221 lines
6.9 KiB
C++
221 lines
6.9 KiB
C++
/* boost random/variate_generator.hpp header file
|
|
*
|
|
* Copyright Jens Maurer 2002
|
|
* Distributed under 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)
|
|
*
|
|
* See http://www.boost.org for most recent version including documentation.
|
|
*
|
|
* $Id: variate_generator.hpp 60755 2010-03-22 00:45:06Z steven_watanabe $
|
|
*
|
|
*/
|
|
|
|
#ifndef BOOST_RANDOM_RANDOM_GENERATOR_HPP
|
|
#define BOOST_RANDOM_RANDOM_GENERATOR_HPP
|
|
|
|
#include <boost/config.hpp>
|
|
|
|
// implementation details
|
|
#include <boost/detail/workaround.hpp>
|
|
#include <boost/random/uniform_01.hpp>
|
|
#include <boost/random/detail/pass_through_engine.hpp>
|
|
#include <boost/random/detail/uniform_int_float.hpp>
|
|
#include <boost/random/detail/ptr_helper.hpp>
|
|
|
|
// Borland C++ 5.6.0 has problems using its numeric_limits traits as
|
|
// template parameters
|
|
#if BOOST_WORKAROUND(__BORLANDC__, <= 0x564)
|
|
#include <boost/type_traits/is_integral.hpp>
|
|
#endif
|
|
|
|
#include <boost/random/detail/disable_warnings.hpp>
|
|
|
|
namespace boost {
|
|
|
|
/// \cond hide_private_members
|
|
|
|
namespace random {
|
|
namespace detail {
|
|
|
|
template<bool have_int, bool want_int>
|
|
struct engine_helper;
|
|
|
|
// for consistency, always have two levels of decorations
|
|
template<>
|
|
struct engine_helper<true, true>
|
|
{
|
|
template<class Engine, class DistInputType>
|
|
struct impl
|
|
{
|
|
typedef pass_through_engine<Engine> type;
|
|
};
|
|
};
|
|
|
|
template<>
|
|
struct engine_helper<false, false>
|
|
{
|
|
template<class Engine, class DistInputType>
|
|
struct impl
|
|
{
|
|
typedef uniform_01<Engine, DistInputType> type;
|
|
};
|
|
};
|
|
|
|
template<>
|
|
struct engine_helper<true, false>
|
|
{
|
|
template<class Engine, class DistInputType>
|
|
struct impl
|
|
{
|
|
typedef uniform_01<Engine, DistInputType> type;
|
|
};
|
|
};
|
|
|
|
template<>
|
|
struct engine_helper<false, true>
|
|
{
|
|
template<class Engine, class DistInputType>
|
|
struct impl
|
|
{
|
|
typedef uniform_int_float<Engine, unsigned long> type;
|
|
};
|
|
};
|
|
|
|
} // namespace detail
|
|
} // namespace random
|
|
|
|
///\endcond
|
|
|
|
/**
|
|
* A random variate generator is used to join a random number
|
|
* generator together with a random number distribution.
|
|
* Boost.Random provides a vast choice of \generators as well
|
|
* as \distributions.
|
|
*
|
|
* Instantations of class template @c variate_generator model
|
|
* a \number_generator.
|
|
*
|
|
* The argument for the template parameter Engine shall be of
|
|
* the form U, U&, or U*, where U models a
|
|
* \uniform_random_number_generator. Then, the member
|
|
* engine_value_type names U (not the pointer or reference to U).
|
|
*
|
|
* Specializations of @c variate_generator satisfy the
|
|
* requirements of CopyConstructible. They also satisfy the
|
|
* requirements of Assignable unless the template parameter
|
|
* Engine is of the form U&.
|
|
*
|
|
* The complexity of all functions specified in this section
|
|
* is constant. No function described in this section except
|
|
* the constructor throws an exception.
|
|
*/
|
|
template<class Engine, class Distribution>
|
|
class variate_generator
|
|
{
|
|
private:
|
|
typedef random::detail::pass_through_engine<Engine> decorated_engine;
|
|
|
|
public:
|
|
typedef typename decorated_engine::base_type engine_value_type;
|
|
typedef Engine engine_type;
|
|
typedef Distribution distribution_type;
|
|
typedef typename Distribution::result_type result_type;
|
|
|
|
/**
|
|
* Constructs a @c variate_generator object with the associated
|
|
* \uniform_random_number_generator eng and the associated
|
|
* \random_distribution d.
