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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H10#define _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H11 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_header23#endif24 25_LIBCPP_PUSH_MACROS26#include <__undef_macros>27 28_LIBCPP_BEGIN_NAMESPACE_STD29 30template <class _Engine, size_t __p, size_t __r>31class 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++0338 static_assert(__r <= numeric_limits<int>::max(), "discard_block_engine invalid parameters");39#endif40 41public:42 // types43 typedef typename _Engine::result_type result_type;44 45 // engine characteristics46 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_LANG50 static const result_type _Min = _Engine::_Min;51 static const result_type _Max = _Engine::_Max;52#else53 static constexpr result_type _Min = _Engine::min();54 static constexpr result_type _Max = _Engine::max();55#endif56 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 functions61 _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_LANG64 _LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(_Engine&& __e) : __e_(std::move(__e)), __n_(0) {}65#endif // _LIBCPP_CXX03_LANG66 _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 functions87 _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 functions94 _LIBCPP_HIDE_FROM_ABI const _Engine& base() const _NOEXCEPT { return __e_; }95 96 template <class _Eng, size_t _Pp, size_t _Rp>97 friend bool98 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 bool102 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 113template <class _Engine, size_t __p, size_t __r>114typename 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 123template <class _Eng, size_t _Pp, size_t _Rp>124inline _LIBCPP_HIDE_FROM_ABI bool125operator==(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 129template <class _Eng, size_t _Pp, size_t _Rp>130inline _LIBCPP_HIDE_FROM_ABI bool131operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y) {132 return !(__x == __y);133}134 135template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>136_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&137operator<<(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 146template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>147_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&148operator>>(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_STD163 164_LIBCPP_POP_MACROS165 166#endif // _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H167