diff options
Diffstat (limited to 'absl/time/internal/cctz/include')
| -rw-r--r-- | absl/time/internal/cctz/include/cctz/civil_time.h | 329 | ||||
| -rw-r--r-- | absl/time/internal/cctz/include/cctz/civil_time_detail.h | 564 | ||||
| -rw-r--r-- | absl/time/internal/cctz/include/cctz/time_zone.h | 316 | ||||
| -rw-r--r-- | absl/time/internal/cctz/include/cctz/zone_info_source.h | 91 |
4 files changed, 1300 insertions, 0 deletions
diff --git a/absl/time/internal/cctz/include/cctz/civil_time.h b/absl/time/internal/cctz/include/cctz/civil_time.h new file mode 100644 index 000000000000..898222b4c7af --- /dev/null +++ b/absl/time/internal/cctz/include/cctz/civil_time.h @@ -0,0 +1,329 @@ +// 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 +// +// http://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 ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_H_ +#define ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_H_ + +#include "absl/time/internal/cctz/include/cctz/civil_time_detail.h" + +namespace absl { +namespace time_internal { +namespace cctz { + +// The term "civil time" refers to the legally recognized human-scale time +// that is represented by the six fields YYYY-MM-DD hh:mm:ss. Modern-day civil +// time follows the Gregorian Calendar and is a time-zone-independent concept. +// A "date" is perhaps the most common example of a civil time (represented in +// this library as cctz::civil_day). This library provides six classes and a +// handful of functions that help with rounding, iterating, and arithmetic on +// civil times while avoiding complications like daylight-saving time (DST). +// +// The following six classes form the core of this civil-time library: +// +// * civil_second +// * civil_minute +// * civil_hour +// * civil_day +// * civil_month +// * civil_year +// +// Each class is a simple value type with the same interface for construction +// and the same six accessors for each of the civil fields (year, month, day, +// hour, minute, and second, aka YMDHMS). These classes differ only in their +// alignment, which is indicated by the type name and specifies the field on +// which arithmetic operates. +// +// Each class can be constructed by passing up to six optional integer +// arguments representing the YMDHMS fields (in that order) to the +// constructor. Omitted fields are assigned their minimum valid value. Hours, +// minutes, and seconds will be set to 0, month and day will be set to 1, and +// since there is no minimum valid year, it will be set to 1970. So, a +// default-constructed civil-time object will have YMDHMS fields representing +// "1970-01-01 00:00:00". Fields that are out-of-range are normalized (e.g., +// October 32 -> November 1) so that all civil-time objects represent valid +// values. +// +// Each civil-time class is aligned to the civil-time field indicated in the +// class's name after normalization. Alignment is performed by setting all the +// inferior fields to their minimum valid value (as described above). The +// following are examples of how each of the six types would align the fields +// representing November 22, 2015 at 12:34:56 in the afternoon. (Note: the +// std::string format used here is not important; it's just a shorthand way of +// showing the six YMDHMS fields.) +// +// civil_second 2015-11-22 12:34:56 +// civil_minute 2015-11-22 12:34:00 +// civil_hour 2015-11-22 12:00:00 +// civil_day 2015-11-22 00:00:00 +// civil_month 2015-11-01 00:00:00 +// civil_year 2015-01-01 00:00:00 +// +// Each civil-time type performs arithmetic on the field to which it is +// aligned. This means that adding 1 to a civil_day increments the day field +// (normalizing as necessary), and subtracting 7 from a civil_month operates +// on the month field (normalizing as necessary). All arithmetic produces a +// valid civil time. Difference requires two similarly aligned civil-time +// objects and returns the scalar answer in units of the objects' alignment. +// For example, the difference between two civil_hour objects will give an +// answer in units of civil hours. +// +// In addition to the six civil-time types just described, there are +// a handful of helper functions and algorithms for performing common +// calculations. These are described below. +// +// Note: In C++14 and later, this library is usable in a constexpr context. +// +// CONSTRUCTION: +// +// Each of the civil-time types can be constructed in two ways: by directly +// passing to the constructor up to six (optional) integers representing the +// YMDHMS fields, or by copying the YMDHMS fields from a differently aligned +// civil-time type. +// +// civil_day default_value; // 1970-01-01 00:00:00 +// +// civil_day a(2015, 2, 3); // 2015-02-03 00:00:00 +// civil_day b(2015, 2, 3, 4, 5, 6); // 2015-02-03 00:00:00 +// civil_day c(2015); // 2015-01-01 00:00:00 +// +// civil_second ss(2015, 2, 3, 4, 5, 6); // 2015-02-03 04:05:06 +// civil_minute mm(ss); // 2015-02-03 04:05:00 +// civil_hour hh(mm); // 2015-02-03 04:00:00 +// civil_day d(hh); // 2015-02-03 00:00:00 +// civil_month m(d); // 2015-02-01 00:00:00 +// civil_year y(m); // 2015-01-01 00:00:00 +// +// m = civil_month(y); // 2015-01-01 00:00:00 +// d = civil_day(m); // 2015-01-01 00:00:00 +// hh = civil_hour(d); // 2015-01-01 00:00:00 +// mm = civil_minute(hh); // 2015-01-01 00:00:00 +// ss = civil_second(mm); // 2015-01-01 00:00:00 +// +// ALIGNMENT CONVERSION: +// +// The alignment of a civil-time object cannot change, but the object may be +// used to construct a new object with a different alignment. This is referred +// to as "realigning". When realigning to a type with the same or more +// precision (e.g., civil_day -> civil_second), the conversion may be +// performed implicitly since no information is lost. However, if information +// could be discarded (e.g., civil_second -> civil_day), the conversion must +// be explicit at the call site. +// +// void fun(const civil_day& day); +// +// civil_second cs; +// fun(cs); // Won't compile because data may be discarded +// fun(civil_day(cs)); // OK: explicit conversion +// +// civil_day cd; +// fun(cd); // OK: no conversion needed +// +// civil_month cm; +// fun(cm); // OK: implicit conversion to civil_day +// +// NORMALIZATION: +// +// Integer arguments passed to the constructor may be out-of-range, in which +// case they are normalized to produce a valid civil-time object. This enables +// natural arithmetic on constructor arguments without worrying about the +// field's range. Normalization guarantees that there are no invalid +// civil-time objects. +// +// civil_day d(2016, 10, 32); // Out-of-range day; normalized to 2016-11-01 +// +// Note: If normalization is undesired, you can signal an error by comparing +// the constructor arguments to the normalized values returned by the YMDHMS +// properties. +// +// PROPERTIES: +// +// All civil-time types have accessors for all six of the civil-time fields: +// year, month, day, hour, minute, and second. Recall that fields inferior to +// the type's aligment will be set to their minimum valid value. +// +// civil_day d(2015, 6, 28); +// // d.year() == 2015 +// // d.month() == 6 +// // d.day() == 28 +// // d.hour() == 0 +// // d.minute() == 0 +// // d.second() == 0 +// +// COMPARISON: +// +// Comparison always considers all six YMDHMS fields, regardless of the type's +// alignment. Comparison between differently aligned civil-time types is +// allowed. +// +// civil_day feb_3(2015, 2, 3); // 2015-02-03 00:00:00 +// civil_day mar_4(2015, 3, 4); // 2015-03-04 00:00:00 +// // feb_3 < mar_4 +// // civil_year(feb_3) == civil_year(mar_4) +// +// civil_second feb_3_noon(2015, 2, 3, 12, 0, 0); // 2015-02-03 12:00:00 +// // feb_3 < feb_3_noon +// // feb_3 == civil_day(feb_3_noon) +// +// // Iterates all the days of February 2015. +// for (civil_day d(2015, 2, 1); d < civil_month(2015, 3); ++d) { +// // ... +// } +// +// STREAMING: +// +// Each civil-time type may be sent to an output stream using operator<<(). +// The output format follows the pattern "YYYY-MM-DDThh:mm:ss" where fields +// inferior to the type's alignment are omitted. +// +// civil_second cs(2015, 2, 3, 4, 5, 6); +// std::cout << cs << "\n"; // Outputs: 2015-02-03T04:05:06 +// +// civil_day cd(cs); +// std::cout << cd << "\n"; // Outputs: 2015-02-03 +// +// civil_year cy(cs); +// std::cout << cy << "\n"; // Outputs: 2015 +// +// ARITHMETIC: +// +// Civil-time types support natural arithmetic operators such as addition, +// subtraction, and difference. Arithmetic operates on the civil-time field +// indicated in the type's name. Difference requires arguments with the same +// alignment and returns the answer in units of the alignment. +// +// civil_day a(2015, 2, 3); +// ++a; // 2015-02-04 00:00:00 +// --a; // 2015-02-03 00:00:00 +// civil_day b = a + 1; // 2015-02-04 00:00:00 +// civil_day c = 1 + b; // 2015-02-05 00:00:00 +// int n = c - a; // n = 2 (civil days) +// int m = c - civil_month(c); // Won't compile: different types. +// +// EXAMPLE: Adding a month to January 31. +// +// One of the classic questions that arises when considering a civil-time +// library (or a date library or a date/time library) is this: "What happens +// when you add a month to January 31?" This is an interesting question +// because there could be a number of possible answers: +// +// 1. March 3 (or 2 if a leap year). This may make sense if the operation +// wants the equivalent of February 31. +// 2. February 28 (or 29 if a leap year). This may make sense if the operation +// wants the last day of January to go to the last day of February. +// 3. Error. The caller may get some error, an exception, an invalid date +// object, or maybe false is returned. This may make sense because there is +// no single unambiguously correct answer to the question. +// +// Practically speaking, any answer that is not what the programmer intended +// is the wrong answer. +// +// This civil-time library avoids the problem by making it impossible to ask +// ambiguous questions. All civil-time objects are aligned to a particular +// civil-field boundary (such as aligned to a year, month, day, hour, minute, +// or second), and arithmetic operates on the field to which the object is +// aligned. This means that in order to "add a month" the object must first be +// aligned to a month boundary, which is equivalent to the first day of that +// month. +// +// Of course, there are ways to compute an answer the question at hand using +// this civil-time library, but they require the programmer to be explicit +// about the answer they expect. To illustrate, let's see how to compute all +// three of the above possible answers to the question of "Jan 31 plus 1 +// month": +// +// const civil_day d(2015, 1, 31); +// +// // Answer 1: +// // Add 1 to the month field in the constructor, and rely on normalization. +// const auto ans_normalized = civil_day(d.year(), d.month() + 1, d.day()); +// // ans_normalized == 2015-03-03 (aka Feb 31) +// +// // Answer 2: +// // Add 1 to month field, capping to the end of next month. +// const auto next_month = civil_month(d) + 1; +// const auto last_day_of_next_month = civil_day(next_month + 1) - 1; +// const auto ans_capped = std::min(ans_normalized, last_day_of_next_month); +// // ans_capped == 2015-02-28 +// +// // Answer 3: +// // Signal an error if the normalized answer is not in next month. +// if (civil_month(ans_normalized) != next_month) { +// // error, month overflow +// } +// +using civil_year = detail::civil_year; +using civil_month = detail::civil_month; +using civil_day = detail::civil_day; +using civil_hour = detail::civil_hour; +using civil_minute = detail::civil_minute; +using civil_second = detail::civil_second; + +// An enum class with members monday, tuesday, wednesday, thursday, friday, +// saturday, and sunday. These enum values may be sent to an output stream +// using operator<<(). The result is the full weekday name in English with a +// leading capital letter. +// +// weekday wd = weekday::thursday; +// std::cout << wd << "\n"; // Outputs: Thursday +// +using detail::weekday; + +// Returns the weekday for the given civil_day. +// +// civil_day a(2015, 8, 13); +// weekday wd = get_weekday(a); // wd == weekday::thursday +// +using detail::get_weekday; + +// Returns the civil_day that strictly follows or precedes the given +// civil_day, and that falls on the given weekday. +// +// For example, given: +// +// August 2015 +// Su Mo Tu We Th Fr Sa +// 1 +// 2 3 4 5 6 7 8 +// 9 10 11 12 13 14 15 +// 16 17 18 19 20 21 22 +// 23 24 25 26 27 28 29 +// 30 31 +// +// civil_day a(2015, 8, 13); // get_weekday(a) == weekday::thursday +// civil_day b = next_weekday(a, weekday::thursday); // b = 2015-08-20 +// civil_day c = prev_weekday(a, weekday::thursday); // c = 2015-08-06 +// +// civil_day d = ... +// // Gets the following Thursday if d is not already Thursday +// civil_day thurs1 = prev_weekday(d, weekday::thursday) + 7; +// // Gets the previous Thursday if d is not already Thursday +// civil_day thurs2 = next_weekday(d, weekday::thursday) - 7; +// +using detail::next_weekday; +using detail::prev_weekday; + +// Returns the day-of-year for the given civil_day. +// +// civil_day a(2015, 1, 1); +// int yd_jan_1 = get_yearday(a); // yd_jan_1 = 1 +// civil_day b(2015, 12, 31); +// int yd_dec_31 = get_yearday(b); // yd_dec_31 = 365 +// +using detail::get_yearday; + +} // namespace cctz +} // namespace time_internal +} // namespace absl + +#endif // ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_H_ diff --git a/absl/time/internal/cctz/include/cctz/civil_time_detail.h b/absl/time/internal/cctz/include/cctz/civil_time_detail.h new file mode 100644 index 000000000000..4c39c7d120e6 --- /dev/null +++ b/absl/time/internal/cctz/include/cctz/civil_time_detail.h @@ -0,0 +1,564 @@ +// 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 +// +// http://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 ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_ +#define ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_ + +#include <cstdint> +#include <limits> +#include <ostream> +#include <type_traits> + +// Disable constexpr support unless we are using clang in C++14 mode. +#if __clang__ && __cpp_constexpr >= 201304 +#define CONSTEXPR_D constexpr // data +#define CONSTEXPR_F constexpr // function +#define CONSTEXPR_M constexpr // member +#else +#define CONSTEXPR_D const +#define CONSTEXPR_F inline +#define CONSTEXPR_M +#endif + +namespace absl { +namespace time_internal { +namespace cctz { + +// Support years that at least span the range of 64-bit time_t values. +using year_t = std::int_fast64_t; + +// Type alias that indicates an argument is not normalized (e.g., the +// constructor parameters and operands/results of addition/subtraction). +using diff_t = std::int_fast64_t; + +namespace detail { + +// Type aliases that indicate normalized argument values. +using month_t = std::int_fast8_t; // [1:12] +using day_t = std::int_fast8_t; // [1:31] +using hour_t = std::int_fast8_t; // [0:23] +using minute_t = std::int_fast8_t; // [0:59] +using second_t = std::int_fast8_t; // [0:59] + +// Normalized civil-time fields: Y-M-D HH:MM:SS. +struct fields { + CONSTEXPR_M fields(year_t year, month_t month, day_t day, + hour_t hour, minute_t minute, second_t second) + : y(year), m(month), d(day), hh(hour), mm(minute), ss(second) {} + std::int_least64_t y; + std::int_least8_t m; + std::int_least8_t d; + std::int_least8_t hh; + std::int_least8_t mm; + std::int_least8_t ss; +}; + +struct second_tag {}; +struct minute_tag : second_tag {}; +struct hour_tag : minute_tag {}; +struct day_tag : hour_tag {}; +struct month_tag : day_tag {}; +struct year_tag : month_tag {}; + +//////////////////////////////////////////////////////////////////////// + +// Field normalization (without avoidable overflow). + +namespace impl { + +CONSTEXPR_F bool is_leap_year(year_t y) noexcept { + return y % 4 == 0 && (y % 100 != 0 || y % 400 == 0); +} +CONSTEXPR_F int year_index(year_t y, month_t m) noexcept { + return (static_cast<int>((y + (m > 2)) % 400) + 400) % 400; +} +CONSTEXPR_F int days_per_century(year_t y, month_t m) noexcept { + const int yi = year_index(y, m); + return 36524 + (yi == 0 || yi > 300); +} +CONSTEXPR_F int days_per_4years(year_t y, month_t m) noexcept { + const int yi = year_index(y, m); + return 1460 + (yi == 0 || yi > 300 || (yi - 1) % 100 < 96); +} +CONSTEXPR_F int days_per_year(year_t y, month_t m) noexcept { + return is_leap_year(y + (m > 2)) ? 366 : 365; +} +CONSTEXPR_F int days_per_month(year_t y, month_t m) noexcept { + CONSTEXPR_D int k_days_per_month[1 + 12] = { + -1, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 // non leap year + }; + return k_days_per_month[m] + (m == 2 && is_leap_year(y)); +} + +CONSTEXPR_F fields n_day(year_t y, month_t m, diff_t d, diff_t cd, + hour_t hh, minute_t mm, second_t ss) noexcept { + y += (cd / 146097) * 400; + cd %= 146097; + if (cd < 0) { + y -= 400; + cd += 146097; + } + y += (d / 146097) * 400; + d = d % 146097 + cd; + if (d > 0) { + if (d > 146097) { + y += 400; + d -= 146097; + } + } else { + if (d > -365) { + // We often hit the previous year when stepping a civil time backwards, + // so special case it to avoid counting up by 100/4/1-year chunks. + y -= 1; + d += days_per_year(y, m); + } else { + y -= 400; + d += 146097; + } + } + if (d > 365) { + for (int n = days_per_century(y, m); d > n; n = days_per_century(y, m)) { + d -= n; + y += 100; + } + for (int n = days_per_4years(y, m); d > n; n = days_per_4years(y, m)) { + d -= n; + y += 4; + } + for (int n = days_per_year(y, m); d > n; n = days_per_year(y, m)) { + d -= n; + ++y; + } + } + if (d > 28) { + for (int n = days_per_month(y, m); d > n; n = days_per_month(y, m)) { + d -= n; + if (++m > 12) { + ++y; + m = 1; + } + } + } + return fields(y, m, static_cast<day_t>(d), hh, mm, ss); +} +CONSTEXPR_F fields n_mon(year_t y, diff_t m, diff_t d, diff_t cd, + hour_t hh, minute_t mm, second_t ss) noexcept { + if (m != 12) { + y += m / 12; + m %= 12; + if (m <= 0) { + y -= 1; + m += 12; + } + } + return