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pow.hh
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25 
26 #ifndef MLN_METAL_MATH_POW_HH
27 # define MLN_METAL_MATH_POW_HH
28 
34 # include <mln/metal/bool.hh>
35 # include <mln/metal/int.hh>
36 
37 
38 # define mlc_pow(X, N) typename mln::metal::math::pow< X, N >::ret
39 # define mlc_pow_int(x, n) mln::metal::math::pow_int< x, n >::value
40 
41 
42 
43 namespace mln
44 {
45 
46  namespace metal
47  {
48 
49  namespace math
50  {
51 
52  // pow_int<x, n>
53 
54  namespace impl
55  {
56 
57  template <int x, int n>
58  struct pow_int_
59  {
60  enum res_ { value = x * pow_int_<x, n-1>::value };
61  };
62 
63  template <int x>
64  struct pow_int_< x, 0 >
65  {
66  enum res_ { value = 1 };
67  };
68 
69  template <>
70  struct pow_int_< 0, 0 >;
71 
72 
73  // Entry.
74 
75  template <int x, int n, bool b>
76  struct pow_int_if_ : pow_int_<x, n>
77  {
78  };
79 
80  template <int x, int n>
81  struct pow_int_if_< x, n, false >
82  {
83  };
84 
85  }
86 
87  template <int x, int n>
88  struct pow_int : impl::pow_int_if_< x, n,
89  (n >= 0 && ! (x == 0 && n == 0)) >
90  {
91  };
92 
93 
94  // pow<X, N>
95 
96  template <typename X, typename N>
97  struct pow;
98 
99  template <int x, int n>
100  struct pow< int_<x>, int_<n> >
101  {
102  typedef int_< pow_int<x, n>::value > ret;
103  };
104 
105 
106  } // end of namespace mln::metal::math
107 
108  } // end of namespace mln::metal
109 
110 } // end of namespace mln
111 
112 
113 #endif // ! MLN_METAL_MATH_POW_HH