libcxx/include/__chrono/exception.h

   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 // For information see https://libcxx.llvm.org/DesignDocs/TimeZone.html
  11
  12 #ifndef _LIBCPP___CHRONO_EXCEPTION_H
  13 #define _LIBCPP___CHRONO_EXCEPTION_H
  14
  15 #include <version>
  16 // Enable the contents of the header only when libc++ was built with experimental features enabled.
  17 #if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
  18
  19 #  include <__chrono/calendar.h>
  20 #  include <__chrono/local_info.h>
  21 #  include <__chrono/time_point.h>
  22 #  include <__config>
  23 #  include <__configuration/availability.h>
  24 #  include <__verbose_abort>
  25 #  include <format>
  26 #  include <stdexcept>
  27 #  include <string>
  28
  29 #  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  30 #    pragma GCC system_header
  31 #  endif
  32
  33 _LIBCPP_BEGIN_NAMESPACE_STD
  34
  35 #  if _LIBCPP_STD_VER >= 20
  36
  37 namespace chrono {
  38
  39 class nonexistent_local_time : public runtime_error {
  40 public:
  41   template <class _Duration>
  42   _LIBCPP_HIDE_FROM_ABI nonexistent_local_time(const local_time<_Duration>& __time, const local_info& __info)
  43       : runtime_error{__create_message(__time, __info)} {
  44     // [time.zone.exception.nonexist]/2
  45     //   Preconditions: i.result == local_info::nonexistent is true.
  46     // The value of __info.result is not used.
  47     _LIBCPP_ASSERT_PEDANTIC(__info.result == local_info::nonexistent,
  48                             "creating an nonexistent_local_time from a local_info that is not non-existent");
  49   }
  50
  51   _LIBCPP_HIDE_FROM_ABI nonexistent_local_time(const nonexistent_local_time&)            = default;
  52   _LIBCPP_HIDE_FROM_ABI nonexistent_local_time& operator=(const nonexistent_local_time&) = default;
  53
  54   _LIBCPP_AVAILABILITY_TZDB _LIBCPP_EXPORTED_FROM_ABI ~nonexistent_local_time() override; // exported as key function
  55
  56 private:
  57   template <class _Duration>
  58   _LIBCPP_HIDE_FROM_ABI string __create_message(const local_time<_Duration>& __time, const local_info& __info) {
  59     return std::format(
  60         R"({} is in a gap between
  61 {} {} and
  62 {} {} which are both equivalent to
  63 {} UTC)",
  64         __time,
  65         local_seconds{__info.first.end.time_since_epoch()} + __info.first.offset,
  66         __info.first.abbrev,
  67         local_seconds{__info.second.begin.time_since_epoch()} + __info.second.offset,
  68         __info.second.abbrev,
  69         __info.first.end);
  70   }
  71 };
  72
  73 template <class _Duration>
  74 [[noreturn]] _LIBCPP_AVAILABILITY_TZDB _LIBCPP_HIDE_FROM_ABI void __throw_nonexistent_local_time(
  75     [[maybe_unused]] const local_time<_Duration>& __time, [[maybe_unused]] const local_info& __info) {
  76 #    if _LIBCPP_HAS_EXCEPTIONS
  77   throw nonexistent_local_time(__time, __info);
  78 #    else
  79   _LIBCPP_VERBOSE_ABORT("nonexistent_local_time was thrown in -fno-exceptions mode");
  80 #    endif
  81 }
  82
  83 class ambiguous_local_time : public runtime_error {
  84 public:
  85   template <class _Duration>
  86   _LIBCPP_HIDE_FROM_ABI ambiguous_local_time(const local_time<_Duration>& __time, const local_info& __info)
  87       : runtime_error{__create_message(__time, __info)} {
  88     // [time.zone.exception.ambig]/2
  89     //   Preconditions: i.result == local_info::ambiguous is true.
  90     // The value of __info.result is not used.
  91     _LIBCPP_ASSERT_PEDANTIC(__info.result == local_info::ambiguous,
  92                             "creating an ambiguous_local_time from a local_info that is not ambiguous");
  93   }
  94
  95   _LIBCPP_HIDE_FROM_ABI ambiguous_local_time(const ambiguous_local_time&)            = default;
  96   _LIBCPP_HIDE_FROM_ABI ambiguous_local_time& operator=(const ambiguous_local_time&) = default;
  97
  98   _LIBCPP_AVAILABILITY_TZDB _LIBCPP_EXPORTED_FROM_ABI ~ambiguous_local_time() override; // exported as key function
  99
 100 private:
 101   template <class _Duration>
 102   _LIBCPP_HIDE_FROM_ABI string __create_message(const local_time<_Duration>& __time, const local_info& __info) {
 103     return std::format(
 104         // There are two spaces after the full-stop; this has been verified
 105         // in the sources of the Standard.
 106         R"({0} is ambiguous.  It could be
 107 {0} {1} == {2} UTC or
 108 {0} {3} == {4} UTC)",
 109         __time,
 110         __info.first.abbrev,
 111         __time - __info.first.offset,
 112         __info.second.abbrev,
 113         __time - __info.second.offset);
 114   }
 115 };
 116
 117 template <class _Duration>
 118 [[noreturn]] _LIBCPP_AVAILABILITY_TZDB _LIBCPP_HIDE_FROM_ABI void __throw_ambiguous_local_time(
 119     [[maybe_unused]] const local_time<_Duration>& __time, [[maybe_unused]] const local_info& __info) {
 120 #    if _LIBCPP_HAS_EXCEPTIONS
 121   throw ambiguous_local_time(__time, __info);
 122 #    else
 123   _LIBCPP_VERBOSE_ABORT("ambiguous_local_time was thrown in -fno-exceptions mode");
 124 #    endif
 125 }
 126
 127 } // namespace chrono
 128
 129 #  endif // _LIBCPP_STD_VER >= 20
 130
 131 _LIBCPP_END_NAMESPACE_STD
 132
 133 #endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
 134
 135 #endif // _LIBCPP___CHRONO_EXCEPTION_H