Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: /// \file functional.hpp
Chris@16: ///
Chris@16: //  Copyright 2005 Eric Niebler. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_NUMERIC_FUNCTIONAL_HPP_EAN_08_12_2005
Chris@16: #define BOOST_NUMERIC_FUNCTIONAL_HPP_EAN_08_12_2005
Chris@16: 
Chris@16: #include <limits>
Chris@16: #include <functional>
Chris@16: #include <boost/static_assert.hpp>
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: #include <boost/mpl/and.hpp>
Chris@16: #include <boost/type_traits/remove_const.hpp>
Chris@16: #include <boost/type_traits/add_reference.hpp>
Chris@16: #include <boost/type_traits/is_empty.hpp>
Chris@16: #include <boost/type_traits/is_integral.hpp>
Chris@16: #include <boost/type_traits/is_floating_point.hpp>
Chris@16: #include <boost/utility/enable_if.hpp>
Chris@16: #include <boost/typeof/typeof.hpp>
Chris@16: #include <boost/accumulators/accumulators_fwd.hpp>
Chris@16: #include <boost/accumulators/numeric/functional_fwd.hpp>
Chris@16: #include <boost/accumulators/numeric/detail/function1.hpp>
Chris@16: #include <boost/accumulators/numeric/detail/function2.hpp>
Chris@16: #include <boost/accumulators/numeric/detail/pod_singleton.hpp>
Chris@16: 
Chris@16: #ifdef BOOST_NUMERIC_FUNCTIONAL_STD_VECTOR_SUPPORT
Chris@16: # include <boost/accumulators/numeric/functional/vector.hpp>
Chris@16: #endif
Chris@16: 
Chris@16: #ifdef BOOST_NUMERIC_FUNCTIONAL_STD_VALARRAY_SUPPORT
Chris@16: # include <boost/accumulators/numeric/functional/valarray.hpp>
Chris@16: #endif
Chris@16: 
Chris@16: #ifdef BOOST_NUMERIC_FUNCTIONAL_STD_COMPLEX_SUPPORT
Chris@16: # include <boost/accumulators/numeric/functional/complex.hpp>
Chris@16: #endif
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: ///
Chris@16: #define BOOST_NUMERIC_FUNCTIONAL_HPP_INCLUDED
Chris@16: 
Chris@16: #ifdef BOOST_NUMERIC_FUNCTIONAL_DOXYGEN_INVOKED
Chris@16: // Hack to make Doxygen show the inheritance relationships
Chris@16: /// INTERNAL ONLY
Chris@16: ///
Chris@16: namespace std
Chris@16: {
Chris@16:     /// INTERNAL ONLY
Chris@16:     ///
Chris@16:     template<class Arg, class Ret> struct unary_function {};
Chris@16:     /// INTERNAL ONLY
Chris@16:     ///
Chris@16:     template<class Left, class Right, class Ret> struct binary_function {};
Chris@16: }
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost { namespace numeric
Chris@16: {
Chris@16:     namespace functional
Chris@16:     {
Chris@16:         /// INTERNAL ONLY
Chris@16:         ///
Chris@16:         template<typename A0, typename A1>
Chris@16:         struct are_integral
Chris@16:           : mpl::and_<is_integral<A0>, is_integral<A1> >
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename Left, typename Right>
Chris@16:         struct left_ref
Chris@16:         {
Chris@16:             typedef Left &type;
Chris@16:         };
Chris@16: 
Chris@16:         namespace detail
Chris@16:         {
Chris@16:             template<typename T>
Chris@16:             T &lvalue_of();
Chris@16:         }
Chris@16:     }
Chris@16: 
Chris@16:     // TODO: handle complex weight, valarray, MTL vectors
Chris@16: 
Chris@16:     /// INTERNAL ONLY
Chris@16:     ///
Chris@16: #define BOOST_NUMERIC_FUNCTIONAL_DEFINE_UNARY_OP(Name, Op)                                      \
Chris@16:     namespace functional                                                                        \
Chris@16:     {                                                                                           \
Chris@16:         template<typename Arg>                                                                  \
Chris@16:         struct result_of_ ## Name                                                               \
Chris@16:         {                                                                                       \
Chris@16:             BOOST_TYPEOF_NESTED_TYPEDEF_TPL(                                                    \
Chris@16:                 nested                                                                          \
Chris@16:               , Op boost::numeric::functional::detail::lvalue_of<Arg>()                         \
Chris@16:             )                                                                                   \
Chris@16:             typedef typename nested::type type;                                                 \
Chris@16:         };                                                                                      \
Chris@16:         template<typename Arg, typename EnableIf>                                               \
Chris@16:         struct Name ## _base                                                                    \
Chris@16:           : std::unary_function<                                                                \
Chris@16:                 typename remove_const<Arg>::type                                                \
Chris@16:               , typename result_of_ ## Name<Arg>::type                                          \
Chris@16:             >                                                                                   \
Chris@16:         {                                                                                       \
Chris@16:             typename result_of_ ## Name<Arg>::type operator ()(Arg &arg) const                  \
