template_tools.h - Engine C API Reference

template_tools.h
  1. #pragma once
  3. #include "assert.h"
  5. namespace stingray_plugin_foundation {
  7. // Convert integer to type.
  8. template <int v>
  9. struct Int2Type { enum {value=v}; };
  11. // Determines if a class is allocator aware.
  12. template <class T>
  13. struct is_allocator_aware {
  15.     template <typename C>
  16.     static char test_fun(typename C::allocator_aware *);
  18.     template <typename C>
  19.     static int test_fun(...);
  21. public:
  22.     enum {
  23.         value = (sizeof(test_fun<T>(0)) == sizeof(char))
  24.     };
  25. };
  27. #define IS_ALLOCATOR_AWARE(T) is_allocator_aware<T>::value
  28. #define IS_ALLOCATOR_AWARE_TYPE(T) Int2Type< IS_ALLOCATOR_AWARE(T) >
  30. // Allocator aware constuction
  31. template <class T> inline T &construct(void *p, Allocator &a, Int2Type<true>) {new (p) T(a); return *(T *)p;}
  33. template <class T> inline T &construct(void *p, Allocator &a, Int2Type<false>) {new (p) T; return *(T *)p;}
  35. template <class T> inline T &construct(void *p, Allocator &a) {return construct<T>(p, a, IS_ALLOCATOR_AWARE_TYPE(T)());}
  37. // Helper for casts using a union. This circumvents the aliasing problem that occurs when
  38. // trying to reinterpret a float as int and vice versa for example.
  39. template<typename A, typename B>
  40. A safe_reinterpret_cast(const B &b) {
  41.     static_assert(sizeof(A) == sizeof(B), "Types must have same size to be cast");
  42.     union U {
  43.         A a;
  44.         B b;
  45.     } u;
  46.     u.b = b;
  47.     return u.a;
  48. }
  50. }
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