tvl-depot/absl/time/time.h
Abseil Team bf29470384 Export of internal Abseil changes.
--
bdce7e57e9e886eff1114d0266781b443f7ec639 by Derek Mauro <dmauro@google.com>:

Change {Get|Set}EnvironmentVariable to {Get|Set}EnvironmentVariableA for
compatibility with /DUNICODE.

PiperOrigin-RevId: 239229514

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2276ed502326a044a84060d34eb19d499e3a3be2 by Derek Mauro <dmauro@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 239228622

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a462efb970ff43b08a362ef2343fb75ac1295a50 by Derek Mauro <dmauro@google.com>:

Adding linking of CoreFoundation to CMakeLists in absl/time.
Import https://github.com/abseil/abseil-cpp/pull/280.

Fix #283

PiperOrigin-RevId: 239220785

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fc23327b97f940c682aae1956cf7a1bf87f88c06 by Derek Mauro <dmauro@google.com>:

Add hermetic test script that uses Docker to build with a very recent
version of gcc (8.3.0 today) with libstdc++ and bazel.

PiperOrigin-RevId: 239220448

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418c08a8f6a53e63b84e39473035774417ca3aa7 by Derek Mauro <dmauro@google.com>:

Disable part of the variant exeception safety test on move assignment
when using versions of libstd++ that contain a bug.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87431#c7

PiperOrigin-RevId: 239062455

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799722217aeda79679577843c91d5be62cbcbb42 by Matt Calabrese <calabrese@google.com>:

Add internal-only IsSwappable traits corresponding to std::is_swappable and std::is_nothrow_swappable, which are used with the swap implementations of optional and variant.

PiperOrigin-RevId: 239049448

--
aa46a036038a3de5c68ac5e5d3b4bf76f818d2ea by CJ Johnson <johnsoncj@google.com>:

Make InlinedVectorStorage constructor explicit

PiperOrigin-RevId: 239044361

--
17949715b3aa21c794701f69f2154e91b6acabc3 by CJ Johnson <johnsoncj@google.com>:

Add absl namesapce to internal/inlined_vector.h

PiperOrigin-RevId: 239030789

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834628325953078cc08ed10d23bb8890e5bec897 by Derek Mauro <dmauro@google.com>:

Add test script that uses Docker to build Abseil with gcc-4.8,
libstdc++, and cmake.

PiperOrigin-RevId: 239028433

--
80fe24149ed73ed2ced995ad1e372fb060c60427 by CJ Johnson <johnsoncj@google.com>:

Factors data members of InlinedVector into an impl type called InlinedVectorStorage so that (in future changes) the contents of a vector can be grouped together with a single pointer.

PiperOrigin-RevId: 239021086

--
585331436d5d4d79f845e45dcf79d918a0dc6169 by Derek Mauro <dmauro@google.com>:

Add -Wno-missing-field-initializers to gcc compiler flags.
gcc-4.x has spurious missing field initializer warnings.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36750

PiperOrigin-RevId: 239017217

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94602fe4e33ee3a552a7f2939c0f57a992f55075 by Abseil Team <absl-team@google.com>:

Formatting fixes.

PiperOrigin-RevId: 238983038

--
a1c1b63c08505574e0a8c491561840cecb2bb93e by Derek Mauro <dmauro@google.com>:

Add hermetic test script that uses Docker to build with a very recent
version of clang with libc++ and bazel.

PiperOrigin-RevId: 238669118

--
e525f8d20bc2f79a0d69336b902f63858f3bff9d by Derek Mauro <dmauro@google.com>:

Disable the test optionalTest.InPlaceTSFINAEBug until libc++ is updated.

PiperOrigin-RevId: 238661703

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f99a2a0b5ec424a059678f7f226600f137b4c74e by Derek Mauro <dmauro@google.com>:

Correct the check for the FlatHashMap-Any test bug (list conditions
instead of platforms when possible)

PiperOrigin-RevId: 238653344

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777928035dbcbf39f361eb7d10dc3696822f692f by Jon Cohen <cohenjon@google.com>:

Add install rules for Abseil CMake.

These are attempted to be limited to in-project installation.  This serves two purposes -- first it's morally the same as using Abseil in-source, except you don't have to rebuild us every time.  Second, the presence of an install rule makes life massively simpler for package manager maintainers.

Currently this doesn't install absl tests or testonly libraries.  This can be added in a follow-up patch.

Fixes #38, Fixes #80, Closes #182

PiperOrigin-RevId: 238645836

--
ded1c6ce697c191b7a6ff14572b3e6d183117b2c by Derek Mauro <dmauro@google.com>:

Add hermetic test script that uses Docker to build with a very recent
version of clang with libstdc++ and bazel.

