How do I use heterogeneous lookup with std::unordered_set?

In C++, heterogeneous lookups allow you to search for different types in a data structure without needing to convert them to a common type first. The `std::unordered_set` is a part of the C++ Standard Library and can be used to implement this feature effectively. You can store elements of different types in an `std::unordered_set` by using `std::any`, `std::variant`, or a custom type that can handle various types efficiently.

Here's an example demonstrating how to utilize heterogeneous lookup with `std::unordered_set` using `std::variant`.


    #include <iostream>
    #include <unordered_set>
    #include <variant>

    using VariantType = std::variant;

    struct VariantHasher {
        std::size_t operator()(const VariantType& v) const {
            return std::visit([](auto&& arg) { return std::hash<:decay_t>>{}(arg); }, v);
        }
    };

    struct VariantEqual {
        bool operator()(const VariantType& lhs, const VariantType& rhs) const {
            return lhs == rhs;
        }
    };

    int main() {
        std::unordered_set mySet;

        mySet.insert(10);
        mySet.insert(std::string("Hello"));

        // Heterogeneous lookups
        for (const auto& value : mySet) {
            std::visit([](auto&& arg) { std::cout << arg << std::endl; }, value);
        }
        
        return 0;
    }

How do I use heterogeneous lookup with std::unordered_set?

Popular Topics

Recent Languages

How do I use heterogeneous lookup with std::unordered_set?

Related Questions

Popular Topics

Recent Languages