Export of internal Abseil changes

--
42dc250867db8816381a38596e00a3b27b7dbc37 by Gennadiy Rozental <rogeeff@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 401863616
GitOrigin-RevId: 42dc250867db8816381a38596e00a3b27b7dbc37
Change-Id: Ia1f100293e0c0845de76d986a170b5ca8d15f1a3

1 files changed, 93 insertions, 20 deletions

diff --git a/absl/time/internal/cctz/include/cctz/time_zone.h b/absl/time/internal/cctz/include/cctz/time_zone.h
index 5562a37b..6e382dc6 100644
--- a/absl/time/internal/cctz/include/cctz/time_zone.h
+++ b/absl/time/internal/cctz/include/cctz/time_zone.h
@@ -22,6 +22,7 @@
 
 #include <chrono>
 #include <cstdint>
+#include <limits>
 #include <string>
 #include <utility>
 
@@ -41,20 +42,9 @@ 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()};
-}
+std::pair<time_point<seconds>, D> split_seconds(const time_point<D>& tp);
+std::pair<time_point<seconds>, seconds> split_seconds(
+    const time_point<seconds>& tp);
 }  // namespace detail
 
 // cctz::time_zone is an opaque, small, value-type class representing a
@@ -279,6 +269,20 @@ 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);
+template <typename Rep, std::intmax_t Denom>
+bool join_seconds(
+    const time_point<seconds>& sec, const femtoseconds& fs,
+    time_point<std::chrono::duration<Rep, std::ratio<1, Denom>>>* tpp);
+template <typename Rep, std::intmax_t Num>
+bool join_seconds(
+    const time_point<seconds>& sec, const femtoseconds& fs,
+    time_point<std::chrono::duration<Rep, std::ratio<Num, 1>>>* tpp);
+template <typename Rep>
+bool join_seconds(
+    const time_point<seconds>& sec, const femtoseconds& fs,
+    time_point<std::chrono::duration<Rep, std::ratio<1, 1>>>* tpp);
+bool join_seconds(const time_point<seconds>& sec, const femtoseconds&,
+                  time_point<seconds>* tpp);
 }  // namespace detail
 
 // Formats the given time_point in the given cctz::time_zone according to
@@ -369,15 +373,84 @@ 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 detail::parse(fmt, input, tz, &sec, &fs) &&
+         detail::join_seconds(sec, fs, tpp);
+}
+
+namespace detail {
+
+// Split a time_point<D> into a time_point<seconds> and a D subseconds.
+// Undefined behavior if time_point<seconds> is not of sufficient range.
+// Note that this means it is UB to call cctz::time_zone::lookup(tp) or
+// cctz::format(fmt, tp, tz) with a time_point that is outside the range
+// of a 64-bit std::time_t.
+template <typename D>
+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 b;
+  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()};
 }
 
+// Join a time_point<seconds> and femto subseconds into a time_point<D>.
+// Floors to the resolution of time_point<D>. Returns false if time_point<D>
+// is not of sufficient range.
+template <typename Rep, std::intmax_t Denom>
+bool join_seconds(
+    const time_point<seconds>& sec, const femtoseconds& fs,
+    time_point<std::chrono::duration<Rep, std::ratio<1, Denom>>>* tpp) {
+  using D = std::chrono::duration<Rep, std::ratio<1, Denom>>;
+  // TODO(#199): Return false if result unrepresentable as a time_point<D>.
+  *tpp = std::chrono::time_point_cast<D>(sec);
+  *tpp += std::chrono::duration_cast<D>(fs);
+  return true;
+}
+
+template <typename Rep, std::intmax_t Num>
+bool join_seconds(
+    const time_point<seconds>& sec, const femtoseconds&,
+    time_point<std::chrono::duration<Rep, std::ratio<Num, 1>>>* tpp) {
+  using D = std::chrono::duration<Rep, std::ratio<Num, 1>>;
+  auto count = sec.time_since_epoch().count();
+  if (count >= 0 || count % Num == 0) {
+    count /= Num;
+  } else {
+    count /= Num;
+    count -= 1;
+  }
+  if (count > (std::numeric_limits<Rep>::max)()) return false;
+  if (count < (std::numeric_limits<Rep>::min)()) return false;
+  *tpp = time_point<D>() + D{static_cast<Rep>(count)};
+  return true;
+}
+
+template <typename Rep>
+bool join_seconds(
+    const time_point<seconds>& sec, const femtoseconds&,
+    time_point<std::chrono::duration<Rep, std::ratio<1, 1>>>* tpp) {
+  using D = std::chrono::duration<Rep, std::ratio<1, 1>>;
+  auto count = sec.time_since_epoch().count();
+  if (count > (std::numeric_limits<Rep>::max)()) return false;
+  if (count < (std::numeric_limits<Rep>::min)()) return false;
+  *tpp = time_point<D>() + D{static_cast<Rep>(count)};
+  return true;
+}
+
+inline bool join_seconds(const time_point<seconds>& sec, const femtoseconds&,
+                         time_point<seconds>* tpp) {
+  *tpp = sec;
+  return true;
+}
+
+}  // namespace detail
 }  // namespace cctz
 }  // namespace time_internal
 ABSL_NAMESPACE_END