如何在自定义列表迭代器类中将迭代器转换为const_iterator？

#include <iostream>
#include <vector>

template <typename T>
class MyList {
public:
    class Iterator {
    protected:
        typename std::vector<T>::iterator it;
    public:
        Iterator(typename std::vector<T>::iterator iterator) : it(iterator) {}

        T& operator*() { return *it; }
        T* operator->() { return &(*it); }
        Iterator& operator++() { ++it; return *this; }
        bool operator!=(const Iterator& other) const { return it != other.it; }
    };

    class ConstIterator {
    protected:
        typename std::vector<T>::const_iterator it;
    public:
        ConstIterator(typename std::vector<T>::const_iterator iterator) : it(iterator) {}
        ConstIterator(const Iterator& iterator) : it(iterator.it) {} // 允许从Iterator转换为ConstIterator

        const T& operator*() const { return *it; }
        const T* operator->() const { return &(*it); }
        ConstIterator& operator++() { ++it; return *this; }
        bool operator!=(const ConstIterator& other) const { return it != other.it; }
    };

    MyList(std::initializer_list<T> init) : data(init) {}

    Iterator begin() { return Iterator(data.begin()); }
    Iterator end() { return Iterator(data.end()); }

    ConstIterator begin() const { return ConstIterator(data.begin()); }
    ConstIterator end() const { return ConstIterator(data.end()); }

private:
    std::vector<T> data;
};

int main() {
    MyList<int> list = {1, 2, 3, 4, 5};

    // 使用普通迭代器
    for (MyList<int>::Iterator it = list.begin(); it != list.end(); ++it) {
        std::cout << *it << ' ';
    }
    std::cout << '\n';

    // 使用const_iterator
    for (MyList<int>::ConstIterator it = list.begin(); it != list.end(); ++it) {
        std::cout << *it << ' ';
    }
    std::cout << '\n';

    // 将普通迭代器转换为const_iterator
    MyList<int>::ConstIterator const_it = MyList<int>::ConstIterator(list.begin());
    std::cout << *const_it << '\n';

    return 0;
}