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  1. #include <cstddef>
  2. #include <iostream>
  3.  
  4. class MenuItem {
  5.     public:
  6. 		constexpr MenuItem (const char* label, size_t subitems)
  7. 			: m_label (label), m_subitems (subitems) { }
  8.  
  9. 		virtual void onKey () const = 0;
  10. 		virtual void onEvent () const = 0;
  11. 		virtual void onDraw () const = 0;
  12.  
  13. 		const char* const m_label;
  14. 		size_t m_subitems;
  15. //		int m_flags;	// Keine Ahnung was das in deinem Code macht, hier würde man das Äquivalent hinpacken
  16. //		void  *Data;
  17. };
  18.  
  19. template <typename... Rest>
  20. class MenuContainer {};
  21.  
  22. template <typename First, typename... Rest>
  23. class MenuContainer<First, Rest...> {
  24. 	public:
  25. 		constexpr MenuContainer (const First& src, const Rest&... rest) : m_item (src), m_rest (rest...) {
  26. 			static_assert (sizeof (First) == sizeof (MenuItem), "All menu items classes must have the same size!");
  27. 		}
  28. 	private:
  29. 		const First m_item;
  30. 		const MenuContainer<Rest...> m_rest;
  31. };
  32.  
  33. template <>
  34. class MenuContainer<> {};
  35.  
  36. template <typename... Items>
  37. class Menu {
  38. 	public:
  39. 		constexpr Menu (const Items&... items) : m_items (items...) {}
  40.  
  41. 		const MenuItem& operator [] (size_t index) const { return ptr () [index]; }
  42.  
  43. 		size_t getSize () const { return sizeof...(Items); }
  44.  
  45. 		const MenuItem* begin () const { return ptr (); }
  46. 		const MenuItem* end () const { return ptr ()+getSize (); }
  47. 	private:
  48. 		const MenuContainer<Items...> m_items;
  49. 		const MenuItem* ptr () const { return reinterpret_cast<const MenuItem*>(&m_items); }
  50. };
  51.  
  52.  
  53.  
  54. class MyMenuItem1 : public MenuItem {
  55. 	public:
  56. 		constexpr MyMenuItem1 (const char* label, size_t subitems)
  57. 			: MenuItem (label, subitems) { }
  58.  
  59. 		virtual void onKey () const {
  60. 			std::cout << "MyMenuAction1::onKey\n";
  61. 		}
  62. 		virtual void onEvent () const {
  63. 			std::cout << "MyMenuAction1::onEvent\n";
  64. 		}
  65. 		virtual void onDraw () const {
  66. 			std::cout << "MyMenuAction1::onDraw\n";
  67. 		}
  68. };
  69.  
  70. class MyMenuItem2 : public MenuItem {
  71. 	public:
  72. 		constexpr MyMenuItem2 (const char* label, size_t subitems)
  73. 			: MenuItem (label, subitems) { }
  74.  
  75. 		virtual void onKey () const {
  76. 			std::cout << "MyMenuAction2::onKey\n";
  77. 		}
  78. 		virtual void onEvent () const {
  79. 			std::cout << "MyMenuAction2::onEvent\n";
  80. 		}
  81. 		virtual void onDraw () const {
  82. 			std::cout << "MyMenuAction2::onDraw\n";
  83. 		}
  84. };
  85.  
  86. template <typename... Items>
  87. constexpr const Menu<Items...> makeMenu (const Items&... items) {
  88. 	return Menu<Items...> (items...);
  89. }
  90.  
  91. constexpr const auto myMainMenu = makeMenu (MyMenuItem1 {"Hello", 0}, MyMenuItem2 {"World", 0});
  92.  
  93. int main () {
  94. 	for (auto& item : myMainMenu) {
  95. 		std::cout << item.m_label << std::endl;
  96. 	}
  97. 	myMainMenu [0].onDraw ();
  98. 	myMainMenu [1].onKey ();
  99. }
  100.  
Success #stdin #stdout 0s 3340KB
comments (?)
stdin
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Standard input is empty
stdout
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Hello
World
MyMenuAction1::onDraw
MyMenuAction2::onKey
https://ideone.com/Xfo20K
C constexpr ROM menu
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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