// Copyright John Maddock 2007. // Use, modification and distribution are subject to the // Boost Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) /* This header defines two traits classes, both in namespace boost::math::tools. is_distribution<D>::value is true iff D has overloaded "cdf" and "quantile" functions, plus member typedefs value_type and policy_type. It's not much of a definitive test frankly, but if it looks like a distribution and quacks like a distribution then it must be a distribution. is_scaled_distribution<D>::value is true iff D is a distribution as defined above, and has member functions "scale" and "location". */ #ifndef BOOST_STATS_IS_DISTRIBUTION_HPP #define BOOST_STATS_IS_DISTRIBUTION_HPP #ifdef _MSC_VER #pragma once #endif #include <boost/mpl/has_xxx.hpp> #include <boost/type_traits/integral_constant.hpp> namespace boost{ namespace math{ namespace tools{ namespace detail{ BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_value_type, value_type, true) BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_policy_type, policy_type, true) template<class D> char cdf(const D& ...); template<class D> char quantile(const D& ...); template <class D> struct has_cdf { static D d; BOOST_STATIC_CONSTANT(bool, value = sizeof(cdf(d, 0.0f)) != 1); }; template <class D> struct has_quantile { static D d; BOOST_STATIC_CONSTANT(bool, value = sizeof(quantile(d, 0.0f)) != 1); }; template <class D> struct is_distribution_imp { BOOST_STATIC_CONSTANT(bool, value = has_quantile<D>::value && has_cdf<D>::value && has_value_type<D>::value && has_policy_type<D>::value); }; template <class sig, sig val> struct result_tag{}; template <class D> double test_has_location(const volatile result_tag<typename D::value_type (D::*)()const, &D::location>*); template <class D> char test_has_location(...); template <class D> double test_has_scale(const volatile result_tag<typename D::value_type (D::*)()const, &D::scale>*); template <class D> char test_has_scale(...); template <class D, bool b> struct is_scaled_distribution_helper { BOOST_STATIC_CONSTANT(bool, value = false); }; template <class D> struct is_scaled_distribution_helper<D, true> { BOOST_STATIC_CONSTANT(bool, value = (sizeof(test_has_location<D>(0)) != 1) && (sizeof(test_has_scale<D>(0)) != 1)); }; template <class D> struct is_scaled_distribution_imp { BOOST_STATIC_CONSTANT(bool, value = (::boost::math::tools::detail::is_scaled_distribution_helper<D, ::boost::math::tools::detail::is_distribution_imp<D>::value>::value)); }; } // namespace detail template <class T> struct is_distribution : public boost::integral_constant<bool, ::boost::math::tools::detail::is_distribution_imp<T>::value> {}; template <class T> struct is_scaled_distribution : public boost::integral_constant<bool, ::boost::math::tools::detail::is_scaled_distribution_imp<T>::value> {}; }}} #endif