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: shuffle_output.hpp,v 1.10 2005/08/25 16:27:22 johnmaddock Exp $

    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 seed) : _rng(seed) { 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_NO_MEMBER_TEMPLATE_FRIENDS

    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