mirror of
https://github.com/RGBCube/serenity
synced 2025-07-25 16:37:35 +00:00
LibJS: Add spec comments to unsigned_right_shift()
This commit is contained in:
parent
b66f9a8718
commit
e27ef63217
1 changed files with 33 additions and 3 deletions
|
@ -1610,20 +1610,50 @@ ThrowCompletionOr<Value> right_shift(VM& vm, Value lhs, Value rhs)
|
|||
}
|
||||
|
||||
// 13.9.3 The Unsigned Right Shift Operator ( >>> ), https://tc39.es/ecma262/#sec-unsigned-right-shift-operator
|
||||
// ShiftExpression : ShiftExpression >>> AdditiveExpression
|
||||
ThrowCompletionOr<Value> unsigned_right_shift(VM& vm, Value lhs, Value rhs)
|
||||
{
|
||||
// 13.15.3 ApplyStringOrNumericBinaryOperator ( lval, opText, rval ), https://tc39.es/ecma262/#sec-applystringornumericbinaryoperator
|
||||
// 1-2, 5-6. N/A.
|
||||
|
||||
// 3. Let lnum be ? ToNumeric(lval).
|
||||
auto lhs_numeric = TRY(lhs.to_numeric(vm));
|
||||
|
||||
// 4. Let rnum be ? ToNumeric(rval).
|
||||
auto rhs_numeric = TRY(rhs.to_numeric(vm));
|
||||
|
||||
// 7. Let operation be the abstract operation associated with opText and Type(lnum) in the following table:
|
||||
// [...]
|
||||
// 8. Return operation(lnum, rnum).
|
||||
if (both_number(lhs_numeric, rhs_numeric)) {
|
||||
// 6.1.6.1.11 Number::unsignedRightShift ( x, y ), https://tc39.es/ecma262/#sec-numeric-types-number-unsignedRightShift
|
||||
|
||||
// OPTIMIZATION: Handle infinite values according to the results returned by ToUint32.
|
||||
if (!lhs_numeric.is_finite_number())
|
||||
return Value(0);
|
||||
if (!rhs_numeric.is_finite_number())
|
||||
return lhs_numeric;
|
||||
// Ok, so this performs toNumber() again but that "can't" throw
|
||||
|
||||
// 1. Let lnum be ! ToUint32(x).
|
||||
auto lhs_u32 = MUST(lhs_numeric.to_u32(vm));
|
||||
auto rhs_u32 = MUST(rhs_numeric.to_u32(vm)) % 32;
|
||||
return Value(lhs_u32 >> rhs_u32);
|
||||
|
||||
// 2. Let rnum be ! ToUint32(y).
|
||||
auto rhs_u32 = MUST(rhs_numeric.to_u32(vm));
|
||||
|
||||
// 3. Let shiftCount be ℝ(rnum) modulo 32.
|
||||
auto shift_count = rhs_u32 % 32;
|
||||
|
||||
// 4. Return the result of performing a zero-filling right shift of lnum by shiftCount bits.
|
||||
// Vacated bits are filled with zero. The mathematical value of the result is exactly representable
|
||||
// as a 32-bit unsigned bit string.
|
||||
return Value(lhs_u32 >> shift_count);
|
||||
}
|
||||
|
||||
// 6. If lnum is a BigInt, then
|
||||
// d. If opText is >>>, return ? BigInt::unsignedRightShift(lnum, rnum).
|
||||
|
||||
// 6.1.6.2.11 BigInt::unsignedRightShift ( x, y ), https://tc39.es/ecma262/#sec-numeric-types-bigint-unsignedRightShift
|
||||
// 1. Throw a TypeError exception.
|
||||
return vm.throw_completion<TypeError>(ErrorType::BigIntBadOperator, "unsigned right-shift");
|
||||
}
|
||||
|
||||
|
|
Loading…
Add table
Add a link
Reference in a new issue