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authorGravatar Abseil Team <absl-team@google.com>2018-10-15 11:30:24 -0700
committerGravatar Xiaoyi Zhang <zhangxy988@gmail.com>2018-10-15 15:32:46 -0400
commit5b70a8910b2e6fb0ce5193a41873139a126d2f7f (patch)
tree1a4a99b5c877f0b69bd8756ea1518dd16f09dd2b /absl/time
parenta00bdd176d66ef0b417d9576052a19091fbdf891 (diff)
Export of internal Abseil changes.
-- f4e870453d02106c2685e0461816469a4704ad25 by Abseil Team <absl-team@google.com>: Expose TimeZone::NextTransition() and PrevTransition() now that we have absl::CivilSecond support in time.h. Note that these are for informational purposes only. General time code should not care when offset changes occur. PiperOrigin-RevId: 217177292 -- cfadd275c7333f7c27c4d682b9d167010d874e69 by Abseil Team <absl-team@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 217153577 -- 6ff5b8c61a1239b9c0478a7c62bcd2844b310307 by Jon Cohen <cohenjon@google.com>: Fix code examples in hash_testing.h. Includes random clang-format changes. PiperOrigin-RevId: 216898995 -- de124129d27f4627dabe193a10bf106a11783fba by Shaindel Schwartz <shaindel@google.com>: Add contribution guidelines describing how we decide whether to include an API in Abseil. PiperOrigin-RevId: 216886943 GitOrigin-RevId: f4e870453d02106c2685e0461816469a4704ad25 Change-Id: Ib9c6706f5bf931b71c0357bf1342053a3bee8ff7
Diffstat (limited to 'absl/time')
-rw-r--r--absl/time/internal/cctz/src/time_zone_lookup_test.cc14
-rw-r--r--absl/time/time.cc22
-rw-r--r--absl/time/time.h40
-rw-r--r--absl/time/time_test.cc63
4 files changed, 132 insertions, 7 deletions
diff --git a/absl/time/internal/cctz/src/time_zone_lookup_test.cc b/absl/time/internal/cctz/src/time_zone_lookup_test.cc
index 280c96b4..f28e7f85 100644
--- a/absl/time/internal/cctz/src/time_zone_lookup_test.cc
+++ b/absl/time/internal/cctz/src/time_zone_lookup_test.cc
@@ -991,15 +991,17 @@ TEST(MakeTime, SysSecondsLimits) {
tp = convert(civil_second::min(), west);
EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
- // Checks that "tm_year + 1900", as used by the "libc" implementation,
- // can produce year values beyond the range on an int without overflow.
+ if (sizeof(std::time_t) >= 8) {
+ // Checks that "tm_year + 1900", as used by the "libc" implementation,
+ // can produce year values beyond the range on an int without overflow.
#if defined(_WIN32) || defined(_WIN64)
- // localtime_s() and gmtime_s() don't believe in years past 3000.
+ // localtime_s() and gmtime_s() don't believe in years past 3000.
#else
- const time_zone libc_utc = LoadZone("libc:UTC");
- tp = convert(civil_year(year_t{2147483648}), libc_utc);
- EXPECT_EQ("2147483648-01-01T00:00:00+00:00", format(RFC3339, tp, libc_utc));
+ const time_zone libc_utc = LoadZone("libc:UTC");
+ tp = convert(civil_year(year_t{2147483648}), libc_utc);
+ EXPECT_EQ("2147483648-01-01T00:00:00+00:00", format(RFC3339, tp, libc_utc));
#endif
+ }
}
TEST(NextTransition, UTC) {
diff --git a/absl/time/time.cc b/absl/time/time.cc
index 0703856f..ac2c8a83 100644
--- a/absl/time/time.cc
+++ b/absl/time/time.cc
@@ -176,6 +176,20 @@ inline int MapWeekday(const cctz::weekday& wd) {
return 1;
}
+bool FindTransition(const cctz::time_zone& tz,
+ bool (cctz::time_zone::*find_transition)(
+ const cctz::time_point<cctz::seconds>& tp,
+ cctz::time_zone::civil_transition* trans) const,
+ Time t, TimeZone::CivilTransition* trans) {
+ // Transitions are second-aligned, so we can discard any fractional part.
+ const auto tp = unix_epoch() + cctz::seconds(ToUnixSeconds(t));
+ cctz::time_zone::civil_transition tr;
+ if (!(tz.*find_transition)(tp, &tr)) return false;
+ trans->from = CivilSecond(tr.from);
+ trans->to = CivilSecond(tr.to);
+ return true;
+}
+
} // namespace
//
@@ -366,6 +380,14 @@ absl::TimeZone::TimeInfo TimeZone::At(CivilSecond ct) const {
return ti;
}
+bool TimeZone::NextTransition(Time t, CivilTransition* trans) const {
+ return FindTransition(cz_, &cctz::time_zone::next_transition, t, trans);
+}
+
+bool TimeZone::PrevTransition(Time t, CivilTransition* trans) const {
+ return FindTransition(cz_, &cctz::time_zone::prev_transition, t, trans);
+}
+
//
// Conversions involving time zones.
//
diff --git a/absl/time/time.h b/absl/time/time.h
index 2858da29..7d5c3fde 100644
--- a/absl/time/time.h
+++ b/absl/time/time.h
@@ -886,7 +886,7 @@ class TimeZone {
struct TimeInfo {
enum CivilKind {
UNIQUE, // the civil time was singular (pre == trans == post)
- SKIPPED, // the civil time did not exist (pre => trans > post)
+ SKIPPED, // the civil time did not exist (pre >= trans > post)
REPEATED, // the civil time was ambiguous (pre < trans <= post)
} kind;
Time pre; // time calculated using the pre-transition offset
@@ -925,6 +925,44 @@ class TimeZone {
// // nov06.post is 2011-11-06 01:15:00 -0800
TimeInfo At(CivilSecond ct) const;
+ // TimeZone::NextTransition()
+ // TimeZone::PrevTransition()
+ //
+ // Finds the time of the next/previous offset change in this time zone.
