Drill 17: Explain each line — Move semantics

#include <cstddef>
#include <iostream>
#include <utility>
#include <vector>

class Buffer {
public:
    explicit Buffer(std::vector<int> data) : data_(std::move(data)) {}

    Buffer(Buffer&& other) noexcept : data_(std::move(other.data_)) {}

    Buffer& operator=(Buffer&& other) noexcept {
        data_ = std::move(other.data_);
        return *this;
    }

    std::size_t size() const { return data_.size(); }

private:
    std::vector<int> data_;
};

Buffer make_buffer() {
    std::vector<int> values{1, 2, 3, 4};
    return Buffer{std::move(values)};
}

int main() {
    Buffer a = make_buffer();
    Buffer b = std::move(a);
    std::cout << b.size() << "\n";
}