Chris@16: /* boost random/uniform_01.hpp header file
Chris@16:  *
Chris@16:  * Copyright Jens Maurer 2000-2001
Chris@16:  * Distributed under the Boost Software License, Version 1.0. (See
Chris@16:  * accompanying file LICENSE_1_0.txt or copy at
Chris@16:  * http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  *
Chris@16:  * See http://www.boost.org for most recent version including documentation.
Chris@16:  *
Chris@101:  * $Id$
Chris@16:  *
Chris@16:  * Revision history
Chris@16:  *  2001-02-18  moved to individual header files
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_RANDOM_UNIFORM_01_HPP
Chris@16: #define BOOST_RANDOM_UNIFORM_01_HPP
Chris@16: 
Chris@16: #include <iostream>
Chris@16: #include <boost/config.hpp>
Chris@16: #include <boost/limits.hpp>
Chris@16: #include <boost/static_assert.hpp>
Chris@16: #include <boost/random/detail/config.hpp>
Chris@16: #include <boost/random/detail/ptr_helper.hpp>
Chris@16: 
Chris@16: #include <boost/random/detail/disable_warnings.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace random {
Chris@16: 
Chris@16: #ifdef BOOST_RANDOM_DOXYGEN
Chris@16: 
Chris@16: /**
Chris@16:  * The distribution function uniform_01 models a \random_distribution.
Chris@16:  * On each invocation, it returns a random floating-point value
Chris@16:  * uniformly distributed in the range [0..1).
Chris@16:  *
Chris@16:  * The template parameter RealType shall denote a float-like value type
Chris@16:  * with support for binary operators +, -, and /.
Chris@16:  *
Chris@16:  * Note: The current implementation is buggy, because it may not fill
Chris@16:  * all of the mantissa with random bits. I'm unsure how to fill a
Chris@16:  * (to-be-invented) @c boost::bigfloat class with random bits efficiently.
Chris@16:  * It's probably time for a traits class.
Chris@16:  */
Chris@16: template<class RealType = double>
Chris@16: class uniform_01
Chris@16: {
Chris@16: public:
Chris@16:   typedef RealType input_type;
Chris@16:   typedef RealType result_type;
Chris@16:   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const;
Chris@16:   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const;
Chris@16:   void reset();
Chris@16: 
Chris@16:   template<class Engine>
Chris@16:   result_type operator()(Engine& eng);
Chris@16: 
Chris@16: #ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
Chris@16:   template<class CharT, class Traits>
Chris@16:   friend std::basic_ostream<CharT,Traits>&
Chris@16:   operator<<(std::basic_ostream<CharT,Traits>& os, const new_uniform_01&)
Chris@16:   {
Chris@16:     return os;
Chris@16:   }
Chris@16: 
Chris@16:   template<class CharT, class Traits>
Chris@16:   friend std::basic_istream<CharT,Traits>&
Chris@16:   operator>>(std::basic_istream<CharT,Traits>& is, new_uniform_01&)
Chris@16:   {
Chris@16:     return is;
Chris@16:   }
Chris@16: #endif
Chris@16: };
Chris@16: 
Chris@16: #else
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16: template<class RealType>
Chris@16: class new_uniform_01
Chris@16: {
Chris@16: public:
Chris@16:   typedef RealType input_type;
Chris@16:   typedef RealType result_type;
Chris@16:   // compiler-generated copy ctor and copy assignment are fine
Chris@16:   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return result_type(0); }
Chris@16:   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return result_type(1); }
Chris@16:   void reset() { }
Chris@16: 
Chris@16:   template<class Engine>
Chris@16:   result_type operator()(Engine& eng) {
Chris@16:     for (;;) {
Chris@16:       typedef typename Engine::result_type base_result;
Chris@16:       result_type factor = result_type(1) /
Chris@16:               (result_type((eng.max)()-(eng.min)()) +
Chris@16:                result_type(std::numeric_limits<base_result>::is_integer ? 1 : 0));
Chris@16:       result_type result = result_type(eng() - (eng.min)()) * factor;
Chris@16:       if (result < result_type(1))
Chris@16:         return result;
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16: #ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
Chris@16:   template<class CharT, class Traits>
Chris@16:   friend std::basic_ostream<CharT,Traits>&
Chris@16:   operator<<(std::basic_ostream<CharT,Traits>& os, const new_uniform_01&)
Chris@16:   {
Chris@16:     return os;
Chris@16:   }
Chris@16: 
Chris@16:   template<class CharT, class Traits>
Chris@16:   friend std::basic_istream<CharT,Traits>&
Chris@16:   operator>>(std::basic_istream<CharT,Traits>& is, new_uniform_01&)
Chris@16:   {
Chris@16:     return is;
Chris@16:   }
Chris@16: #endif
Chris@16: };
Chris@16: 
Chris@16: template<class UniformRandomNumberGenerator, class RealType>
Chris@16: class backward_compatible_uniform_01
Chris@16: {
Chris@16:   typedef boost::random::detail::ptr_helper<UniformRandomNumberGenerator> traits;
Chris@16: public:
Chris@16:   typedef UniformRandomNumberGenerator base_type;
Chris@16:   typedef RealType result_type;
Chris@16: 
Chris@16:   BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
Chris@16: 
Chris@101: #if !defined(BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS)
Chris@16:   BOOST_STATIC_ASSERT(!std::numeric_limits<RealType>::is_integer);
Chris@16: #endif
Chris@16: 
