Export of internal Abseil changes.

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906c47420646d510edd2479d5542c56f5fa31b65 by CJ Johnson <johnsoncj@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 216573923

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74560d4afd2b605909e677c6fc3076049fb3010a by Eric Fiselier <ericwf@google.com>:

Avoid -Wformat-pedantic in benchmark.

PiperOrigin-RevId: 216523769

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9bcc9da8b03e6d1ea43ee78931256c5541cb9686 by Eric Fiselier <ericwf@google.com>:

Delete unused CityHash functions.

PiperOrigin-RevId: 216464492

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a42563b394c89fbb4c55cb5a6a5edbf96d271eea by Abseil Team <absl-team@google.com>:

Introduce new Abseil interfaces for converting between civil
times and absolute times.s

Deprecates absl::ConvertDateTime() and absl::FromDateTime().

PiperOrigin-RevId: 216424948

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088e11235124267517d7f137854fa5554679c24f by Eric Fiselier <ericwf@google.com>:

Remove unneeded break statements in test.

PiperOrigin-RevId: 216403321
GitOrigin-RevId: 906c47420646d510edd2479d5542c56f5fa31b65
Change-Id: Idb44420be623e369c66f5a9c92bdc9ab46d3ec92

1 files changed, 88 insertions, 0 deletions

diff --git a/absl/time/civil_time.cc b/absl/time/civil_time.cc
new file mode 100644
index 0000000..5654179
--- /dev/null
+++ b/absl/time/civil_time.cc
@@ -0,0 +1,88 @@
+// Copyright 2018 The Abseil Authors.
+//
+// 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.
+
+#include "absl/time/civil_time.h"
+
+#include <cstdlib>
+#include <string>
+
+#include "absl/strings/str_cat.h"
+#include "absl/time/time.h"
+
+namespace absl {
+
+namespace {
+
+// Since a civil time has a larger year range than absl::Time (64-bit years vs
+// 64-bit seconds, respectively) we normalize years to roughly +/- 400 years
+// around the year 2400, which will produce an equivalent year in a range that
+// absl::Time can handle.
+inline civil_year_t NormalizeYear(civil_year_t year) {
+  return 2400 + year % 400;
+}
+
+// Formats the given CivilSecond according to the given format.
+std::string FormatYearAnd(string_view fmt, CivilSecond cs) {
+  const CivilSecond ncs(NormalizeYear(cs.year()), cs.month(), cs.day(),
+                        cs.hour(), cs.minute(), cs.second());
+  const TimeZone utc = UTCTimeZone();
+  // TODO(absl-team): Avoid conversion of fmt std::string.
+  return StrCat(cs.year(), FormatTime(std::string(fmt), FromCivil(ncs, utc), utc));
+}
+
+}  // namespace
+
+std::string FormatCivilTime(CivilSecond c) {
+  return FormatYearAnd("-%m-%dT%H:%M:%S", c);
+}
+std::string FormatCivilTime(CivilMinute c) {
+  return FormatYearAnd("-%m-%dT%H:%M", c);
+}
+std::string FormatCivilTime(CivilHour c) {
+  return FormatYearAnd("-%m-%dT%H", c);
+}
+std::string FormatCivilTime(CivilDay c) {
+  return FormatYearAnd("-%m-%d", c);
+}
+std::string FormatCivilTime(CivilMonth c) {
+  return FormatYearAnd("-%m", c);
+}
+std::string FormatCivilTime(CivilYear c) {
+  return FormatYearAnd("", c);
+}
+
+namespace time_internal {
+
+std::ostream& operator<<(std::ostream& os, CivilYear y) {
+  return os << FormatCivilTime(y);
+}
+std::ostream& operator<<(std::ostream& os, CivilMonth m) {
+  return os << FormatCivilTime(m);
+}
+std::ostream& operator<<(std::ostream& os, CivilDay d) {
+  return os << FormatCivilTime(d);
+}
+std::ostream& operator<<(std::ostream& os, CivilHour h) {
+  return os << FormatCivilTime(h);
+}
+std::ostream& operator<<(std::ostream& os, CivilMinute m) {
+  return os << FormatCivilTime(m);
+}
+std::ostream& operator<<(std::ostream& os, CivilSecond s) {
+  return os << FormatCivilTime(s);
+}
+
+}  // namespace time_internal
+
+}  // namespace absl