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/local_info.h> 20 #include <__chrono/month.h> 21 #include <__chrono/month_weekday.h> 22 #include <__chrono/monthday.h> 23 #include <__chrono/statically_widen.h> 24 #include <__chrono/sys_info.h> 25 #include <__chrono/system_clock.h> 26 #include <__chrono/time_point.h> 27 #include <__chrono/weekday.h> 28 #include <__chrono/year.h> 29 #include <__chrono/year_month.h> 30 #include <__chrono/year_month_day.h> 31 #include <__chrono/year_month_weekday.h> 32 #include <__chrono/zoned_time.h> 33 #include <__concepts/same_as.h> 34 #include <__config> 35 #include <__format/format_error.h> 36 #include <__memory/addressof.h> 37 #include <__type_traits/is_convertible.h> 38 #include <__type_traits/is_specialization.h> 39 #include <cstdint> 40 #include <ctime> 41 #include <limits> 42 43 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 44 # pragma GCC system_header 45 #endif 46 47 _LIBCPP_PUSH_MACROS 48 #include <__undef_macros> 49 50 _LIBCPP_BEGIN_NAMESPACE_STD 51 52 #if _LIBCPP_STD_VER >= 20 53 54 // Conerts a chrono date and weekday to a given _Tm type. 55 // 56 // This is an implementation detail for the function 57 // template <class _Tm, class _ChronoT> 58 // _Tm __convert_to_tm(const _ChronoT& __value) 59 // 60 // This manually converts the two values to the proper type. It is possible to 61 // convert from sys_days to time_t and then to _Tm. But this leads to the Y2K 62 // bug when time_t is a 32-bit signed integer. Chrono considers years beyond 63 // the year 2038 valid, so instead do the transformation manually. 64 template <class _Tm, class _Date> 65 requires(same_as<_Date, chrono::year_month_day> || same_as<_Date, chrono::year_month_day_last>) 66 _LIBCPP_HIDE_FROM_ABI _Tm __convert_to_tm(const _Date& __date, chrono::weekday __weekday) { 67 _Tm __result = {}; 68 # ifdef __GLIBC__ 69 __result.tm_zone = "UTC"; 70 # endif 71 __result.tm_year = static_cast<int>(__date.year()) - 1900; 72 __result.tm_mon = static_cast<unsigned>(__date.month()) - 1; 73 __result.tm_mday = static_cast<unsigned>(__date.day()); 74 __result.tm_wday = static_cast<unsigned>(__weekday.c_encoding()); 75 __result.tm_yday = 76 (static_cast<chrono::sys_days>(__date) - 77 static_cast<chrono::sys_days>(chrono::year_month_day{__date.year(), chrono::January, chrono::day{1}})) 78 .count(); 79 80 return __result; 81 } 82 83 template <class _Tm, class _Duration> 84 _LIBCPP_HIDE_FROM_ABI _Tm __convert_to_tm(const chrono::sys_time<_Duration> __tp) { 85 chrono::sys_days __days = chrono::floor<chrono::days>(__tp); 86 chrono::year_month_day __ymd{__days}; 87 88 _Tm __result = std::__convert_to_tm<_Tm>(chrono::year_month_day{__ymd}, chrono::weekday{__days}); 89 90 uint64_t __sec = 91 chrono::duration_cast<chrono::seconds>(__tp - chrono::time_point_cast<chrono::seconds>(__days)).count(); 92 __sec %= 24 * 3600; 93 __result.tm_hour = __sec / 3600; 94 __sec %= 3600; 95 __result.tm_min = __sec / 60; 96 __result.tm_sec = __sec % 60; 97 98 return __result; 99 } 100 101 // Convert a chrono (calendar) time point, or dururation to the given _Tm type, 102 // which must have the same properties as std::tm. 103 template <class _Tm, class _ChronoT> 104 _LIBCPP_HIDE_FROM_ABI _Tm __convert_to_tm(const _ChronoT& __value) { 105 _Tm __result = {}; 106 # ifdef __GLIBC__ 107 __result.tm_zone = "UTC"; 108 # endif 109 110 if constexpr (__is_time_point<_ChronoT>) { 111 if constexpr (same_as<typename _ChronoT::clock, chrono::system_clock>) 112 return std::__convert_to_tm<_Tm>(__value); 113 else if constexpr (same_as<typename _ChronoT::clock, chrono::file_clock>) 114 return std::__convert_to_tm<_Tm>(_ChronoT::clock::to_sys(__value)); 115 else if constexpr (same_as<typename _ChronoT::clock, chrono::local_t>) 116 return std::__convert_to_tm<_Tm>(chrono::sys_time<typename _ChronoT::duration>{__value.time_since_epoch()}); 117 else 118 static_assert(sizeof(_ChronoT) == 0, "TODO: Add the missing clock specialization"); 119 } else if constexpr (chrono::__is_duration<_ChronoT>::value) { 120 // [time.format]/6 121 // ... However, if a flag refers to a "time of day" (e.g. %H, %I, %p, 122 // etc.), then a specialization of duration is interpreted as the time of 123 // day elapsed since midnight. 