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// Demo of polymorphism in C++
#include <iostream>
#include <memory>
#include <vector>
// Shape definition
// ============================================================
struct Point {
float x, y;
};
std::ostream& operator<<(std::ostream& os, const Point& p) {
os << " (" << p.x << "," << p.y << ")";
return os;
}
struct Shape {
virtual ~Shape();
virtual void draw() const = 0;
uint32_t color;
uint16_t style;
uint8_t thickness;
uint8_t hardness;
};
Shape::~Shape()
{
std::cout << "base destructed" << std::endl;
}
// Triangle implementation
// ============================================================
struct Triangle : public Shape
{
Triangle(Point a, Point b, Point c);
void draw() const override;
private: Point p[3];
};
Triangle::Triangle(Point a, Point b, Point c)
: p{a, b, c} {}
void Triangle::draw() const
{
std::cout << "Triangle :"
<< p[0] << p[1] << p[2]
<< std::endl;
}
// Polygon implementation
// ============================================================
struct Polygon : public Shape
{
~Polygon();
void draw() const override;
void addPoint(const Point& p);
private: std::vector<Point> points;
};
void Polygon::addPoint(const Point& p)
{
points.push_back(p);
}
Polygon::~Polygon()
{
std::cout << "poly destructed" << std::endl;
}
void Polygon::draw() const
{
std::cout << "Polygon :";
for (auto& p : points)
std::cout << p ;
std::cout << std::endl;
}
// Test
// ============================================================
void testShape(const Shape* shape)
{
shape->draw();
}
#include <array>
int main(void)
{
std::vector<std::unique_ptr<Shape>> shapes;
auto tri1 = std::make_unique<Triangle>(Point{5, 7}, Point{12, 7}, Point{12, 20});
auto pol1 = std::make_unique<Polygon>();
auto pol2 = std::make_unique<Polygon>();
for (auto& p: std::array<Point, 4>
{{{50, 72}, {123, 73}, {127, 201}, {828, 333}}})
pol1->addPoint(p);
for (auto& p: std::array<Point, 5>
{{{5, 7}, {12, 7}, {12, 20}, {82, 33}, {17, 56}}})
pol2->addPoint(p);
shapes.push_back(std::move(tri1));
shapes.push_back(std::move(pol1));
shapes.push_back(std::move(pol2));
for (auto& shape: shapes)
testShape(shape.get());
}
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