PiperOrigin-RevId: 238517815
GitOrigin-RevId: bdce7e57e9e886eff1114d0266781b443f7ec639
Change-Id: I6f745869cb8ef63851891ccac05ae9a7dd241c4f
2019-03-19 14:19:10 -04:00

1559 lines
58 KiB
C++

// Copyright 2017 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
//
// 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.
//
// -----------------------------------------------------------------------------
// File: time.h
// -----------------------------------------------------------------------------
//
// This header file defines abstractions for computing with absolute points
// in time, durations of time, and formatting and parsing time within a given
// time zone. The following abstractions are defined:
//
// * `absl::Time` defines an absolute, specific instance in time
// * `absl::Duration` defines a signed, fixed-length span of time
// * `absl::TimeZone` defines geopolitical time zone regions (as collected
// within the IANA Time Zone database (https://www.iana.org/time-zones)).
//
// Note: Absolute times are distinct from civil times, which refer to the
// human-scale time commonly represented by `YYYY-MM-DD hh:mm:ss`. The mapping
// between absolute and civil times can be specified by use of time zones
// (`absl::TimeZone` within this API). That is:
//
// Civil Time = F(Absolute Time, Time Zone)
// Absolute Time = G(Civil Time, Time Zone)
//
// See civil_time.h for abstractions related to constructing and manipulating
// civil time.
//
// Example:
//
// absl::TimeZone nyc;
// // LoadTimeZone() may fail so it's always better to check for success.
// if (!absl::LoadTimeZone("America/New_York", &nyc)) {
// // handle error case
// }
//
// // My flight leaves NYC on Jan 2, 2017 at 03:04:05
// absl::CivilSecond cs(2017, 1, 2, 3, 4, 5);
// absl::Time takeoff = absl::FromCivil(cs, nyc);
//
// absl::Duration flight_duration = absl::Hours(21) + absl::Minutes(35);
// absl::Time landing = takeoff + flight_duration;
//
// absl::TimeZone syd;
// if (!absl::LoadTimeZone("Australia/Sydney", &syd)) {
// // handle error case
// }
// std::string s = absl::FormatTime(
// "My flight will land in Sydney on %Y-%m-%d at %H:%M:%S",
// landing, syd);
#ifndef ABSL_TIME_TIME_H_
#define ABSL_TIME_TIME_H_
#if !defined(_MSC_VER)
#include <sys/time.h>
#else
#include <winsock2.h>
#endif
#include <chrono> // NOLINT(build/c++11)
#include <cmath>
#include <cstdint>
#include <ctime>
#include <ostream>
#include <string>
#include <type_traits>
#include <utility>
#include "absl/strings/string_view.h"
#include "absl/time/civil_time.h"
#include "absl/time/internal/cctz/include/cctz/time_zone.h"
namespace absl {
class Duration; // Defined below
class Time; // Defined below
class TimeZone; // Defined below
namespace time_internal {
int64_t IDivDuration(bool satq, Duration num, Duration den, Duration* rem);
constexpr Time FromUnixDuration(Duration d);
constexpr Duration ToUnixDuration(Time t);
constexpr int64_t GetRepHi(Duration d);
constexpr uint32_t GetRepLo(Duration d);
constexpr Duration MakeDuration(int64_t hi, uint32_t lo);
constexpr Duration MakeDuration(int64_t hi, int64_t lo);
inline Duration MakePosDoubleDuration(double n);
constexpr int64_t kTicksPerNanosecond = 4;
constexpr int64_t kTicksPerSecond = 1000 * 1000 * 1000 * kTicksPerNanosecond;
template <std::intmax_t N>
constexpr Duration FromInt64(int64_t v, std::ratio<1, N>);
constexpr Duration FromInt64(int64_t v, std::ratio<60>);
constexpr Duration FromInt64(int64_t v, std::ratio<3600>);
template <typename T>
using EnableIfIntegral = typename std::enable_if<
std::is_integral<T>::value || std::is_enum<T>::value, int>::type;
template <typename T>
using EnableIfFloat =
typename std::enable_if<std::is_floating_point<T>::value, int>::type;
} // namespace time_internal
// Duration
//
// The `absl::Duration` class represents a signed, fixed-length span of time.
// A `Duration` is generated using a unit-specific factory function, or is
// the result of subtracting one `absl::Time` from another. Durations behave
// like unit-safe integers and they support all the natural integer-like
// arithmetic operations. Arithmetic overflows and saturates at +/- infinity.
// `Duration` should be passed by value rather than const reference.
//
// Factory functions `Nanoseconds()`, `Microseconds()`, `Milliseconds()`,
// `Seconds()`, `Minutes()`, `Hours()` and `InfiniteDuration()` allow for
// creation of constexpr `Duration` values
//
// Examples:
//
// constexpr absl::Duration ten_ns = absl::Nanoseconds(10);
// constexpr absl::Duration min = absl::Minutes(1);
