ceph/src/boost/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 BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_backend_type, backend_type, true)
  38
  39 template<class D>
  40 char cdf(const D& ...);
  41 template<class D>
  42 char quantile(const D& ...);
  43
  44 template <class D>
  45 struct has_cdf
  46 {
  47    static D d;
  48    BOOST_STATIC_CONSTANT(bool, value = sizeof(cdf(d, 0.0f)) != 1);
  49 };
  50
  51 template <class D>
  52 struct has_quantile
  53 {
  54    static D d;
  55    BOOST_STATIC_CONSTANT(bool, value = sizeof(quantile(d, 0.0f)) != 1);
  56 };
  57
  58 template <class D>
  59 struct is_distribution_imp
  60 {
  61    BOOST_STATIC_CONSTANT(bool, value =
  62       has_quantile<D>::value
  63       && has_cdf<D>::value
  64       && has_value_type<D>::value
  65       && has_policy_type<D>::value);
  66 };
  67
  68 template <class sig, sig val>
  69 struct result_tag{};
  70
  71 template <class D>
  72 double test_has_location(const volatile result_tag<typename D::value_type (D::*)()const, &D::location>*);
  73 template <class D>
  74 char test_has_location(...);
  75
  76 template <class D>
  77 double test_has_scale(const volatile result_tag<typename D::value_type (D::*)()const, &D::scale>*);
  78 template <class D>
  79 char test_has_scale(...);
  80
  81 template <class D, bool b>
  82 struct is_scaled_distribution_helper
  83 {
  84    BOOST_STATIC_CONSTANT(bool, value = false);
  85 };
  86
  87 template <class D>
  88 struct is_scaled_distribution_helper<D, true>
  89 {
  90    BOOST_STATIC_CONSTANT(bool, value =
  91       (sizeof(test_has_location<D>(0)) != 1)
  92       &&
  93       (sizeof(test_has_scale<D>(0)) != 1));
  94 };
  95
  96 template <class D>
  97 struct is_scaled_distribution_imp
  98 {
  99    BOOST_STATIC_CONSTANT(bool, value = (::boost::math::tools::detail::is_scaled_distribution_helper<D, ::boost::math::tools::detail::is_distribution_imp<D>::value>::value));
 100 };
 101
 102 } // namespace detail
 103
 104 template <class T> struct is_distribution : public boost::integral_constant<bool, ::boost::math::tools::detail::is_distribution_imp<T>::value> {};
 105 template <class T> struct is_scaled_distribution : public boost::integral_constant<bool, ::boost::math::tools::detail::is_scaled_distribution_imp<T>::value> {};
 106
 107 }}}
 108
 109 #endif
 110
 111