boost/random/shuffle_output.hpp

   1 /* boost random/shuffle_output.hpp header file
   2  *
   3  * Copyright Jens Maurer 2000-2001
   4  * Distributed under the Boost Software License, Version 1.0. (See
   5  * accompanying file LICENSE_1_0.txt or copy at
   6  * http://www.boost.org/LICENSE_1_0.txt)
   7  *
   8  * See http://www.boost.org for most recent version including documentation.
   9  *
  10  * $Id$
  11  *
  12  * Revision history
  13  *  2001-02-18  moved to individual header files
  14  */
  15
  16 #ifndef BOOST_RANDOM_SHUFFLE_OUTPUT_HPP
  17 #define BOOST_RANDOM_SHUFFLE_OUTPUT_HPP
  18
  19 #include <iostream>
  20 #include <algorithm>     // std::copy
  21 #include <cassert>
  22 #include <boost/config.hpp>
  23 #include <boost/limits.hpp>
  24 #include <boost/static_assert.hpp>
  25 #include <boost/cstdint.hpp>
  26 #include <boost/random/linear_congruential.hpp>
  27
  28 namespace boost {
  29 namespace random {
  30
  31 // Carter Bays and S.D. Durham 1979
  32 template<class UniformRandomNumberGenerator, int k,
  33 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS
  34   typename UniformRandomNumberGenerator::result_type
  35 #else
  36   uint32_t
  37 #endif
  38   val = 0>
  39 class shuffle_output
  40 {
  41 public:
  42   typedef UniformRandomNumberGenerator base_type;
  43   typedef typename base_type::result_type result_type;
  44
  45   BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
  46   BOOST_STATIC_CONSTANT(int, buffer_size = k);
  47
  48   shuffle_output() : _rng() { init(); }
  49 #if defined(BOOST_MSVC) && _MSC_VER < 1300
  50   // MSVC does not implicitly generate the copy constructor here
  51   shuffle_output(const shuffle_output & x)
  52     : _rng(x._rng), y(x.y) { std::copy(x.v, x.v+k, v); }
  53 #endif
  54   template<class T>
  55   explicit shuffle_output(T s) : _rng(s) { init(); }
  56   explicit shuffle_output(const base_type & rng) : _rng(rng) { init(); }
  57   template<class It> shuffle_output(It& first, It last)
  58     : _rng(first, last) { init(); }
  59   void seed() { _rng.seed(); init(); }
  60   template<class T>
  61   void seed(T s) { _rng.seed(s); init(); }
  62   template<class It> void seed(It& first, It last)
  63   {
  64     _rng.seed(first, last);
  65     init();
  66   }
  67
  68   const base_type& base() const { return _rng; }
  69
  70   result_type operator()() {
  71     // calculating the range every time may seem wasteful.  However, this
  72     // makes the information locally available for the optimizer.
  73     result_type range = (max)()-(min)()+1;
  74     int j = k*(y-(min)())/range;
  75     // assert(0 <= j && j < k);
  76     y = v[j];
  77     v[j] = _rng();
  78     return y;
  79   }
  80
  81   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_rng.min)(); }
  82   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_rng.max)(); }
  83   static bool validation(result_type x) { return val == x; }
  84
  85 #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE
  86
  87 #ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
  88   template<class CharT, class Traits>
  89   friend std::basic_ostream<CharT,Traits>&
  90   operator<<(std::basic_ostream<CharT,Traits>& os, const shuffle_output& s)
  91   {
  92     os << s._rng << " " << s.y << " ";
  93     for(int i = 0; i < s.buffer_size; ++i)
  94       os << s.v[i] << " ";
  95     return os;
  96   }
  97
  98   template<class CharT, class Traits>
  99   friend std::basic_istream<CharT,Traits>&
 100   operator>>(std::basic_istream<CharT,Traits>& is, shuffle_output& s)
 101   {
 102     is >> s._rng >> std::ws >> s.y >> std::ws;
 103     for(int i = 0; i < s.buffer_size; ++i)
 104       is >> s.v[i] >> std::ws;
 105     return is;
 106   }
 107 #endif
 108
 109   friend bool operator==(const shuffle_output& x, const shuffle_output& y)
 110   { return x._rng == y._rng && x.y == y.y && std::equal(x.v, x.v+k, y.v); }
 111   friend bool operator!=(const shuffle_output& x, const shuffle_output& y)
 112   { return !(x == y); }
 113 #else
 114   // Use a member function; Streamable concept not supported.
 115   bool operator==(const shuffle_output& rhs) const
 116   { return _rng == rhs._rng && y == rhs.y && std::equal(v, v+k, rhs.v); }
 117   bool operator!=(const shuffle_output& rhs) const
 118   { return !(*this == rhs); }
 119 #endif
 120 private:
 121   void init()
 122   {
 123 #ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
 124     BOOST_STATIC_ASSERT(std::numeric_limits<result_type>::is_integer);
 125 #endif
 126     result_type range = (max)()-(min)();
 127     assert(range > 0);      // otherwise there would be little choice
 128     if(static_cast<unsigned long>(k * range) <
 129        static_cast<unsigned long>(range))  // not a sufficient condition
 130       // likely overflow with bucket number computation
 131       assert(!"overflow will occur");
 132
 133     // we cannot use std::generate, because it uses pass-by-value for _rng
 134     for(result_type * p = v; p != v+k; ++p)
 135       *p = _rng();
 136     y = _rng();
 137   }
 138
 139   base_type _rng;
 140   result_type v[k];
 141   result_type y;
 142 };
 143
 144 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
 145 //  A definition is required even for integral static constants
 146 template<class UniformRandomNumberGenerator, int k,
 147 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS
 148   typename UniformRandomNumberGenerator::result_type
 149 #else
 150   uint32_t
 151 #endif
 152   val>
 153 const bool shuffle_output<UniformRandomNumberGenerator, k, val>::has_fixed_range;
 154
 155 template<class UniformRandomNumberGenerator, int k,
 156 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS
 157   typename UniformRandomNumberGenerator::result_type
 158 #else
 159   uint32_t
 160 #endif
 161   val>
 162 const int shuffle_output<UniformRandomNumberGenerator, k, val>::buffer_size;
 163 #endif
 164
 165 } // namespace random
 166
 167 // validation by experiment from Harry Erwin's generator.h (private e-mail)
 168 typedef random::shuffle_output<
 169     random::linear_congruential<uint32_t, 1366, 150889, 714025, 0>,
 170   97, 139726> kreutzer1986;
 171
 172
 173 } // namespace boost
 174
 175 #endif // BOOST_RANDOM_SHUFFLE_OUTPUT_HPP