Operator Macros

If you got here without reading the Operators section, go read that first. Here are the operator macros and their uses:

Table 1.1. Unary and Binary Operator-Defining Macros

Macro	Use	First/Left Operand Type	Right Operand Type	Notes
`BOOST_YAP_USER_UNARY_OPERATOR`	Unary operators.	An Expression instantiated from ExpressionTemplate macro parameter `expr_template`.	--
`BOOST_YAP_USER_BINARY_OPERATOR`	Binary operators.	Any type.	Any type.	At least one parameter must be an Expression instantiated from ExpressionTemplate macro parameter `expr_template`.
`BOOST_YAP_USER_UDT_UNARY_OPERATOR`	Free operators defined over non-Expression types constrained by a type trait (e.g. all `std::map<>`s).	Any non-Expression that satisfies the given type trait.	--
`BOOST_YAP_USER_UDT_UDT_BINARY_OPERATOR`	Free operators defined over non-Expression types constrained by a pair of type traits (e.g. a `std::map<>` on the left, and a `std::vector<>` on the right). Useful for type-asymmetric operators.	Any non-Expression that satisfies the left-hand type trait.	Any non-Expression that satisfies the right-hand type trait.
`BOOST_YAP_USER_UDT_ANY_BINARY_OPERATOR`	Free operators defined over pairs of non-Expression types, one constrained by a type trait and one not (e.g. a `std::list<>` on either side, and anything on the other).	Any non-Expression.	--	At least one parameter must satisfy the given type trait.

Some operators may only be defined as member functions, and so are not covered by general-purpose the unary and binary operator macros above:

Table 1.2. The Member-Only Operator Macros

Macro	Use	Operands	Notes
`BOOST_YAP_USER_ASSIGN_OPERATOR`	Assignment operator.	Any type except `decltype(*this)`.	Does not conflict with the assignment or move assignment operators.
`BOOST_YAP_USER_SUBSCRIPT_OPERATOR`	Subscript operator.	Any type.
`BOOST_YAP_USER_CALL_OPERATOR`	Call operator taking any number of parameters.	Any type.
`BOOST_YAP_USER_CALL_OPERATOR_N`	Call operator taking exactly N parameters.	Any type.

Table 1.3. if_else Psuedo-Operator Macros

Macro	Use	Operands	Notes
`BOOST_YAP_USER_EXPR_IF_ELSE`	Free `if_else()` function that requires at least one parameter to be an expression.	Any type.	At least one parameter must be an Expression.
`BOOST_YAP_USER_UDT_ANY_IF_ELSE`	Free `if_else()` function for non-Expression types that requires at least one parameter to satisfy the given type trait.	Any non-Expression.	At least one parameter must satisfy the given type trait.

	Note
	Operands are handled in a uniform way across all functions defined by all the macros listed here. See How Expression Operands Are Treated for details.