#include "crany.hpp"
 
 #include <cmath>
 #include <iostream>
 #include <vector>
 
 
 auto constexpr pi = std::acos(-1.0F);
 
 
 struct Circle
 {
     float radius;
     void  scale(float scale)       { radius *= scale;         }
     float area()             const { return pi*radius*radius; }
     float circumference()    const { return 2.0F*pi*radius;   }
 };
 
 struct Rectangle
 {
     float side1;
     float side2;
     void  scale(float scale)       { side1 *= scale; side2 *= scale; }
     float area()             const { return side1*side2;             }
 };
 
 
 template<typename Self>
 struct ShapeConcept : Self
 {
     using Self::self;
     virtual void  scale(float value)       { return self().scale(value); }
     virtual float area()             const { return self().area();       }
 };
 
 using Shape = Crany<ShapeConcept>;
 using Shapes = std::vector<Shape>;
 
 
 int main()
 {
     static_assert(std::is_standard_layout   <Circle>{}, "Circle not is standard layout");
     static_assert(std::is_trivially_copyable<Circle>{}, "Circle not is trivially copyable");
 
     auto shapes = Shapes{
         Circle{1.0F},
         Rectangle{2.0F, 3.0F},
     };
     shapes.push_back(shapes.front());
     shapes.back().scale(2.0F);
 
     std::cout << std::boolalpha;
     for (auto const & shape : shapes)
         std::cout
             << shape.area()
             << " "
             << bool(crany_cast<Circle>(&shape))
             << "\n";
 }