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>
76 _LIBCPP_INLINE_VISIBILITY
77 explicit discard_block_engine(_Sseq& __q,
78 typename enable_if<__is_seed_sequence<_Sseq, discard_block_engine>::value &&
79 !is_convertible<_Sseq, _Engine>::value>::type* = 0)
__e_(__q)80 : __e_(__q), __n_(0) {}
81 _LIBCPP_INLINE_VISIBILITY
seed()82 void seed() {__e_.seed(); __n_ = 0;}
83 _LIBCPP_INLINE_VISIBILITY
seed(result_type __sd)84 void seed(result_type __sd) {__e_.seed(__sd); __n_ = 0;}
85 template<class _Sseq>
86 _LIBCPP_INLINE_VISIBILITY
87 typename enable_if
88 <
89 __is_seed_sequence<_Sseq, discard_block_engine>::value,
90 void
91 >::type
seed(_Sseq & __q)92 seed(_Sseq& __q) {__e_.seed(__q); __n_ = 0;}
93
94 // generating functions
95 _LIBCPP_HIDE_FROM_ABI result_type operator()();
96 _LIBCPP_INLINE_VISIBILITY
discard(unsigned long long __z)97 void discard(unsigned long long __z) {for (; __z; --__z) operator()();}
98
99 // property functions
100 _LIBCPP_INLINE_VISIBILITY
base()101 const _Engine& base() const _NOEXCEPT {return __e_;}
102
103 template<class _Eng, size_t _Pp, size_t _Rp>
104 friend
105 bool
106 operator==(
107 const discard_block_engine<_Eng, _Pp, _Rp>& __x,
108 const discard_block_engine<_Eng, _Pp, _Rp>& __y);
109
110 template<class _Eng, size_t _Pp, size_t _Rp>
111 friend
112 bool
113 operator!=(
114 const discard_block_engine<_Eng, _Pp, _Rp>& __x,
115 const discard_block_engine<_Eng, _Pp, _Rp>& __y);
116
117 template <class _CharT, class _Traits,
118 class _Eng, size_t _Pp, size_t _Rp>
119 friend
120 basic_ostream<_CharT, _Traits>&
121 operator<<(basic_ostream<_CharT, _Traits>& __os,
122 const discard_block_engine<_Eng, _Pp, _Rp>& __x);
123
124 template <class _CharT, class _Traits,
125 class _Eng, size_t _Pp, size_t _Rp>
126 friend
127 basic_istream<_CharT, _Traits>&
128 operator>>(basic_istream<_CharT, _Traits>& __is,
129 discard_block_engine<_Eng, _Pp, _Rp>& __x);
130 };
131
132 template<class _Engine, size_t __p, size_t __r>
133 _LIBCPP_CONSTEXPR const size_t discard_block_engine<_Engine, __p, __r>::block_size;
134
135 template<class _Engine, size_t __p, size_t __r>
136 _LIBCPP_CONSTEXPR const size_t discard_block_engine<_Engine, __p, __r>::used_block;
137
138 template<class _Engine, size_t __p, size_t __r>
139 typename discard_block_engine<_Engine, __p, __r>::result_type
operator()140 discard_block_engine<_Engine, __p, __r>::operator()()
141 {
142 if (__n_ >= static_cast<int>(__r))
143 {
144 __e_.discard(__p - __r);
145 __n_ = 0;
146 }
147 ++__n_;
148 return __e_();
149 }
150
151 template<class _Eng, size_t _Pp, size_t _Rp>
152 inline _LIBCPP_INLINE_VISIBILITY
153 bool
154 operator==(const discard_block_engine<_Eng, _Pp, _Rp>& __x,
155 const discard_block_engine<_Eng, _Pp, _Rp>& __y)
156 {
157 return __x.__n_ == __y.__n_ && __x.__e_ == __y.__e_;
158 }
159
160 template<class _Eng, size_t _Pp, size_t _Rp>
161 inline _LIBCPP_INLINE_VISIBILITY
162 bool
163 operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x,
164 const discard_block_engine<_Eng, _Pp, _Rp>& __y)
165 {
166 return !(__x == __y);
167 }
168
169 template <class _CharT, class _Traits,
170 class _Eng, size_t _Pp, size_t _Rp>
171 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
172 operator<<(basic_ostream<_CharT, _Traits>& __os,
173 const discard_block_engine<_Eng, _Pp, _Rp>& __x)
174 {
175 __save_flags<_CharT, _Traits> __lx(__os);
176 typedef basic_ostream<_CharT, _Traits> _Ostream;
177 __os.flags(_Ostream::dec | _Ostream::left);
178 _CharT __sp = __os.widen(' ');
179 __os.fill(__sp);
180 return __os << __x.__e_ << __sp << __x.__n_;
181 }
182
183 template <class _CharT, class _Traits,
184 class _Eng, size_t _Pp, size_t _Rp>
185 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
186 operator>>(basic_istream<_CharT, _Traits>& __is,
187 discard_block_engine<_Eng, _Pp, _Rp>& __x)
188 {
189 __save_flags<_CharT, _Traits> __lx(__is);
190 typedef basic_istream<_CharT, _Traits> _Istream;
191 __is.flags(_Istream::dec | _Istream::skipws);
192 _Eng __e;
193 int __n;
194 __is >> __e >> __n;
195 if (!__is.fail())
196 {
197 __x.__e_ = __e;
198 __x.__n_ = __n;
199 }
200 return __is;
201 }
202
203 _LIBCPP_END_NAMESPACE_STD
204
205 _LIBCPP_POP_MACROS
206
207 #endif // _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H
208