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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.
// Parsing of a POSIX zone spec as described in the TZ part of section 8.3 in
// http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html.
//
// The current POSIX spec for America/Los_Angeles is "PST8PDT,M3.2.0,M11.1.0",
// which would be broken down as ...
//
// PosixTimeZone {
// std_abbr = "PST"
// std_offset = -28800
// dst_abbr = "PDT"
// dst_offset = -25200
// dst_start = PosixTransition {
// date {
// m {
// month = 3
// week = 2
// weekday = 0
// }
// }
// time {
// offset = 7200
// }
// }
// dst_end = PosixTransition {
// date {
// m {
// month = 11
// week = 1
// weekday = 0
// }
// }
// time {
// offset = 7200
// }
// }
// }
#ifndef CCTZ_TIME_ZONE_POSIX_H_
#define CCTZ_TIME_ZONE_POSIX_H_
#include <cstdint>
#include <string>
namespace cctz {
// The date/time of the transition. The date is specified as either:
// (J) the Nth day of the year (1 <= N <= 365), excluding leap days, or
// (N) the Nth day of the year (0 <= N <= 365), including leap days, or
// (M) the Nth weekday of a month (e.g., the 2nd Sunday in March).
// The time, specified as a day offset, identifies the particular moment
// of the transition, and may be negative or >= 24h, and in which case
// it would take us to another day, and perhaps week, or even month.
struct PosixTransition {
enum DateFormat { J, N, M };
struct Date {
struct NonLeapDay {
std::int_fast16_t day; // day of non-leap year [1:365]
};
struct Day {
std::int_fast16_t day; // day of year [0:365]
};
struct MonthWeekWeekday {
std::int_fast8_t month; // month of year [1:12]
std::int_fast8_t week; // week of month [1:5] (5==last)
std::int_fast8_t weekday; // 0==Sun, ..., 6=Sat
};
DateFormat fmt;
union {
NonLeapDay j;
Day n;
MonthWeekWeekday m;
};
};
struct Time {
std::int_fast32_t offset; // seconds before/after 00:00:00
};
Date date;
Time time;
};
// The entirety of a POSIX-string specified time-zone rule. The standard
// abbreviation and offset are always given. If the time zone includes
// daylight saving, then the daylight abbrevation is non-empty and the
// remaining fields are also valid. Note that the start/end transitions
// are not ordered---in the southern hemisphere the transition to end
// daylight time occurs first in any particular year.
struct PosixTimeZone {
std::string std_abbr;
std::int_fast32_t std_offset;
std::string dst_abbr;
std::int_fast32_t dst_offset;
PosixTransition dst_start;
PosixTransition dst_end;
};
// Breaks down a POSIX time-zone specification into its constituent pieces,
// filling in any missing values (DST offset, or start/end transition times)
// with the standard-defined defaults. Returns false if the specification
// could not be parsed (although some fields of *res may have been altered).
bool ParsePosixSpec(const std::string& spec, PosixTimeZone* res);
} // namespace cctz
#endif // CCTZ_TIME_ZONE_POSIX_H_
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