boost/math/common_factor_ct.hpp

   1 //  Boost common_factor_ct.hpp header file  ----------------------------------//
   2
   3 //  (C) Copyright Daryle Walker and Stephen Cleary 2001-2002.
   4 //  Distributed under the Boost Software License, Version 1.0. (See
   5 //  accompanying file LICENSE_1_0.txt or copy at
   6 //  http://www.boost.org/LICENSE_1_0.txt)
   7
   8 //  See http://www.boost.org for updates, documentation, and revision history.
   9
  10 #ifndef BOOST_MATH_COMMON_FACTOR_CT_HPP
  11 #define BOOST_MATH_COMMON_FACTOR_CT_HPP
  12
  13 #include <boost/math_fwd.hpp>  // self include
  14
  15 #include <boost/config.hpp>  // for BOOST_STATIC_CONSTANT, etc.
  16
  17
  18 namespace boost
  19 {
  20 namespace math
  21 {
  22
  23
  24 //  Implementation details  --------------------------------------------------//
  25
  26 namespace detail
  27 {
  28 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  29     // Build GCD with Euclid's recursive algorithm
  30     template < unsigned long Value1, unsigned long Value2 >
  31     struct static_gcd_helper_t
  32     {
  33     private:
  34         BOOST_STATIC_CONSTANT( unsigned long, new_value1 = Value2 );
  35         BOOST_STATIC_CONSTANT( unsigned long, new_value2 = Value1 % Value2 );
  36
  37         #ifndef __BORLANDC__
  38         #define BOOST_DETAIL_GCD_HELPER_VAL(Value) static_cast<unsigned long>(Value)
  39         #else
  40         typedef static_gcd_helper_t  self_type;
  41         #define BOOST_DETAIL_GCD_HELPER_VAL(Value)  (self_type:: Value )
  42         #endif
  43
  44         typedef static_gcd_helper_t< BOOST_DETAIL_GCD_HELPER_VAL(new_value1),
  45          BOOST_DETAIL_GCD_HELPER_VAL(new_value2) >  next_step_type;
  46
  47         #undef BOOST_DETAIL_GCD_HELPER_VAL
  48
  49     public:
  50         BOOST_STATIC_CONSTANT( unsigned long, value = next_step_type::value );
  51     };
  52
  53     // Non-recursive case
  54     template < unsigned long Value1 >
  55     struct static_gcd_helper_t< Value1, 0UL >
  56     {
  57         BOOST_STATIC_CONSTANT( unsigned long, value = Value1 );
  58     };
  59 #else
  60     // Use inner class template workaround from Peter Dimov
  61     template < unsigned long Value1 >
  62     struct static_gcd_helper2_t
  63     {
  64         template < unsigned long Value2 >
  65         struct helper
  66         {
  67             BOOST_STATIC_CONSTANT( unsigned long, value
  68              = static_gcd_helper2_t<Value2>::BOOST_NESTED_TEMPLATE
  69              helper<Value1 % Value2>::value );
  70         };
  71
  72         template <  >
  73         struct helper< 0UL >
  74         {
  75             BOOST_STATIC_CONSTANT( unsigned long, value = Value1 );
  76         };
  77     };
  78
  79     // Special case
  80     template <  >
  81     struct static_gcd_helper2_t< 0UL >
  82     {
  83         template < unsigned long Value2 >
  84         struct helper
  85         {
  86             BOOST_STATIC_CONSTANT( unsigned long, value = Value2 );
  87         };
  88     };
  89
  90     // Build the GCD from the above template(s)
  91     template < unsigned long Value1, unsigned long Value2 >
  92     struct static_gcd_helper_t
  93     {
  94         BOOST_STATIC_CONSTANT( unsigned long, value
  95          = static_gcd_helper2_t<Value1>::BOOST_NESTED_TEMPLATE
  96          helper<Value2>::value );
  97     };
  98 #endif
  99
 100 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 101     // Build the LCM from the GCD
 102     template < unsigned long Value1, unsigned long Value2 >
 103     struct static_lcm_helper_t
 104     {
 105         typedef static_gcd_helper_t<Value1, Value2>  gcd_type;
 106
 107         BOOST_STATIC_CONSTANT( unsigned long, value = Value1 / gcd_type::value
 108          * Value2 );
 109     };
 110
 111     // Special case for zero-GCD values
 112     template < >
 113     struct static_lcm_helper_t< 0UL, 0UL >
 114     {
 115         BOOST_STATIC_CONSTANT( unsigned long, value = 0UL );
 116     };
 117 #else
 118     // Adapt GCD's inner class template workaround for LCM
 119     template < unsigned long Value1 >
 120     struct static_lcm_helper2_t
 121     {
 122         template < unsigned long Value2 >
 123         struct helper
 124         {
 125             typedef static_gcd_helper_t<Value1, Value2>  gcd_type;
 126
 127             BOOST_STATIC_CONSTANT( unsigned long, value = Value1
 128              / gcd_type::value * Value2 );
 129         };
 130
 131         template <  >
 132         struct helper< 0UL >
 133         {
 134             BOOST_STATIC_CONSTANT( unsigned long, value = 0UL );
 135         };
 136     };
 137
 138     // Special case
 139     template <  >
 140     struct static_lcm_helper2_t< 0UL >
 141     {
 142         template < unsigned long Value2 >
 143         struct helper
 144         {
 145             BOOST_STATIC_CONSTANT( unsigned long, value = 0UL );
 146         };
 147     };
 148
 149     // Build the LCM from the above template(s)
 150     template < unsigned long Value1, unsigned long Value2 >
 151     struct static_lcm_helper_t
 152     {
 153         BOOST_STATIC_CONSTANT( unsigned long, value
 154          = static_lcm_helper2_t<Value1>::BOOST_NESTED_TEMPLATE
 155          helper<Value2>::value );
 156     };
 157 #endif
 158
 159 }  // namespace detail
 160
 161
 162 //  Compile-time greatest common divisor evaluator class declaration  --------//
 163
 164 template < unsigned long Value1, unsigned long Value2 >
 165 struct static_gcd
 166 {
 167     BOOST_STATIC_CONSTANT( unsigned long, value
 168      = (detail::static_gcd_helper_t<Value1, Value2>::value) );
 169
 170 };  // boost::math::static_gcd
 171
 172
 173 //  Compile-time least common multiple evaluator class declaration  ----------//
 174
 175 template < unsigned long Value1, unsigned long Value2 >
 176 struct static_lcm
 177 {
 178     BOOST_STATIC_CONSTANT( unsigned long, value
 179      = (detail::static_lcm_helper_t<Value1, Value2>::value) );
 180
 181 };  // boost::math::static_lcm
 182
 183
 184 }  // namespace math
 185 }  // namespace boost
 186
 187
 188 #endif  // BOOST_MATH_COMMON_FACTOR_CT_HPP