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// 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 
// 
//   https://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 CCTZ_TIME_ZONE_IF_H_ 
#define CCTZ_TIME_ZONE_IF_H_ 
 
#include <chrono> 
#include <cstdint> 
#include <memory> 
#include <string> 
 
#include "cctz/civil_time.h"
#include "cctz/time_zone.h"
 
namespace cctz { 
 
// A simple interface used to hide time-zone complexities from time_zone::Impl. 
// Subclasses implement the functions for civil-time conversions in the zone. 
class TimeZoneIf { 
 public: 
  // A factory function for TimeZoneIf implementations. 
  static std::unique_ptr<TimeZoneIf> Load(const std::string& name); 
 
  virtual ~TimeZoneIf();
 
  virtual time_zone::absolute_lookup BreakTime( 
      const time_point<seconds>& tp) const = 0;
  virtual time_zone::civil_lookup MakeTime( 
      const civil_second& cs) const = 0; 
 
  virtual bool NextTransition(const time_point<seconds>& tp,
                              time_zone::civil_transition* trans) const = 0;
  virtual bool PrevTransition(const time_point<seconds>& tp,
                              time_zone::civil_transition* trans) const = 0;

  virtual std::string Version() const = 0;
  virtual std::string Description() const = 0; 
 
 protected: 
  TimeZoneIf() {} 
}; 
 
// Convert between time_point<seconds> and a count of seconds since the
// Unix epoch.  We assume that the std::chrono::system_clock and the
// Unix clock are second aligned, but not that they share an epoch. 
inline std::int_fast64_t ToUnixSeconds(const time_point<seconds>& tp) {
  return (tp - std::chrono::time_point_cast<seconds>(
                   std::chrono::system_clock::from_time_t(0))).count();
} 
inline time_point<seconds> FromUnixSeconds(std::int_fast64_t t) {
  return std::chrono::time_point_cast<seconds>(
             std::chrono::system_clock::from_time_t(0)) + seconds(t);
} 
 
}  // namespace cctz 
 
#endif  // CCTZ_TIME_ZONE_IF_H_