// constexpr absl::Duration hour = absl::Hours(1);
// absl::Duration dur = 60 * min; // dur == hour
// absl::Duration half_sec = absl::Milliseconds(500);
// absl::Duration quarter_sec = 0.25 * absl::Seconds(1);
//
// `Duration` values can be easily converted to an integral number of units
// using the division operator.
//
// Example:
//
// constexpr absl::Duration dur = absl::Milliseconds(1500);
// int64_t ns = dur / absl::Nanoseconds(1); // ns == 1500000000
// int64_t ms = dur / absl::Milliseconds(1); // ms == 1500
// int64_t sec = dur / absl::Seconds(1); // sec == 1 (subseconds truncated)
// int64_t min = dur / absl::Minutes(1); // min == 0
//
// See the `IDivDuration()` and `FDivDuration()` functions below for details on
// how to access the fractional parts of the quotient.
//
// Alternatively, conversions can be performed using helpers such as
// `ToInt64Microseconds()` and `ToDoubleSeconds()`.
class Duration {
public:
// Value semantics.
constexpr Duration() : rep_hi_(0), rep_lo_(0) {} // zero-length duration
// Copyable.
#if !defined(__clang__) && defined(_MSC_VER) && _MSC_VER < 1910
// Explicitly defining the constexpr copy constructor avoids an MSVC bug.
constexpr Duration(const Duration& d)
: rep_hi_(d.rep_hi_), rep_lo_(d.rep_lo_) {}
#else
constexpr Duration(const Duration& d) = default;
#endif
Duration& operator=(const Duration& d) = default;
// Compound assignment operators.
Duration& operator+=(Duration d);
Duration& operator-=(Duration d);
Duration& operator*=(int64_t r);
Duration& operator*=(double r);
Duration& operator/=(int64_t r);
Duration& operator/=(double r);
Duration& operator%=(Duration rhs);
// Overloads that forward to either the int64_t or double overloads above.
template <typename T>
Duration& operator*=(T r) {
int64_t x = r;
return *this *= x;
}
template <typename T>
Duration& operator/=(T r) {
int64_t x = r;
return *this /= x;
}
Duration& operator*=(float r) { return *this *= static_cast<double>(r); }
Duration& operator/=(float r) { return *this /= static_cast<double>(r); }
template <typename H>
friend H AbslHashValue(H h, Duration d) {
return H::combine(std::move(h), d.rep_hi_, d.rep_lo_);
}
private:
friend constexpr int64_t time_internal::GetRepHi(Duration d);
friend constexpr uint32_t time_internal::GetRepLo(Duration d);
friend constexpr Duration time_internal::MakeDuration(int64_t hi,
uint32_t lo);
constexpr Duration(int64_t hi, uint32_t lo) : rep_hi_(hi), rep_lo_(lo) {}
int64_t rep_hi_;
uint32_t rep_lo_;
};
// Relational Operators
constexpr bool operator<(Duration lhs, Duration rhs);
constexpr bool operator>(Duration lhs, Duration rhs) { return rhs < lhs; }
constexpr bool operator>=(Duration lhs, Duration rhs) { return !(lhs < rhs); }
constexpr bool operator<=(Duration lhs, Duration rhs) { return !(rhs < lhs); }
constexpr bool operator==(Duration lhs, Duration rhs);
constexpr bool operator!=(Duration lhs, Duration rhs) { return !(lhs == rhs); }
// Additive Operators
constexpr Duration operator-(Duration d);
inline Duration operator+(Duration lhs, Duration rhs) { return lhs += rhs; }
inline Duration operator-(Duration lhs, Duration rhs) { return lhs -= rhs; }
// Multiplicative Operators
template <typename T>
Duration operator*(Duration lhs, T rhs) {
return lhs *= rhs;
}
template <typename T>
Duration operator*(T lhs, Duration rhs) {
return rhs *= lhs;
}
template <typename T>
Duration operator/(Duration lhs, T rhs) {
return lhs /= rhs;
}
inline int64_t operator/(Duration lhs, Duration rhs) {
return time_internal::IDivDuration(true, lhs, rhs,
&lhs); // trunc towards zero
}
inline Duration operator%(Duration lhs, Duration rhs) { return lhs %= rhs; }
// IDivDuration()
//
// Divides a numerator `Duration` by a denominator `Duration`, returning the
// quotient and remainder. The remainder always has the same sign as the
// numerator. The returned quotient and remainder respect the identity:
//
// numerator = denominator * quotient + remainder
//
// Returned quotients are capped to the range of `int64_t`, with the difference
// spilling into the remainder to uphold the above identity. This means that the
// remainder returned could differ from the remainder returned by
// `Duration::operator%` for huge quotients.
//
// See also the notes on `InfiniteDuration()` below regarding the behavior of
// division involving zero and infinite durations.
//
// Example:
//
// constexpr absl::Duration a =
// absl::Seconds(std::numeric_limits<int64_t>::max()); // big
// constexpr absl::Duration b = absl::Nanoseconds(1); // small
//
// absl::Duration rem = a % b;