Chris@16:             {                                                                                   \
Chris@16:                 return Op arg;                                                                  \
Chris@16:             }                                                                                   \
Chris@16:         };                                                                                      \
Chris@16:         template<typename Arg, typename ArgTag>                                                 \
Chris@16:         struct Name                                                                             \
Chris@16:           : Name ## _base<Arg, void>                                                            \
Chris@16:         {};                                                                                     \
Chris@16:     }                                                                                           \
Chris@16:     namespace op                                                                                \
Chris@16:     {                                                                                           \
Chris@16:         struct Name                                                                             \
Chris@16:           : boost::detail::function1<functional::Name<_, functional::tag<_> > >                 \
Chris@16:         {};                                                                                     \
Chris@16:     }                                                                                           \
Chris@16:     namespace                                                                                   \
Chris@16:     {                                                                                           \
Chris@16:         op::Name const &Name = boost::detail::pod_singleton<op::Name>::instance;                \
Chris@16:     }                                                                                           \
Chris@16:     /**/
Chris@16: 
Chris@16:     /// INTERNAL ONLY
Chris@16:     ///
Chris@16: #define BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(Name, Op, RetType)                            \
Chris@16:     namespace functional                                                                        \
Chris@16:     {                                                                                           \
Chris@16:         template<typename Left, typename Right, typename EnableIf>                              \
Chris@16:         struct result_of_ ## Name                                                               \
Chris@16:         {                                                                                       \
Chris@16:             RetType(Left, Op, Right)                                                            \
Chris@16:         };                                                                                      \
Chris@16:         template<typename Left, typename Right, typename EnableIf>                              \
Chris@16:         struct Name ## _base                                                                    \
Chris@16:           : std::binary_function<                                                               \
Chris@16:                 typename remove_const<Left>::type                                               \
Chris@16:               , typename remove_const<Right>::type                                              \
Chris@16:               , typename result_of_ ## Name<Left, Right>::type                                  \
Chris@16:             >                                                                                   \
Chris@16:         {                                                                                       \
Chris@16:             typename result_of_ ## Name<Left, Right>::type                                      \
Chris@16:             operator ()(Left &left, Right &right) const                                         \
Chris@16:             {                                                                                   \
Chris@16:                 return left Op right;                                                           \
Chris@16:             }                                                                                   \
Chris@16:         };                                                                                      \
Chris@16:         template<typename Left, typename Right, typename LeftTag, typename RightTag>            \
Chris@16:         struct Name                                                                             \
Chris@16:           : Name ## _base<Left, Right, void>                                                    \
Chris@16:         {};                                                                                     \
Chris@16:     }                                                                                           \
Chris@16:     namespace op                                                                                \
Chris@16:     {                                                                                           \
Chris@16:         struct Name                                                                             \
