ceph/src/boost/libs/math/include/boost/math/tools/traits.hpp

   1 //  Copyright John Maddock 2007.
   2
   3 //  Use, modification and distribution are subject to the
   4 //  Boost Software License, Version 1.0. (See accompanying file
   5 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 /*
   8 This header defines two traits classes, both in namespace boost::math::tools.
   9
  10 is_distribution<D>::value is true iff D has overloaded "cdf" and
  11 "quantile" functions, plus member typedefs value_type and policy_type.
  12 It's not much of a definitive test frankly,
  13 but if it looks like a distribution and quacks like a distribution
  14 then it must be a distribution.
  15
  16 is_scaled_distribution<D>::value is true iff D is a distribution
  17 as defined above, and has member functions "scale" and "location".
  18
  19 */
  20
  21 #ifndef BOOST_STATS_IS_DISTRIBUTION_HPP
  22 #define BOOST_STATS_IS_DISTRIBUTION_HPP
  23
  24 #ifdef _MSC_VER
  25 #pragma once
  26 #endif
  27
  28 #include <boost/mpl/has_xxx.hpp>
  29 #include <boost/type_traits/integral_constant.hpp>
  30
  31 namespace boost{ namespace math{ namespace tools{
  32
  33 namespace detail{
  34
  35 BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_value_type, value_type, true)
  36 BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_policy_type, policy_type, true)
  37
  38 template<class D>
  39 char cdf(const D& ...);
  40 template<class D>
  41 char quantile(const D& ...);
  42
  43 template <class D>
  44 struct has_cdf
  45 {
  46    static D d;
  47    BOOST_STATIC_CONSTANT(bool, value = sizeof(cdf(d, 0.0f)) != 1);
  48 };
  49
  50 template <class D>
  51 struct has_quantile
  52 {
  53    static D d;
  54    BOOST_STATIC_CONSTANT(bool, value = sizeof(quantile(d, 0.0f)) != 1);
  55 };
  56
  57 template <class D>
  58 struct is_distribution_imp
  59 {
  60    BOOST_STATIC_CONSTANT(bool, value =
  61       has_quantile<D>::value
  62       && has_cdf<D>::value
  63       && has_value_type<D>::value
  64       && has_policy_type<D>::value);
  65 };
  66
  67 template <class sig, sig val>
  68 struct result_tag{};
  69
  70 template <class D>
  71 double test_has_location(const volatile result_tag<typename D::value_type (D::*)()const, &D::location>*);
  72 template <class D>
  73 char test_has_location(...);
  74
  75 template <class D>
  76 double test_has_scale(const volatile result_tag<typename D::value_type (D::*)()const, &D::scale>*);
  77 template <class D>
  78 char test_has_scale(...);
  79
  80 template <class D, bool b>
  81 struct is_scaled_distribution_helper
  82 {
  83    BOOST_STATIC_CONSTANT(bool, value = false);
  84 };
  85
  86 template <class D>
  87 struct is_scaled_distribution_helper<D, true>
  88 {
  89    BOOST_STATIC_CONSTANT(bool, value =
  90       (sizeof(test_has_location<D>(0)) != 1)
  91       &&
  92       (sizeof(test_has_scale<D>(0)) != 1));
  93 };
  94
  95 template <class D>
  96 struct is_scaled_distribution_imp
  97 {
  98    BOOST_STATIC_CONSTANT(bool, value = (::boost::math::tools::detail::is_scaled_distribution_helper<D, ::boost::math::tools::detail::is_distribution_imp<D>::value>::value));
  99 };
 100
 101 } // namespace detail
 102
 103 template <class T> struct is_distribution : public boost::integral_constant<bool, ::boost::math::tools::detail::is_distribution_imp<T>::value> {};
 104 template <class T> struct is_scaled_distribution : public boost::integral_constant<bool, ::boost::math::tools::detail::is_scaled_distribution_imp<T>::value> {};
 105
 106 }}}
 107
 108 #endif
 109
 110