError>(global_object, "Overflow in target byte index");
+ return vm.throw_completion<RangeError>(global_object, "Overflow in target byte index");
  auto target_byte_index = checked_target_byte_index.value();
 
+ // 23. Let limit be targetByteIndex + targetElementSize × srcLength.
  Checked<size_t> checked_limit(source_length);
- checked_limit *= typed_array->element_size();
+ checked_limit *= target_element_size;
  checked_limit += target_byte_index;
  if (checked_limit.has_overflow())
- return vm.throw_completion<JS::RangeError>(global_object, "Overflow in target limit");
+ return vm.throw_completion<RangeError>(global_object, "Overflow in target limit");
  auto limit = checked_limit.value();
 
+ // 24. If srcType is the same as targetType, then
  if (source_typed_array.element_size() == typed_array->element_size()) {
- // FIXME: SharedBuffers use a different mechanism, implement that when SharedBuffers are implemented.
+ // a. NOTE: If srcType and targetType are the same, the transfer must be performed in a manner that preserves the bit-level encoding of the source data.
+ // b. Repeat, while targetByteIndex < limit,
+ // i. Let value be GetValueFromBuffer(srcBuffer, srcByteIndex, Uint8, true, Unordered).
+ // ii. Perform SetValueInBuffer(targetBuffer, targetByteIndex, Uint8, value, true, Unordered).
+ // iii. Set srcByteIndex to srcByteIndex + 1.
+ // iv. Set targetByteIndex to targetByteIndex + 1.
  target_buffer->buffer().overwrite(target_byte_index, source_buffer->buffer().data(), limit - target_byte_index);
  } else {
+ // a. Repeat, while targetByteIndex < limit,
  while (target_byte_index < limit) {
+ // i. Let value be GetValueFromBuffer(srcBuffer, srcByteIndex, srcType, true, Unordered).
  auto value = source_typed_array.get_value_from_buffer(source_byte_index, ArrayBuffer::Unordered);
+ // ii. Perform SetValueInBuffer(targetBuffer, targetByteIndex, targetType, value, true, Unordered).
  typed_array->set_value_in_buffer(target_byte_index, value, ArrayBuffer::Unordered);
- source_byte_index += source_typed_array.element_size();
+ // iii. Set srcByteIndex to srcByteIndex + srcElementSize.
+ source_byte_index += source_element_size;
+ // iv. Set targetByteIndex to targetByteIndex + targetElementSize.
  target_byte_index += typed_array->element_size();
  }
  }
- } else {
+ }
+ // 7. Else,
+ else {
+ // a. Perform ? SetTypedArrayFromArrayLike(target, targetOffset, source).
+
  // 23.2.3.23.2 SetTypedArrayFromArrayLike ( target, targetOffset, source ), https://tc39.es/ecma262/#sec-settypedarrayfromarraylike
- auto target_buffer = typed_array->viewed_array_buffer();
+
+ // 1. Let targetBuffer be target.[[ViewedArrayBuffer]].
+ auto* target_buffer = typed_array->viewed_array_buffer();
+
+ // 2. If IsDetachedBuffer(targetBuffer) is true, throw a TypeError exception.
  if (target_buffer->is_detached())
- return vm.throw_completion<JS::TypeError>(global_object, ErrorType::DetachedArrayBuffer);
+ return vm.throw_completion<TypeError>(global_object, ErrorType::DetachedArrayBuffer);
+
+ // 3. Let targetLength be target.[[ArrayLength]].
  auto target_length = typed_array->array_length();
+
+ // 4. Let targetName be the String value of target.[[TypedArrayName]].
+ // 5. Let targetElementSize be the Element Size value specified in Table 69 for targetName.
+ // 6. Let targetType be the Element Type value in Table 69 for targetName.
+ auto target_element_size = typed_array->element_size();
+
+ // 7. Let targetByteOffset be target.[[ByteOffset]].
  auto target_byte_offset = typed_array->byte_offset();
 
- auto src = TRY(source.to_object(global_object));
+ // 8. Let src be ? ToObject(source).
+ auto* src = TRY(source.to_object(global_object));
+
+ // 9. Let srcLength be ? LengthOfArrayLike(src).
  auto source_length = TRY(length_of_array_like(global_object, *src));
 
+ // 10. If targetOffset is +∞, throw a RangeError exception.
  if (isinf(target_offset))
- return vm.throw_completion<JS::RangeError>(global_object, "Invalid target offset");
+ return vm.throw_completion<RangeError>(global_object, "Invalid target offset");
 
+ // 11. If srcLength + targetOffset > targetLength, throw a RangeError exception.
  Checked<size_t> checked = source_length;
  checked += static_cast<u32>(target_offset);
  if (checked.has_overflow() || checked.value() > target_length)
- return vm.throw_completion<JS::RangeError>(global_object, "Overflow or out of bounds in target length");
+ return vm.throw_completion<RangeError>(global_object, "Overflow or out of bounds in target length");
 
+ // 12. Let targetByteIndex be targetOffset × targetElementSize + targetByteOffset.
  Checked<size_t> checked_target_byte_index(static_cast<size_t>(target_offset));
- checked_target_byte_index *= typed_array->element_size();
+ checked_target_byte_index *= target_element_size;
  checked_target_byte_index += target_byte_offset;
  if (checked_target_byte_index.has_overflow())
- return vm.throw_completion<JS::RangeError>(global_object, "Overflow in target byte index");
+ return vm.throw_completion<RangeError>(global_object, "Overflow in target byte index");
  auto target_byte_index = checked_target_byte_index.value();
 
+ // 13. Let k be 0.
+ auto k = 0;
+
+ // 14. Let limit be targetByteIndex + targetElementSize × srcLength.
  Checked<size_t> checked_limit(source_length);
- checked_limit *= typed_array->element_size();
+ checked_limit *= target_element_size;
  checked_limit += target_byte_index;
  if (checked_limit.has_overflow())
- return vm.throw_completion<JS::RangeError>(global_object, "Overflow in target limit");
-
+ return vm.throw_completion<RangeError>(global_object, "Overflow in target limit");
  auto limit = checked_limit.value();
- auto k = 0;
+
+ // 15. Repeat, while targetByteIndex < limit,
  while (target_byte_index < limit) {
+ // a. Let Pk be ! ToString(𝔽(k)).
+ // b. Let value be ? Get(src, Pk).
  auto value = TRY(src->get(k));
+
+ // c. If target.[[ContentType]] is BigInt, set value to ? ToBigInt(value).
  if (typed_array->content_type() == TypedArrayBase::ContentType::BigInt)
  value = TRY(value.to_bigint(global_object));
+ // d. Otherwise, set value to ? ToNumber(value).
  else
  value = TRY(value.to_number(global_object));
 
+ // e. If IsDetachedBuffer(targetBuffer) is true, throw a TypeError exception.
  if (target_buffer->is_detached())
- return vm.throw_completion<JS::TypeError>(global_object, ErrorType::DetachedArrayBuffer);
+ return vm.throw_completion<TypeError>(global_object, ErrorType::DetachedArrayBuffer);
 
+ // f. Perform SetValueInBuffer(targetBuffer, targetByteIndex, targetType, value, true, Unordered).
  typed_array->set_value_in_buffer(target_byte_index, value, ArrayBuffer::Unordered);
+
+ // g. Set k to k + 1.
  ++k;
- target_byte_index += typed_array->element_size();
+
+ // h. Set targetByteIndex to targetByteIndex + targetElementSize.
+ target_byte_index += target_element_size;
  }
  }
+
+ // 8. Return undefined.
  return js_undefined();
 }