// // rem == absl::ZeroDuration()
//
// // Here, q would overflow int64_t, so rem accounts for the difference.
// int64_t q = absl::IDivDuration(a, b, &rem);
// // q == std::numeric_limits<int64_t>::max(), rem == a - b * q
inline int64_t IDivDuration(Duration num, Duration den, Duration* rem) {
return time_internal::IDivDuration(true, num, den,
rem); // trunc towards zero
}
// FDivDuration()
//
// Divides a `Duration` numerator into a fractional number of units of a
// `Duration` denominator.
//
// See also the notes on `InfiniteDuration()` below regarding the behavior of
// division involving zero and infinite durations.
//
// Example:
//
// double d = absl::FDivDuration(absl::Milliseconds(1500), absl::Seconds(1));
// // d == 1.5
double FDivDuration(Duration num, Duration den);
// ZeroDuration()
//
// Returns a zero-length duration. This function behaves just like the default
// constructor, but the name helps make the semantics clear at call sites.
constexpr Duration ZeroDuration() { return Duration(); }
// AbsDuration()
//
// Returns the absolute value of a duration.
inline Duration AbsDuration(Duration d) {
return (d < ZeroDuration()) ? -d : d;
}
// Trunc()
//
// Truncates a duration (toward zero) to a multiple of a non-zero unit.
//
// Example:
//
// absl::Duration d = absl::Nanoseconds(123456789);
// absl::Duration a = absl::Trunc(d, absl::Microseconds(1)); // 123456us
Duration Trunc(Duration d, Duration unit);
// Floor()
//
// Floors a duration using the passed duration unit to its largest value not
// greater than the duration.
//
// Example:
//
// absl::Duration d = absl::Nanoseconds(123456789);
// absl::Duration b = absl::Floor(d, absl::Microseconds(1)); // 123456us
Duration Floor(Duration d, Duration unit);
// Ceil()
//
// Returns the ceiling of a duration using the passed duration unit to its
// smallest value not less than the duration.
//
// Example:
//
// absl::Duration d = absl::Nanoseconds(123456789);
// absl::Duration c = absl::Ceil(d, absl::Microseconds(1)); // 123457us
Duration Ceil(Duration d, Duration unit);
// InfiniteDuration()
//
// Returns an infinite `Duration`. To get a `Duration` representing negative
// infinity, use `-InfiniteDuration()`.
//
// Duration arithmetic overflows to +/- infinity and saturates. In general,
// arithmetic with `Duration` infinities is similar to IEEE 754 infinities
// except where IEEE 754 NaN would be involved, in which case +/-
// `InfiniteDuration()` is used in place of a "nan" Duration.
//
// Examples:
//
// constexpr absl::Duration inf = absl::InfiniteDuration();
// const absl::Duration d = ... any finite duration ...
//
// inf == inf + inf
// inf == inf + d
// inf == inf - inf
// -inf == d - inf
//
// inf == d * 1e100
// inf == inf / 2
// 0 == d / inf
// INT64_MAX == inf / d
//
// d < inf
// -inf < d
//
// // Division by zero returns infinity, or INT64_MIN/MAX where appropriate.
// inf == d / 0
// INT64_MAX == d / absl::ZeroDuration()
//
// The examples involving the `/` operator above also apply to `IDivDuration()`
// and `FDivDuration()`.
constexpr Duration InfiniteDuration();
// Nanoseconds()
// Microseconds()
// Milliseconds()
// Seconds()
// Minutes()
// Hours()
//
// Factory functions for constructing `Duration` values from an integral number
// of the unit indicated by the factory function's name.
//
// Note: no "Days()" factory function exists because "a day" is ambiguous.
// Civil days are not always 24 hours long, and a 24-hour duration often does
// not correspond with a civil day. If a 24-hour duration is needed, use
// `absl::Hours(24)`. (If you actually want a civil day, use absl::CivilDay
// from civil_time.h.)
//
// Example:
//
// absl::Duration a = absl::Seconds(60);
// absl::Duration b = absl::Minutes(1); // b == a
constexpr Duration Nanoseconds(int64_t n);
constexpr Duration Microseconds(int64_t n);
constexpr Duration Milliseconds(int64_t n);
constexpr Duration Seconds(int64_t n);
constexpr Duration Minutes(int64_t n);
constexpr Duration Hours(int64_t n);
// Factory overloads for constructing `Duration` values from a floating-point
// number of the unit indicated by the factory function's name. These functions
// exist for convenience, but they are not as efficient as the integral
// factories, which should be preferred.
//
// Example:
//
// auto a = absl::Seconds(1.5); // OK
// auto b = absl::Milliseconds(1500); // BETTER
template <typename T, time_internal::EnableIfFloat<T> = 0>
Duration Nanoseconds(T n) {
return n * Nanoseconds(1);
}
template <typename T, time_internal::EnableIfFloat<T> = 0>
