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authorGravatar Abseil Team <absl-team@google.com>2018-06-29 14:00:35 -0700
committerGravatar Titus Winters <titus@google.com>2018-07-02 09:58:35 -0400
commit134496a31d8b324f762de3bee9a002658c984456 (patch)
treeeb3d81ec6bb667c8f360e6898411a275a19f46c5 /absl/time/internal/cctz/include
parentba8d6cf07766263723e86736f20a51c1c9c67b19 (diff)
Export of internal Abseil changes.
-- aa9e2bff92652605b8244677058be787c872f99c by Abseil Team <absl-team@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 202702969 -- d26c857c203589892a84bc44d789f2a15a60f234 by Abseil Team <absl-team@google.com>: Cleans up the FixedArray code (formatting, renames, etc) without changing the functionality PiperOrigin-RevId: 202538159 GitOrigin-RevId: aa9e2bff92652605b8244677058be787c872f99c Change-Id: I6561257232c6cc8e1cbf51d7e26bae5f8760551e
Diffstat (limited to 'absl/time/internal/cctz/include')
-rw-r--r--absl/time/internal/cctz/include/cctz/time_zone.h77
-rw-r--r--absl/time/internal/cctz/include/cctz/zone_info_source.h5
2 files changed, 75 insertions, 7 deletions
diff --git a/absl/time/internal/cctz/include/cctz/time_zone.h b/absl/time/internal/cctz/include/cctz/time_zone.h
index 55804ba6..0b9764ea 100644
--- a/absl/time/internal/cctz/include/cctz/time_zone.h
+++ b/absl/time/internal/cctz/include/cctz/time_zone.h
@@ -119,7 +119,7 @@ class time_zone {
// 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
+ // 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.
//
@@ -159,17 +159,79 @@ class time_zone {
};
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);
+ }
+
class Impl;
private:
explicit time_zone(const Impl* impl) : impl_(impl) {}
+ const Impl& effective_impl() const; // handles implicit UTC
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.
@@ -184,6 +246,7 @@ time_zone utc_time_zone();
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
@@ -227,7 +290,7 @@ bool parse(const std::string&, const std::string&, const time_zone&,
// - %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
+// 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
@@ -254,7 +317,7 @@ inline std::string format(const std::string& fmt, const time_point<D>& tp,
// 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
+// 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
diff --git a/absl/time/internal/cctz/include/cctz/zone_info_source.h b/absl/time/internal/cctz/include/cctz/zone_info_source.h
index 4d9d8f87..20a76979 100644
--- a/absl/time/internal/cctz/include/cctz/zone_info_source.h
+++ b/absl/time/internal/cctz/include/cctz/zone_info_source.h
@@ -31,6 +31,11 @@ class 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()
+
+ // Until the zoneinfo data supports versioning information, we provide
+ // a way for a ZoneInfoSource to indicate it out-of-band. The default
+ // implementation returns an empty std::string.
+ virtual std::string Version() const;
};
} // namespace cctz