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force_exact.hh
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25 
26 #ifndef MLN_CORE_INTERNAL_FORCE_EXACT_HH
27 # define MLN_CORE_INTERNAL_FORCE_EXACT_HH
28 
31 
32 #include <cstddef>
33 
34 
35 namespace mln
36 {
37 
38  namespace internal
39  {
40 
49  template <typename E, typename T>
50  E& force_exact(const T& ref)
51  {
52  static const E* exact_obj;
53  static const T& exact_obj_ref = *exact_obj;
54  static const ptrdiff_t exact_offset =
55  (const char*)(void*)(&exact_obj_ref)
56  - (const char*)(void*)(exact_obj);
57  return *(E*)((char*)(&ref) - exact_offset);
58  }
59 
60  } // end of namespace mln::internal
61 
62 } // end of namespace mln
63 
64 
65 #endif // ! MLN_CORE_INTERNAL_FORCE_EXACT_HH