/* 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,v 1.10 2005/08/25 16:27:22 johnmaddock Exp $

  *

  * 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 {

 // Carter Bays and S.D. Durham 1979

 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);

   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

   template<class T>

   explicit shuffle_output(T seed) : _rng(seed) { init(); }

   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(); }

   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_NO_MEMBER_TEMPLATE_FRIENDS

   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)

 typedef random::shuffle_output<

     random::linear_congruential<uint32_t, 1366, 150889, 714025, 0>,

   97, 139726> kreutzer1986;

 } // namespace boost

 #endif // BOOST_RANDOM_SHUFFLE_OUTPUT_HPP