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. |
69 | struct PosixTransition { |
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 | }; |
79 | struct MonthWeekWeekday { |
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 | |
85 | DateFormat fmt; |
86 | |
87 | union { |
88 | NonLeapDay j; |
89 | Day n; |
90 | MonthWeekWeekday m; |
91 | }; |
92 | }; |
93 | |
94 | struct Time { |
95 | std::int_fast32_t offset; // seconds before/after 00:00:00 |
96 | }; |
97 | |
98 | Date date; |
99 | Time time; |
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. |
108 | struct PosixTimeZone { |
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; |
114 | PosixTransition dst_start; |
115 | PosixTransition dst_end; |
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_ |
129 | |