Duration Microseconds(T n) {
return n * Microseconds(1);
}
template <typename T, time_internal::EnableIfFloat<T> = 0>
Duration Milliseconds(T n) {
return n * Milliseconds(1);
}
template <typename T, time_internal::EnableIfFloat<T> = 0>
Duration Seconds(T n) {
if (n >= 0) { // Note: `NaN >= 0` is false.
if (n >= (std::numeric_limits<int64_t>::max)()) return InfiniteDuration();
return time_internal::MakePosDoubleDuration(n);
} else {
if (std::isnan(n))
return std::signbit(n) ? -InfiniteDuration() : InfiniteDuration();
if (n <= (std::numeric_limits<int64_t>::min)()) return -InfiniteDuration();
return -time_internal::MakePosDoubleDuration(-n);
}
}
template <typename T, time_internal::EnableIfFloat<T> = 0>
Duration Minutes(T n) {
return n * Minutes(1);
}
template <typename T, time_internal::EnableIfFloat<T> = 0>
Duration Hours(T n) {
return n * Hours(1);
}
// ToInt64Nanoseconds()
// ToInt64Microseconds()
// ToInt64Milliseconds()
// ToInt64Seconds()
// ToInt64Minutes()
// ToInt64Hours()
//
// Helper functions that convert a Duration to an integral count of the
// indicated unit. These functions are shorthand for the `IDivDuration()`
// function above; see its documentation for details about overflow, etc.
//
// Example:
//
// absl::Duration d = absl::Milliseconds(1500);
// int64_t isec = absl::ToInt64Seconds(d); // isec == 1
int64_t ToInt64Nanoseconds(Duration d);
int64_t ToInt64Microseconds(Duration d);
int64_t ToInt64Milliseconds(Duration d);
int64_t ToInt64Seconds(Duration d);
int64_t ToInt64Minutes(Duration d);
int64_t ToInt64Hours(Duration d);
// ToDoubleNanoSeconds()
// ToDoubleMicroseconds()
// ToDoubleMilliseconds()
// ToDoubleSeconds()
// ToDoubleMinutes()
// ToDoubleHours()
//
// Helper functions that convert a Duration to a floating point count of the
// indicated unit. These functions are shorthand for the `FDivDuration()`
// function above; see its documentation for details about overflow, etc.
//
// Example:
//
// absl::Duration d = absl::Milliseconds(1500);
// double dsec = absl::ToDoubleSeconds(d); // dsec == 1.5
double ToDoubleNanoseconds(Duration d);
double ToDoubleMicroseconds(Duration d);
double ToDoubleMilliseconds(Duration d);
double ToDoubleSeconds(Duration d);
double ToDoubleMinutes(Duration d);
double ToDoubleHours(Duration d);
// FromChrono()
//
// Converts any of the pre-defined std::chrono durations to an absl::Duration.
//
// Example:
//
// std::chrono::milliseconds ms(123);
// absl::Duration d = absl::FromChrono(ms);
constexpr Duration FromChrono(const std::chrono::nanoseconds& d);
constexpr Duration FromChrono(const std::chrono::microseconds& d);
constexpr Duration FromChrono(const std::chrono::milliseconds& d);
constexpr Duration FromChrono(const std::chrono::seconds& d);
constexpr Duration FromChrono(const std::chrono::minutes& d);
constexpr Duration FromChrono(const std::chrono::hours& d);
// ToChronoNanoseconds()
// ToChronoMicroseconds()
// ToChronoMilliseconds()
// ToChronoSeconds()
// ToChronoMinutes()
// ToChronoHours()
//
// Converts an absl::Duration to any of the pre-defined std::chrono durations.
// If overflow would occur, the returned value will saturate at the min/max
// chrono duration value instead.
//
// Example:
//
// absl::Duration d = absl::Microseconds(123);
// auto x = absl::ToChronoMicroseconds(d);
// auto y = absl::ToChronoNanoseconds(d); // x == y
// auto z = absl::ToChronoSeconds(absl::InfiniteDuration());
// // z == std::chrono::seconds::max()
std::chrono::nanoseconds ToChronoNanoseconds(Duration d);
std::chrono::microseconds ToChronoMicroseconds(Duration d);
std::chrono::milliseconds ToChronoMilliseconds(Duration d);
std::chrono::seconds ToChronoSeconds(Duration d);
std::chrono::minutes ToChronoMinutes(Duration d);
std::chrono::hours ToChronoHours(Duration d);
// FormatDuration()
//
// Returns a string representing the duration in the form "72h3m0.5s".
// Returns "inf" or "-inf" for +/- `InfiniteDuration()`.
std::string FormatDuration(Duration d);
// Output stream operator.
inline std::ostream& operator<<(std::ostream& os, Duration d) {
return os << FormatDuration(d);
}
// ParseDuration()
//
// Parses a duration string consisting of a possibly signed sequence of
// decimal numbers, each with an optional fractional part and a unit
// suffix. The valid suffixes are "ns", "us" "ms", "s", "m", and "h".
// Simple examples include "300ms", "-1.5h", and "2h45m". Parses "0" as
// `ZeroDuration()`. Parses "inf" and "-inf" as +/- `InfiniteDuration()`.
bool ParseDuration(const std::string& dur_string, Duration* d);
