williamr@2: /* boost random/discard_block.hpp header file
williamr@2:  *
williamr@2:  * Copyright Jens Maurer 2002
williamr@2:  * Distributed under the Boost Software License, Version 1.0. (See
williamr@2:  * accompanying file LICENSE_1_0.txt or copy at
williamr@2:  * http://www.boost.org/LICENSE_1_0.txt)
williamr@2:  *
williamr@2:  * See http://www.boost.org for most recent version including documentation.
williamr@2:  *
williamr@2:  * $Id: discard_block.hpp,v 1.12 2005/05/21 15:57:00 dgregor Exp $
williamr@2:  *
williamr@2:  * Revision history
williamr@2:  *  2001-03-02  created
williamr@2:  */
williamr@2: 
williamr@2: #ifndef BOOST_RANDOM_DISCARD_BLOCK_HPP
williamr@2: #define BOOST_RANDOM_DISCARD_BLOCK_HPP
williamr@2: 
williamr@2: #include <iostream>
williamr@2: #include <boost/config.hpp>
williamr@2: #include <boost/limits.hpp>
williamr@2: #include <boost/static_assert.hpp>
williamr@2: 
williamr@2: 
williamr@2: namespace boost {
williamr@2: namespace random {
williamr@2: 
williamr@2: template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>
williamr@2: class discard_block
williamr@2: {
williamr@2: public:
williamr@2:   typedef UniformRandomNumberGenerator base_type;
williamr@2:   typedef typename base_type::result_type result_type;
williamr@2: 
williamr@2:   BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
williamr@2:   BOOST_STATIC_CONSTANT(unsigned int, total_block = p);
williamr@2:   BOOST_STATIC_CONSTANT(unsigned int, returned_block = r);
williamr@2: 
williamr@2: #ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
williamr@2:   BOOST_STATIC_ASSERT(total_block >= returned_block);
williamr@2: #endif
williamr@2: 
williamr@2:   discard_block() : _rng(), _n(0) { }
williamr@2:   explicit discard_block(const base_type & rng) : _rng(rng), _n(0) { }
williamr@2:   template<class It> discard_block(It& first, It last)
williamr@2:     : _rng(first, last), _n(0) { }
williamr@2:   void seed() { _rng.seed(); _n = 0; }
williamr@2:   template<class T> void seed(T s) { _rng.seed(s); _n = 0; }
williamr@2:   template<class It> void seed(It& first, It last)
williamr@2:   { _n = 0; _rng.seed(first, last); }
williamr@2: 
williamr@2:   const base_type& base() const { return _rng; }
williamr@2: 
williamr@2:   result_type operator()()
williamr@2:   {
williamr@2:     if(_n >= returned_block) {
williamr@2:       // discard values of random number generator
williamr@2:       for( ; _n < total_block; ++_n)
williamr@2:         _rng();
williamr@2:       _n = 0;
williamr@2:     }
williamr@2:     ++_n;
williamr@2:     return _rng();
williamr@2:   }
williamr@2: 
williamr@2:   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_rng.min)(); }
williamr@2:   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_rng.max)(); }
williamr@2:   static bool validation(result_type x) { return true; }  // dummy
williamr@2: 
williamr@2: #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE
williamr@2: 
williamr@2: #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
williamr@2:   template<class CharT, class Traits>
williamr@2:   friend std::basic_ostream<CharT,Traits>&
williamr@2:   operator<<(std::basic_ostream<CharT,Traits>& os, const discard_block& s)
williamr@2:   {
williamr@2:     os << s._rng << " " << s._n << " ";
williamr@2:     return os;
williamr@2:   }
williamr@2: 
williamr@2:   template<class CharT, class Traits>
williamr@2:   friend std::basic_istream<CharT,Traits>&
williamr@2:   operator>>(std::basic_istream<CharT,Traits>& is, discard_block& s)
williamr@2:   {
williamr@2:     is >> s._rng >> std::ws >> s._n >> std::ws;
williamr@2:     return is;
williamr@2:   }
williamr@2: #endif
williamr@2: 
williamr@2:   friend bool operator==(const discard_block& x, const discard_block& y)
williamr@2:   { return x._rng == y._rng && x._n == y._n; }
williamr@2:   friend bool operator!=(const discard_block& x, const discard_block& y)
williamr@2:   { return !(x == y); }
williamr@2: #else
williamr@2:   // Use a member function; Streamable concept not supported.
williamr@2:   bool operator==(const discard_block& rhs) const
williamr@2:   { return _rng == rhs._rng && _n == rhs._n; }
williamr@2:   bool operator!=(const discard_block& rhs) const
williamr@2:   { return !(*this == rhs); }
williamr@2: #endif
williamr@2: 
williamr@2: private:
williamr@2:   base_type _rng;
williamr@2:   unsigned int _n;
williamr@2: };
williamr@2: 
williamr@2: #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
williamr@2: //  A definition is required even for integral static constants
williamr@2: template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>
williamr@2: const bool discard_block<UniformRandomNumberGenerator, p, r>::has_fixed_range;
williamr@2: template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>
williamr@2: const unsigned int discard_block<UniformRandomNumberGenerator, p, r>::total_block;
williamr@2: template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>
williamr@2: const unsigned int discard_block<UniformRandomNumberGenerator, p, r>::returned_block;
williamr@2: #endif
williamr@2: 
williamr@2: } // namespace random
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_RANDOM_DISCARD_BLOCK_HPP