source: NonGTP/Boost/boost/random/discard_block.hpp @ 857

Revision 857, 3.8 KB checked in by igarcia, 19 years ago (diff)
Line 
1/* boost random/discard_block.hpp header file
2 *
3 * Copyright Jens Maurer 2002
4 * Distributed under the Boost Software License, Version 1.0. (See
5 * accompanying file LICENSE_1_0.txt or copy at
6 * http://www.boost.org/LICENSE_1_0.txt)
7 *
8 * See http://www.boost.org for most recent version including documentation.
9 *
10 * $Id: discard_block.hpp,v 1.12 2005/05/21 15:57:00 dgregor Exp $
11 *
12 * Revision history
13 *  2001-03-02  created
14 */
15
16#ifndef BOOST_RANDOM_DISCARD_BLOCK_HPP
17#define BOOST_RANDOM_DISCARD_BLOCK_HPP
18
19#include <iostream>
20#include <boost/config.hpp>
21#include <boost/limits.hpp>
22#include <boost/static_assert.hpp>
23
24
25namespace boost {
26namespace random {
27
28template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>
29class discard_block
30{
31public:
32  typedef UniformRandomNumberGenerator base_type;
33  typedef typename base_type::result_type result_type;
34
35  BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
36  BOOST_STATIC_CONSTANT(unsigned int, total_block = p);
37  BOOST_STATIC_CONSTANT(unsigned int, returned_block = r);
38
39#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
40  BOOST_STATIC_ASSERT(total_block >= returned_block);
41#endif
42
43  discard_block() : _rng(), _n(0) { }
44  explicit discard_block(const base_type & rng) : _rng(rng), _n(0) { }
45  template<class It> discard_block(It& first, It last)
46    : _rng(first, last), _n(0) { }
47  void seed() { _rng.seed(); _n = 0; }
48  template<class T> void seed(T s) { _rng.seed(s); _n = 0; }
49  template<class It> void seed(It& first, It last)
50  { _n = 0; _rng.seed(first, last); }
51
52  const base_type& base() const { return _rng; }
53
54  result_type operator()()
55  {
56    if(_n >= returned_block) {
57      // discard values of random number generator
58      for( ; _n < total_block; ++_n)
59        _rng();
60      _n = 0;
61    }
62    ++_n;
63    return _rng();
64  }
65
66  result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_rng.min)(); }
67  result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_rng.max)(); }
68  static bool validation(result_type x) { return true; }  // dummy
69
70#ifndef BOOST_NO_OPERATORS_IN_NAMESPACE
71
72#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
73  template<class CharT, class Traits>
74  friend std::basic_ostream<CharT,Traits>&
75  operator<<(std::basic_ostream<CharT,Traits>& os, const discard_block& s)
76  {
77    os << s._rng << " " << s._n << " ";
78    return os;
79  }
80
81  template<class CharT, class Traits>
82  friend std::basic_istream<CharT,Traits>&
83  operator>>(std::basic_istream<CharT,Traits>& is, discard_block& s)
84  {
85    is >> s._rng >> std::ws >> s._n >> std::ws;
86    return is;
87  }
88#endif
89
90  friend bool operator==(const discard_block& x, const discard_block& y)
91  { return x._rng == y._rng && x._n == y._n; }
92  friend bool operator!=(const discard_block& x, const discard_block& y)
93  { return !(x == y); }
94#else
95  // Use a member function; Streamable concept not supported.
96  bool operator==(const discard_block& rhs) const
97  { return _rng == rhs._rng && _n == rhs._n; }
98  bool operator!=(const discard_block& rhs) const
99  { return !(*this == rhs); }
100#endif
101
102private:
103  base_type _rng;
104  unsigned int _n;
105};
106
107#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
108//  A definition is required even for integral static constants
109template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>
110const bool discard_block<UniformRandomNumberGenerator, p, r>::has_fixed_range;
111template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>
112const unsigned int discard_block<UniformRandomNumberGenerator, p, r>::total_block;
113template<class UniformRandomNumberGenerator, unsigned int p, unsigned int r>
114const unsigned int discard_block<UniformRandomNumberGenerator, p, r>::returned_block;
115#endif
116
117} // namespace random
118
119} // namespace boost
120
121#endif // BOOST_RANDOM_DISCARD_BLOCK_HPP
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