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

// license: Apache-2.0

// reference solution for: dslings/cpp11/05-move-semantics-0.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-0.cpp

//

// 教学要点: 让 Buffer 在拷贝时也"转移"资源, 只做一次资源分配和释放,

// 这样每个传递点最终都指向同一块缓冲区, 三个 d2x_assert 都通过。

#include <d2x/cpp/common.hpp>

#include <iostream>

struct Buffer {

int *data;

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

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

}

// 让 "拷贝" 也变成转移资源, 保证只做一次分配/释放

Buffer(const Buffer &other) {

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

data = other.data;

const_cast<Buffer&>(other).data = nullptr;

}

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() {

if (data) {

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

delete[] data;

}

}

const int * data_ptr() const { return data; }

};

Buffer process(Buffer buff) {

std::cout << "process(): " << buff.data << std::endl;

return buff;

}

int main() {

{

Buffer buff1 = process(Buffer());

auto buff1DataPtr = buff1.data_ptr();

std::cout << " --- " << std::endl;

Buffer buff2(std::move(buff1));

auto buff2DataPtr = buff2.data_ptr();

d2x_assert(buff1DataPtr == buff2DataPtr);

Buffer buff3 = buff2;

auto buff3DataPtr = buff3.data_ptr();

d2x_assert(buff2DataPtr == buff3DataPtr);

Buffer buff4 = process(buff3);

auto buff4DataPtr = buff4.data_ptr();

d2x_assert(buff3DataPtr == buff4DataPtr);

}

return 0;

}