crow

Utility library

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Enumeration Tools

Crow Library by Ross Smith

#include "crow/enum.hpp"
namespace Crow;

This header defines preprocessor macros that help to define enumeration types.

Contents

• Enumeration Tools
  • Contents
  • Enumeration definitions
  • Bitmask enumerations

Enumeration definitions

#define CROW_ENUM_UNSCOPED(EnumName, IntType, ...)
#define CROW_ENUM_SCOPED(EnumName, IntType, ...)

These define an enum or enum class type. The macro arguments are the type name, the underlying integer type, and a list of enumeration constants in the usual format.

This works only at namespace scope; it can’t be used to define class member types.

Example:

CROW_ENUM_CLASS(MyEnumClass, int, alpha = 1, bravo, charlie)

This is equivalent to:

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

In addition to defining the enumeration itself, the macros also define the following functions:

std::vector<std::pair<EnumName, std::string>> enum_value_name_vector(EnumName);
std::unordered_map<EnumName, std::string> enum_value_name_map(EnumName);
std::unordered_map<std::string, EnumName> enum_name_value_map(EnumName);

These return a collection of paired enumeration values and their unqualified names as strings, in various forms. For all of these functions, the argument is ignored and only exists to allow the correct function to be resolved via argument dependent lookup. If an enumeration contains duplicate values, the name associated with an ambiguous value in enum_value_name_map() is the first name associated with that value in the original definition.

std::string to_string(EnumName value);
std::ostream& operator<<(std::ostream& out, EnumName x);

Convert an enumeration value to a string containing the unqualified name. If the argument is not a named enumeration value, the decimal integer value will be returned.

bool enum_value(const std::string& name, EnumName& value);

Convert an unqualified name to an enumeration value. If the name is not one of the enumeration names, this will leave the second argument unchanged and return false.

Bitmask enumerations

#define CROW_ENUM_BITMASK(EnumName, IntType, ...)

This defines a scoped enumeration in the same way as CROW_ENUM_SCOPED(), and also defines the standard bitwise operators on the type, allowing an enumeration to be used as a set of bitmask values. The following operators are defined:

• Unary operators: ! ~
• Binary operators: & | ^ &= |= ^=

These all have their natural meaning in terms of the corresponding operations on the underlying integer type.

#define CROW_ENUM_BITMASK_OPERATORS(EnumName)

This defines the same operators on an existing enumeration type. If the enumeration is a class member type, the macro must be used in namespace scope outside the class.