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LibJS: Add spec comments to add()

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Linus Groh 2022-12-10 00:07:37 +00:00
parent e27ef63217
commit d5359164b1
1 changed files with 44 additions and 4 deletions
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48
Userland/Libraries/LibJS/Runtime/Value.cpp
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@ -1658,8 +1658,14 @@ ThrowCompletionOr<Value> unsigned_right_shift(VM& vm, Value lhs, Value rhs)
}
// 13.8.1 The Addition Operator ( + ), https://tc39.es/ecma262/#sec-addition-operator-plus
// AdditiveExpression : AdditiveExpression + MultiplicativeExpression
ThrowCompletionOr<Value> add(VM& vm, Value lhs, Value rhs)
{
// 13.15.3 ApplyStringOrNumericBinaryOperator ( lval, opText, rval ), https://tc39.es/ecma262/#sec-applystringornumericbinaryoperator
// 1. If opText is +, then
// OPTIMIZATION: If both values are i32 or double, we can do a direct addition without the type conversions below.
if (both_number(lhs, rhs)) {
if (lhs.is_int32() && rhs.is_int32()) {
Checked<i32> result;
@ -1670,21 +1676,55 @@ ThrowCompletionOr<Value> add(VM& vm, Value lhs, Value rhs)
}
return Value(lhs.as_double() + rhs.as_double());
}
// a. Let lprim be ? ToPrimitive(lval).
auto lhs_primitive = TRY(lhs.to_primitive(vm));
// b. Let rprim be ? ToPrimitive(rval).
auto rhs_primitive = TRY(rhs.to_primitive(vm));
// c. If lprim is a String or rprim is a String, then
if (lhs_primitive.is_string() || rhs_primitive.is_string()) {
// i. Let lstr be ? ToString(lprim).
auto lhs_string = TRY(lhs_primitive.to_primitive_string(vm));
// ii. Let rstr be ? ToString(rprim).
auto rhs_string = TRY(rhs_primitive.to_primitive_string(vm));
// iii. Return the string-concatenation of lstr and rstr.
return PrimitiveString::create(vm, *lhs_string, *rhs_string);
}
// d. Set lval to lprim.
// e. Set rval to rprim.
// 2. NOTE: At this point, it must be a numeric operation.
// 3. Let lnum be ? ToNumeric(lval).
auto lhs_numeric = TRY(lhs_primitive.to_numeric(vm));
// 4. Let rnum be ? ToNumeric(rval).
auto rhs_numeric = TRY(rhs_primitive.to_numeric(vm));
if (both_number(lhs_numeric, rhs_numeric))
return Value(lhs_numeric.as_double() + rhs_numeric.as_double());
if (both_bigint(lhs_numeric, rhs_numeric))
return BigInt::create(vm, lhs_numeric.as_bigint().big_integer().plus(rhs_numeric.as_bigint().big_integer()));
// 6. N/A.
// 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)) {
// 6.1.6.1.7 Number::add ( x, y ), https://tc39.es/ecma262/#sec-numeric-types-number-add
auto x = lhs_numeric.as_double();
auto y = rhs_numeric.as_double();
return Value(x + y);
}
if (both_bigint(lhs_numeric, rhs_numeric)) {
// 6.1.6.2.7 BigInt::add ( x, y ), https://tc39.es/ecma262/#sec-numeric-types-bigint-add
auto x = lhs_numeric.as_bigint().big_integer();
auto y = rhs_numeric.as_bigint().big_integer();
return BigInt::create(vm, x.plus(y));
}
// 5. If Type(lnum) is different from Type(rnum), throw a TypeError exception.
return vm.throw_completion<TypeError>(ErrorType::BigIntBadOperatorOtherType, "addition");
}