1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___CHRONO_CONVERT_TO_TM_H 11 #define _LIBCPP___CHRONO_CONVERT_TO_TM_H 12 13 #include <__chrono/calendar.h> 14 #include <__chrono/concepts.h> 15 #include <__chrono/day.h> 16 #include <__chrono/duration.h> 17 #include <__chrono/file_clock.h> 18 #include <__chrono/hh_mm_ss.h> 19 #include <__chrono/month.h> 20 #include <__chrono/month_weekday.h> 21 #include <__chrono/monthday.h> 22 #include <__chrono/statically_widen.h> 23 #include <__chrono/system_clock.h> 24 #include <__chrono/time_point.h> 25 #include <__chrono/weekday.h> 26 #include <__chrono/year.h> 27 #include <__chrono/year_month.h> 28 #include <__chrono/year_month_day.h> 29 #include <__chrono/year_month_weekday.h> 30 #include <__concepts/same_as.h> 31 #include <__config> 32 #include <__format/format_error.h> 33 #include <__memory/addressof.h> 34 #include <__type_traits/is_convertible.h> 35 #include <cstdint> 36 #include <ctime> 37 #include <limits> 38 39 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 40 # pragma GCC system_header 41 #endif 42 43 _LIBCPP_PUSH_MACROS 44 #include <__undef_macros> 45 46 _LIBCPP_BEGIN_NAMESPACE_STD 47 48 #if _LIBCPP_STD_VER >= 20 49 50 // Conerts a chrono date and weekday to a given _Tm type. 51 // 52 // This is an implementation detail for the function 53 // template <class _Tm, class _ChronoT> 54 // _Tm __convert_to_tm(const _ChronoT& __value) 55 // 56 // This manually converts the two values to the proper type. It is possible to 57 // convert from sys_days to time_t and then to _Tm. But this leads to the Y2K 58 // bug when time_t is a 32-bit signed integer. Chrono considers years beyond 59 // the year 2038 valid, so instead do the transformation manually. 60 template <class _Tm, class _Date> 61 requires(same_as<_Date, chrono::year_month_day> || same_as<_Date, chrono::year_month_day_last>) 62 _LIBCPP_HIDE_FROM_ABI _Tm __convert_to_tm(const _Date& __date, chrono::weekday __weekday) { 63 _Tm __result = {}; 64 # ifdef __GLIBC__ 65 __result.tm_zone = "UTC"; 66 # endif 67 __result.tm_year = static_cast<int>(__date.year()) - 1900; 68 __result.tm_mon = static_cast<unsigned>(__date.month()) - 1; 69 __result.tm_mday = static_cast<unsigned>(__date.day()); 70 __result.tm_wday = static_cast<unsigned>(__weekday.c_encoding()); 71 __result.tm_yday = 72 (static_cast<chrono::sys_days>(__date) - 73 static_cast<chrono::sys_days>(chrono::year_month_day{__date.year(), chrono::January, chrono::day{1}})) 74 .count(); 75 76 return __result; 77 } 78 79 template <class _Tm, class _Duration> 80 _LIBCPP_HIDE_FROM_ABI _Tm __convert_to_tm(const chrono::sys_time<_Duration> __tp) { 81 chrono::sys_days __days = chrono::floor<chrono::days>(__tp); 82 chrono::year_month_day __ymd{__days}; 83 84 _Tm __result = std::__convert_to_tm<_Tm>(chrono::year_month_day{__ymd}, chrono::weekday{__days}); 85 86 uint64_t __sec = 87 chrono::duration_cast<chrono::seconds>(__tp - chrono::time_point_cast<chrono::seconds>(__days)).count(); 88 __sec %= 24 * 3600; 89 __result.tm_hour = __sec / 3600; 90 __sec %= 3600; 91 __result.tm_min = __sec / 60; 92 __result.tm_sec = __sec % 60; 93 94 return __result; 95 } 96 97 // Convert a chrono (calendar) time point, or dururation to the given _Tm type, 98 // which must have the same properties as std::tm. 99 template <class _Tm, class _ChronoT> 100 _LIBCPP_HIDE_FROM_ABI _Tm __convert_to_tm(const _ChronoT& __value) { 101 _Tm __result = {}; 102 # ifdef __GLIBC__ 103 __result.tm_zone = "UTC"; 104 # endif 105 106 if constexpr (__is_time_point<_ChronoT>) { 107 if constexpr (same_as<typename _ChronoT::clock, chrono::system_clock>) 108 return std::__convert_to_tm<_Tm>(__value); 109 else if constexpr (same_as<typename _ChronoT::clock, chrono::file_clock>) 110 return std::__convert_to_tm<_Tm>(_ChronoT::clock::to_sys(__value)); 111 else if constexpr (same_as<typename _ChronoT::clock, chrono::local_t>) 112 return std::__convert_to_tm<_Tm>(chrono::sys_time<typename _ChronoT::duration>{__value.time_since_epoch()}); 113 else 114 static_assert(sizeof(_ChronoT) == 0, "TODO: Add the missing clock specialization"); 115 } else if constexpr (chrono::__is_duration<_ChronoT>::value) { 116 // [time.format]/6 117 // ... However, if a flag refers to a "time of day" (e.g. %H, %I, %p, 118 // etc.), then a specialization of duration is interpreted as the time of 119 // day elapsed since midnight. 