// Support for flag values of type Duration. Duration flags must be specified
// in a format that is valid input for absl::ParseDuration().
bool ParseFlag(const std::string& text, Duration* dst, std::string* error);
std::string UnparseFlag(Duration d);
// Time
//
// An `absl::Time` represents a specific instant in time. Arithmetic operators
// are provided for naturally expressing time calculations. Instances are
// created using `absl::Now()` and the `absl::From*()` factory functions that
// accept the gamut of other time representations. Formatting and parsing
// functions are provided for conversion to and from strings. `absl::Time`
// should be passed by value rather than const reference.
//
// `absl::Time` assumes there are 60 seconds in a minute, which means the
// underlying time scales must be "smeared" to eliminate leap seconds.
// See https://developers.google.com/time/smear.
//
// Even though `absl::Time` supports a wide range of timestamps, exercise
// caution when using values in the distant past. `absl::Time` uses the
// Proleptic Gregorian calendar, which extends the Gregorian calendar backward
// to dates before its introduction in 1582.
// See https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar
// for more information. Use the ICU calendar classes to convert a date in
// some other calendar (http://userguide.icu-project.org/datetime/calendar).
//
// Similarly, standardized time zones are a reasonably recent innovation, with
// the Greenwich prime meridian being established in 1884. The TZ database
// itself does not profess accurate offsets for timestamps prior to 1970. The
// breakdown of future timestamps is subject to the whim of regional
// governments.
//
// The `absl::Time` class represents an instant in time as a count of clock
// ticks of some granularity (resolution) from some starting point (epoch).
//
// `absl::Time` uses a resolution that is high enough to avoid loss in
// precision, and a range that is wide enough to avoid overflow, when
// converting between tick counts in most Google time scales (i.e., resolution
// of at least one nanosecond, and range +/-100 billion years). Conversions
// between the time scales are performed by truncating (towards negative
// infinity) to the nearest representable point.
//
// Examples:
//
// absl::Time t1 = ...;
// absl::Time t2 = t1 + absl::Minutes(2);
// absl::Duration d = t2 - t1; // == absl::Minutes(2)
//
class Time {
public:
// Value semantics.
// Returns the Unix epoch. However, those reading your code may not know
// or expect the Unix epoch as the default value, so make your code more
// readable by explicitly initializing all instances before use.
//
// Example:
// absl::Time t = absl::UnixEpoch();
// absl::Time t = absl::Now();
// absl::Time t = absl::TimeFromTimeval(tv);
// absl::Time t = absl::InfinitePast();
constexpr Time() = default;
// Copyable.
constexpr Time(const Time& t) = default;
Time& operator=(const Time& t) = default;
// Assignment operators.
Time& operator+=(Duration d) {
rep_ += d;
return *this;
}
Time& operator-=(Duration d) {
rep_ -= d;
return *this;
}
// Time::Breakdown
//
// The calendar and wall-clock (aka "civil time") components of an
// `absl::Time` in a certain `absl::TimeZone`. This struct is not
// intended to represent an instant in time. So, rather than passing
// a `Time::Breakdown` to a function, pass an `absl::Time` and an
// `absl::TimeZone`.
//
// Deprecated. Use `absl::TimeZone::CivilInfo`.
struct
Breakdown {
int64_t year; // year (e.g., 2013)
int month; // month of year [1:12]
int day; // day of month [1:31]
int hour; // hour of day [0:23]
int minute; // minute of hour [0:59]
int second; // second of minute [0:59]
Duration subsecond; // [Seconds(0):Seconds(1)) if finite
int weekday; // 1==Mon, ..., 7=Sun
int yearday; // day of year [1:366]
// 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 FormatTime().
// These fields are undefined for InfiniteFuture() and InfinitePast().
int offset; // seconds east of UTC
bool is_dst; // is offset non-standard?
const char* zone_abbr; // time-zone abbreviation (e.g., "PST")
};
// Time::In()
//
// Returns the breakdown of this instant in the given TimeZone.
//
// Deprecated. Use `absl::TimeZone::At(Time)`.
Breakdown In(TimeZone tz) const;
template <typename H>
friend H AbslHashValue(H h, Time t) {
return H::combine(std::move(h), t.rep_);
}
private:
friend constexpr Time time_internal::FromUnixDuration(Duration d);
friend constexpr Duration time_internal::ToUnixDuration(Time t);
friend constexpr bool operator<(Time lhs, Time rhs);
