1// Copyright 2016 Google Inc. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#ifndef CCTZ_TIME_ZONE_IF_H_
16#define CCTZ_TIME_ZONE_IF_H_
17
18#include <chrono>
19#include <cstdint>
20#include <memory>
21#include <string>
22
23#include "cctz/civil_time.h"
24#include "cctz/time_zone.h"
25
26namespace cctz {
27
28// A simple interface used to hide time-zone complexities from time_zone::Impl.
29// Subclasses implement the functions for civil-time conversions in the zone.
30class TimeZoneIf {
31 public:
32 // A factory function for TimeZoneIf implementations.
33 static std::unique_ptr<TimeZoneIf> Load(const std::string& name);
34
35 virtual ~TimeZoneIf();
36
37 virtual time_zone::absolute_lookup BreakTime(
38 const time_point<sys_seconds>& tp) const = 0;
39 virtual time_zone::civil_lookup MakeTime(
40 const civil_second& cs) const = 0;
41
42 virtual std::string Description() const = 0;
43 virtual bool NextTransition(time_point<sys_seconds>* tp) const = 0;
44 virtual bool PrevTransition(time_point<sys_seconds>* tp) const = 0;
45
46 protected:
47 TimeZoneIf() {}
48};
49
50// Convert between time_point<sys_seconds> and a count of seconds since
51// the Unix epoch. We assume that the std::chrono::system_clock and the
52// Unix clock are second aligned, but not that they share an epoch.
53inline std::int_fast64_t ToUnixSeconds(const time_point<sys_seconds>& tp) {
54 return (tp - std::chrono::time_point_cast<sys_seconds>(
55 std::chrono::system_clock::from_time_t(0)))
56 .count();
57}
58inline time_point<sys_seconds> FromUnixSeconds(std::int_fast64_t t) {
59 return std::chrono::time_point_cast<sys_seconds>(
60 std::chrono::system_clock::from_time_t(0)) +
61 sys_seconds(t);
62}
63
64} // namespace cctz
65
66#endif // CCTZ_TIME_ZONE_IF_H_
67