--- /dev/null
+// 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.
+
+// 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 seconds = std::chrono::duration<std::int_fast64_t>;
+using sys_seconds = seconds; // Deprecated. Use cctz::seconds instead.
+
+namespace detail {
+template <typename D>
+inline std::pair<time_point<seconds>, D>
+split_seconds(const time_point<D>& tp) {
+ auto sec = std::chrono::time_point_cast<seconds>(tp);
+ auto sub = tp - sec;
+ if (sub.count() < 0) {
+ sec -= seconds(1);
+ sub += seconds(1);
+ }
+ return {sec, std::chrono::duration_cast<D>(sub)};
+}
+inline std::pair<time_point<seconds>, seconds>
+split_seconds(const time_point<seconds>& tp) {
+ return {tp, seconds::zero()};
+}
+} // 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
+// - https://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<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<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<seconds> pre; // uses the pre-transition offset
+ time_point<seconds> trans; // instant of civil-offset change
+ time_point<seconds> post; // uses the post-transition offset
+ };
+ civil_lookup lookup(const civil_second& cs) const;
+
+ // Finds the time of the next/previous offset change in this time zone.
+ //
+ // By definition, next_transition(tp, &trans) returns false when tp has
+ // its maximum value, and prev_transition(tp, &trans) returns false
+ // when tp has its minimum value. If the zone has no transitions, the
+ // result will also be false no matter what the argument.
+ //
+ // Otherwise, when tp has its minimum value, next_transition(tp, &trans)
+ // returns true and sets trans to the first recorded transition. Chains
+ // of calls to next_transition()/prev_transition() will eventually return
+ // false, but it is unspecified exactly when next_transition(tp, &trans)
+ // jumps to false, or what time is set by prev_transition(tp, &trans) for
+ // a very distant tp.
+ //
+ // Note: Enumeration of time-zone transitions is for informational purposes
+ // only. Modern time-related code should not care about when offset changes
+ // occur.
+ //
+ // Example:
+ // cctz::time_zone nyc;
+ // if (!cctz::load_time_zone("America/New_York", &nyc)) { ... }
+ // const auto now = std::chrono::system_clock::now();
+ // auto tp = cctz::time_point<cctz::seconds>::min();
+ // cctz::time_zone::civil_transition trans;
+ // while (tp <= now && nyc.next_transition(tp, &trans)) {
+ // // transition: trans.from -> trans.to
+ // tp = nyc.lookup(trans.to).trans;
+ // }
+ struct civil_transition {
+ civil_second from; // the civil time we jump from
+ civil_second to; // the civil time we jump to
+ };
+ bool next_transition(const time_point<seconds>& tp,
+ civil_transition* trans) const;
+ template <typename D>
+ bool next_transition(const time_point<D>& tp,
+ civil_transition* trans) const {
+ return next_transition(detail::split_seconds(tp).first, trans);
+ }
+ bool prev_transition(const time_point<seconds>& tp,
+ civil_transition* trans) const;
+ template <typename D>
+ bool prev_transition(const time_point<D>& tp,
+ civil_transition* trans) const {
+ return prev_transition(detail::split_seconds(tp).first, trans);
+ }
+
+ // version() and description() provide additional information about the
+ // time zone. The content of each of the returned strings is unspecified,
+ // however, when the IANA Time Zone Database is the underlying data source
+ // the version() std::string will be in the familar form (e.g, "2018e") or
+ // empty when unavailable.
+ //
+ // Note: These functions are for informational or testing purposes only.
+ std::string version() const; // empty when unknown
+ std::string description() const;
+
+ // Relational operators.
+ friend bool operator==(time_zone lhs, time_zone rhs) {
+ return &lhs.effective_impl() == &rhs.effective_impl();
+ }
+ friend bool operator!=(time_zone lhs, time_zone rhs) {
+ return !(lhs == rhs);
+ }
+
+ template <typename H>
+ friend H AbslHashValue(H h, time_zone tz) {
+ return H::combine(std::move(h), &tz.effective_impl());
+ }
+
+ class Impl;
+
+ private:
+ explicit time_zone(const Impl* impl) : impl_(impl) {}
+ const Impl& effective_impl() const; // handles implicit UTC
+ const Impl* impl_;
+};
+
+// 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 seconds& offset);
+
+// Returns a time zone representing the local time zone. Falls back to UTC.
+// Note: local_time_zone.name() may only be something like "localtime".
+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<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<seconds>&,
+ const femtoseconds&, const time_zone&);
+bool parse(const std::string&, const std::string&, const time_zone&,
+ time_point<seconds>*, femtoseconds*, std::string* err = nullptr);
+} // namespace detail
+
+// Formats the given time_point in the given cctz::time_zone according to
+// the provided format 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 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 string according to the provided format 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 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<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_
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