friend constexpr bool operator==(Time lhs, Time rhs);
friend Duration operator-(Time lhs, Time rhs);
friend constexpr Time UniversalEpoch();
friend constexpr Time InfiniteFuture();
friend constexpr Time InfinitePast();
constexpr explicit Time(Duration rep) : rep_(rep) {}
Duration rep_;
};
// Relational Operators
constexpr bool operator<(Time lhs, Time rhs) { return lhs.rep_ < rhs.rep_; }
constexpr bool operator>(Time lhs, Time rhs) { return rhs < lhs; }
constexpr bool operator>=(Time lhs, Time rhs) { return !(lhs < rhs); }
constexpr bool operator<=(Time lhs, Time rhs) { return !(rhs < lhs); }
constexpr bool operator==(Time lhs, Time rhs) { return lhs.rep_ == rhs.rep_; }
constexpr bool operator!=(Time lhs, Time rhs) { return !(lhs == rhs); }
// Additive Operators
inline Time operator+(Time lhs, Duration rhs) { return lhs += rhs; }
inline Time operator+(Duration lhs, Time rhs) { return rhs += lhs; }
inline Time operator-(Time lhs, Duration rhs) { return lhs -= rhs; }
inline Duration operator-(Time lhs, Time rhs) { return lhs.rep_ - rhs.rep_; }
// UnixEpoch()
//
// Returns the `absl::Time` representing "1970-01-01 00:00:00.0 +0000".
constexpr Time UnixEpoch() { return Time(); }
// UniversalEpoch()
//
// Returns the `absl::Time` representing "0001-01-01 00:00:00.0 +0000", the
// epoch of the ICU Universal Time Scale.
constexpr Time UniversalEpoch() {
// 719162 is the number of days from 0001-01-01 to 1970-01-01,
// assuming the Gregorian calendar.
return Time(time_internal::MakeDuration(-24 * 719162 * int64_t{3600}, 0U));
}
// InfiniteFuture()
//
// Returns an `absl::Time` that is infinitely far in the future.
constexpr Time InfiniteFuture() {
return Time(
time_internal::MakeDuration((std::numeric_limits<int64_t>::max)(), ~0U));
}
// InfinitePast()
//
// Returns an `absl::Time` that is infinitely far in the past.
constexpr Time InfinitePast() {
return Time(
time_internal::MakeDuration((std::numeric_limits<int64_t>::min)(), ~0U));
}
// FromUnixNanos()
// FromUnixMicros()
// FromUnixMillis()
// FromUnixSeconds()
// FromTimeT()
// FromUDate()
// FromUniversal()
//
// Creates an `absl::Time` from a variety of other representations.
constexpr Time FromUnixNanos(int64_t ns);
constexpr Time FromUnixMicros(int64_t us);
constexpr Time FromUnixMillis(int64_t ms);
constexpr Time FromUnixSeconds(int64_t s);
constexpr Time FromTimeT(time_t t);
Time FromUDate(double udate);
Time FromUniversal(int64_t universal);
// ToUnixNanos()
// ToUnixMicros()
// ToUnixMillis()
// ToUnixSeconds()
// ToTimeT()
// ToUDate()
// ToUniversal()
//
// Converts an `absl::Time` to a variety of other representations. Note that
// these operations round down toward negative infinity where necessary to
// adjust to the resolution of the result type. Beware of possible time_t
// over/underflow in ToTime{T,val,spec}() on 32-bit platforms.
int64_t ToUnixNanos(Time t);
int64_t ToUnixMicros(Time t);
int64_t ToUnixMillis(Time t);
int64_t ToUnixSeconds(Time t);
time_t ToTimeT(Time t);
double ToUDate(Time t);
int64_t ToUniversal(Time t);
// DurationFromTimespec()
// DurationFromTimeval()
// ToTimespec()
// ToTimeval()
// TimeFromTimespec()
// TimeFromTimeval()
// ToTimespec()
// ToTimeval()
//
// Some APIs use a timespec or a timeval as a Duration (e.g., nanosleep(2)
// and select(2)), while others use them as a Time (e.g. clock_gettime(2)
// and gettimeofday(2)), so conversion functions are provided for both cases.
// The "to timespec/val" direction is easily handled via overloading, but
// for "from timespec/val" the desired type is part of the function name.
Duration DurationFromTimespec(timespec ts);
Duration DurationFromTimeval(timeval tv);
timespec ToTimespec(Duration d);
timeval ToTimeval(Duration d);
Time TimeFromTimespec(timespec ts);
Time TimeFromTimeval(timeval tv);
timespec ToTimespec(Time t);
timeval ToTimeval(Time t);
// FromChrono()
//
// Converts a std::chrono::system_clock::time_point to an absl::Time.
//
// Example:
//
// auto tp = std::chrono::system_clock::from_time_t(123);
// absl::Time t = absl::FromChrono(tp);
// // t == absl::FromTimeT(123)
Time FromChrono(const std::chrono::system_clock::time_point& tp);
// ToChronoTime()
//
// Converts an absl::Time to a std::chrono::system_clock::time_point. If
// overflow would occur, the returned value will saturate at the min/max time
// point value instead.
//
// Example:
//
// absl::Time t = absl::FromTimeT(123);
// auto tp = absl::ToChronoTime(t);
// // tp == std::chrono::system_clock::from_time_t(123);
std::chrono::system_clock::time_point ToChronoTime(Time);
