flags17/main.cpp at master · basicpp/flags17 · GitHub

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#include<cinttypes>
#include<iostream>

namespacelegacy_enum_approach {
enum Animals {
ANIMALS_CAT = 1 << 0,
ANIMALS_DOG = 1 << 1,
ANIMALS_WOLF = 1 << 3,
};
static_assert(std::is_same_v<decltype(std::declval<Animals>() | std::declval<Animals>()), int>, //
"default fallback to int");

autooperator|(Animals a, Animals b) -> Animals { returnAnimals(int(a) | b); }
autooperator&(Animals a, Animals b) -> Animals { returnAnimals(int(a) & b); }

static_assert(std::is_same_v<decltype(std::declval<Animals>() | std::declval<Animals>()), Animals>,
"operator keeps types");

autooperator<<(std::ostream &out, Animals a) -> std::ostream & {
auto p = [&, first = true ](constchar *t) mutable {
if (first)
 first = false;
else
 out << " | ";
 out << t;
 };
if (a & ANIMALS_CAT) p("Cat");
if (a & ANIMALS_DOG) p("Dog");
if (a & ANIMALS_WOLF) p("Wolf");
return out;
}

voidusage() {
constexprauto Cat = ANIMALS_CAT;
auto a = Cat | ANIMALS_DOG;
 std::cout << Cat << '\n';
 std::cout << a << '\n';
 std::cout << ((a & Cat) | ANIMALS_WOLF) << '\n';
}
} // namespace legacy_enum_approach

#include"classic/Flags.h"
namespaceclassic_enum_class_approach {
enumclassAnimal {
 Cat = 1 << 0,
 Dog = 1 << 1,
 Wolf = 1 << 3,
};
using Animals = classic::Flags<Animal>;

// hint: use this outside of namespace or it wont be usable there!
ENABLE_CLASSIC_FLAGS_OP(Animals)

autooperator<<(std::ostream &out, Animal a) -> std::ostream & {
switch (a) {
case Animal::Cat: return out << "Cat";
case Animal::Dog: return out << "Dog";
case Animal::Wolf: return out << "Wolf";
 }
}

voidusage() {
constexprauto Cat = Animal::Cat;
auto a = Cat | Animal::Dog;
 std::cout << Cat << '\n';
 std::cout << a << '\n';
 std::cout << ((a & Cat) | Animal::Wolf) << '\n';
}

} // namespace classic_enum_class_approach

#include"bitnumber/Flags.h"
namespacebit_number_approach {
enumclassAnimal { Cat, Dog, Wolf = 3 };
using Animals = bitnumber::Flags<Animal>;

// hint: use this outside of namespace or it wont be usable there!
ENABLE_BITNUMBER_FLAGS_OP(Animals)

autooperator<<(std::ostream &out, Animal a) -> std::ostream & {
switch (a) {
case Animal::Cat: return out << "Cat";
case Animal::Dog: return out << "Dog";
case Animal::Wolf: return out << "Wolf";
 }
}

voidusage() {
constexprauto Cat = Animal::Cat;
auto a = Cat | Animal::Dog;
 std::cout << Cat << '\n';
 std::cout << a << '\n';
 std::cout << ((a & Cat) | Animal::Wolf) << '\n';
}
} // namespace bit_number_approach

#include"tagtype/Flags.h"
namespacetag_type_approach {

structAnimal {
structCat;
structDog;
structWolf;
};
using Animals = tagtype::Flags<Animal::Cat, Animal::Dog, void, Animal::Wolf>;

using AnimalCat = Animal::Cat;
autooperator<<(std::ostream &out, tagtype::Flag<AnimalCat>) -> std::ostream & { return out << "Cat"; }
autooperator<<(std::ostream &out, tagtype::Flag<Animal::Dog>) -> std::ostream & { return out << "Dog"; }
autooperator<<(std::ostream &out, tagtype::Flag<Animal::Wolf>) -> std::ostream & { return out << "Wolf"; }