Chris@16:           : boost::detail::function2<                                                           \
Chris@16:                 functional::Name<_1, _2, functional::tag<_1>, functional::tag<_2> >             \
Chris@16:             >                                                                                   \
Chris@16:         {};                                                                                     \
Chris@16:     }                                                                                           \
Chris@16:     namespace                                                                                   \
Chris@16:     {                                                                                           \
Chris@16:         op::Name const &Name = boost::detail::pod_singleton<op::Name>::instance;                \
Chris@16:     }                                                                                           \
Chris@16:     BOOST_ACCUMULATORS_IGNORE_GLOBAL(Name)                                                      \
Chris@16:     /**/
Chris@16: 
Chris@16:     /// INTERNAL ONLY
Chris@16:     ///
Chris@16: #define BOOST_NUMERIC_FUNCTIONAL_DEDUCED(Left, Op, Right)                                       \
Chris@16:     BOOST_TYPEOF_NESTED_TYPEDEF_TPL(                                                            \
Chris@16:         nested                                                                                  \
Chris@16:       , boost::numeric::functional::detail::lvalue_of<Left>() Op                                \
Chris@16:         boost::numeric::functional::detail::lvalue_of<Right>()                                  \
Chris@16:     )                                                                                           \
Chris@16:     typedef typename nested::type type;                                                         \
Chris@16:     /**/
Chris@16: 
Chris@16:     /// INTERNAL ONLY
Chris@16:     ///
Chris@16: #define BOOST_NUMERIC_FUNCTIONAL_LEFT(Left, Op, Right)                                          \
Chris@16:     typedef Left &type;                                                                         \
Chris@16:     /**/
Chris@16: 
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(plus, +, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(minus, -, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(multiplies, *, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(divides, /, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(modulus, %, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(greater, >, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(greater_equal, >=, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(less, <, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(less_equal, <=, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(equal_to, ==, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(not_equal_to, !=, BOOST_NUMERIC_FUNCTIONAL_DEDUCED)
Chris@16: 
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(assign, =, BOOST_NUMERIC_FUNCTIONAL_LEFT)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(plus_assign, +=, BOOST_NUMERIC_FUNCTIONAL_LEFT)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(minus_assign, -=, BOOST_NUMERIC_FUNCTIONAL_LEFT)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(multiplies_assign, *=, BOOST_NUMERIC_FUNCTIONAL_LEFT)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(divides_assign, /=, BOOST_NUMERIC_FUNCTIONAL_LEFT)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP(modulus_assign, %=, BOOST_NUMERIC_FUNCTIONAL_LEFT)
Chris@16: 
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_UNARY_OP(unary_plus, +)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_UNARY_OP(unary_minus, -)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_UNARY_OP(complement, ~)
Chris@16:     BOOST_NUMERIC_FUNCTIONAL_DEFINE_UNARY_OP(logical_not, !)
Chris@16: 
Chris@16: #undef BOOST_NUMERIC_FUNCTIONAL_LEFT
Chris@16: #undef BOOST_NUMERIC_FUNCTIONAL_DEDUCED
Chris@16: #undef BOOST_NUMERIC_FUNCTIONAL_DEFINE_UNARY_OP
Chris@16: #undef BOOST_NUMERIC_FUNCTIONAL_DEFINE_BINARY_OP
Chris@16: 
Chris@16:     namespace functional
Chris@16:     {
Chris@16:         template<typename Left, typename Right, typename EnableIf>
Chris@16:         struct min_assign_base
Chris@16:           : std::binary_function<Left, Right, void>
Chris@16:         {
Chris@16:             void operator ()(Left &left, Right &right) const
Chris@16:             {
Chris@16:                 if(numeric::less(right, left))
Chris@16:                 {
Chris@16:                     left = right;
Chris@16:                 }
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename Left, typename Right, typename EnableIf>
Chris@16:         struct max_assign_base
Chris@16:           : std::binary_function<Left, Right, void>
Chris@16:         {
Chris@16:             void operator ()(Left &left, Right &right) const
Chris@16:             {
Chris@16:                 if(numeric::greater(right, left))
Chris@16:                 {
Chris@16:                     left = right;
Chris@16:                 }
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename Left, typename Right, typename EnableIf>
Chris@16:         struct fdiv_base
Chris@16:           : functional::divides<Left, Right>
Chris@16:         {};
