/* boost random/discard_block.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: discard_block.hpp,v 1.12 2005/05/21 15:57:00 dgregor Exp $

  *

  * Revision history

  *  2001-03-02  created

  */

 #ifndef BOOST_RANDOM_DISCARD_BLOCK_HPP

 #define BOOST_RANDOM_DISCARD_BLOCK_HPP

 #include <iostream>

 #include <boost/config.hpp>

 #include <boost/limits.hpp>

 #include <boost/static_assert.hpp>

 namespace boost {

 namespace random {

 template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>

 class discard_block

 {

 public:

   typedef UniformRandomNumberGenerator base_type;

   typedef typename base_type::result_type result_type;

   BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);

   BOOST_STATIC_CONSTANT(unsigned int, total_block = p);

   BOOST_STATIC_CONSTANT(unsigned int, returned_block = r);

 #ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS

   BOOST_STATIC_ASSERT(total_block >= returned_block);

 #endif

   discard_block() : _rng(), _n(0) { }

   explicit discard_block(const base_type & rng) : _rng(rng), _n(0) { }

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

     : _rng(first, last), _n(0) { }

   void seed() { _rng.seed(); _n = 0; }

   template<class T> void seed(T s) { _rng.seed(s); _n = 0; }

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

   { _n = 0; _rng.seed(first, last); }

   const base_type& base() const { return _rng; }

   result_type operator()()

   {

     if(_n >= returned_block) {

       // discard values of random number generator

       for( ; _n < total_block; ++_n)

         _rng();

       _n = 0;

     }

     ++_n;

     return _rng();

   }

   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 true; }  // dummy

 #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 discard_block& s)

   {

     os << s._rng << " " << s._n << " ";

     return os;

   }

   template<class CharT, class Traits>

   friend std::basic_istream<CharT,Traits>&

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

   {

     is >> s._rng >> std::ws >> s._n >> std::ws;

     return is;

   }

 #endif

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

   { return x._rng == y._rng && x._n == y._n; }

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

   { return !(x == y); }

 #else

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

   bool operator==(const discard_block& rhs) const

   { return _rng == rhs._rng && _n == rhs._n; }

   bool operator!=(const discard_block& rhs) const

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

 #endif

 private:

   base_type _rng;

   unsigned int _n;

 };

 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION

 //  A definition is required even for integral static constants

 template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>

 const bool discard_block<UniformRandomNumberGenerator, p, r>::has_fixed_range;

 template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>

 const unsigned int discard_block<UniformRandomNumberGenerator, p, r>::total_block;

 template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>

 const unsigned int discard_block<UniformRandomNumberGenerator, p, r>::returned_block;

 #endif

 } // namespace random

 } // namespace boost

 #endif // BOOST_RANDOM_DISCARD_BLOCK_HPP