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if.hh
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26 
27 #ifndef MLN_METAL_IF_HH
28 # define MLN_METAL_IF_HH
29 
35 # include <mln/metal/bool.hh>
36 
37 # define mlc_if(Cond, Then, Else) typename mln::metal::if_< Cond, Then, Else >::ret
38 
39 
40 
41 namespace mln
42 {
43 
44  namespace metal
45  {
46 
47  namespace internal
48  {
49 
50  template <bool cond, typename Then, typename Else>
51  struct helper_if_;
52 
53  template <typename Then, typename Else>
54  struct helper_if_< true, Then, Else >
55  {
56  typedef Then ret;
57  };
58 
59  template <typename Then, typename Else>
60  struct helper_if_< false, Then, Else >
61  {
62  typedef Else ret;
63  };
64 
65  } // end of namespace mln::metal::internal
66 
67 
74  template <typename Cond, typename Then, typename Else>
75  struct if_ : internal::helper_if_< Cond::value, Then, Else >
76  {
77  // ret is inherited.
78  };
79 
80 
81  } // end of namespace mln::metal
82 
83 } // end of namespace mln
84 
85 
86 #endif // ! MLN_METAL_IF_HH