Chris@16: 
Chris@16:         // partial specialization that promotes the arguments to double for
Chris@16:         // integral division.
Chris@16:         template<typename Left, typename Right>
Chris@16:         struct fdiv_base<Left, Right, typename enable_if<are_integral<Left, Right> >::type>
Chris@16:           : functional::divides<double const, double const>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename To, typename From, typename EnableIf>
Chris@16:         struct promote_base
Chris@16:           : std::unary_function<From, To>
Chris@16:         {
Chris@16:             To operator ()(From &from) const
Chris@16:             {
Chris@16:                 return from;
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename ToFrom>
Chris@16:         struct promote_base<ToFrom, ToFrom, void>
Chris@16:           : std::unary_function<ToFrom, ToFrom>
Chris@16:         {
Chris@16:             ToFrom &operator ()(ToFrom &tofrom)
Chris@16:             {
Chris@16:                 return tofrom;
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename Arg, typename EnableIf>
Chris@16:         struct as_min_base
Chris@16:           : std::unary_function<Arg, typename remove_const<Arg>::type>
Chris@16:         {
Chris@16:             BOOST_STATIC_ASSERT(std::numeric_limits<typename remove_const<Arg>::type>::is_specialized);
Chris@16: 
Chris@16:             typename remove_const<Arg>::type operator ()(Arg &) const
Chris@16:             {
Chris@16:                 return (std::numeric_limits<typename remove_const<Arg>::type>::min)();
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename Arg>
Chris@16:         struct as_min_base<Arg, typename enable_if<is_floating_point<Arg> >::type>
Chris@16:           : std::unary_function<Arg, typename remove_const<Arg>::type>
Chris@16:         {
Chris@16:             BOOST_STATIC_ASSERT(std::numeric_limits<typename remove_const<Arg>::type>::is_specialized);
Chris@16: 
Chris@16:             typename remove_const<Arg>::type operator ()(Arg &) const
Chris@16:             {
Chris@16:                 return -(std::numeric_limits<typename remove_const<Arg>::type>::max)();
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename Arg, typename EnableIf>
Chris@16:         struct as_max_base
Chris@16:           : std::unary_function<Arg, typename remove_const<Arg>::type>
Chris@16:         {
Chris@16:             BOOST_STATIC_ASSERT(std::numeric_limits<typename remove_const<Arg>::type>::is_specialized);
Chris@16: 
Chris@16:             typename remove_const<Arg>::type operator ()(Arg &) const
Chris@16:             {
Chris@16:                 return (std::numeric_limits<typename remove_const<Arg>::type>::max)();
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename Arg, typename EnableIf>
Chris@16:         struct as_zero_base
Chris@16:           : std::unary_function<Arg, typename remove_const<Arg>::type>
Chris@16:         {
Chris@16:             typename remove_const<Arg>::type operator ()(Arg &) const
Chris@16:             {
Chris@16:                 return numeric::zero<typename remove_const<Arg>::type>::value;
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename Arg, typename EnableIf>
Chris@16:         struct as_one_base
Chris@16:           : std::unary_function<Arg, typename remove_const<Arg>::type>
Chris@16:         {
Chris@16:             typename remove_const<Arg>::type operator ()(Arg &) const
Chris@16:             {
Chris@16:                 return numeric::one<typename remove_const<Arg>::type>::value;
Chris@16:             }
Chris@16:         };
Chris@16: 
Chris@16:         template<typename To, typename From, typename ToTag, typename FromTag>
Chris@16:         struct promote
Chris@16:           : promote_base<To, From, void>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename Left, typename Right, typename LeftTag, typename RightTag>
Chris@16:         struct min_assign
Chris@16:           : min_assign_base<Left, Right, void>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename Left, typename Right, typename LeftTag, typename RightTag>
Chris@16:         struct max_assign
Chris@16:           : max_assign_base<Left, Right, void>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename Left, typename Right, typename LeftTag, typename RightTag>
Chris@16:         struct fdiv
Chris@16:           : fdiv_base<Left, Right, void>
Chris@16:         {};
Chris@16: 
Chris@16:         /// INTERNAL ONLY 
Chris@16:         /// For back-compat only. Use fdiv.
Chris@16:         template<typename Left, typename Right, typename LeftTag, typename RightTag>
Chris@16:         struct average
Chris@16:           : fdiv<Left, Right, LeftTag, RightTag>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename Arg, typename Tag>
Chris@16:         struct as_min
Chris@16:           : as_min_base<Arg, void>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename Arg, typename Tag>
Chris@16:         struct as_max
Chris@16:           : as_max_base<Arg, void>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename Arg, typename Tag>
Chris@16:         struct as_zero
Chris@16:           : as_zero_base<Arg, void>
Chris@16:         {};
Chris@16: 
Chris@16:         template<typename Arg, typename Tag>
Chris@16:         struct as_one
Chris@16:           : as_one_base<Arg, void>
Chris@16:         {};
Chris@16:     }
