Przejdź do głównej zawartości

C++ named requirements:BitmaskType

Defines a type that can be used to represent a set of constant values or any combination of those values. This trait is typically implemented by integer types, std::bitset, or enumerations (scoped and unscoped) with additional operator overloads.

Requirements

The bitmask type supports a finite number of bitmask elements, which are distinct non-zero values of the bitmask type, such that, for any pair Ci and Cj, Ci & Ci is nonzero and Ci & Cj is zero. In addition, the value ​0​ is used to represent an empty bitmask, with no values set.

The bitwise operators operator&, operator|, operator^, operator~, operator&=, operator|=, and operator^= are defined for values of the bitmask type and have the same semantics as the corresponding built-in operators on unsigned integers would have if the bitmask elements were the distinct integer powers of two.

The following expressions are well-formed and have the following meaning for any BitmaskType:

pubX |= Ysets the value Y in the object X
pubX &= ~Yclears the value Y in the object X
pubX & Ynonzero result indicates that the value Y is set in the object X

Each representable bitmask element is defined as a inline (od C++17) constexpr value of the bitmask type

Usage

The following standard library types satisfy BitmaskType:

Code that relies on some particular implementation option (e.g. int n = std::ios_base::hex), is nonportable because std::ios_base::fmtflags is not necessarily implicitly convertible to int.

C++ named requirements:BitmaskType

Defines a type that can be used to represent a set of constant values or any combination of those values. This trait is typically implemented by integer types, std::bitset, or enumerations (scoped and unscoped) with additional operator overloads.

Requirements

The bitmask type supports a finite number of bitmask elements, which are distinct non-zero values of the bitmask type, such that, for any pair Ci and Cj, Ci & Ci is nonzero and Ci & Cj is zero. In addition, the value ​0​ is used to represent an empty bitmask, with no values set.

The bitwise operators operator&, operator|, operator^, operator~, operator&=, operator|=, and operator^= are defined for values of the bitmask type and have the same semantics as the corresponding built-in operators on unsigned integers would have if the bitmask elements were the distinct integer powers of two.

The following expressions are well-formed and have the following meaning for any BitmaskType:

pubX |= Ysets the value Y in the object X
pubX &= ~Yclears the value Y in the object X
pubX & Ynonzero result indicates that the value Y is set in the object X

Each representable bitmask element is defined as a inline (od C++17) constexpr value of the bitmask type

Usage

The following standard library types satisfy BitmaskType:

Code that relies on some particular implementation option (e.g. int n = std::ios_base::hex), is nonportable because std::ios_base::fmtflags is not necessarily implicitly convertible to int.