n_day(y, static_cast<month_t>(m), d, cd, hh, mm, ss); +} +CONSTEXPR_F fields n_hour(year_t y, diff_t m, diff_t d, diff_t cd, + diff_t hh, minute_t mm, second_t ss) noexcept { + cd += hh / 24; + hh %= 24; + if (hh < 0) { + cd -= 1; + hh += 24; + } + return n_mon(y, m, d, cd, static_cast<hour_t>(hh), mm, ss); +} +CONSTEXPR_F fields n_min(year_t y, diff_t m, diff_t d, diff_t hh, diff_t ch, + diff_t mm, second_t ss) noexcept { + ch += mm / 60; + mm %= 60; + if (mm < 0) { + ch -= 1; + mm += 60; + } + return n_hour(y, m, d, hh / 24 + ch / 24, hh % 24 + ch % 24, + static_cast<minute_t>(mm), ss); +} +CONSTEXPR_F fields n_sec(year_t y, diff_t m, diff_t d, diff_t hh, diff_t mm, + diff_t ss) noexcept { + // Optimization for when (non-constexpr) fields are already normalized. + if (0 <= ss && ss < 60) { + const second_t nss = static_cast<second_t>(ss); + if (0 <= mm && mm < 60) { + const minute_t nmm = static_cast<minute_t>(mm); + if (0 <= hh && hh < 24) { + const hour_t nhh = static_cast<hour_t>(hh); + if (1 <= d && d <= 28 && 1 <= m && m <= 12) { + const day_t nd = static_cast<day_t>(d); + const month_t nm = static_cast<month_t>(m); + return fields(y, nm, nd, nhh, nmm, nss); + } + return n_mon(y, m, d, 0, nhh, nmm, nss); + } + return n_hour(y, m, d, hh / 24, hh % 24, nmm, nss); + } + return n_min(y, m, d, hh, mm / 60, mm % 60, nss); + } + diff_t cm = ss / 60; + ss %= 60; + if (ss < 0) { + cm -= 1; + ss += 60; + } + return n_min(y, m, d, hh, mm / 60 + cm / 60, mm % 60 + cm % 60, + static_cast<second_t>(ss)); +} + +} // namespace impl + +//////////////////////////////////////////////////////////////////////// + +// Increments the indicated (normalized) field by "n". +CONSTEXPR_F fields step(second_tag, fields f, diff_t n) noexcept { + return impl::n_sec(f.y, f.m, f.d, f.hh, f.mm + n / 60, f.ss + n % 60); +} +CONSTEXPR_F fields step(minute_tag, fields f, diff_t n) noexcept { + return impl::n_min(f.y, f.m, f.d, f.hh + n / 60, 0, f.mm + n % 60, f.ss); +} +CONSTEXPR_F fields step(hour_tag, fields f, diff_t n) noexcept { + return impl::n_hour(f.y, f.m, f.d + n / 24, 0, f.hh + n % 24, f.mm, f.ss); +} +CONSTEXPR_F fields step(day_tag, fields f, diff_t n) noexcept { + return impl::n_day(f.y, f.m, f.d, n, f.hh, f.mm, f.ss); +} +CONSTEXPR_F fields step(month_tag, fields f, diff_t n) noexcept { + return impl::n_mon(f.y + n / 12, f.m + n % 12, f.d, 0, f.hh, f.mm, f.ss); +} +CONSTEXPR_F fields step(year_tag, fields f, diff_t n) noexcept { + return fields(f.y + n, f.m, f.d, f.hh, f.mm, f.ss); +} + +//////////////////////////////////////////////////////////////////////// + +namespace impl { + +// Returns (v * f + a) but avoiding intermediate overflow when possible. +CONSTEXPR_F diff_t scale_add(diff_t v, diff_t f, diff_t a) noexcept { + return (v < 0) ? ((v + 1) * f + a) - f : ((v - 1) * f + a) + f; +} + +// Map a (normalized) Y/M/D to the number of days before/after 1970-01-01. +// Probably overflows for years outside [-292277022656:292277026595]. +CONSTEXPR_F diff_t ymd_ord(year_t y, month_t m, day_t d) noexcept { + const diff_t eyear = (m <= 2) ? y - 1 : y; + const diff_t era = (eyear >= 0 ? eyear : eyear - 399) / 400; + const diff_t yoe = eyear - era * 400; + const diff_t doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1; + const diff_t doe = yoe * 365 + yoe / 4 - yoe / 100 + doy; + return era * 146097 + doe - 719468; +} + +// Returns the difference in days between two normalized Y-M-D tuples. +// ymd_ord() will encounter integer overflow given extreme year values, +// yet the difference between two such extreme values may actually be +// small, so we take a little care to avoid overflow when possible by +// exploiting the 146097-day cycle. +CONSTEXPR_F diff_t day_difference(year_t y1, month_t m1, day_t d1, + year_t y2, month_t m2, day_t d2) noexcept { + const diff_t a_c4_off = y1 % 400; + const diff_t b_c4_off = y2 % 400; + diff_t c4_diff = (y1 - a_c4_off) - (y2 - b_c4_off); + diff_t delta = ymd_ord(a_c4_off, m1, d1) - ymd_ord(b_c4_off, m2, d2); + if (c4_diff > 0 && delta < 0) { + delta += 2 * 146097; + c4_diff -= 2 * 400; + } else if (c4_diff < 0 && delta > 0) { + delta -= 2 * 146097; + c4_diff += 2 * 400; + } + return (c4_diff / 400 * 146097) + delta; +} + +} // namespace impl + +// Returns the difference between fields structs using the indicated unit. +CONSTEXPR_F diff_t difference(year_tag, fields f1, fields f2) noexcept { + return f1.y - f2.y; +} +CONSTEXPR_F diff_t difference(month_tag, fields f1, fields f2) noexcept { + return impl::scale_add(difference(year_tag{}, f1, f2), 12, (f1.m - f2.m)); +} +CONSTEXPR_F diff_t difference(day_tag, fields f1, fields f2) noexcept { + return impl::day_difference(f1.y, f1.m, f1.d, f2.y, f2.m, f2.d); +} +CONSTEXPR_F diff_t difference(hour_tag, fields f1, fields f2) noexcept { + return impl::scale_add(difference(day_tag{}, f1, f2), 24, (f1.hh - f2.hh)); +} +CONSTEXPR_F diff_t difference(minute_tag, fields f1, fields f2) noexcept { + return impl::scale_add(difference(hour_tag{}, f1, f2), 60, (f1.mm - f2.mm)); +} +CONSTEXPR_F diff_t difference(second_tag, fields f1, fields f2) noexcept { + return impl::scale_add(difference(minute_tag{}, f1, f2), 60, f1.ss - f2.ss); +} + +//////////////////////////////////////////////////////////////////////// + +// Aligns the (normalized) fields struct to the indicated field. +CONSTEXPR_F fields align(second_tag, fields f) noexcept { + return f; +} +CONSTEXPR_F fields align(minute_tag, fields f) noexcept { + return fields{f.y, f.m, f.d, f.hh, f.mm, 0}; +} +CONSTEXPR_F fields align(hour_tag, fields f) noexcept { + return fields{f.y, f.m, f.d, f.hh, 0, 0}; +} +CONSTEXPR_F fields align(day_tag, fields f) noexcept { + return fields{f.y, f.m, f.d, 0, 0, 0}; +} +CONSTEXPR_F fields align(month_tag, fields f) noexcept { + return fields{f.y, f.m, 1, 0, 0, 0}; +} +CONSTEXPR_F fields align(year_tag, fields f) noexcept { + return fields{f.y, 1, 1, 0, 0, 0}; +} + +//////////////////////////////////////////////////////////////////////// + +template <typename T> +class civil_time { + public: + explicit CONSTEXPR_M