1 ////////////////////////////////////////////////////////////////////
2 //
3 // Copyright Vicente J. Botet Escriba 2010
4 //
5 // Distributed under the Boost Software License, Version 1.0.
6 // (See accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt)
8 //
9 // See http://www.boost.org/libs/mpl for documentation.
10 //
11 ////////////////////////////////////////////////////////////////////
12 #ifndef BOOST_MPL_LCM_HPP_INCLUDED
13 #define BOOST_MPL_LCM_HPP_INCLUDED
14 
15 #include <boost/mpl/integral_c.hpp>
16 #include <boost/ratio/detail/mpl/abs.hpp>
17 #include <boost/mpl/aux_/largest_int.hpp>
18 #include <boost/mpl/aux_/na_spec.hpp>
19 #include <boost/mpl/aux_/lambda_support.hpp>
20 #include <boost/mpl/aux_/config/integral.hpp>
21 #include <boost/mpl/aux_/config/static_constant.hpp>
22 #include <boost/mpl/aux_/config/dependent_nttp.hpp>
23 #include <boost/cstdint.hpp>
24 
25 #if    !defined(BOOST_MPL_CFG_NO_NESTED_VALUE_ARITHMETIC_2) \
26     && !defined(BOOST_MPL_PREPROCESSING_MODE) \
27     && !defined(__CUDACC__) \
28     && ( defined(BOOST_MSVC) \
29         || BOOST_WORKAROUND(__EDG_VERSION__, <= 238) \
30         )
31 
32 #   define BOOST_MPL_CFG_NO_NESTED_VALUE_ARITHMETIC_2
33 
34 #endif
35 
36 namespace boost { namespace mpl {
37 
38 template< typename Tag1, typename Tag2 > struct lcm_impl;
39 
40 template< typename T > struct lcm_tag
41 {
42     typedef typename T::tag type;
43 };
44 
45 template<
46       typename BOOST_MPL_AUX_NA_PARAM(N1)
47     , typename BOOST_MPL_AUX_NA_PARAM(N2)
48     >
49 struct lcm
50     : lcm_impl<
51           typename lcm_tag<N1>::type
52         , typename lcm_tag<N2>::type
53         >::template apply<N1, N2>::type
54 {
55     BOOST_MPL_AUX_LAMBDA_SUPPORT(2, lcm, (N1, N2))
56 };
57 
58 BOOST_MPL_AUX_NA_SPEC(2, lcm)
59 
60 template<
61       typename T
62     , T n1
63     , T n2
64     >
65 struct lcm_c
66     : lcm<integral_c<T,n1>,integral_c<T,n2> >
67 {
68 };
69 
70 
71 namespace aux {
72   // Workaround for error: the type of partial specialization template parameter constant "n2"
73   // depends on another template parameter
74   // Note: this solution could be wrong for n1 or n2 = [2**63 .. 2**64-1]
75   #if defined(BOOST_MPL_CFG_NO_DEPENDENT_NONTYPE_PARAMETER_IN_PARTIAL_SPEC)
76   template< typename T1, boost::intmax_t n1, bool n1_is_0
77                           , typename T2, boost::intmax_t n2, bool n2_is_0 >
78       struct lcm_aux
79           : abs<integral_c< typename aux::largest_int<T1, T2>::type,
80               ( n1 / gcd<integral_c<T1,n1>, integral_c<T2,n2> >::value * n2 )
81           > >
82       {};
83 
84       template <typename T1, boost::intmax_t n1, typename T2, boost::intmax_t n2>
85       struct lcm_aux<T1, n1, false, T2, n2, true> : integral_c<T2, 0>
86       {};
87 
88       template <typename T1, boost::intmax_t n1, typename T2, boost::intmax_t n2, bool C>
89       struct lcm_aux<T1, n1, true, T2, n2, C> : integral_c<T1, 0>
90       {};
91 
92 
93 #else // defined(BOOST_MPL_CFG_NO_DEPENDENT_NONTYPE_PARAMETER_IN_PARTIAL_SPEC)
94 
95 
96     template< typename T1, T1 n1, bool n1_is_0, typename T2, T2 n2, bool n2_is_0 >
97     struct lcm_aux
98 
99         : abs<integral_c< typename aux::largest_int<T1, T2>::type,
100             ( n1 / gcd<integral_c<T1,n1>, integral_c<T2,n2> >::value * n2 )
101         > >
102     {};
103 
104     template <typename T1, T1 n1, typename T2, T2 n2>
105     struct lcm_aux<T1, n1, false, T2, n2, true> : integral_c<T2, 0>
106     {};
107 
108     template <typename T1, T1 n1, typename T2, T2 n2, bool C>
109     struct lcm_aux<T1, n1, true, T2, n2, C> : integral_c<T1, 0>
110     {};
111 #endif // defined(BOOST_MPL_CFG_NO_DEPENDENT_NONTYPE_PARAMETER_IN_PARTIAL_SPEC)
112 }
113 
114 template<>
115 struct lcm_impl<integral_c_tag, integral_c_tag>
116 {
117     template< typename N1, typename N2 > struct apply
118         : abs<aux::lcm_aux< typename N1::value_type, N1::value, N1::value==0,
119                         typename N2::value_type, N2::value, N2::value==0  > >
120     {
121     };
122 };
123 
124 }}
125 
126 #endif // BOOST_MPL_LCM_HPP_INCLUDED
127