// d2mcpp: https://github.com/mcpp-community/d2mcpp

// license: Apache-2.0

// reference solution for: dslings/cpp11/05-move-semantics-2.cpp

//

// 用途: 仅给 CI 与维护者参考使用，不是教程入口。

// 教程练习入口: dslings/cpp11/05-move-semantics-2.cpp

//

#include <d2x/cpp/common.hpp>

#include <iostream>

struct Buffer {

int *data;

Buffer() : data { new int[2] {0, 1} } {

std::cout << "Buffer():" << data << std::endl;

}

Buffer(const Buffer &other) {

std::cout << "Buffer(const Buffer&):" << data << std::endl;

data = new int[2];

data[0] = other.data[0];

data[1] = other.data[1];

}

Buffer(Buffer&& other) : data { other.data } {

std::cout << "Buffer(Buffer&&):" << data << std::endl;

other.data = nullptr; // 让原对象的指针失效

}

Buffer & operator=(const Buffer &other) {

std::cout << "Buffer& operator=(const Buffer&):" << data << std::endl;

if (this != &other) {

delete[] data; // 释放旧资源

data = new int[2];

data[0] = other.data[0];

data[1] = other.data[1];

}

return *this;

}

Buffer & operator=(Buffer&& other) {

std::cout << "Buffer& operator=(Buffer&&):" << data << std::endl;

if (this != &other) {

delete[] data; // 释放旧资源 - 步骤1

data = other.data; // 转移资源 - 步骤2

other.data = nullptr; // 让原对象的指针失效 - 步骤3

}

return *this;

}

~Buffer() {

if (data) {

std::cout << "~Buffer():" << data << std::endl;

delete[] data;

}

}

const int * data_ptr() const {

return data;

}

};

int main() { // 移动语义 - 移动的是资源而不是对象演示

{

Buffer b1; // 调用默认构造函数

auto old_b1_data_ptr = b1.data_ptr();

Buffer b2 = std::move(b1); // 触发移动构造

d2x_assert(&b1 != &b2); // b1 和 b2 是不同的对象

d2x_assert(old_b1_data_ptr == b2.data_ptr());

d2x_assert(b1.data_ptr() == nullptr); // b1 的资源被移动了

}

return 0;

}