C++中如何实现策略模式 函数对象与lambda表达式应用

#include <iostream>
#include <vector>
#include <algorithm>

// 策略接口 (使用std::function)
using SortingStrategy = std::function<void(std::vector<int>&)>;

// 上下文类
class Sorter {
public:
    Sorter(SortingStrategy strategy) : sortingStrategy(strategy) {}

    void sort(std::vector<int>& data) {
        sortingStrategy(data);
    }

    void setStrategy(SortingStrategy strategy) {
        sortingStrategy = strategy;
    }

private:
    SortingStrategy sortingStrategy;
};

// 具体策略 (Lambda 表达式)
auto bubbleSort = [](std::vector<int>& data) {
    std::cout << "Using Bubble Sort" << std::endl;
    // Bubble Sort 实现 (简化)
    for (size_t i = 0; i < data.size() - 1; ++i) {
        for (size_t j = 0; j < data.size() - i - 1; ++j) {
            if (data[j] > data[j + 1]) {
                std::swap(data[j], data[j + 1]);
            }
        }
    }
};

auto quickSort = [](std::vector<int>& data) {
    std::cout << "Using Quick Sort (std::sort)" << std::endl;
    // 使用 std::sort 实现快速排序
    std::sort(data.begin(), data.end());
};

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

    // 使用 Bubble Sort
    Sorter sorter(bubbleSort);
    sorter.sort(numbers);
    for (int num : numbers) {
        std::cout << num << " ";
    }
    std::cout << std::endl;

    numbers = {5, 2, 8, 1, 9, 4}; // 重置数据

    // 切换到 Quick Sort
    sorter.setStrategy(quickSort);
    sorter.sort(numbers);
    for (int num : numbers) {
        std::cout << num << " ";
    }
    std::cout << std::endl;

    return 0;
}