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 <__cstddef/size_t.h> 14 #include <__random/is_seed_sequence.h> 15 #include <__type_traits/enable_if.h> 16 #include <__type_traits/is_convertible.h> 17 #include <__utility/move.h> 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 _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 #ifndef _LIBCPP_CXX03_LANG // numeric_limits::max() is not constexpr in C++03 38 static_assert(__r <= numeric_limits<int>::max(), "discard_block_engine invalid parameters"); 39 #endif 40 41 public: 42 // types 43 typedef typename _Engine::result_type result_type; 44 45 // engine characteristics 46 static inline _LIBCPP_CONSTEXPR const size_t block_size = __p; 47 static inline _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 constexpr result_type _Min = _Engine::min(); 54 static constexpr result_type _Max = _Engine::max(); 55 #endif 56 57 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type min() { return _Engine::min(); } 58 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type max() { return _Engine::max(); } 59 60 // constructors and seeding functions 61 _LIBCPP_HIDE_FROM_ABI discard_block_engine() : __n_(0) {} 62 _LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(const _Engine& __e) : __e_(__e), __n_(0) {} 63 #ifndef _LIBCPP_CXX03_LANG 64 _LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(_Engine&& __e) : __e_(std::move(__e)), __n_(0) {} 65 #endif // _LIBCPP_CXX03_LANG 66 _LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(result_type __sd) : __e_(__sd), __n_(0) {} 67 template < 68 class _Sseq, 69 __enable_if_t<__is_seed_sequence<_Sseq, discard_block_engine>::value && !is_convertible<_Sseq, _Engine>::value, 70 int> = 0> 71 _LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(_Sseq& __q) : __e_(__q), __n_(0) {} 72 _LIBCPP_HIDE_FROM_ABI void seed() { 73 __e_.seed(); 74 __n_ = 0; 75 } 76 _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd) { 77 __e_.seed(__sd); 78 __n_ = 0; 79 } 80 template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, discard_block_engine>::value, int> = 0> 81 _LIBCPP_HIDE_FROM_ABI void seed(_Sseq& __q) { 82 __e_.seed(__q); 83 __n_ = 0; 84 } 85 86 // generating functions 87 _LIBCPP_HIDE_FROM_ABI result_type operator()(); 88 _LIBCPP_HIDE_FROM_ABI void discard(unsigned long long __z) { 89 for (; __z; --__z) 90 operator()(); 91 } 92 93 // property functions 94 _LIBCPP_HIDE_FROM_ABI const _Engine& base() const _NOEXCEPT { return __e_; } 95 96 template <class _Eng, size_t _Pp, size_t _Rp> 97 friend bool 98 operator==(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y); 99 100 template <class _Eng, size_t _Pp, size_t _Rp> 101 friend bool 102 operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y); 103 104 template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp> 105 friend basic_ostream<_CharT, _Traits>& 106 operator<<(basic_ostream<_CharT, _Traits>& __os, const discard_block_engine<_Eng, _Pp, _Rp>& __x); 107 108 template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp> 109 friend basic_istream<_CharT, _Traits>& 110 operator>>(basic_istream<_CharT, _Traits>& __is, discard_block_engine<_Eng, _Pp, _Rp>& __x); 111 }; 112 113 template <class _Engine, size_t __p, size_t __r> 114 typename discard_block_engine<_Engine, __p, __r>::result_type discard_block_engine<_Engine, __p, __r>::operator()() { 115 if (__n_ >= static_cast<int>(__r)) { 116 __e_.discard(__p - __r); 117 __n_ = 0; 118 } 119 ++__n_; 120 return __e_(); 121 } 122 123 template <class _Eng, size_t _Pp, size_t _Rp> 124 inline _LIBCPP_HIDE_FROM_ABI bool 125 operator==(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y) { 126 return __x.__n_ == __y.__n_ && __x.__e_ == __y.__e_; 127 } 128 129 template <class _Eng, size_t _Pp, size_t _Rp> 130 inline _LIBCPP_HIDE_FROM_ABI bool 131 operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y) { 132 return !(__x == __y); 133 } 134 135 template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp> 136 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& 137 operator<<(basic_ostream<_CharT, _Traits>& __os, const discard_block_engine<_Eng, _Pp, _Rp>& __x) { 138 __save_flags<_CharT, _Traits> __lx(__os); 139 typedef basic_ostream<_CharT, _Traits> _Ostream; 140 __os.flags(_Ostream::dec | _Ostream::left); 141 _CharT __sp = __os.widen(' '); 142 __os.fill(__sp); 143 return __os << __x.__e_ << __sp << __x.__n_; 144 } 145 146 template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp> 147 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& 148 operator>>(basic_istream<_CharT, _Traits>& __is, discard_block_engine<_Eng, _Pp, _Rp>& __x) { 149 __save_flags<_CharT, _Traits> __lx(__is); 150 typedef basic_istream<_CharT, _Traits> _Istream; 151 __is.flags(_Istream::dec | _Istream::skipws); 152 _Eng __e; 153 int __n; 154 __is >> __e >> __n; 155 if (!__is.fail()) { 156 __x.__e_ = __e; 157 __x.__n_ = __n; 158 } 159 return __is; 160 } 161 162 _LIBCPP_END_NAMESPACE_STD 163 164 _LIBCPP_POP_MACROS 165 166 #endif // _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H 167