civil_time(year_t y, diff_t m = 1, diff_t d = 1, + diff_t hh = 0, diff_t mm = 0, + diff_t ss = 0) noexcept + : civil_time(impl::n_sec(y, m, d, hh, mm, ss)) {} + + CONSTEXPR_M civil_time() noexcept : f_{1970, 1, 1, 0, 0, 0} {} + civil_time(const civil_time&) = default; + civil_time& operator=(const civil_time&) = default; + + // Conversion between civil times of different alignment. Conversion to + // a more precise alignment is allowed implicitly (e.g., day -> hour), + // but conversion where information is discarded must be explicit + // (e.g., second -> minute). + template <typename U, typename S> + using preserves_data = + typename std::enable_if<std::is_base_of<U, S>::value>::type; + template <typename U> + CONSTEXPR_M civil_time(const civil_time<U>& ct, + preserves_data<T, U>* = nullptr) noexcept + : civil_time(ct.f_) {} + template <typename U> + explicit CONSTEXPR_M civil_time(const civil_time<U>& ct, + preserves_data<U, T>* = nullptr) noexcept + : civil_time(ct.f_) {} + + // Factories for the maximum/minimum representable civil_time. + static civil_time max() { + const auto max_year = std::numeric_limits<std::int_least64_t>::max(); + return civil_time(max_year, 12, 31, 23, 59, 59); + } + static civil_time min() { + const auto min_year = std::numeric_limits<std::int_least64_t>::min(); + return civil_time(min_year, 1, 1, 0, 0, 0); + } + + // Field accessors. Note: All but year() return an int. + CONSTEXPR_M year_t year() const noexcept { return f_.y; } + CONSTEXPR_M int month() const noexcept { return f_.m; } + CONSTEXPR_M int day() const noexcept { return f_.d; } + CONSTEXPR_M int hour() const noexcept { return f_.hh; } + CONSTEXPR_M int minute() const noexcept { return f_.mm; } + CONSTEXPR_M int second() const noexcept { return f_.ss; } + + // Assigning arithmetic. + CONSTEXPR_M civil_time& operator+=(diff_t n) noexcept { + f_ = step(T{}, f_, n); + return *this; + } + CONSTEXPR_M civil_time& operator-=(diff_t n) noexcept { + if (n != std::numeric_limits<diff_t>::min()) { + f_ = step(T{}, f_, -n); + } else { + f_ = step(T{}, step(T{}, f_, -(n + 1)), 1); + } + return *this; + } + CONSTEXPR_M civil_time& operator++() noexcept { + return *this += 1; + } + CONSTEXPR_M civil_time operator++(int) noexcept { + const civil_time a = *this; + ++*this; + return a; + } + CONSTEXPR_M civil_time& operator--() noexcept { + return *this -= 1; + } + CONSTEXPR_M civil_time operator--(int) noexcept { + const civil_time a = *this; + --*this; + return a; + } + + // Binary arithmetic operators. + inline friend CONSTEXPR_M civil_time operator+(civil_time a, + diff_t n) noexcept { + return a += n; + } + inline friend CONSTEXPR_M civil_time operator+(diff_t n, + civil_time a) noexcept { + return a += n; + } + inline friend CONSTEXPR_M civil_time operator-(civil_time a, + diff_t n) noexcept { + return a -= n; + } + inline friend CONSTEXPR_M diff_t operator-(const civil_time& lhs, + const civil_time& rhs) noexcept { + return difference(T{}, lhs.f_, rhs.f_); + } + + private: + // All instantiations of this template are allowed to call the following + // private constructor and access the private fields member. + template <typename U> + friend class civil_time; + + // The designated constructor that all others eventually call. + explicit CONSTEXPR_M civil_time(fields f) noexcept : f_(align(T{}, f)) {} + + fields f_; +}; + +// Disallows difference between differently aligned types. +// auto n = civil_day(...) - civil_hour(...); // would be confusing. +template <typename Tag1, typename Tag2> +CONSTEXPR_F diff_t operator-(civil_time<Tag1>, civil_time<Tag2>) = delete; + +using civil_year = civil_time<year_tag>; +using civil_month = civil_time<month_tag>; +using civil_day = civil_time<day_tag>; +using civil_hour = civil_time<hour_tag>; +using civil_minute = civil_time<minute_tag>; +using civil_second = civil_time<second_tag>; + +//////////////////////////////////////////////////////////////////////// + +// Relational operators that work with differently aligned objects. +// Always compares all six fields. +template <typename T1, typename T2> +CONSTEXPR_F bool operator<(const civil_time<T1>& lhs, + const civil_time<T2>& rhs) noexcept { + return (lhs.year() < rhs.year() || + (lhs.year() == rhs.year() && + (lhs.month() < rhs.month() || + (lhs.month() == rhs.month() && + (lhs.day() < rhs.day() || + (lhs.day() == rhs.day() && + (lhs.hour() < rhs.hour() || + (lhs.hour() == rhs.hour() && + (lhs.minute() < rhs.minute() || + (lhs.minute() == rhs.minute() && + (lhs.second() < rhs.second()))))))))))); +} +template <typename T1, typename T2> +CONSTEXPR_F bool operator<=(const civil_time<T1>& lhs, + const civil_time<T2>& rhs) noexcept { + return !(rhs < lhs); +} +template <typename T1, typename T2> +CONSTEXPR_F bool operator>=(const civil_time<T1>& lhs, + const civil_time<T2>& rhs) noexcept { + return !(lhs < rhs); +} +template <typename T1, typename T2> +CONSTEXPR_F bool operator>(const civil_time<T1>& lhs, + const civil_time<T2>& rhs) noexcept { + return rhs < lhs; +} +template <typename T1, typename T2> +CONSTEXPR_F bool operator==(const civil_time<T1>& lhs, + const civil_time<T2>& rhs) noexcept { + return lhs.year() == rhs.year() && lhs.month() == rhs.month() && + lhs.day() == rhs.day() && lhs.hour() == rhs.hour() && + lhs.minute() == rhs.minute() && lhs.second() == rhs.second(); +} +template <typename T1, typename T2> +CONSTEXPR_F bool operator!=(const civil_time<T1>& lhs, + const civil_time<T2>& rhs) noexcept { + return !