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  1. 	#include <iostream>
  2.  
  3. 	template<typename T, size_t D>
  4. 	struct VectorBase;
  5.  
  6. 	template<typename T>
  7. 	struct VectorBase<T, 2>
  8. 	{
  9. 		constexpr VectorBase() : v{} {}
  10. 		union {
  11. 			T v[2];
  12. 			struct { T x, y; };
  13. 		};
  14. 	};
  15.  
  16. 	template<typename T>
  17. 	struct VectorBase<T, 3>
  18. 	{
  19. 		constexpr VectorBase() : v{} {}
  20. 		union {
  21. 			T v[3];
  22. 			struct { T x, y, z; };
  23. 		};
  24. 	};
  25.  
  26. 	template<typename T>
  27. 	struct VectorBase<T, 4>
  28. 	{
  29. 		constexpr VectorBase() : v{} {}
  30. 		union {
  31. 			T v[4];
  32. 			struct { T x, y, z, w; };
  33. 		};
  34. 	};
  35.  
  36. 	template<typename T, size_t D>
  37. 	struct Vector : public VectorBase<T, D>
  38. 	{
  39. 		using VectorBase<T, D>::v;
  40. 		using size_type = decltype(D);
  41. 		using value_type = T;
  42.  
  43. 		constexpr Vector() : VectorBase<T,D>{} {}
  44. 		constexpr Vector(T scalar) {
  45. 			std::fill(std::begin(v), std::end(v), scalar);
  46. 		}
  47.  
  48. 		constexpr T& operator[](size_type i) const noexcept { return v[i]; }
  49. 		constexpr const T& operator[](size_type i) noexcept { return v[i]; }
  50.  
  51. 		constexpr size_type size() const noexcept { return D; }
  52.  
  53. 		constexpr T* data() noexcept { return &v[0]; }
  54. 		constexpr const T* data() const noexcept { return &v[0]; }
  55. 	};
  56.  
  57.     template<typename T>
  58.     using Vector2 = Vector<T, 2>;
  59.     template<typename T>
  60.     using Vector3 = Vector<T, 3>;
  61.     template<typename T>
  62.     using Vector4 = Vector<T, 4>;
  63.  
  64. 	int main() {
  65. 		Vector3<int> v{1};
  66.  
  67. 		std::cout << v[0] << ", " << v.z << "\n";
  68. 		return 0;
  69. 	}
  70.  
  71.  
Success #stdin #stdout 0s 3468KB
comments (?)
stdin 
Standard input is empty
stdout 
1, 1
https://ideone.com/T3QHoq
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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