|
|
*
|
|
* Throws: If and what the copy constructor of Engine or
|
|
* Distribution throws.
|
|
*/
|
|
variate_generator(Engine e, Distribution d)
|
|
: _eng(decorated_engine(e)), _dist(d) { }
|
|
|
|
/**
|
|
* Returns: distribution()(e)
|
|
*
|
|
* Notes: The sequence of numbers produced by the
|
|
* \uniform_random_number_generator e, s<sub>e</sub>, is
|
|
* obtained from the sequence of numbers produced by the
|
|
* associated \uniform_random_number_generator eng, s<sub>eng</sub>,
|
|
* as follows: Consider the values of @c numeric_limits<T>::is_integer
|
|
* for @c T both @c Distribution::input_type and
|
|
* @c engine_value_type::result_type. If the values for both types are
|
|
* true, then se is identical to s<sub>eng</sub>. Otherwise, if the
|
|
* values for both types are false, then the numbers in s<sub>eng</sub>
|
|
* are divided by engine().max()-engine().min() to obtain the numbers
|
|
* in s<sub>e</sub>. Otherwise, if the value for
|
|
* @c engine_value_type::result_type is true and the value for
|
|
* @c Distribution::input_type is false, then the numbers in s<sub>eng</sub>
|
|
* are divided by engine().max()-engine().min()+1 to obtain the numbers in
|
|
* s<sub>e</sub>. Otherwise, the mapping from s<sub>eng</sub> to
|
|
* s<sub>e</sub> is implementation-defined. In all cases, an
|
|
* implicit conversion from @c engine_value_type::result_type to
|
|
* @c Distribution::input_type is performed. If such a conversion does
|
|
* not exist, the program is ill-formed.
|
|
*/
|
|
result_type operator()() { return _dist(_eng); }
|
|
/**
|
|
* Returns: distribution()(e, value).
|
|
* For the semantics of e, see the description of operator()().
|
|
*/
|
|
template<class T>
|
|
result_type operator()(T value) { return _dist(_eng, value); }
|
|
|
|
/**
|
|
* Returns: A reference to the associated uniform random number generator.
|
|
*/
|
|
engine_value_type& engine() { return _eng.base().base(); }
|
|
/**
|
|
* Returns: A reference to the associated uniform random number generator.
|
|
*/
|
|
const engine_value_type& engine() const { return _eng.base().base(); }
|
|
|
|
/**
|
|
* Returns: A reference to the associated random distribution.
|
|
*/
|
|
distribution_type& distribution() { return _dist; }
|
|
/**
|
|
* Returns: A reference to the associated random distribution.
|
|
*/
|
|
const distribution_type& distribution() const { return _dist; }
|
|
|
|
/**
|
|
* Precondition: distribution().min() is well-formed
|
|
*
|
|
* Returns: distribution().min()
|
|
*/
|
|
result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (distribution().min)(); }
|
|
/**
|
|
* Precondition: distribution().max() is well-formed
|
|
*
|
|
* Returns: distribution().max()
|
|
*/
|
|
result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (distribution().max)(); }
|
|
|
|
private:
|
|
#if BOOST_WORKAROUND(__BORLANDC__, <= 0x564)
|
|
typedef typename random::detail::engine_helper<
|
|
::boost::is_integral<typename decorated_engine::result_type>::value,
|
|
::boost::is_integral<typename Distribution::input_type>::value
|
|
>::BOOST_NESTED_TEMPLATE impl<decorated_engine, typename Distribution::input_type>::type internal_engine_type;
|
|
#else
|
|
enum {
|
|
have_int = std::numeric_limits<typename decorated_engine::result_type>::is_integer,
|
|
want_int = std::numeric_limits<typename Distribution::input_type>::is_integer
|
|
};
|
|
typedef typename random::detail::engine_helper<have_int, want_int>::BOOST_NESTED_TEMPLATE impl<decorated_engine, typename Distribution::input_type>::type internal_engine_type;
|
|
#endif
|
|
|
|
internal_engine_type _eng;
|
|
distribution_type _dist;
|
|
};
|
|
|
|
} // namespace boost
|
|
|
|
#include <boost/random/detail/disable_warnings.hpp>
|
|
|
|
#endif // BOOST_RANDOM_RANDOM_GENERATOR_HPP
|