// Support for flag values of type Time. Time flags must be specified in a
// format that matches absl::RFC3339_full. For example:
//
// --start_time=2016-01-02T03:04:05.678+08:00
//
// Note: A UTC offset (or 'Z' indicating a zero-offset from UTC) is required.
//
// Additionally, if you'd like to specify a time as a count of
// seconds/milliseconds/etc from the Unix epoch, use an absl::Duration flag
// and add that duration to absl::UnixEpoch() to get an absl::Time.
bool ParseFlag(const std::string& text, Time* t, std::string* error);
std::string UnparseFlag(Time t);
// TimeZone
//
// The `absl::TimeZone` is an opaque, small, value-type class representing a
// geo-political region within which particular rules are used for converting
// between absolute and civil times (see https://git.io/v59Ly). `absl::TimeZone`
// values are named using the TZ identifiers from the IANA Time Zone Database,
// such as "America/Los_Angeles" or "Australia/Sydney". `absl::TimeZone` values
// are created from factory functions such as `absl::LoadTimeZone()`. Note:
// strings like "PST" and "EDT" are not valid TZ identifiers. Prefer to pass by
// value rather than const reference.
//
// For more on the fundamental concepts of time zones, absolute times, and civil
// times, see https://github.com/google/cctz#fundamental-concepts
//
// Examples:
//
// absl::TimeZone utc = absl::UTCTimeZone();
// absl::TimeZone pst = absl::FixedTimeZone(-8 * 60 * 60);
// absl::TimeZone loc = absl::LocalTimeZone();
// absl::TimeZone lax;
// if (!absl::LoadTimeZone("America/Los_Angeles", &lax)) {
// // handle error case
// }
//
// See also:
// - https://github.com/google/cctz
// - https://www.iana.org/time-zones
// - https://en.wikipedia.org/wiki/Zoneinfo
class TimeZone {
public:
explicit TimeZone(time_internal::cctz::time_zone tz) : cz_(tz) {}
TimeZone() = default; // UTC, but prefer UTCTimeZone() to be explicit.
// Copyable.
TimeZone(const TimeZone&) = default;
TimeZone& operator=(const TimeZone&) = default;
explicit operator time_internal::cctz::time_zone() const { return cz_; }
std::string name() const { return cz_.name(); }
// TimeZone::CivilInfo
//
// Information about the civil time corresponding to an absolute time.
// This struct is not intended to represent an instant in time. So, rather
// than passing a `TimeZone::CivilInfo` to a function, pass an `absl::Time`
// and an `absl::TimeZone`.
struct CivilInfo {
CivilSecond cs;
Duration subsecond;
// 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 FormatTime().
// These fields are undefined for InfiniteFuture() and InfinitePast().
int offset; // seconds east of UTC
bool is_dst; // is offset non-standard?
const char* zone_abbr; // time-zone abbreviation (e.g., "PST")
};
// TimeZone::At(Time)
//
// Returns the civil time for this TimeZone at a certain `absl::Time`.
// If the input time is infinite, the output civil second will be set to
// CivilSecond::max() or min(), and the subsecond will be infinite.
//
// Example:
//
// const auto epoch = lax.At(absl::UnixEpoch());
// // epoch.cs == 1969-12-31 16:00:00
// // epoch.subsecond == absl::ZeroDuration()
// // epoch.offset == -28800
// // epoch.is_dst == false
// // epoch.abbr == "PST"
CivilInfo At(Time t) const;
// TimeZone::TimeInfo
//
// Information about the absolute times corresponding to a civil time.
// (Subseconds must be handled separately.)
//
// It is possible for a caller to pass a civil-time value that does
// not represent an actual or unique instant in time (due to a shift
// in UTC offset in the TimeZone, which results in a discontinuity in
// the civil-time components). For example, a daylight-saving-time
// transition skips or repeats civil times---in the United States,
// March 13, 2011 02:15 never occurred, while November 6, 2011 01:15
// occurred twice---so requests for such times are not well-defined.
// To account for these possibilities, `absl::TimeZone::TimeInfo` is
// richer than just a single `absl::Time`.
struct TimeInfo {
enum CivilKind {
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 pre; // time calculated using the pre-transition offset
Time trans; // when the civil-time discontinuity occurred
Time post; // time calculated using the post-transition offset
};
// TimeZone::At(CivilSecond)
//
// Returns an `absl::TimeInfo` containing the absolute time(s) for this
// TimeZone at an `absl::CivilSecond`. When the civil time is skipped or
// repeated, returns times calculated using the pre-transition and post-
// transition UTC offsets, plus the transition time itself.
//
// