| /* boost random/shuffle_output.hpp header file |
| * |
| * Copyright Jens Maurer 2000-2001 |
| * 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: shuffle_output.hpp 60755 2010-03-22 00:45:06Z steven_watanabe $ |
| * |
| * Revision history |
| * 2001-02-18 moved to individual header files |
| */ |
| |
| #ifndef BOOST_RANDOM_SHUFFLE_OUTPUT_HPP |
| #define BOOST_RANDOM_SHUFFLE_OUTPUT_HPP |
| |
| #include <iostream> |
| #include <algorithm> // std::copy |
| #include <cassert> |
| #include <boost/config.hpp> |
| #include <boost/limits.hpp> |
| #include <boost/static_assert.hpp> |
| #include <boost/cstdint.hpp> |
| #include <boost/random/linear_congruential.hpp> |
| |
| namespace boost { |
| namespace random { |
| |
| /** |
| * Instatiations of class template shuffle_output model a |
| * \pseudo_random_number_generator. It mixes the output |
| * of some (usually \linear_congruential) \uniform_random_number_generator |
| * to get better statistical properties. |
| * The algorithm is described in |
| * |
| * @blockquote |
| * "Improving a poor random number generator", Carter Bays |
| * and S.D. Durham, ACM Transactions on Mathematical Software, |
| * Vol 2, No. 1, March 1976, pp. 59-64. |
| * http://doi.acm.org/10.1145/355666.355670 |
| * @endblockquote |
| * |
| * The output of the base generator is buffered in an array of |
| * length k. Every output X(n) has a second role: It gives an |
| * index into the array where X(n+1) will be retrieved. Used |
| * array elements are replaced with fresh output from the base |
| * generator. |
| * |
| * Template parameters are the base generator and the array |
| * length k, which should be around 100. The template parameter |
| * val is the validation value checked by validation. |
| */ |
| template<class UniformRandomNumberGenerator, int k, |
| #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS |
| typename UniformRandomNumberGenerator::result_type |
| #else |
| uint32_t |
| #endif |
| val = 0> |
| class shuffle_output |
| { |
| public: |
| typedef UniformRandomNumberGenerator base_type; |
| typedef typename base_type::result_type result_type; |
| |
| BOOST_STATIC_CONSTANT(bool, has_fixed_range = false); |
| BOOST_STATIC_CONSTANT(int, buffer_size = k); |
| |
| /** |
| * Constructs a @c shuffle_output generator by invoking the |
| * default constructor of the base generator. |
| * |
| * Complexity: Exactly k+1 invocations of the base generator. |
| */ |
| shuffle_output() : _rng() { init(); } |
| #if defined(BOOST_MSVC) && _MSC_VER < 1300 |
| // MSVC does not implicitly generate the copy constructor here |
| shuffle_output(const shuffle_output & x) |
| : _rng(x._rng), y(x.y) { std::copy(x.v, x.v+k, v); } |
| #endif |
| /** |
| * Constructs a shuffle_output generator by invoking the one-argument |
| * constructor of the base generator with the parameter seed. |
| * |
| * Complexity: Exactly k+1 invocations of the base generator. |
| */ |
| template<class T> |
| explicit shuffle_output(T s) : _rng(s) { init(); } |
| /** |
| * Constructs a shuffle_output generator by using a copy |
| * of the provided generator. |
| * |
| * Precondition: The template argument UniformRandomNumberGenerator |
| * shall denote a CopyConstructible type. |
| * |
| * Complexity: Exactly k+1 invocations of the base generator. |
| */ |
| explicit shuffle_output(const base_type & rng) : _rng(rng) { init(); } |
| template<class It> shuffle_output(It& first, It last) |
| : _rng(first, last) { init(); } |
| void seed() { _rng.seed(); init(); } |
| /** |
| * Invokes the one-argument seed method of the base generator |
| * with the parameter seed and re-initializes the internal buffer array. |
| * |
| * Complexity: Exactly k+1 invocations of the base generator. |
| */ |
| template<class T> |
| void seed(T s) { _rng.seed(s); init(); } |
| template<class It> void seed(It& first, It last) |
| { |
| _rng.seed(first, last); |
| init(); |
| } |
| |
| const base_type& base() const { return _rng; } |
| |
| result_type operator()() { |
| // calculating the range every time may seem wasteful. However, this |
| // makes the information locally available for the optimizer. |
| result_type range = (max)()-(min)()+1; |
| int j = k*(y-(min)())/range; |
| // assert(0 <= j && j < k); |
| y = v[j]; |
| v[j] = _rng(); |
| return y; |
| } |
| |
| result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_rng.min)(); } |
| result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_rng.max)(); } |
| static bool validation(result_type x) { return val == x; } |
| |
| #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE |
| |
| #ifndef BOOST_RANDOM_NO_STREAM_OPERATORS |
| template<class CharT, class Traits> |
| friend std::basic_ostream<CharT,Traits>& |
| operator<<(std::basic_ostream<CharT,Traits>& os, const shuffle_output& s) |
| { |
| os << s._rng << " " << s.y << " "; |
| for(int i = 0; i < s.buffer_size; ++i) |
| os << s.v[i] << " "; |
| return os; |
| } |
| |
| template<class CharT, class Traits> |
| friend std::basic_istream<CharT,Traits>& |
| operator>>(std::basic_istream<CharT,Traits>& is, shuffle_output& s) |
| { |
| is >> s._rng >> std::ws >> s.y >> std::ws; |
| for(int i = 0; i < s.buffer_size; ++i) |
| is >> s.v[i] >> std::ws; |
| return is; |
| } |
| #endif |
| |
| friend bool operator==(const shuffle_output& x, const shuffle_output& y) |
| { return x._rng == y._rng && x.y == y.y && std::equal(x.v, x.v+k, y.v); } |
| friend bool operator!=(const shuffle_output& x, const shuffle_output& y) |
| { return !(x == y); } |
| #else |
| // Use a member function; Streamable concept not supported. |
| bool operator==(const shuffle_output& rhs) const |
| { return _rng == rhs._rng && y == rhs.y && std::equal(v, v+k, rhs.v); } |
| bool operator!=(const shuffle_output& rhs) const |
| { return !(*this == rhs); } |
| #endif |
| private: |
| void init() |
| { |
| #ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS |
| BOOST_STATIC_ASSERT(std::numeric_limits<result_type>::is_integer); |
| #endif |
| result_type range = (max)()-(min)(); |
| assert(range > 0); // otherwise there would be little choice |
| if(static_cast<unsigned long>(k * range) < |
| static_cast<unsigned long>(range)) // not a sufficient condition |
| // likely overflow with bucket number computation |
| assert(!"overflow will occur"); |
| |
| // we cannot use std::generate, because it uses pass-by-value for _rng |
| for(result_type * p = v; p != v+k; ++p) |
| *p = _rng(); |
| y = _rng(); |
| } |
| |
| base_type _rng; |
| result_type v[k]; |
| result_type y; |
| }; |
| |
| #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION |
| // A definition is required even for integral static constants |
| template<class UniformRandomNumberGenerator, int k, |
| #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS |
| typename UniformRandomNumberGenerator::result_type |
| #else |
| uint32_t |
| #endif |
| val> |
| const bool shuffle_output<UniformRandomNumberGenerator, k, val>::has_fixed_range; |
| |
| template<class UniformRandomNumberGenerator, int k, |
| #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS |
| typename UniformRandomNumberGenerator::result_type |
| #else |
| uint32_t |
| #endif |
| val> |
| const int shuffle_output<UniformRandomNumberGenerator, k, val>::buffer_size; |
| #endif |
| |
| } // namespace random |
| |
| // validation by experiment from Harry Erwin's generator.h (private e-mail) |
| /** |
| * According to Harry Erwin (private e-mail), the specialization |
| * @c kreutzer1986 was suggested in: |
| * |
| * @blockquote |
| * "System Simulation: Programming Styles and Languages (International |
| * Computer Science Series)", Wolfgang Kreutzer, Addison-Wesley, December 1986. |
| * @endblockquote |
| */ |
| typedef random::shuffle_output< |
| random::linear_congruential<uint32_t, 1366, 150889, 714025, 0>, |
| 97, 139726> kreutzer1986; |
| |
| |
| } // namespace boost |
| |
| #endif // BOOST_RANDOM_SHUFFLE_OUTPUT_HPP |