rs-core

Core utilities

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Enumeration Helpers

Core utility library by Ross Smith

#include "rs-core/enum.hpp"
namespace RS;

Contents

• Enumeration Helpers
  • Contents
  • Scoped enumeration types
  • Bitmask types

Scoped enumeration types

#define RS_ENUM(EnumType, IntType, ...)

This macro defines a scoped enumeration type with a user-supplied list of values. It also defines a few additional features around the new type:

• const std::set<EnumType>& enum_values(EnumType)
  • Returns a collection of all the enumeration values. This uses a dummy argument to identify the type (instead of a template parameter) so the function can be found by ADL.
• std::string to_string(EnumType t)
  • Returns the unqualified enumeration value name as a string.
• std::formatter<EnumType>
  • Formatter that calls to_strig().

The list of enumeration values can include explicit integer values, but the macro does not understand values based on other identifiers or arithmetic expressions. For example, my_volue=0x100 is fine, but my_value=another_value+2 will not work.

Example:

RS_ENUM(MyEnum, int,
    alpha = 1,
    bravo,
    charlie,
)

This is equivalent to:

enum class MyEnum: int {
    alpha = 1,
    bravo,
    charlie,
};

const std::set<MyEnum>& enum_values(MyEnum);
std::string to_string(MyEnum t);
template <> struct std::formatter<MyEnum>;

Bitmask types

#define RS_BITMASK(EnumType, IntType, ...)

This generates all the same features as RS_ENUM(), but also creates a full set of operators that perform bitwise operations on the enumeration type:

constexpr bool operator!(EnumType t) noexcept;
constexpr EnumType operator~(EnumType t) noexcept;
constexpr EnumType operator&(EnumType t, EnumType u) noexcept;
constexpr EnumType operator|(EnumType t, EnumType u) noexcept;
constexpr EnumType operator^(EnumType t, EnumType u) noexcept;
constexpr EnumType& operator&=(EnumType& t, EnumType u) noexcept;
constexpr EnumType& operator|=(EnumType& t, EnumType u) noexcept;
constexpr EnumType& operator^=(EnumType& t, EnumType u) noexcept;

The version of to_string() generated for bitmasks will break down a composite value into its individual named bitmask elements.

Example:

RS_BITMASK(MyBitmask, unsigned,
    none     = 0,
    alpha    = 1,
    bravo    = 2,
    charlie  = 4,
)

auto mask = MyBitmask::alpha | MyBitmask::bravo | MyBitmask::charlie;
std::println("{}", mask);

This will print "alpha|bravo|charlie".