libcxx/test/std/time/time.zone/time.zone.zonedtime/test_offset_time_zone.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 #ifndef TEST_STD_TIME_TIME_ZONE_TIME_ZONE_ZONEDTIME_TEST_OFFSET_TIME_ZONE_H
  11 #define TEST_STD_TIME_TIME_ZONE_TIME_ZONE_ZONEDTIME_TEST_OFFSET_TIME_ZONE_H
  12
  13 #include <cassert>
  14 #include <charconv>
  15 #include <chrono>
  16 #include <format>
  17 #include <string_view>
  18 #include <system_error>
  19 #include <type_traits>
  20
  21 enum class offset_time_zone_flags {
  22   none             = 0,
  23   has_default_zone = 1,
  24   has_locate_zone  = 2,
  25   both             = has_default_zone | has_locate_zone
  26 };
  27
  28 // The enforcement of the flags is done in the zoned_traits
  29 template <offset_time_zone_flags flags = offset_time_zone_flags::both>
  30 class offset_time_zone {
  31 public:
  32   offset_time_zone() : offset_{std::chrono::seconds{0}} {}
  33   explicit offset_time_zone(std::string_view name) {
  34     int count;
  35     const char* begin             = name.data();
  36     const char* end               = begin + name.size();
  37     std::from_chars_result result = std::from_chars(begin, end, count);
  38     assert(result == std::from_chars_result(end, std::errc{}));
  39
  40     offset_ = std::chrono::seconds(count);
  41   }
  42
  43   std::chrono::seconds offset() const { return offset_; }
  44
  45   offset_time_zone* operator->() { return this; }
  46
  47   const offset_time_zone* operator->() const { return this; }
  48
  49   template <class Duration>
  50   std::chrono::sys_time<std::common_type_t<Duration, std::chrono::seconds>>
  51   to_sys(const std::chrono::local_time<Duration>& local) const {
  52     return std::chrono::sys_time<std::common_type_t<Duration, std::chrono::seconds>>{
  53         local.time_since_epoch() + offset_};
  54   }
  55
  56   template <class Duration>
  57   std::chrono::local_time<std::common_type_t<Duration, std::chrono::seconds>>
  58   to_local(const std::chrono::sys_time<Duration>& sys) const {
  59     return std::chrono::local_time<std::common_type_t<Duration, std::chrono::seconds>>{
  60         sys.time_since_epoch() - offset_};
  61   }
  62
  63   template <class Duration>
  64   std::chrono::sys_info get_info(const std::chrono::sys_time<Duration>&) const {
  65     return {std::chrono::sys_seconds::min(),
  66             std::chrono::sys_seconds::max(),
  67             offset_,
  68             std::chrono::minutes{0},
  69             std::format("{:+03d}s", offset_.count())};
  70   }
  71
  72 private:
  73   std::chrono::seconds offset_;
  74 };
  75
  76 template <>
  77 struct std::chrono::zoned_traits<offset_time_zone<offset_time_zone_flags::has_default_zone>> {
  78   using type = offset_time_zone<offset_time_zone_flags::has_default_zone>;
  79
  80   static type default_zone() { return {}; }
  81 };
  82
  83 template <>
  84 struct std::chrono::zoned_traits<offset_time_zone<offset_time_zone_flags::has_locate_zone>> {
  85   using type = offset_time_zone<offset_time_zone_flags::has_locate_zone>;
  86
  87   static type locate_zone(std::string_view name) { return type{name}; }
  88 };
  89
  90 template <>
  91 struct std::chrono::zoned_traits<offset_time_zone<offset_time_zone_flags::both>> {
  92   using type = offset_time_zone<offset_time_zone_flags::both>;
  93
  94   static type default_zone() { return {}; }
  95   static type locate_zone(std::string_view name) { return type{name}; }
  96 };
  97
  98 #endif // TEST_STD_TIME_TIME_ZONE_TIME_ZONE_ZONEDTIME_TEST_OFFSET_TIME_ZONE_H