/* 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