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| #include <iostream>
#include <string>
#include <functional>
#include <cmath>
#include <utility>
#include <algorithm>
// 图形基类，使用std::function替代虚函数
class Figure {
public:
// 定义函数类型
using GetNameFunc = std::function<std::string()>;
using GetAreaFunc = std::function<double()>;
// 构造函数，接受函数对象并移动它们
Figure(GetNameFunc nameFunc, GetAreaFunc areaFunc)
: getNameFunc(std::move(nameFunc)),
getAreaFunc(std::move(areaFunc)) {}
// 移动构造函数
Figure(Figure&& other) noexcept
: getNameFunc(std::move(other.getNameFunc)),
getAreaFunc(std::move(other.getAreaFunc)) {}
// 移动赋值运算符
Figure& operator=(Figure&& other) noexcept {
if (this != &other) {
getNameFunc = std::move(other.getNameFunc);
getAreaFunc = std::move(other.getAreaFunc);
}
return *this;
}
// 禁用拷贝操作
Figure(const Figure&) = delete;
Figure& operator=(const Figure&) = delete;
// 接口方法
std::string getName() const { return getNameFunc(); }
double getArea() const { return getAreaFunc(); }
virtual ~Figure() = default;
private:
GetNameFunc getNameFunc;
GetAreaFunc getAreaFunc;
};
// 矩形类
class Rectangle : public Figure {
public:
Rectangle(double len, double wid)
: Figure(
[this]() { return "矩形"; },
[this]() { return _length * _width; }),
_length(len), _width(wid) {}
// 移动构造函数
Rectangle(Rectangle&& other) noexcept
: Figure(std::move(other)),
_length(std::exchange(other._length, 0)),
_width(std::exchange(other._width, 0)) {}
// 移动赋值运算符
Rectangle& operator=(Rectangle&& other) noexcept {
if (this != &other) {
Figure::operator=(std::move(other));
_length = std::exchange(other._length, 0);
_width = std::exchange(other._width, 0);
}
return *this;
}
// 禁用拷贝操作
Rectangle(const Rectangle&) = delete;
Rectangle& operator=(const Rectangle&) = delete;
private:
double _length;
double _width;
};
// 圆形类
class Circle : public Figure {
public:
Circle(double radius)
: Figure(
[this]() { return "圆形"; },
[this]() { return M_PI * _radius * _radius; }),
_radius(radius) {}
// 移动构造函数
Circle(Circle&& other) noexcept
: Figure(std::move(other)),
_radius(std::exchange(other._radius, 0)) {}
// 移动赋值运算符
Circle& operator=(Circle&& other) noexcept {
if (this != &other) {
Figure::operator=(std::move(other));
_radius = std::exchange(other._radius, 0);
}
return *this;
}
// 禁用拷贝操作
Circle(const Circle&) = delete;
Circle& operator=(const Circle&) = delete;
private:
double _radius;
};
// 三角形类
class Triangle : public Figure {
public:
Triangle(double a, double b, double c)
: Figure(
[this]() { return "三角形"; },
[this]() {
double p = (_a + _b + _c) / 2;
return std::sqrt(p * (p - _a) * (p - _b) * (p - _c));
}),
_a(a), _b(b), _c(c) {}
// 移动构造函数
Triangle(Triangle&& other) noexcept
: Figure(std::move(other)),
_a(std::exchange(other._a, 0)),
_b(std::exchange(other._b, 0)),
_c(std::exchange(other._c, 0)) {}
// 移动赋值运算符
Triangle& operator=(Triangle&& other) noexcept {
if (this != &other) {
Figure::operator=(std::move(other));
_a = std::exchange(other._a, 0);
_b = std::exchange(other._b, 0);
_c = std::exchange(other._c, 0);
}
return *this;
}
// 禁用拷贝操作
Triangle(const Triangle&) = delete;
Triangle& operator=(const Triangle&) = delete;
private:
double _a, _b, _c;
};
// 显示图形信息的函数
void display(const Figure& fig) {
std::cout << fig.getName() << "的面积：" << fig.getArea() << std::endl;
}
// 测试函数
void test() {
// 创建图形对象
Rectangle rect(3, 4);
Circle circle(5);
Triangle triangle(3, 4, 5);
std::cout << "初始对象：" << std::endl;
display(rect);
display(circle);
display(triangle);
// 演示移动语义
std::cout << "\n移动后：" << std::endl;
Rectangle rect2 = std::move(rect);
Circle circle2 = std::move(circle);
Triangle triangle2 = std::move(triangle);
display(rect2);
display(circle2);
display(triangle2);
}
int main() {
test();
return 0;
}
|
