time_zone_posix.h
Go to the documentation of this file.
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 // https://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 // Parsing of a POSIX zone spec as described in the TZ part of section 8.3 in
16 // http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html.
17 //
18 // The current POSIX spec for America/Los_Angeles is "PST8PDT,M3.2.0,M11.1.0",
19 // which would be broken down as ...
20 //
21 // PosixTimeZone {
22 // std_abbr = "PST"
23 // std_offset = -28800
24 // dst_abbr = "PDT"
25 // dst_offset = -25200
26 // dst_start = PosixTransition {
27 // date {
28 // m {
29 // month = 3
30 // week = 2
31 // weekday = 0
32 // }
33 // }
34 // time {
35 // offset = 7200
36 // }
37 // }
38 // dst_end = PosixTransition {
39 // date {
40 // m {
41 // month = 11
42 // week = 1
43 // weekday = 0
44 // }
45 // }
46 // time {
47 // offset = 7200
48 // }
49 // }
50 // }
51 
52 #ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_POSIX_H_
53 #define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_POSIX_H_
54 
55 #include <cstdint>
56 #include <string>
57 
58 namespace absl {
59 namespace time_internal {
60 namespace cctz {
61 
62 // The date/time of the transition. The date is specified as either:
63 // (J) the Nth day of the year (1 <= N <= 365), excluding leap days, or
64 // (N) the Nth day of the year (0 <= N <= 365), including leap days, or
65 // (M) the Nth weekday of a month (e.g., the 2nd Sunday in March).
66 // The time, specified as a day offset, identifies the particular moment
67 // of the transition, and may be negative or >= 24h, and in which case
68 // it would take us to another day, and perhaps week, or even month.
70  enum DateFormat { J, N, M };
71 
72  struct Date {
73  struct NonLeapDay {
74  std::int_fast16_t day; // day of non-leap year [1:365]
75  };
76  struct Day {
77  std::int_fast16_t day; // day of year [0:365]
78  };
80  std::int_fast8_t month; // month of year [1:12]
81  std::int_fast8_t week; // week of month [1:5] (5==last)
82  std::int_fast8_t weekday; // 0==Sun, ..., 6=Sat
83  };
84 
86 
87  union {
89  Day n;
91  };
92  };
93 
94  struct Time {
95  std::int_fast32_t offset; // seconds before/after 00:00:00
96  };
97 
100 };
101 
102 // The entirety of a POSIX-string specified time-zone rule. The standard
103 // abbreviation and offset are always given. If the time zone includes
104 // daylight saving, then the daylight abbrevation is non-empty and the
105 // remaining fields are also valid. Note that the start/end transitions
106 // are not ordered---in the southern hemisphere the transition to end
107 // daylight time occurs first in any particular year.
109  std::string std_abbr;
110  std::int_fast32_t std_offset;
111 
112  std::string dst_abbr;
113  std::int_fast32_t dst_offset;
116 };
117 
118 // Breaks down a POSIX time-zone specification into its constituent pieces,
119 // filling in any missing values (DST offset, or start/end transition times)
120 // with the standard-defined defaults. Returns false if the specification
121 // could not be parsed (although some fields of *res may have been altered).
122 bool ParsePosixSpec(const std::string& spec, PosixTimeZone* res);
123 
124 } // namespace cctz
125 } // namespace time_internal
126 } // namespace absl
127 
128 #endif // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_POSIX_H_
bool ParsePosixSpec(const std::string &spec, PosixTimeZone *res)
Definition: algorithm.h:29


abseil_cpp
Author(s):
autogenerated on Tue Jun 18 2019 19:44:37