在C++中存储视图类型的引用变体

#include <iostream>
#include <variant>
#include <string_view>
#include <vector>

// 自定义视图类型
template<typename T>
class CustomView {
public:
    CustomView(T& data) : data_(data) {}
    void print() const { std::cout << data_ << std::endl; }
private:
    T& data_;
};

int main() {
    std::string str = "Hello, World!";
    std::vector<int> vec = {1, 2, 3, 4, 5};

    // 使用std::variant存储不同类型的视图引用
    std::variant<std::string_view, std::span<int>, CustomView<std::vector<int>>> viewVariant;

    // 存储std::string_view
    viewVariant = std::string_view(str);
    std::visit([](auto&& arg) { std::cout << arg << std::endl; }, viewVariant);

    // 存储std::span<int>
    viewVariant = std::span<int>(vec);
    std::visit([](auto&& arg) { for (auto& elem : arg) std::cout << elem << " "; std::cout << std::endl; }, viewVariant);

    // 存储自定义视图类型
    viewVariant = CustomView<std::vector<int>>(vec);
    std::visit([](auto&& arg) { arg.print(); }, viewVariant);

    return 0;
}

#include <iostream>
#include <variant>
#include <memory>

class MyClass {
public:
    void print() const { std::cout << "MyClass instance" << std::endl; }
};

int main() {
    auto sharedPtr = std::make_shared<MyClass>();

    // 使用std::variant存储智能指针的引用
    std::variant<std::shared_ptr<MyClass>&> variantRef;

    variantRef = sharedPtr;
    std::visit([](auto&& arg) { arg->print(); }, variantRef);

    return 0;
}