+ //
+ // By definition, `NextTransition(t, &trans)` returns false when `t` is
+ // `InfiniteFuture()`, and `PrevTransition(t, &trans)` returns false
+ // when `t` is `InfinitePast()`. If the zone has no transitions, the
+ // result will also be false no matter what the argument.
+ //
+ // Otherwise, when `t` is `InfinitePast()`, `NextTransition(t, &trans)`
+ // returns true and sets `trans` to the first recorded transition. Chains
+ // of calls to `NextTransition()/PrevTransition()` will eventually return
+ // false, but it is unspecified exactly when `NextTransition(t, &trans)`
+ // jumps to false, or what time is set by `PrevTransition(t, &trans)` for
+ // a very distant `t`.
+ //
+ // Note: Enumeration of time-zone transitions is for informational purposes
+ // only. Modern time-related code should not care about when offset changes
+ // occur.
+ //
+ // Example:
+ // absl::TimeZone nyc;
+ // if (!absl::LoadTimeZone("America/New_York", &nyc)) { ... }
+ // const auto now = absl::Now();
+ // auto t = absl::InfinitePast();
+ // absl::TimeZone::CivilTransition trans;
+ // while (t <= now && nyc.NextTransition(t, &trans)) {
+ // // transition: trans.from -> trans.to
+ // t = nyc.At(trans.to).trans;
+ // }
+ struct CivilTransition {
+ CivilSecond from; // the civil time we jump from
+ CivilSecond to; // the civil time we jump to
+ };
+ bool NextTransition(Time t, CivilTransition* trans) const;
+ bool PrevTransition(Time t, CivilTransition* trans) const;
+
template <typename H>
friend H AbslHashValue(H h, TimeZone tz) {
return H::combine(std::move(h), tz.cz_);
diff --git a/absl/time/time_test.cc b/absl/time/time_test.cc
index feca4587..4d710709 100644
--- a/absl/time/time_test.cc
+++ b/absl/time/time_test.cc
@@ -1135,4 +1135,67 @@ TEST(Time, LegacyDateTime) {
EXPECT_EQ("2014-10-29 22:58:59", absl::FormatTime(ymdhms, t, utc));
}
+TEST(Time, NextTransitionUTC) {
+ const auto tz = absl::UTCTimeZone();
+ absl::TimeZone::CivilTransition trans;
+
+ auto t = absl::InfinitePast();
+ EXPECT_FALSE(tz.NextTransition(t, &trans));
+
+ t = absl::InfiniteFuture();
+ EXPECT_FALSE(tz.NextTransition(t, &trans));
+}
+
+TEST(Time, PrevTransitionUTC) {
+ const auto tz = absl::UTCTimeZone();
+ absl::TimeZone::CivilTransition trans;
+
+ auto t = absl::InfiniteFuture();
+ EXPECT_FALSE(tz.PrevTransition(t, &trans));
+
+ t = absl::InfinitePast();
+ EXPECT_FALSE(tz.PrevTransition(t, &trans));
+}
+
+TEST(Time, NextTransitionNYC) {
+ const auto tz = absl::time_internal::LoadTimeZone("America/New_York");
+ absl::TimeZone::CivilTransition trans;
+
+ auto t = absl::FromCivil(absl::CivilSecond(2018, 6, 30, 0, 0, 0), tz);
+ EXPECT_TRUE(tz.NextTransition(t, &trans));
+ EXPECT_EQ(absl::CivilSecond(2018, 11, 4, 2, 0, 0), trans.from);
+ EXPECT_EQ(absl::CivilSecond(2018, 11, 4, 1, 0, 0), trans.to);
+
+ t = absl::InfiniteFuture();
+ EXPECT_FALSE(tz.NextTransition(t, &trans));
+
+ t = absl::InfinitePast();
+ EXPECT_TRUE(tz.NextTransition(t, &trans));
+ if (trans.from == absl::CivilSecond(1918, 03, 31, 2, 0, 0)) {
+ // It looks like the tzdata is only 32 bit (probably macOS),
+ // which bottoms out at 1901-12-13T20:45:52+00:00.
+ EXPECT_EQ(absl::CivilSecond(1918, 3, 31, 3, 0, 0), trans.to);
+ } else {
+ EXPECT_EQ(absl::CivilSecond(1883, 11, 18, 12, 3, 58), trans.from);
+ EXPECT_EQ(absl::CivilSecond(1883, 11, 18, 12, 0, 0), trans.to);
+ }
+}
+
+TEST(Time, PrevTransitionNYC) {
+ const auto tz = absl::time_internal::LoadTimeZone("America/New_York");
+ absl::TimeZone::CivilTransition trans;
+
+ auto t = absl::FromCivil(absl::CivilSecond(2018, 6, 30, 0, 0, 0), tz);
+ EXPECT_TRUE(tz.PrevTransition(t, &trans));
+ EXPECT_EQ(absl::CivilSecond(2018, 3, 11, 2, 0, 0), trans.from);
+ EXPECT_EQ(absl::CivilSecond(2018, 3, 11, 3, 0, 0), trans.to);
+
+ t = absl::InfinitePast();
+ EXPECT_FALSE(tz.PrevTransition(t, &trans));
+
+ t = absl::InfiniteFuture();
+ EXPECT_TRUE(tz.PrevTransition(t, &trans));
+ // We have a transition but we don't know which one.
+}
+
} // namespace