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Diffstat (limited to 'absl/time/internal/cctz/src/time_zone_info.h')
| -rw-r--r-- | absl/time/internal/cctz/src/time_zone_info.h | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/absl/time/internal/cctz/src/time_zone_info.h b/absl/time/internal/cctz/src/time_zone_info.h new file mode 100644 index 00000000..b4d1696b --- /dev/null +++ b/absl/time/internal/cctz/src/time_zone_info.h @@ -0,0 +1,132 @@ +// Copyright 2016 Google Inc. All Rights Reserved. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_INFO_H_ +#define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_INFO_H_ + +#include <atomic> +#include <cstddef> +#include <cstdint> +#include <string> +#include <vector> + +#include "absl/time/internal/cctz/include/cctz/civil_time.h" +#include "absl/time/internal/cctz/include/cctz/time_zone.h" +#include "absl/time/internal/cctz/include/cctz/zone_info_source.h" +#include "time_zone_if.h" +#include "tzfile.h" + +namespace absl { +namespace time_internal { +namespace cctz { + +// A transition to a new UTC offset. +struct Transition { + std::int_least64_t unix_time; // the instant of this transition + std::uint_least8_t type_index; // index of the transition type + civil_second civil_sec; // local civil time of transition + civil_second prev_civil_sec; // local civil time one second earlier + + struct ByUnixTime { + inline bool operator()(const Transition& lhs, const Transition& rhs) const { + return lhs.unix_time < rhs.unix_time; + } + }; + struct ByCivilTime { + inline bool operator()(const Transition& lhs, const Transition& rhs) const { + return lhs.civil_sec < rhs.civil_sec; + } + }; +}; + +// The characteristics of a particular transition. +struct TransitionType { + std::int_least32_t utc_offset; // the new prevailing UTC offset + civil_second civil_max; // max convertible civil time for offset + civil_second civil_min; // min convertible civil time for offset + bool is_dst; // did we move into daylight-saving time + std::uint_least8_t abbr_index; // index of the new abbreviation +}; + +// A time zone backed by the IANA Time Zone Database (zoneinfo). +class TimeZoneInfo : public TimeZoneIf { + public: + TimeZoneInfo() = default; + TimeZoneInfo(const TimeZoneInfo&) = delete; + TimeZoneInfo& operator=(const TimeZoneInfo&) = delete; + + // Loads the zoneinfo for the given name, returning true if successful. + bool Load(const std::string& name); + + // TimeZoneIf implementations. + time_zone::absolute_lookup BreakTime( + const time_point<sys_seconds>& tp) const override; + time_zone::civil_lookup MakeTime( + const civil_second& cs) const override; + std::string Description() const override; + bool NextTransition(time_point<sys_seconds>* tp) const override; + bool PrevTransition(time_point<sys_seconds>* tp) const override; + + private: + struct Header { // counts of: + std::size_t timecnt; // transition times + std::size_t typecnt; // transition types + std::size_t charcnt; // zone abbreviation characters + std::size_t leapcnt; // leap seconds (we expect none) + std::size_t ttisstdcnt; // UTC/local indicators (unused) + std::size_t ttisgmtcnt; // standard/wall indicators (unused) + + bool Build(const tzhead& tzh); + std::size_t DataLength(std::size_t time_len) const; + }; + + void CheckTransition(const std::string& name, const TransitionType& tt, + std::int_fast32_t offset, bool is_dst, + const std::string& abbr) const; + bool EquivTransitions(std::uint_fast8_t tt1_index, + std::uint_fast8_t tt2_index) const; + void ExtendTransitions(const std::string& name, const Header& hdr); + + bool ResetToBuiltinUTC(const sys_seconds& offset); + bool Load(const std::string& name, ZoneInfoSource* zip); + + // Helpers for BreakTime() and MakeTime(). + time_zone::absolute_lookup LocalTime(std::int_fast64_t unix_time, + const TransitionType& tt) const; + time_zone::absolute_lookup LocalTime(std::int_fast64_t unix_time, + const Transition& tr) const; + time_zone::civil_lookup TimeLocal(const civil_second& cs, + year_t c4_shift) const; + + std::vector<Transition> transitions_; // ordered by unix_time and civil_sec + std::vector<TransitionType> transition_types_; // distinct transition types + std::uint_fast8_t default_transition_type_; // for before first transition + std::string abbreviations_; // all the NUL-terminated abbreviations + + std::string future_spec_; // for after the last zic transition + bool extended_; // future_spec_ was used to generate transitions + year_t last_year_; // the final year of the generated transitions + + // We remember the transitions found during the last BreakTime() and + // MakeTime() calls. If the next request is for the same transition we + // will avoid re-searching. + mutable std::atomic<std::size_t> local_time_hint_ = {}; // BreakTime() hint + mutable std::atomic<std::size_t> time_local_hint_ = {}; // MakeTime() hint +}; + +} // namespace cctz +} // namespace time_internal +} // namespace absl + +#endif // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_INFO_H_ |