1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #ifndef _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H
10 #define _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H
11
12 #include <__config>
13 #include <__random/is_seed_sequence.h>
14 #include <__type_traits/enable_if.h>
15 #include <__type_traits/is_convertible.h>
16 #include <__utility/move.h>
17 #include <cstddef>
18 #include <iosfwd>
19 #include <limits>
20
21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22 # pragma GCC system_header
23 #endif
24
25 _LIBCPP_PUSH_MACROS
26 #include <__undef_macros>
27
28 _LIBCPP_BEGIN_NAMESPACE_STD
29
30 template<class _Engine, size_t __p, size_t __r>
31 class _LIBCPP_TEMPLATE_VIS discard_block_engine
32 {
33 _Engine __e_;
34 int __n_;
35
36 static_assert( 0 < __r, "discard_block_engine invalid parameters");
37 static_assert(__r <= __p, "discard_block_engine invalid parameters");
38 #ifndef _LIBCPP_CXX03_LANG // numeric_limits::max() is not constexpr in C++03
39 static_assert(__r <= numeric_limits<int>::max(), "discard_block_engine invalid parameters");
40 #endif
41 public:
42 // types
43 typedef typename _Engine::result_type result_type;
44
45 // engine characteristics
46 static _LIBCPP_CONSTEXPR const size_t block_size = __p;
47 static _LIBCPP_CONSTEXPR const size_t used_block = __r;
48
49 #ifdef _LIBCPP_CXX03_LANG
50 static const result_type _Min = _Engine::_Min;
51 static const result_type _Max = _Engine::_Max;
52 #else
53 static _LIBCPP_CONSTEXPR const result_type _Min = _Engine::min();
54 static _LIBCPP_CONSTEXPR const result_type _Max = _Engine::max();
55 #endif
56
57 _LIBCPP_INLINE_VISIBILITY
min()58 static _LIBCPP_CONSTEXPR result_type min() { return _Engine::min(); }
59 _LIBCPP_INLINE_VISIBILITY
max()60 static _LIBCPP_CONSTEXPR result_type max() { return _Engine::max(); }
61
62 // constructors and seeding functions
63 _LIBCPP_INLINE_VISIBILITY
discard_block_engine()64 discard_block_engine() : __n_(0) {}
65 _LIBCPP_INLINE_VISIBILITY
discard_block_engine(const _Engine & __e)66 explicit discard_block_engine(const _Engine& __e)
67 : __e_(__e), __n_(0) {}
68 #ifndef _LIBCPP_CXX03_LANG
69 _LIBCPP_INLINE_VISIBILITY
discard_block_engine(_Engine && __e)70 explicit discard_block_engine(_Engine&& __e)
71 : __e_(_VSTD::move(__e)), __n_(0) {}
72 #endif // _LIBCPP_CXX03_LANG
73 _LIBCPP_INLINE_VISIBILITY
discard_block_engine(result_type __sd)74 explicit discard_block_engine(result_type __sd) : __e_(__sd), __n_(0) {}
75 template<class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, discard_block_engine>::value &&
76 !is_convertible<_Sseq, _Engine>::value, int> = 0>
77 _LIBCPP_INLINE_VISIBILITY
discard_block_engine(_Sseq & __q)78 explicit discard_block_engine(_Sseq& __q)
79 : __e_(__q), __n_(0) {}
80 _LIBCPP_INLINE_VISIBILITY
seed()81 void seed() {__e_.seed(); __n_ = 0;}
82 _LIBCPP_INLINE_VISIBILITY
seed(result_type __sd)83 void seed(result_type __sd) {__e_.seed(__sd); __n_ = 0;}
84 template<class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, discard_block_engine>::value, int> = 0>
85 _LIBCPP_INLINE_VISIBILITY
86 void
seed(_Sseq & __q)87 seed(_Sseq& __q) {__e_.seed(__q); __n_ = 0;}
88
89 // generating functions
90 _LIBCPP_HIDE_FROM_ABI result_type operator()();
91 _LIBCPP_INLINE_VISIBILITY
discard(unsigned long long __z)92 void discard(unsigned long long __z) {for (; __z; --__z) operator()();}
