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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___CXX03___RANDOM_DISCARD_BLOCK_ENGINE_H10#define _LIBCPP___CXX03___RANDOM_DISCARD_BLOCK_ENGINE_H11 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_header23#endif24 25_LIBCPP_PUSH_MACROS26#include <__cxx03/__undef_macros>27 28_LIBCPP_BEGIN_NAMESPACE_STD29 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 // types40 typedef typename _Engine::result_type result_type;41 42 // engine characteristics43 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 functions53 _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 functions76 _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 functions83 _LIBCPP_HIDE_FROM_ABI const _Engine& base() const _NOEXCEPT { return __e_; }84 85 template <class _Eng, size_t _Pp, size_t _Rp>86 friend bool87 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 bool91 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 bool120operator==(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 bool126operator!=(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_STD158 159_LIBCPP_POP_MACROS160 161#endif // _LIBCPP___CXX03___RANDOM_DISCARD_BLOCK_ENGINE_H162