使用惰性迭代器的C++过滤

#include <iostream>
#include <vector>
#include <iterator>

// 定义一个惰性迭代器类
template<typename Iterator, typename Predicate>
class LazyFilterIterator {
public:
    LazyFilterIterator(Iterator begin, Iterator end, Predicate pred)
        : current(begin), end(end), predicate(pred) {}

    bool hasNext() const {
        return current != end;
    }

    auto next() {
        while (current != end) {
            if (predicate(*current)) {
                return *current++;
            }
            ++current;
        }
        throw std::out_of_range("No more elements");
    }

private:
    Iterator current;
    Iterator end;
    Predicate predicate;
};

// 辅助函数，用于创建惰性迭代器
template<typename Container, typename Predicate>
LazyFilterIterator<typename Container::iterator, Predicate> make_lazy_filter_iterator(Container& container, Predicate pred) {
    return LazyFilterIterator<typename Container::iterator, Predicate>(container.begin(), container.end(), pred);
}

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    // 使用lambda表达式定义过滤条件
    auto is_even = [](int n) { return n % 2 == 0; };

    // 创建惰性迭代器
    auto lazy_iter = make_lazy_filter_iterator(numbers, is_even);

    // 使用惰性迭代器遍历并打印符合条件的元素
    while (lazy_iter.hasNext()) {
        std::cout << lazy_iter.next() << " ";
    }

    return 0;
}