Chris@16:   explicit backward_compatible_uniform_01(typename traits::rvalue_type rng)
Chris@16:     : _rng(rng),
Chris@16:       _factor(result_type(1) /
Chris@16:               (result_type((base().max)()-(base().min)()) +
Chris@16:                result_type(std::numeric_limits<base_result>::is_integer ? 1 : 0)))
Chris@16:   {
Chris@16:   }
Chris@16:   // compiler-generated copy ctor and copy assignment are fine
Chris@16: 
Chris@16:   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return result_type(0); }
Chris@16:   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return result_type(1); }
Chris@16:   typename traits::value_type& base() { return traits::ref(_rng); }
Chris@16:   const typename traits::value_type& base() const { return traits::ref(_rng); }
Chris@16:   void reset() { }
Chris@16: 
Chris@16:   result_type operator()() {
Chris@16:     for (;;) {
Chris@16:       result_type result = result_type(base()() - (base().min)()) * _factor;
Chris@16:       if (result < result_type(1))
Chris@16:         return result;
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16: #if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
Chris@16:   template<class CharT, class Traits>
Chris@16:   friend std::basic_ostream<CharT,Traits>&
Chris@16:   operator<<(std::basic_ostream<CharT,Traits>& os, const backward_compatible_uniform_01& u)
Chris@16:   {
Chris@16:     os << u._rng;
Chris@16:     return os;
Chris@16:   }
Chris@16: 
Chris@16:   template<class CharT, class Traits>
Chris@16:   friend std::basic_istream<CharT,Traits>&
Chris@16:   operator>>(std::basic_istream<CharT,Traits>& is, backward_compatible_uniform_01& u)
Chris@16:   {
Chris@16:     is >> u._rng;
Chris@16:     return is;
Chris@16:   }
Chris@16: #endif
Chris@16: 
Chris@16: private:
Chris@16:   typedef typename traits::value_type::result_type base_result;
Chris@16:   UniformRandomNumberGenerator _rng;
Chris@16:   result_type _factor;
Chris@16: };
Chris@16: 
Chris@16: #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
Chris@16: //  A definition is required even for integral static constants
Chris@16: template<class UniformRandomNumberGenerator, class RealType>
Chris@16: const bool backward_compatible_uniform_01<UniformRandomNumberGenerator, RealType>::has_fixed_range;
Chris@16: #endif
Chris@16: 
Chris@16: template<class UniformRandomNumberGenerator>
Chris@16: struct select_uniform_01
Chris@16: {
Chris@16:   template<class RealType>
Chris@16:   struct apply
Chris@16:   {
Chris@16:     typedef backward_compatible_uniform_01<UniformRandomNumberGenerator, RealType> type;
Chris@16:   };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct select_uniform_01<float>
Chris@16: {
Chris@16:   template<class RealType>
Chris@16:   struct apply
Chris@16:   {
Chris@16:     typedef new_uniform_01<float> type;
Chris@16:   };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct select_uniform_01<double>
Chris@16: {
Chris@16:   template<class RealType>
Chris@16:   struct apply
Chris@16:   {
Chris@16:     typedef new_uniform_01<double> type;
Chris@16:   };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct select_uniform_01<long double>
Chris@16: {
Chris@16:   template<class RealType>
Chris@16:   struct apply
Chris@16:   {
Chris@16:     typedef new_uniform_01<long double> type;
Chris@16:   };
Chris@16: };
Chris@16: 
Chris@16: }
Chris@16: 
Chris@16: // Because it is so commonly used: uniform distribution on the real [0..1)
Chris@16: // range.  This allows for specializations to avoid a costly int -> float
Chris@16: // conversion plus float multiplication
Chris@16: template<class UniformRandomNumberGenerator = double, class RealType = double>
Chris@16: class uniform_01
Chris@16:   : public detail::select_uniform_01<UniformRandomNumberGenerator>::BOOST_NESTED_TEMPLATE apply<RealType>::type
Chris@16: {
Chris@16:   typedef typename detail::select_uniform_01<UniformRandomNumberGenerator>::BOOST_NESTED_TEMPLATE apply<RealType>::type impl_type;
Chris@16:   typedef boost::random::detail::ptr_helper<UniformRandomNumberGenerator> traits;
Chris@16: public:
Chris@16: 
Chris@16:   uniform_01() {}
Chris@16: 
Chris@16:   explicit uniform_01(typename traits::rvalue_type rng)
Chris@16:     : impl_type(rng)
Chris@16:   {
Chris@16:   }
Chris@16: 
Chris@16: #if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
Chris@16:   template<class CharT, class Traits>
Chris@16:   friend std::basic_ostream<CharT,Traits>&
Chris@16:   operator<<(std::basic_ostream<CharT,Traits>& os, const uniform_01& u)
Chris@16:   {
Chris@16:     os << static_cast<const impl_type&>(u);
Chris@16:     return os;
Chris@16:   }
Chris@16: 
Chris@16:   template<class CharT, class Traits>
Chris@16:   friend std::basic_istream<CharT,Traits>&
Chris@16:   operator>>(std::basic_istream<CharT,Traits>& is, uniform_01& u)
Chris@16:   {
Chris@16:     is >> static_cast<impl_type&>(u);
Chris@16:     return is;
Chris@16:   }
Chris@16: #endif
Chris@16: };
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: } // namespace random
Chris@16: 
Chris@16: using random::uniform_01;
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/random/detail/enable_warnings.hpp>
Chris@16: 
Chris@16: #endif // BOOST_RANDOM_UNIFORM_01_HPP