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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___CXX03___RANDOM_DISCARD_BLOCK_ENGINE_H
10#define _LIBCPP___CXX03___RANDOM_DISCARD_BLOCK_ENGINE_H
11
12#include <__cxx03/__config>
13#include <__cxx03/__random/is_seed_sequence.h>
14#include <__cxx03/__type_traits/enable_if.h>
15#include <__cxx03/__type_traits/is_convertible.h>
16#include <__cxx03/__utility/move.h>
17#include <__cxx03/cstddef>
18#include <__cxx03/iosfwd>
19#include <__cxx03/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 <__cxx03/__undef_macros>
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30template <class _Engine, size_t __p, size_t __r>
31class _LIBCPP_TEMPLATE_VIS discard_block_engine {
32 _Engine __e_;
33 int __n_;
34
35 static_assert(0 < __r, "discard_block_engine invalid parameters");
36 static_assert(__r <= __p, "discard_block_engine invalid parameters");
37
38public:
39 // types
40 typedef typename _Engine::result_type result_type;
41
42 // engine characteristics
43 static const size_t block_size = __p;
44 static const size_t used_block = __r;
45
46 static const result_type _Min = _Engine::_Min;
47 static const result_type _Max = _Engine::_Max;
48
49 _LIBCPP_HIDE_FROM_ABI static result_type min() { return _Engine::min(); }
50 _LIBCPP_HIDE_FROM_ABI static result_type max() { return _Engine::max(); }
51
52 // constructors and seeding functions
53 _LIBCPP_HIDE_FROM_ABI discard_block_engine() : __n_(0) {}
54 _LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(const _Engine& __e) : __e_(__e), __n_(0) {}
55 _LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(result_type __sd) : __e_(__sd), __n_(0) {}
56 template <
57 class _Sseq,
58 __enable_if_t<__is_seed_sequence<_Sseq, discard_block_engine>::value && !is_convertible<_Sseq, _Engine>::value,
59 int> = 0>
60 _LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(_Sseq& __q) : __e_(__q), __n_(0) {}
61 _LIBCPP_HIDE_FROM_ABI void seed() {
62 __e_.seed();
63 __n_ = 0;
64 }
65 _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd) {
66 __e_.seed(__sd);
67 __n_ = 0;
68 }
69 template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, discard_block_engine>::value, int> = 0>
70 _LIBCPP_HIDE_FROM_ABI void seed(_Sseq& __q) {
71 __e_.seed(__q);
72 __n_ = 0;
73 }
74
75 // generating functions
76 _LIBCPP_HIDE_FROM_ABI result_type operator()();
77 _LIBCPP_HIDE_FROM_ABI void discard(unsigned long long __z) {
78 for (; __z; --__z)
79 operator()();
80 }
81
82 // property functions
83 _LIBCPP_HIDE_FROM_ABI const _Engine& base() const _NOEXCEPT { return __e_; }
84
85 template <class _Eng, size_t _Pp, size_t _Rp>
86 friend bool
87 operator==(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y);
88
89 template <class _Eng, size_t _Pp, size_t _Rp>
90 friend bool
91 operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y);
92
93 template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>
94 friend basic_ostream<_CharT, _Traits>&
95 operator<<(basic_ostream<_CharT, _Traits>& __os, const discard_block_engine<_Eng, _Pp, _Rp>& __x);
96
97 template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>
98 friend basic_istream<_CharT, _Traits>&
99 operator>>(basic_istream<_CharT, _Traits>& __is, discard_block_engine<_Eng, _Pp, _Rp>& __x);
100};
101
102template <class _Engine, size_t __p, size_t __r>
103const size_t discard_block_engine<_Engine, __p, __r>::block_size;
104
105template <class _Engine, size_t __p, size_t __r>
106const size_t discard_block_engine<_Engine, __p, __r>::used_block;
107
108template <class _Engine, size_t __p, size_t __r>
109typename discard_block_engine<_Engine, __p, __r>::result_type discard_block_engine<_Engine, __p, __r>::operator()() {
110 if (__n_ >= static_cast<int>(__r)) {
111 __e_.discard(__p - __r);
112 __n_ = 0;
113 }
114 ++__n_;
115 return __e_();
116}
117
118template <class _Eng, size_t _Pp, size_t _Rp>
119inline _LIBCPP_HIDE_FROM_ABI bool
120operator==(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y) {
121 return __x.__n_ == __y.__n_ && __x.__e_ == __y.__e_;
122}
123
124template <class _Eng, size_t _Pp, size_t _Rp>
125inline _LIBCPP_HIDE_FROM_ABI bool
126operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y) {
127 return !(__x == __y);
128}
129
130template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>
131_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
132operator<<(basic_ostream<_CharT, _Traits>& __os, const discard_block_engine<_Eng, _Pp, _Rp>& __x) {
133 __save_flags<_CharT, _Traits> __lx(__os);
134 typedef basic_ostream<_CharT, _Traits> _Ostream;
135 __os.flags(_Ostream::dec | _Ostream::left);
136 _CharT __sp = __os.widen(' ');
137 __os.fill(__sp);
138 return __os << __x.__e_ << __sp << __x.__n_;
139}
140
141template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>
142_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
143operator>>(basic_istream<_CharT, _Traits>& __is, discard_block_engine<_Eng, _Pp, _Rp>& __x) {
144 __save_flags<_CharT, _Traits> __lx(__is);
145 typedef basic_istream<_CharT, _Traits> _Istream;
146 __is.flags(_Istream::dec | _Istream::skipws);
147 _Eng __e;
148 int __n;
149 __is >> __e >> __n;
150 if (!__is.fail()) {
151 __x.__e_ = __e;
152 __x.__n_ = __n;
153 }
154 return __is;
155}
156
157_LIBCPP_END_NAMESPACE_STD
158
159_LIBCPP_POP_MACROS
160
161#endif // _LIBCPP___CXX03___RANDOM_DISCARD_BLOCK_ENGINE_H
162

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source code of libcxx/include/__cxx03/__random/discard_block_engine.h