1 /* boost random/xor_combine.hpp header file

     2  *

     3  * Copyright Jens Maurer 2002

     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: xor_combine.hpp,v 1.13 2005/05/21 15:57:00 dgregor Exp $

    11  *

    12  */

    13 

    14 #ifndef BOOST_RANDOM_XOR_COMBINE_HPP

    15 #define BOOST_RANDOM_XOR_COMBINE_HPP

    16 

    17 #include <iostream>

    18 #include <cassert>

    19 #include <algorithm> // for std::min and std::max

    20 #include <boost/config.hpp>

    21 #include <boost/limits.hpp>

    22 #include <boost/static_assert.hpp>

    23 #include <boost/cstdint.hpp>     // uint32_t

    24 

    25 

    26 namespace boost {

    27 namespace random {

    28 

    29 template<class URNG1, int s1, class URNG2, int s2,

    30 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS

    31   typename URNG1::result_type 

    32 #else

    33   uint32_t

    34 #endif

    35   val = 0>

    36 class xor_combine

    37 {

    38 public:

    39   typedef URNG1 base1_type;

    40   typedef URNG2 base2_type;

    41   typedef typename base1_type::result_type result_type;

    42 

    43   BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);

    44   BOOST_STATIC_CONSTANT(int, shift1 = s1);

    45   BOOST_STATIC_CONSTANT(int, shfit2 = s2);

    46 

    47   xor_combine() : _rng1(), _rng2()

    48   { }

    49   xor_combine(const base1_type & rng1, const base2_type & rng2)

    50     : _rng1(rng1), _rng2(rng2) { }

    51   template<class It> xor_combine(It& first, It last)

    52     : _rng1(first, last), _rng2( /* advanced by other call */ first, last) { }

    53   void seed() { _rng1.seed(); _rng2.seed(); }

    54   template<class It> void seed(It& first, It last)

    55   {

    56     _rng1.seed(first, last);

    57     _rng2.seed(first, last);

    58   }

    59 

    60   const base1_type& base1() { return _rng1; }

    61   const base2_type& base2() { return _rng2; }

    62 

    63   result_type operator()()

    64   {

    65     // MSVC fails BOOST_STATIC_ASSERT with std::numeric_limits at class scope

    66 #if !defined(BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS) && !(defined(BOOST_MSVC) && BOOST_MSVC <= 1300)

    67     BOOST_STATIC_ASSERT(std::numeric_limits<typename base1_type::result_type>::is_integer);

    68     BOOST_STATIC_ASSERT(std::numeric_limits<typename base2_type::result_type>::is_integer);

    69     BOOST_STATIC_ASSERT(std::numeric_limits<typename base1_type::result_type>::digits >= std::numeric_limits<typename base2_type::result_type>::digits);

    70 #endif

    71     return (_rng1() << s1) ^ (_rng2() << s2);

    72   }

    73 

    74   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return std::min BOOST_PREVENT_MACRO_SUBSTITUTION((_rng1.min)(), (_rng2.min)()); }

    75   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return std::max BOOST_PREVENT_MACRO_SUBSTITUTION((_rng1.min)(), (_rng2.max)()); }

    76   static bool validation(result_type x) { return val == x; }

    77 

    78 #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE

    79 

    80 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS

    81   template<class CharT, class Traits>

    82   friend std::basic_ostream<CharT,Traits>&

    83   operator<<(std::basic_ostream<CharT,Traits>& os, const xor_combine& s)

    84   {

    85     os << s._rng1 << " " << s._rng2 << " ";

    86     return os;

    87   }

    88 

    89   template<class CharT, class Traits>

    90   friend std::basic_istream<CharT,Traits>&

    91   operator>>(std::basic_istream<CharT,Traits>& is, xor_combine& s)

    92   {

    93     is >> s._rng1 >> std::ws >> s._rng2 >> std::ws;

    94     return is;

    95   }

    96 #endif

    97 

    98   friend bool operator==(const xor_combine& x, const xor_combine& y)

    99   { return x._rng1 == y._rng1 && x._rng2 == y._rng2; }

   100   friend bool operator!=(const xor_combine& x, const xor_combine& y)

   101   { return !(x == y); }

   102 #else

   103   // Use a member function; Streamable concept not supported.

   104   bool operator==(const xor_combine& rhs) const

   105   { return _rng1 == rhs._rng1 && _rng2 == rhs._rng2; }

   106   bool operator!=(const xor_combine& rhs) const

   107   { return !(*this == rhs); }

   108 #endif

   109 

   110 private:

   111   base1_type _rng1;

   112   base2_type _rng2;

   113 };

   114 

   115 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION

   116 //  A definition is required even for integral static constants

   117 template<class URNG1, int s1, class URNG2, int s2,

   118 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS

   119   typename URNG1::result_type 

   120 #else

   121   uint32_t

   122 #endif

   123   val>

   124 const bool xor_combine<URNG1, s1, URNG2, s2, val>::has_fixed_range;

   125 #endif

   126 

   127 } // namespace random

   128 } // namespace boost

   129 

   130 #endif // BOOST_RANDOM_XOR_COMBINE_HPP