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#include <iostream>
#include <vector>
struct Cat;
struct Dog;
struct Animal {
const char* name;
Animal(const char* name) : name(name) {
}
virtual ~Animal() {
}
virtual void meet(Animal& other, std::ostream& os) = 0;
virtual void meet_cat(Cat& other, std::ostream& os) = 0;
virtual void meet_dog(Dog& other, std::ostream& os) = 0;
};
struct Cat : Animal {
using Animal::Animal;
void meet(Animal& other, std::ostream& os) override;
void meet_cat(Cat& other, std::ostream& os) override;
void meet_dog(Dog& other, std::ostream& os) override;
};
struct Dog : Animal {
using Animal::Animal;
void meet(Animal& other, std::ostream& os) override;
void meet_cat(Cat& other, std::ostream& os) override;
void meet_dog(Dog& other, std::ostream& os) override;
};
void meet_animals(const std::vector<Animal*>& animals, std::ostream& os) {
for (auto animal : animals) {
for (auto other : animals) {
if (animal != other) {
animal->meet(*other, os);
}
}
}
}
auto main() -> int {
Dog hector{"Hector"}, snoopy{"Snoopy"};
Cat felix{"Felix"}, sylvester{"Sylvester"};
std::vector<Animal*> animals = {&hector, &felix, &sylvester, &snoopy};
meet_animals(animals, std::cout);
}
void Cat::meet(Animal& other, std::ostream& os) {
other.meet_cat(*this, os);
}
void Cat::meet_cat(Cat& other, std::ostream& os) {
os << name << " ignores " << other.name << "\n";
}
void Cat::meet_dog(Dog& other, std::ostream& os) {
os << name << " runs away from " << other.name << "\n";
}
void Dog::meet(Animal& other, std::ostream& os) {
other.meet_dog(*this, os);
}
void Dog::meet_cat(Cat& other, std::ostream& os) {
os << name << " chases " << other.name << "\n";
}
void Dog::meet_dog(Dog& other, std::ostream& os) {
os << name << " wags tail at " << other.name << "\n";
}
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