template<classT>
constexprauto Flag = tagtype::Flag<T>{};

voidusage() {
using Cat = Animal::Cat; // use type aliases for shorter names
constexprauto DogF = Flag<Animal::Dog>; // flag types works only if you use them one by one
auto a = Animals(Flag<Cat>, DogF);
 std::cout << Flag<Cat> << '\n';
 std::cout << a << '\n';
 std::cout << (a & Flag<Cat> | Flag<Animal::Wolf>) << '\n';
}
} // namespace tag_type_approach

#include"tagvalue/Flags.h"
namespacetag_value_approach {

enumclassAnimal { Cat, Dog };
enumclassAnimalWolf {};
constexprauto AnimalCat = Animal::Cat;

using Animals = tagvalue::Flags<AnimalCat, Animal::Dog, nullptr, AnimalWolf{}>;

#if true // one stream operator per type
using tagvalue::operator<<;
autooperator<<(std::ostream &out, tagvalue::Typed<Animal> a) -> std::ostream & {
switch (a.value) {
case AnimalCat: return out << "Cat";
case Animal::Dog: return out << "Dog";
 }
}
autooperator<<(std::ostream &out, tagvalue::Typed<AnimalWolf>) -> std::ostream & { return out << "Wolf"; }
#else// individual stream operators
} // namespace tag_value_approach
namespacemeta {
autooperator<<(std::ostream &out, tagvalue::Flag<tag_value_approach::AnimalCat>) -> std::ostream & {
return out << "Cat";
}
autooperator<<(std::ostream &out, tagvalue::Flag<tag_value_approach::Animal::Dog>) -> std::ostream & {
return out << "Dog";
}
autooperator<<(std::ostream &out, tagvalue::Flag<tag_value_approach::AnimalWolf{}>) -> std::ostream & {
return out << "Wolf";
}
} // namespace meta
namespacetag_value_approach {
#endif

template<auto V>
constexprauto Flag = tagvalue::Flag<V>{};

voidusage() {
constexprauto Cat = Animal::Cat;
constexprauto DogF = Flag<Animal::Dog>;
auto a = Animals(Flag<Cat>, DogF);
 std::cout << Flag<Cat> << '\n';
 std::cout << a << '\n';
 std::cout << (a & Flag<Cat> | Flag<AnimalWolf{}>) << '\n';
}
} // namespace tag_value_approach

#include"repeated/Flags.h"
namespacerepeated_bit_approach {

enumclassAnimal { Cat, Dog, Wolf = 3 };
constexprauto AnimalCat = Animal::Cat;

using Animals = repeated::Flags<AnimalCat, Animal::Dog, Animal::Wolf>;
ENABLE_REPEATED_FLAGS_OP(Animals)

autooperator<<(std::ostream &out, Animal a) -> std::ostream & {
switch (a) {
case AnimalCat: return out << "Cat";
case Animal::Dog: return out << "Dog";
case Animal::Wolf: return out << "Wolf";
 }
}

voidusage() {
constexprauto Cat = Animal::Cat;
auto a = Cat | Animal::Dog;
 std::cout << Cat << '\n';
 std::cout << a << '\n';
 std::cout << ((a & Cat) | Animal::Wolf) << '\n';
}
} // namespace repeated_bit_approach

intmain() {
 std::cout << "\n-- legacy enum approach --\n";
legacy_enum_approach::usage();

 std::cout << "\n-- classic enum class approach --\n";
classic_enum_class_approach::usage();

 std::cout << "\n-- bit number approach --\n";
bit_number_approach::usage();

 std::cout << "\n-- tag type approach --\n";
tag_type_approach::usage();

 std::cout << "\n-- tag value approach --\n";
tag_value_approach::usage();

 std::cout << "\n-- repeated bit approach --\n";
repeated_bit_approach::usage();
}