williamr@2: /* boost random/variate_generator.hpp header file
williamr@2:  *
williamr@2:  * Copyright Jens Maurer 2002
williamr@2:  * Distributed under the Boost Software License, Version 1.0. (See
williamr@2:  * accompanying file LICENSE_1_0.txt or copy at
williamr@2:  * http://www.boost.org/LICENSE_1_0.txt)
williamr@2:  *
williamr@2:  * See http://www.boost.org for most recent version including documentation.
williamr@2:  *
williamr@2:  * $Id: variate_generator.hpp,v 1.8 2005/02/14 11:53:50 johnmaddock Exp $
williamr@2:  *
williamr@2:  */
williamr@2: 
williamr@2: #ifndef BOOST_RANDOM_RANDOM_GENERATOR_HPP
williamr@2: #define BOOST_RANDOM_RANDOM_GENERATOR_HPP
williamr@2: 
williamr@2: #include <boost/config.hpp>
williamr@2: 
williamr@2: // implementation details
williamr@2: #include <boost/detail/workaround.hpp>
williamr@2: #include <boost/random/uniform_01.hpp>
williamr@2: #include <boost/random/detail/pass_through_engine.hpp>
williamr@2: #include <boost/random/detail/uniform_int_float.hpp>
williamr@2: #include <boost/random/detail/ptr_helper.hpp>
williamr@2: 
williamr@2: // Borland C++ 5.6.0 has problems using its numeric_limits traits as
williamr@2: // template parameters
williamr@2: #if BOOST_WORKAROUND(__BORLANDC__, <= 0x564)
williamr@2: #include <boost/type_traits/is_integral.hpp>
williamr@2: #endif
williamr@2: 
williamr@2: namespace boost {
williamr@2: 
williamr@2: namespace random {
williamr@2: namespace detail {
williamr@2: 
williamr@2: template<bool have_int, bool want_int>
williamr@2: struct engine_helper;
williamr@2: 
williamr@2: // for consistency, always have two levels of decorations
williamr@2: template<>
williamr@2: struct engine_helper<true, true>
williamr@2: {
williamr@2:   template<class Engine, class DistInputType>
williamr@2:   struct impl
williamr@2:   {
williamr@2:     typedef pass_through_engine<Engine> type;
williamr@2:   };
williamr@2: };
williamr@2: 
williamr@2: template<>
williamr@2: struct engine_helper<false, false>
williamr@2: {
williamr@2:   template<class Engine, class DistInputType>
williamr@2:   struct impl
williamr@2:   {
williamr@2:     typedef uniform_01<Engine, DistInputType> type;
williamr@2:   };
williamr@2: };
williamr@2: 
williamr@2: template<>
williamr@2: struct engine_helper<true, false>
williamr@2: {
williamr@2:   template<class Engine, class DistInputType>
williamr@2:   struct impl
williamr@2:   {
williamr@2:     typedef uniform_01<Engine, DistInputType> type;
williamr@2:   };
williamr@2: };
williamr@2: 
williamr@2: template<>
williamr@2: struct engine_helper<false, true>
williamr@2: {
williamr@2:   template<class Engine, class DistInputType>
williamr@2:   struct impl
williamr@2:   {
williamr@2:     typedef uniform_int_float<Engine, unsigned long> type;
williamr@2:   };
williamr@2: };
williamr@2: 
williamr@2: } // namespace detail
williamr@2: } // namespace random
williamr@2: 
williamr@2: 
williamr@2: template<class Engine, class Distribution>
williamr@2: class variate_generator
williamr@2: {
williamr@2: private:
williamr@2:   typedef random::detail::pass_through_engine<Engine> decorated_engine;
williamr@2: 
williamr@2: public:
williamr@2:   typedef typename decorated_engine::base_type engine_value_type;
williamr@2:   typedef Engine engine_type;
williamr@2:   typedef Distribution distribution_type;
williamr@2:   typedef typename Distribution::result_type result_type;
williamr@2: 
williamr@2:   variate_generator(Engine e, Distribution d)
williamr@2:     : _eng(decorated_engine(e)), _dist(d) { }
williamr@2: 
williamr@2:   result_type operator()() { return _dist(_eng); }
williamr@2:   template<class T>
williamr@2:   result_type operator()(T value) { return _dist(_eng, value); }
williamr@2: 
williamr@2:   engine_value_type& engine() { return _eng.base().base(); }
williamr@2:   const engine_value_type& engine() const { return _eng.base().base(); }
williamr@2: 
williamr@2:   distribution_type& distribution() { return _dist; }
williamr@2:   const distribution_type& distribution() const { return _dist; }
williamr@2: 
williamr@2:   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (distribution().min)(); }
williamr@2:   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (distribution().max)(); }
williamr@2: 
williamr@2: private:
williamr@2: #if BOOST_WORKAROUND(__BORLANDC__, <= 0x564)
williamr@2:   typedef typename random::detail::engine_helper<
williamr@2:     boost::is_integral<typename decorated_engine::result_type>::value,
williamr@2:     boost::is_integral<typename Distribution::input_type>::value
williamr@2:     >::BOOST_NESTED_TEMPLATE impl<decorated_engine, typename Distribution::input_type>::type internal_engine_type;
williamr@2: #else
williamr@2:   enum {
williamr@2:     have_int = std::numeric_limits<typename decorated_engine::result_type>::is_integer,
williamr@2:     want_int = std::numeric_limits<typename Distribution::input_type>::is_integer
williamr@2:   };
williamr@2:   typedef typename random::detail::engine_helper<have_int, want_int>::BOOST_NESTED_TEMPLATE impl<decorated_engine, typename Distribution::input_type>::type internal_engine_type;
williamr@2: #endif
williamr@2: 
williamr@2:   internal_engine_type _eng;
williamr@2:   distribution_type _dist;
williamr@2: };
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_RANDOM_RANDOM_GENERATOR_HPP