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

  *

  */

 #ifndef BOOST_RANDOM_XOR_COMBINE_HPP

 #define BOOST_RANDOM_XOR_COMBINE_HPP

 #include <iostream>

 #include <cassert>

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

 #include <boost/config.hpp>

 #include <boost/limits.hpp>

 #include <boost/static_assert.hpp>

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

 namespace boost {

 namespace random {

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

 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS

   typename URNG1::result_type 

 #else

   uint32_t

 #endif

   val = 0>

 class xor_combine

 {

 public:

   typedef URNG1 base1_type;

   typedef URNG2 base2_type;

   typedef typename base1_type::result_type result_type;

   BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);

   BOOST_STATIC_CONSTANT(int, shift1 = s1);

   BOOST_STATIC_CONSTANT(int, shfit2 = s2);

   xor_combine() : _rng1(), _rng2()

   { }

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

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

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

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

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

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

   {

     _rng1.seed(first, last);

     _rng2.seed(first, last);

   }

   const base1_type& base1() { return _rng1; }

   const base2_type& base2() { return _rng2; }

   result_type operator()()

   {

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

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

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

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

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

 #endif

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

   }

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

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

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

 #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE

 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS

   template<class CharT, class Traits>

   friend std::basic_ostream<CharT,Traits>&

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

   {

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

     return os;

   }

   template<class CharT, class Traits>

   friend std::basic_istream<CharT,Traits>&

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

   {

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

     return is;

   }

 #endif

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

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

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

   { return !(x == y); }

 #else

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

   bool operator==(const xor_combine& rhs) const

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

   bool operator!=(const xor_combine& rhs) const

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

 #endif

 private:

   base1_type _rng1;

   base2_type _rng2;

 };

 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION

 //  A definition is required even for integral static constants

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

 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS

   typename URNG1::result_type 

 #else

   uint32_t

 #endif

   val>

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

 #endif

 } // namespace random

 } // namespace boost

 #endif // BOOST_RANDOM_XOR_COMBINE_HPP