I just finished the first draft of the implementation of my enum_extend library. It is available via github.
It offers
- Ranges over all defined enumerated values
- Filtered ranges over a subset of enumerated values
- ++ and — pre- and postfix operators
- Attaching a textual representation to each enumerated value
Some examples:
using enum_extend::range;
using enum_extend::extender;
using enum_extend::filtered_range;
enum class Color
{
Red = 0,
Green = 4,
Blue = 8
};
// Let's walk over all defined values
for (auto c : range<Color>()) {
// ...
}
auto c = Color::Red;
// we can increment as well
++c;
// We iterate in reverse order over all defined values
std::vector<Color> allReverseColors;
std::copy(extender<Color>::rbegin(),
extender<Color>::rend(),
std::back_inserter(allReverseColors));
// Just iterate over all values that match a certain criteria;
// usefull if the enumerated values are defined as combined bit fields
auto FilterRed = [](Color c) { return c == Color::Red; };
for (auto c : filtered_range<Color>(FilterRed)) {
// Do just something with red values
}
Only this specialization and the implementation of the operators is necessary:
template <>
enum_extend::extender<Color>::instances
enum_extend::extender<Color>::all_values = { Color::Red, Color::Green, Color::Blue };
Color& operator++(Color& e) {
return enum_extend::extender<Color>::increment(e);
}
Color& operator--(Color& e) {
return enum_extend::extender<Color>::decrement(e);
}
Color operator++(Color& e, int) {
auto tmp = e;
enum_extend::extender<Color>::increment(e);
return tmp;
}
Color operator--(Color& e, int) {
auto tmp = e;
enum_extend::extender<Color>::decrement(e);
return tmp;
}
There exists a set of macros that simplifies the process of specializing the extender and implementing the operators.
Much more details and examples can be found in this first tutorial
Feedback is welcome!