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Sacado_mpl_is_convertible.hpp
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29 
30 #ifndef SACADO_MPL_IS_CONVERTIBLE_HPP
31 #define SACADO_MPL_IS_CONVERTIBLE_HPP
32 
33 #include "Sacado_ConfigDefs.h"
34 
35 #ifdef HAVE_SACADO_CXX11
36 
37 #include <type_traits>
38 namespace Sacado {
39  namespace mpl {
40  using std::is_convertible;
41  }
42 }
43 
44 #else
45 
46 namespace Sacado {
47 
48  namespace mpl {
49 
50  //
51  // A simplified implementation of boost type-trait
52  // is_convertible<From,To>. We use this in a much more limited context
53  // within Sacado, and so the easy implementation should always work.
54  // We assume From and To are "scalar" types, e.g., are not pointer or
55  // reference types.
56  //
57 
59  typedef char yes; // sizeof(yes) == 1
60  typedef char (&no)[2]; // sizeof(no) == 2
61 
62  // A function that takes anything convertible to a To
63  template <typename To> static yes tester(To);
64 
65  // Overload resolution prefers anything over ...
66  template <typename To> static no tester(...);
67 
68  // Check if From is convertible to To
69  template <typename From, typename To>
70  struct checker {
71  static From& f;
72  static const bool value = sizeof(tester<To>(f)) == sizeof(yes);
73  };
74  };
75 
76  template <typename From, typename To>
77  struct is_convertible {
79  };
80 
81  }
82 
83 }
84 
85 #endif
86 
87 #endif // SACADO_MPL_IS_CONVERTIBLE_HPP