120 121 // Not all values can be converted to hours, it may run into ratio 122 // conversion errors. In that case the conversion to seconds works. 123 if constexpr (is_convertible_v<_ChronoT, chrono::hours>) { 124 auto __hour = chrono::floor<chrono::hours>(__value); 125 auto __sec = chrono::duration_cast<chrono::seconds>(__value - __hour); 126 __result.tm_hour = __hour.count() % 24; 127 __result.tm_min = __sec.count() / 60; 128 __result.tm_sec = __sec.count() % 60; 129 } else { 130 uint64_t __sec = chrono::duration_cast<chrono::seconds>(__value).count(); 131 __sec %= 24 * 3600; 132 __result.tm_hour = __sec / 3600; 133 __sec %= 3600; 134 __result.tm_min = __sec / 60; 135 __result.tm_sec = __sec % 60; 136 } 137 } else if constexpr (same_as<_ChronoT, chrono::day>) 138 __result.tm_mday = static_cast<unsigned>(__value); 139 else if constexpr (same_as<_ChronoT, chrono::month>) 140 __result.tm_mon = static_cast<unsigned>(__value) - 1; 141 else if constexpr (same_as<_ChronoT, chrono::year>) 142 __result.tm_year = static_cast<int>(__value) - 1900; 143 else if constexpr (same_as<_ChronoT, chrono::weekday>) 144 __result.tm_wday = __value.c_encoding(); 145 else if constexpr (same_as<_ChronoT, chrono::weekday_indexed> || same_as<_ChronoT, chrono::weekday_last>) 146 __result.tm_wday = __value.weekday().c_encoding(); 147 else if constexpr (same_as<_ChronoT, chrono::month_day>) { 148 __result.tm_mday = static_cast<unsigned>(__value.day()); 149 __result.tm_mon = static_cast<unsigned>(__value.month()) - 1; 150 } else if constexpr (same_as<_ChronoT, chrono::month_day_last>) { 151 __result.tm_mon = static_cast<unsigned>(__value.month()) - 1; 152 } else if constexpr (same_as<_ChronoT, chrono::month_weekday> || same_as<_ChronoT, chrono::month_weekday_last>) { 153 __result.tm_wday = __value.weekday_indexed().weekday().c_encoding(); 154 __result.tm_mon = static_cast<unsigned>(__value.month()) - 1; 155 } else if constexpr (same_as<_ChronoT, chrono::year_month>) { 156 __result.tm_year = static_cast<int>(__value.year()) - 1900; 157 __result.tm_mon = static_cast<unsigned>(__value.month()) - 1; 158 } else if constexpr (same_as<_ChronoT, chrono::year_month_day> || same_as<_ChronoT, chrono::year_month_day_last>) { 159 return std::__convert_to_tm<_Tm>( 160 chrono::year_month_day{__value}, chrono::weekday{static_cast<chrono::sys_days>(__value)}); 161 } else if constexpr (same_as<_ChronoT, chrono::year_month_weekday> || 162 same_as<_ChronoT, chrono::year_month_weekday_last>) { 163 return std::__convert_to_tm<_Tm>(chrono::year_month_day{static_cast<chrono::sys_days>(__value)}, __value.weekday()); 164 } else if constexpr (__is_hh_mm_ss<_ChronoT>) { 165 __result.tm_sec = __value.seconds().count(); 166 __result.tm_min = __value.minutes().count(); 167 // In libc++ hours is stored as a long. The type in std::tm is an int. So 168 // the overflow can only occur when hour uses more bits than an int 169 // provides. 170 if constexpr (sizeof(std::chrono::hours::rep) > sizeof(__result.tm_hour)) 171 if (__value.hours().count() > std::numeric_limits<decltype(__result.tm_hour)>::max()) 172 std::__throw_format_error("Formatting hh_mm_ss, encountered an hour overflow"); 173 __result.tm_hour = __value.hours().count(); 174 } else 175 static_assert(sizeof(_ChronoT) == 0, "Add the missing type specialization"); 176 177 return __result; 178 } 179 180 #endif // if _LIBCPP_STD_VER >= 20 181 182 _LIBCPP_END_NAMESPACE_STD 183 184 _LIBCPP_POP_MACROS 185 186 #endif // _LIBCPP___CHRONO_CONVERT_TO_TM_H 187