(lhs == rhs); +} + +//////////////////////////////////////////////////////////////////////// + +enum class weekday { + monday, + tuesday, + wednesday, + thursday, + friday, + saturday, + sunday, +}; + +CONSTEXPR_F weekday get_weekday(const civil_day& cd) noexcept { + CONSTEXPR_D weekday k_weekday_by_sun_off[7] = { + weekday::sunday, weekday::monday, weekday::tuesday, + weekday::wednesday, weekday::thursday, weekday::friday, + weekday::saturday, + }; + CONSTEXPR_D int k_weekday_offsets[1 + 12] = { + -1, 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4, + }; + year_t wd = cd.year() - (cd.month() < 3); + if (wd >= 0) { + wd += wd / 4 - wd / 100 + wd / 400; + } else { + wd += (wd - 3) / 4 - (wd - 99) / 100 + (wd - 399) / 400; + } + wd += k_weekday_offsets[cd.month()] + cd.day(); + return k_weekday_by_sun_off[(wd % 7 + 7) % 7]; +} + +//////////////////////////////////////////////////////////////////////// + +CONSTEXPR_F civil_day next_weekday(civil_day cd, weekday wd) noexcept { + do { cd += 1; } while (get_weekday(cd) != wd); + return cd; +} + +CONSTEXPR_F civil_day prev_weekday(civil_day cd, weekday wd) noexcept { + do { cd -= 1; } while (get_weekday(cd) != wd); + return cd; +} + +CONSTEXPR_F int get_yearday(const civil_day& cd) noexcept { + CONSTEXPR_D int k_month_offsets[1 + 12] = { + -1, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, + }; + const int feb29 = (cd.month() > 2 && impl::is_leap_year(cd.year())); + return k_month_offsets[cd.month()] + feb29 + cd.day(); +} + +//////////////////////////////////////////////////////////////////////// + +std::ostream& operator<<(std::ostream& os, const civil_year& y); +std::ostream& operator<<(std::ostream& os, const civil_month& m); +std::ostream& operator<<(std::ostream& os, const civil_day& d); +std::ostream& operator<<(std::ostream& os, const civil_hour& h); +std::ostream& operator<<(std::ostream& os, const civil_minute& m); +std::ostream& operator<<(std::ostream& os, const civil_second& s); +std::ostream& operator<<(std::ostream& os, weekday wd); + +} // namespace detail +} // namespace cctz +} // namespace time_internal +} // namespace absl + +#undef CONSTEXPR_M +#undef CONSTEXPR_F +#undef CONSTEXPR_D + +#endif // ABSL_TIME_INTERNAL_CCTZ_CIVIL_TIME_DETAIL_H_ diff --git a/absl/time/internal/cctz/include/cctz/time_zone.h b/absl/time/internal/cctz/include/cctz/time_zone.h new file mode 100644 index 000000000000..31abc2c4bbdf --- /dev/null +++ b/absl/time/internal/cctz/include/cctz/time_zone.h @@ -0,0 +1,316 @@ +// 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 +// +// http://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. + +// A library for translating between absolute times (represented by +// std::chrono::time_points of the std::chrono::system_clock) and civil +// times (represented by cctz::civil_second) using the rules defined by +// a time zone (cctz::time_zone). + +#ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_H_ +#define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_H_ + +#include <chrono> +#include <cstdint> +#include <string> +#include <utility> + +#include "absl/time/internal/cctz/include/cctz/civil_time.h" + +namespace absl { +namespace time_internal { +namespace cctz { + +// Convenience aliases. Not intended as public API points. +template <typename D> +using time_point = std::chrono::time_point<std::chrono::system_clock, D>; +using sys_seconds = std::chrono::duration<std::int_fast64_t>; + +namespace detail { +template <typename D> +inline std::pair<time_point<sys_seconds>, D> +split_seconds(const time_point<D>& tp) { + auto sec = std::chrono::time_point_cast<sys_seconds>(tp); + auto sub = tp - sec; + if (sub.count() < 0) { + sec -= sys_seconds(1); + sub += sys_seconds(1); + } + return {sec, std::chrono::duration_cast<D>(sub)}; +} +inline std::pair<time_point<sys_seconds>, sys_seconds> +split_seconds(const time_point<sys_seconds>& tp) { + return {tp, sys_seconds(0)}; +} +} // namespace detail + +// cctz::time_zone is an opaque, small, value-type class representing a +// geo-political region within which particular rules are used for mapping +// between absolute and civil times. Time zones are named using the TZ +// identifiers from the IANA Time Zone Database, such as "America/Los_Angeles" +// or "Australia/Sydney". Time zones are created from factory functions such +// as load_time_zone(). Note: strings like "PST" and "EDT" are not valid TZ +// identifiers. +// +// Example: +// cctz::time_zone utc = cctz::utc_time_zone(); +// cctz::time_zone pst = cctz::fixed_time_zone(std::chrono::hours(-8)); +// cctz::time_zone loc = cctz::local_time_zone(); +// cctz::time_zone lax; +// if (!cctz::load_time_zone("America/Los_Angeles", &lax)) { ... } +// +// See also: +// - http://www.iana.org/time-zones +// - http://en.wikipedia.org/wiki/Zoneinfo +class time_zone { + public: + time_zone() : time_zone(nullptr) {} // Equivalent to UTC + time_zone(const time_zone&) = default; + time_zone& operator=(const time_zone&) = default; + + std::string name() const; + + // An absolute_lookup represents the civil time (cctz::civil_second) within + // this time_zone at the given absolute time (time_point). There are + // additionally a few other fields that may be useful when working with + // older APIs, such as std::tm. + // + // Example: + // const cctz::time_zone tz = ... + // const auto tp = std::chrono::system_clock::now(); + // const cctz::time_zone::absolute_lookup al = tz.lookup(tp); + struct absolute_lookup { + civil_second cs; + // Note: The following fields exist for backward compatibility with older + // APIs. Accessing these fields directly is a sign of imprudent logic in + // the calling code. Modern time-related code should only access this data + // indirectly by way of cctz::format(). + int offset; // civil seconds east of UTC + bool is_dst; // is offset non-standard? + const char* abbr; // time-zone abbreviation (e.g., "PST") + }; + absolute_lookup lookup(const time_point<sys_seconds>& tp) const; + template <typename D> + absolute_lookup lookup(const time_point<D>& tp) const { + return lookup(detail::split_seconds(tp).first); + } + + // A civil_lookup represents the absolute time(s) (time_point) that + // correspond to the given civil time (cctz::civil_second) within this + // time_zone. Usually the given civil time represents a unique instant + // in time, in which case the conversion is unambiguous. However, + // within this time zone, the given civil time may be skipped (e.g., + // during a positive UTC offset shift), or repeated (e.g., during a + // negative UTC offset shift). To account for