Binary Expressions

Binary Expressions

Binary expressions are expressions that operate on two operands. Each operator has an associated std::ops::XXX class, where the Rhs and Out types are specialized for the left-hand-side type. For example, std::ops::add::Add[Rhs=std::string::Str, Out=std::string::Str] is implemented for the std::string::Str type:

sup std::Str ext std::ops::Add[Rhs=std::Str, Out=std::Str] {
    fun add(self, rhs: std::Str) -> std::Str {
        ...
    }
}

The only special binary operator that doesn’t have an associated std::ops::XXX class is the is operator. The right-hand-side isn’t an expression, but a local variable declaration pattern. For example, case optional_type is std::option::Some(value) { ... }.

Operator Precedence

The following table shows the precedence of the binary operators, from highest to lowest:

Operator token	Operation	Associated type and method	Precedence
|=	Bitwise OR Assignment	std::ops::bit_ior::BitIorAssign::bit_ior_assign	0
^=	Bitwise XOR Assignment	std::ops::bit_xor::BitXorAssign::bit_xor_assign	0
&=	Bitwise AND Assignment	std::ops::bit_and::BitAndAssign::bit_and_assign	0
<<=	Shift left Assignment	std::ops::bit_shl::BitShlAssign::bit_shl_assign	0
>>=	Shift right Assignment	std::ops::bit_shr::BitShrAssign::bit_shr_assign	0
+=	Addition Assignment	std::ops::add::AddAssign::add_assign	0
-=	Subtraction Assignment	std::ops::sub::SubAssign::sub_assign	0
*=	Multiplication Assignment	std::ops::mul::MulAssign::mul_assign	0
/=	Division Assignment	std::ops::div::DivAssign::div_assign	0
%=	Remainder Assignment	std::ops::rem::RemAssign::rem_assign	0
**=	Power Assignment	std::ops::pow::PowAssign::pow_assign	0
or	Logical OR	std::ops::ior::Ior::ior_	1
and	Logical AND	std::ops::and_::And::and_	2
is	Type check	N/A	3
==	Equality	std::ops::eq::Eq::eq	4
!=	Inequality	std::ops::ne::Ne::ne	4
<	Less than	std::ops::lt::Lt::lt	4
>	Greater than	std::ops::gt::Gt::gt	4
<=	Less equal	std::ops::le::Le::le	4
>=	Greater equal	std::ops::ge::Ge::ge	4
|	Bitwise OR	std::ops::bit_ior::BitIir::bit_ior	5
^	Bitwise XOR	std::ops::bit_xor::BitXor::bit_xor	6
&	Bitwise AND	std::ops::bit_and::BitAnd::bit_and	7
<<	Shift left	std::ops::bit_shl::BitShl::bit_shl	8
>>	Shift right	std::ops::bit_shr::BitShr::bit_shr	8
+	Addition	std::ops::add::Add::add	9
-	Subtraction	std::ops::sub::Sub::sub	9
*	Multiplication	std::ops::mul::Mul::mul	10
/	Division	std::ops::div::Div::div	10
%	Remainder	std::ops::rem::Rem::rem	10
**	Power	std::ops::pow::Pow::pow	10