Chris@16: 
Chris@16:     namespace op
Chris@16:     {
Chris@16:         template<typename To>
Chris@16:         struct promote
Chris@16:           : boost::detail::function1<functional::promote<To, _, typename functional::tag<To>::type, functional::tag<_> > >
Chris@16:         {};
Chris@16: 
Chris@16:         struct min_assign
Chris@16:           : boost::detail::function2<functional::min_assign<_1, _2, functional::tag<_1>, functional::tag<_2> > >
Chris@16:         {};
Chris@16: 
Chris@16:         struct max_assign
Chris@16:           : boost::detail::function2<functional::max_assign<_1, _2, functional::tag<_1>, functional::tag<_2> > >
Chris@16:         {};
Chris@16: 
Chris@16:         struct fdiv
Chris@16:           : boost::detail::function2<functional::fdiv<_1, _2, functional::tag<_1>, functional::tag<_2> > >
Chris@16:         {};
Chris@16: 
Chris@16:         /// INTERNAL ONLY
Chris@16:         struct average
Chris@16:           : boost::detail::function2<functional::fdiv<_1, _2, functional::tag<_1>, functional::tag<_2> > >
Chris@16:         {};
Chris@16: 
Chris@16:         struct as_min
Chris@16:           : boost::detail::function1<functional::as_min<_, functional::tag<_> > >
Chris@16:         {};
Chris@16: 
Chris@16:         struct as_max
Chris@16:           : boost::detail::function1<functional::as_max<_, functional::tag<_> > >
Chris@16:         {};
Chris@16: 
Chris@16:         struct as_zero
Chris@16:           : boost::detail::function1<functional::as_zero<_, functional::tag<_> > >
Chris@16:         {};
Chris@16: 
Chris@16:         struct as_one
Chris@16:           : boost::detail::function1<functional::as_one<_, functional::tag<_> > >
Chris@16:         {};
Chris@16:     }
Chris@16: 
Chris@16:     namespace
Chris@16:     {
Chris@16:         op::min_assign const &min_assign = boost::detail::pod_singleton<op::min_assign>::instance;
Chris@16:         op::max_assign const &max_assign = boost::detail::pod_singleton<op::max_assign>::instance;
Chris@16:         op::fdiv const &fdiv = boost::detail::pod_singleton<op::fdiv>::instance;
Chris@16:         op::fdiv const &average = boost::detail::pod_singleton<op::fdiv>::instance; ///< INTERNAL ONLY
Chris@16:         op::as_min const &as_min = boost::detail::pod_singleton<op::as_min>::instance;
Chris@16:         op::as_max const &as_max = boost::detail::pod_singleton<op::as_max>::instance;
Chris@16:         op::as_zero const &as_zero = boost::detail::pod_singleton<op::as_zero>::instance;
Chris@16:         op::as_one const &as_one = boost::detail::pod_singleton<op::as_one>::instance;
Chris@16: 
Chris@16:         BOOST_ACCUMULATORS_IGNORE_GLOBAL(min_assign)
Chris@16:         BOOST_ACCUMULATORS_IGNORE_GLOBAL(max_assign)
Chris@16:         BOOST_ACCUMULATORS_IGNORE_GLOBAL(fdiv)
Chris@16:         BOOST_ACCUMULATORS_IGNORE_GLOBAL(average)
Chris@16:         BOOST_ACCUMULATORS_IGNORE_GLOBAL(as_min)
Chris@16:         BOOST_ACCUMULATORS_IGNORE_GLOBAL(as_max)
Chris@16:         BOOST_ACCUMULATORS_IGNORE_GLOBAL(as_zero)
Chris@16:         BOOST_ACCUMULATORS_IGNORE_GLOBAL(as_one)
Chris@16:     }
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////////
Chris@16:     // promote
Chris@16:     template<typename To, typename From>
Chris@16:     typename lazy_disable_if<is_const<From>, mpl::if_<is_same<To, From>, To &, To> >::type
Chris@16:     promote(From &from)
Chris@16:     {
Chris@16:         return functional::promote<To, From>()(from);
Chris@16:     }
Chris@16: 
Chris@16:     template<typename To, typename From>
Chris@16:     typename mpl::if_<is_same<To const, From const>, To const &, To const>::type
Chris@16:     promote(From const &from)
Chris@16:     {
Chris@16:         return functional::promote<To const, From const>()(from);
Chris@16:     }
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct default_
Chris@16:     {
Chris@16:         typedef default_ type;
Chris@16:         typedef T value_type;
Chris@16:         static T const value;
Chris@16: 
Chris@16:         operator T const & () const
Chris@16:         {
Chris@16:             return default_::value;
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     T const default_<T>::value = T();
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct one
Chris@16:     {
Chris@16:         typedef one type;
Chris@16:         typedef T value_type;
Chris@16:         static T const value;
Chris@16: 
Chris@16:         operator T const & () const
Chris@16:         {
Chris@16:             return one::value;
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     T const one<T>::value = T(1);
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct zero
Chris@16:     {
Chris@16:         typedef zero type;
Chris@16:         typedef T value_type;
Chris@16:         static T const value;
Chris@16: 
Chris@16:         operator T const & () const
Chris@16:         {
Chris@16:             return zero::value;
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     T const zero<T>::value = T();
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct one_or_default
Chris@16:       : mpl::if_<is_empty<T>, default_<T>, one<T> >::type
Chris@16:     {};
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct zero_or_default
Chris@16:       : mpl::if_<is_empty<T>, default_<T>, zero<T> >::type
Chris@16:     {};
Chris@16: 
Chris@16: }} // namespace boost::numeric
Chris@16: 
Chris@16: #endif