93
94 // property functions
95 _LIBCPP_INLINE_VISIBILITY
base()96 const _Engine& base() const _NOEXCEPT {return __e_;}
97
98 template<class _Eng, size_t _Pp, size_t _Rp>
99 friend
100 bool
101 operator==(
102 const discard_block_engine<_Eng, _Pp, _Rp>& __x,
103 const discard_block_engine<_Eng, _Pp, _Rp>& __y);
104
105 template<class _Eng, size_t _Pp, size_t _Rp>
106 friend
107 bool
108 operator!=(
109 const discard_block_engine<_Eng, _Pp, _Rp>& __x,
110 const discard_block_engine<_Eng, _Pp, _Rp>& __y);
111
112 template <class _CharT, class _Traits,
113 class _Eng, size_t _Pp, size_t _Rp>
114 friend
115 basic_ostream<_CharT, _Traits>&
116 operator<<(basic_ostream<_CharT, _Traits>& __os,
117 const discard_block_engine<_Eng, _Pp, _Rp>& __x);
118
119 template <class _CharT, class _Traits,
120 class _Eng, size_t _Pp, size_t _Rp>
121 friend
122 basic_istream<_CharT, _Traits>&
123 operator>>(basic_istream<_CharT, _Traits>& __is,
124 discard_block_engine<_Eng, _Pp, _Rp>& __x);
125 };
126
127 template<class _Engine, size_t __p, size_t __r>
128 _LIBCPP_CONSTEXPR const size_t discard_block_engine<_Engine, __p, __r>::block_size;
129
130 template<class _Engine, size_t __p, size_t __r>
131 _LIBCPP_CONSTEXPR const size_t discard_block_engine<_Engine, __p, __r>::used_block;
132
133 template<class _Engine, size_t __p, size_t __r>
134 typename discard_block_engine<_Engine, __p, __r>::result_type
operator()135 discard_block_engine<_Engine, __p, __r>::operator()()
136 {
137 if (__n_ >= static_cast<int>(__r))
138 {
139 __e_.discard(__p - __r);
140 __n_ = 0;
141 }
142 ++__n_;
143 return __e_();
144 }
145
146 template<class _Eng, size_t _Pp, size_t _Rp>
147 inline _LIBCPP_INLINE_VISIBILITY
148 bool
149 operator==(const discard_block_engine<_Eng, _Pp, _Rp>& __x,
150 const discard_block_engine<_Eng, _Pp, _Rp>& __y)
151 {
152 return __x.__n_ == __y.__n_ && __x.__e_ == __y.__e_;
153 }
154
155 template<class _Eng, size_t _Pp, size_t _Rp>
156 inline _LIBCPP_INLINE_VISIBILITY
157 bool
158 operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x,
159 const discard_block_engine<_Eng, _Pp, _Rp>& __y)
160 {
161 return !(__x == __y);
162 }
163
164 template <class _CharT, class _Traits,
165 class _Eng, size_t _Pp, size_t _Rp>
166 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
167 operator<<(basic_ostream<_CharT, _Traits>& __os,
168 const discard_block_engine<_Eng, _Pp, _Rp>& __x)
169 {
170 __save_flags<_CharT, _Traits> __lx(__os);
171 typedef basic_ostream<_CharT, _Traits> _Ostream;
172 __os.flags(_Ostream::dec | _Ostream::left);
173 _CharT __sp = __os.widen(' ');
174 __os.fill(__sp);
175 return __os << __x.__e_ << __sp << __x.__n_;
176 }
177
178 template <class _CharT, class _Traits,
179 class _Eng, size_t _Pp, size_t _Rp>
180 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
181 operator>>(basic_istream<_CharT, _Traits>& __is,
182 discard_block_engine<_Eng, _Pp, _Rp>& __x)
183 {
184 __save_flags<_CharT, _Traits> __lx(__is);
185 typedef basic_istream<_CharT, _Traits> _Istream;
186 __is.flags(_Istream::dec | _Istream::skipws);
187 _Eng __e;
188 int __n;
189 __is >> __e >> __n;
190 if (!__is.fail())
191 {
192 __x.__e_ = __e;
193 __x.__n_ = __n;
194 }
195 return __is;
196 }
197
198 _LIBCPP_END_NAMESPACE_STD
199
200 _LIBCPP_POP_MACROS
201
202 #endif // _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H
203