MY_ENUM

MY_ENUM is a small c++ macro library to add compile-time introspection to c++ enum classes.

Examples

For example MY_ENUM(FooBar, int, (foo, bar)); defines an enum class

enum class FooBar : int {
  foo,
  bar
};

with the following free functions:

// Returns corresponding string of given value
//
// Preconditions: value must be a valid enum value, i.e. FooBar::foo, or
//                FooBar::bar.
//
std::string toString(FooBar value);

// Returns corresponding string of given value, or `defaultIfInvalid` if the
// given value does not correspond to an enum element.
//
std::string tryToString(FooBar value, string_view defaultIfInvalid);

// Returns corresponding string view of given value
//
// Preconditions: value must be a valid enum value, i.e. FooBar::foo, or
//                FooBar::bar.
//
string_view toStringView(FooBar value);

// Returns pretty string representation of given value
//
// Preconditions: value must be a valid enum value, i.e. FooBar::foo, or
//                FooBar::bar.
//
std::string toPretty(FooBar value);

// Sets enum given corresponding string, if string is valid (i.e. "foo" or
// "bar"). Returns false otherwise.
//
bool trySetFromString(FooBar& value, std::string str);

// Sets enum given corresponding string, if string matches case-insensitive
// (i.e. "foo" and "Foo" will both match). Returns false otherwise.
//
bool trySetFromStringCaseInsensitive(FooBar& value, string_view str);

// Returns count of enum type. First argument is needed for ADL only.
//
constexpr size_t getCount(FooBar) {
  return 2;
}

// Returns string views of enum type. First argument is needed for ADL only.
std::array<string_view, 2> getStrings(FooBar) {
  return {"foo", "bar"};
}

// Returns string view of enum names. First argument is needed for ADL only.
string_view getStringOfNames(FooBar) {
  return "foo, bar";
}

// Returns values of enum type. First argument is needed for ADL only.
constexpr std::array<int, 2> getValues(FooBar) {
  return {0, 1};
}

// Returns elements of enum type. First argument is needed for ADL only.
constexpr std::array<FooBar, 2> getElements(FooBar) {
  return {FooBar::foo, FooBar::bar};
}

// Returns the position of enum value in the enum class. This is the inverse
// of `getValues(FooBar)[i]`.
constexpr size_t getPosition(FooBar value) {
  switch(value) {
    case FooBar::foo: { return 0; }
    case FooBar::bar: { return 1; }
  }
}

// Returns string representation of type name. First argument is needed for
// ADL only.
string_view getTypeName(FooBar) {
  return "FooBar";
}

Requirements

MY_ENUM is a c++ macro library.

• CMake configuration and build steps are tested on MacOS and Linux.
• It depends on the BOOST preprocessor library.
• It depends on a string_view implementation: either std::string_view (c++17), or fmt::string_view from the {fmt} library.
• MY_ENUM tests depend on googletest which are pulled in through git sub-modules.
• The MY_ENUM CliExample depends on CLI11.

Building MY_ENUM

In the following, we detail how to build MY_ENUM for Ubuntu 18.04.

Install BOOST preprocessor headers:

sudo apt install libboost-system-dev

Install CLI11 if you want to build the CliExample application:

git clone https://github.com/CLIUtils/CLI11.git
cd CLI11
git checkout v1.9.0
mkdir build
cd build
cmake .. -DCLI11_BUILD_TESTS=OFF
make -j2
sudo make install

Now checkout MY_ENUM from the repo and build the MY_ENUM tests and example:

git clone https://github.com/facebook/MY_ENUM
cd MY_ENUM
git submodule update --init --recursive
mkdir build
cd build
cmake ..
make -j2

Join the MY_ENUM community

• file issues here: https://github.com/facebook/MY_ENUM/issues

See the CONTRIBUTING file for how to help out.

License

MY_ENUM is MIT licensed, as found in the LICENSE file.