these possibilities, + // civil_lookup is richer than just a single time_point. + // + // In all cases the civil_lookup::kind enum will indicate the nature + // of the given civil-time argument, and the pre, trans, and post + // members will give the absolute time answers using the pre-transition + // offset, the transition point itself, and the post-transition offset, + // respectively (all three times are equal if kind == UNIQUE). If any + // of these three absolute times is outside the representable range of a + // time_point<sys_seconds> the field is set to its maximum/minimum value. + // + // Example: + // cctz::time_zone lax; + // if (!cctz::load_time_zone("America/Los_Angeles", &lax)) { ... } + // + // // A unique civil time. + // auto jan01 = lax.lookup(cctz::civil_second(2011, 1, 1, 0, 0, 0)); + // // jan01.kind == cctz::time_zone::civil_lookup::UNIQUE + // // jan01.pre is 2011/01/01 00:00:00 -0800 + // // jan01.trans is 2011/01/01 00:00:00 -0800 + // // jan01.post is 2011/01/01 00:00:00 -0800 + // + // // A Spring DST transition, when there is a gap in civil time. + // auto mar13 = lax.lookup(cctz::civil_second(2011, 3, 13, 2, 15, 0)); + // // mar13.kind == cctz::time_zone::civil_lookup::SKIPPED + // // mar13.pre is 2011/03/13 03:15:00 -0700 + // // mar13.trans is 2011/03/13 03:00:00 -0700 + // // mar13.post is 2011/03/13 01:15:00 -0800 + // + // // A Fall DST transition, when civil times are repeated. + // auto nov06 = lax.lookup(cctz::civil_second(2011, 11, 6, 1, 15, 0)); + // // nov06.kind == cctz::time_zone::civil_lookup::REPEATED + // // nov06.pre is 2011/11/06 01:15:00 -0700 + // // nov06.trans is 2011/11/06 01:00:00 -0800 + // // nov06.post is 2011/11/06 01:15:00 -0800 + struct civil_lookup { + enum civil_kind { + UNIQUE, // the civil time was singular (pre == trans == post) + SKIPPED, // the civil time did not exist (pre >= trans > post) + REPEATED, // the civil time was ambiguous (pre < trans <= post) + } kind; + time_point<sys_seconds> pre; // uses the pre-transition offset + time_point<sys_seconds> trans; // instant of civil-offset change + time_point<sys_seconds> post; // uses the post-transition offset + }; + civil_lookup lookup(const civil_second& cs) const; + + class Impl; + + private: + explicit time_zone(const Impl* impl) : impl_(impl) {} + const Impl* impl_; +}; + +// Relational operators. +bool operator==(time_zone lhs, time_zone rhs); +inline bool operator!=(time_zone lhs, time_zone rhs) { return !(lhs == rhs); } + +// Loads the named time zone. May perform I/O on the initial load. +// If the name is invalid, or some other kind of error occurs, returns +// false and "*tz" is set to the UTC time zone. +bool load_time_zone(const std::string& name, time_zone* tz); + +// Returns a time_zone representing UTC. Cannot fail. +time_zone utc_time_zone(); + +// Returns a time zone that is a fixed offset (seconds east) from UTC. +// Note: If the absolute value of the offset is greater than 24 hours +// you'll get UTC (i.e., zero offset) instead. +time_zone fixed_time_zone(const sys_seconds& offset); + +// Returns a time zone representing the local time zone. Falls back to UTC. +time_zone local_time_zone(); + +// Returns the civil time (cctz::civil_second) within the given time zone at +// the given absolute time (time_point). Since the additional fields provided +// by the time_zone::absolute_lookup struct should rarely be needed in modern +// code, this convert() function is simpler and should be preferred. +template <typename D> +inline civil_second convert(const time_point<D>& tp, const time_zone& tz) { + return tz.lookup(tp).cs; +} + +// Returns the absolute time (time_point) that corresponds to the given civil +// time within the given time zone. If the civil time is not unique (i.e., if +// it was either repeated or non-existent), then the returned time_point is +// the best estimate that preserves relative order. That is, this function +// guarantees that if cs1 < cs2, then convert(cs1, tz) <= convert(cs2, tz). +inline time_point<sys_seconds> convert(const civil_second& cs, + const time_zone& tz) { + const time_zone::civil_lookup cl = tz.lookup(cs); + if (cl.kind == time_zone::civil_lookup::SKIPPED) return cl.trans; + return cl.pre; +} + +namespace detail { +using femtoseconds = std::chrono::duration<std::int_fast64_t, std::femto>; +std::string format(const std::string&, const time_point<sys_seconds>&, + const femtoseconds&, const time_zone&); +bool parse(const std::string&, const std::string&, const time_zone&, + time_point<sys_seconds>*, femtoseconds*, std::string* err = nullptr); +} // namespace detail + +// Formats the given time_point in the given cctz::time_zone according to +// the provided format std::string. Uses strftime()-like formatting options, +// with the following extensions: +// +// - %Ez - RFC3339-compatible numeric UTC offset (+hh:mm or -hh:mm) +// - %E*z - Full-resolution numeric UTC offset (+hh:mm:ss or -hh:mm:ss) +// - %E#S - Seconds with # digits of fractional precision +// - %E*S - Seconds with full fractional precision (a literal '*') +// - %E#f - Fractional seconds with # digits of precision +// - %E*f - Fractional seconds with full precision (a literal '*') +// - %E4Y - Four-character years (-999 ... -001, 0000, 0001 ... 