124 125 // Not all values can be converted to hours, it may run into ratio 126 // conversion errors. In that case the conversion to seconds works. 127 if constexpr (is_convertible_v<_ChronoT, chrono::hours>) { 128 auto __hour = chrono::floor<chrono::hours>(__value); 129 auto __sec = chrono::duration_cast<chrono::seconds>(__value - __hour); 130 __result.tm_hour = __hour.count() % 24; 131 __result.tm_min = __sec.count() / 60; 132 __result.tm_sec = __sec.count() % 60; 133 } else { 134 uint64_t __sec = chrono::duration_cast<chrono::seconds>(__value).count(); 135 __sec %= 24 * 3600; 136 __result.tm_hour = __sec / 3600; 137 __sec %= 3600; 138 __result.tm_min = __sec / 60; 139 __result.tm_sec = __sec % 60; 140 } 141 } else if constexpr (same_as<_ChronoT, chrono::day>) 142 __result.tm_mday = static_cast<unsigned>(__value); 143 else if constexpr (same_as<_ChronoT, chrono::month>) 144 __result.tm_mon = static_cast<unsigned>(__value) - 1; 145 else if constexpr (same_as<_ChronoT, chrono::year>) 146 __result.tm_year = static_cast<int>(__value) - 1900; 147 else if constexpr (same_as<_ChronoT, chrono::weekday>) 148 __result.tm_wday = __value.c_encoding(); 149 else if constexpr (same_as<_ChronoT, chrono::weekday_indexed> || same_as<_ChronoT, chrono::weekday_last>) 150 __result.tm_wday = __value.weekday().c_encoding(); 151 else if constexpr (same_as<_ChronoT, chrono::month_day>) { 152 __result.tm_mday = static_cast<unsigned>(__value.day()); 153 __result.tm_mon = static_cast<unsigned>(__value.month()) - 1; 154 } else if constexpr (same_as<_ChronoT, chrono::month_day_last>) { 155 __result.tm_mon = static_cast<unsigned>(__value.month()) - 1; 156 } else if constexpr (same_as<_ChronoT, chrono::month_weekday> || same_as<_ChronoT, chrono::month_weekday_last>) { 157 __result.tm_wday = __value.weekday_indexed().weekday().c_encoding(); 158 __result.tm_mon = static_cast<unsigned>(__value.month()) - 1; 159 } else if constexpr (same_as<_ChronoT, chrono::year_month>) { 160 __result.tm_year = static_cast<int>(__value.year()) - 1900; 161 __result.tm_mon = static_cast<unsigned>(__value.month()) - 1; 162 } else if constexpr (same_as<_ChronoT, chrono::year_month_day> || same_as<_ChronoT, chrono::year_month_day_last>) { 163 return std::__convert_to_tm<_Tm>( 164 chrono::year_month_day{__value}, chrono::weekday{static_cast<chrono::sys_days>(__value)}); 165 } else if constexpr (same_as<_ChronoT, chrono::year_month_weekday> || 166 same_as<_ChronoT, chrono::year_month_weekday_last>) { 167 return std::__convert_to_tm<_Tm>(chrono::year_month_day{static_cast<chrono::sys_days>(__value)}, __value.weekday()); 168 } else if constexpr (__is_hh_mm_ss<_ChronoT>) { 169 __result.tm_sec = __value.seconds().count(); 170 __result.tm_min = __value.minutes().count(); 171 // In libc++ hours is stored as a long. The type in std::tm is an int. So 172 // the overflow can only occur when hour uses more bits than an int 173 // provides. 174 if constexpr (sizeof(std::chrono::hours::rep) > sizeof(__result.tm_hour)) 175 if (__value.hours().count() > std::numeric_limits<decltype(__result.tm_hour)>::max()) 176 std::__throw_format_error("Formatting hh_mm_ss, encountered an hour overflow"); 177 __result.tm_hour = __value.hours().count(); 178 # if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB) 179 } else if constexpr (same_as<_ChronoT, chrono::sys_info>) { 180 // Has no time information. 181 } else if constexpr (same_as<_ChronoT, chrono::local_info>) { 182 // Has no time information. 183 # if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) && \ 184 !defined(_LIBCPP_HAS_NO_LOCALIZATION) 185 } else if constexpr (__is_specialization_v<_ChronoT, chrono::zoned_time>) { 186 return std::__convert_to_tm<_Tm>( 187 chrono::sys_time<typename _ChronoT::duration>{__value.get_local_time().time_since_epoch()}); 188 # endif 189 # endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB) 190 } else 191 static_assert(sizeof(_ChronoT) == 0, "Add the missing type specialization"); 192 193 return __result; 194 } 195 196 #endif // if _LIBCPP_STD_VER >= 20 197 198 _LIBCPP_END_NAMESPACE_STD 199 200 _LIBCPP_POP_MACROS 201 202 #endif // _LIBCPP___CHRONO_CONVERT_TO_TM_H 203