9999) +// +// Note that %E0S behaves like %S, and %E0f produces no characters. In +// contrast %E*f always produces at least one digit, which may be '0'. +// +// Note that %Y produces as many characters as it takes to fully render the +// year. A year outside of [-999:9999] when formatted with %E4Y will produce +// more than four characters, just like %Y. +// +// Tip: Format strings should include the UTC offset (e.g., %z, %Ez, or %E*z) +// so that the resulting std::string uniquely identifies an absolute time. +// +// Example: +// cctz::time_zone lax; +// if (!cctz::load_time_zone("America/Los_Angeles", &lax)) { ... } +// auto tp = cctz::convert(cctz::civil_second(2013, 1, 2, 3, 4, 5), lax); +// std::string f = cctz::format("%H:%M:%S", tp, lax); // "03:04:05" +// f = cctz::format("%H:%M:%E3S", tp, lax); // "03:04:05.000" +template <typename D> +inline std::string format(const std::string& fmt, const time_point<D>& tp, + const time_zone& tz) { + const auto p = detail::split_seconds(tp); + const auto n = std::chrono::duration_cast<detail::femtoseconds>(p.second); + return detail::format(fmt, p.first, n, tz); +} + +// Parses an input std::string according to the provided format std::string and +// returns the corresponding time_point. Uses strftime()-like formatting +// options, with the same extensions as cctz::format(), but with the +// exceptions that %E#S is interpreted as %E*S, and %E#f as %E*f. %Ez +// and %E*z also accept the same inputs. +// +// %Y consumes as many numeric characters as it can, so the matching data +// should always be terminated with a non-numeric. %E4Y always consumes +// exactly four characters, including any sign. +// +// Unspecified fields are taken from the default date and time of ... +// +// "1970-01-01 00:00:00.0 +0000" +// +// For example, parsing a std::string of "15:45" (%H:%M) will return a time_point +// that represents "1970-01-01 15:45:00.0 +0000". +// +// Note that parse() returns time instants, so it makes most sense to parse +// fully-specified date/time strings that include a UTC offset (%z, %Ez, or +// %E*z). +// +// Note also that parse() only heeds the fields year, month, day, hour, +// minute, (fractional) second, and UTC offset. Other fields, like weekday (%a +// or %A), while parsed for syntactic validity, are ignored in the conversion. +// +// Date and time fields that are out-of-range will be treated as errors rather +// than normalizing them like cctz::civil_second() would do. For example, it +// is an error to parse the date "Oct 32, 2013" because 32 is out of range. +// +// A second of ":60" is normalized to ":00" of the following minute with +// fractional seconds discarded. The following table shows how the given +// seconds and subseconds will be parsed: +// +// "59.x" -> 59.x // exact +// "60.x" -> 00.0 // normalized +// "00.x" -> 00.x // exact +// +// Errors are indicated by returning false. +// +// Example: +// const cctz::time_zone tz = ... +// std::chrono::system_clock::time_point tp; +// if (cctz::parse("%Y-%m-%d", "2015-10-09", tz, &tp)) { +// ... +// } +template <typename D> +inline bool parse(const std::string& fmt, const std::string& input, + const time_zone& tz, time_point<D>* tpp) { + time_point<sys_seconds> sec; + detail::femtoseconds fs; + const bool b = detail::parse(fmt, input, tz, &sec, &fs); + if (b) { + // TODO: Return false if unrepresentable as a time_point<D>. + *tpp = std::chrono::time_point_cast<D>(sec); + *tpp += std::chrono::duration_cast<D>(fs); + } + return b; +} + +} // namespace cctz +} // namespace time_internal +} // namespace absl + +#endif // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_H_ diff --git a/absl/time/internal/cctz/include/cctz/zone_info_source.h b/absl/time/internal/cctz/include/cctz/zone_info_source.h new file mode 100644 index 000000000000..4d9d8f875ed8 --- /dev/null +++ b/absl/time/internal/cctz/include/cctz/zone_info_source.h @@ -0,0 +1,91 @@ +// 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 +// +// http://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 ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_ +#define ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_ + +#include <cstddef> +#include <functional> +#include <memory> +#include <string> + +namespace absl { +namespace time_internal { +namespace cctz { + +// A stdio-like interface for providing zoneinfo data for a particular zone. +class ZoneInfoSource { + public: + virtual ~ZoneInfoSource(); + + virtual std::size_t Read(void* ptr, std::size_t size) = 0; // like fread() + virtual int Skip(std::size_t offset) = 0; // like fseek() +}; + +} // namespace cctz +} // namespace time_internal +} // namespace absl + +namespace absl { +namespace time_internal { +namespace cctz_extension { + +// A function-pointer type for a factory that returns a ZoneInfoSource +// given the name of a time zone and a fallback factory. Returns null +// when the data for the named zone cannot be found. +using ZoneInfoSourceFactory = + std::unique_ptr<absl::time_internal::cctz::ZoneInfoSource> (*)( + const std::string&, + const std::function<std::unique_ptr<absl::time_internal::cctz::ZoneInfoSource>( + const std::string&)>&); + +// The user can control the mapping of zone names to zoneinfo data by +// providing a definition for cctz_extension::zone_info_source_factory. +// For example, given functions my_factory() and my_other_factory() that +// can return a ZoneInfoSource for a named zone, we could inject them into +// cctz::load_time_zone() with: +// +// namespace cctz_extension { +// namespace { +// std::unique_ptr<cctz::ZoneInfoSource> CustomFactory( +// const std::string& name, +// const std::function<std::unique_ptr<cctz::ZoneInfoSource>( +// const std::string& name)>& fallback_factory) { +// if (auto zip = my_factory(name)) return zip; +// if (auto zip = fallback_factory(name)) return zip; +// if (auto zip = my_other_factory(name)) return zip; +// return nullptr; +// } +// } // namespace +// ZoneInfoSourceFactory zone_info_source_factory = CustomFactory; +// } // namespace cctz_extension +// +// This might be used, say, to use zoneinfo data embedded in the program, +// or read from a (possibly compressed) file archive, or both. +// +// cctz_extension::zone_info_source_factory() will be called: +// (1) from the same thread as the cctz::load_time_zone() call, +// (2) only once for any zone name, and +// (3) serially (i.e., no concurrent execution). +// +// The fallback factory obtains zoneinfo data by reading files in ${TZDIR}, +// and it is used automatically when no zone_info_source_factory definition +// is linked into the program. +extern ZoneInfoSourceFactory zone_info_source_factory; + +} // namespace cctz_extension +} // namespace time_internal +} // namespace absl + +#endif // ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_ |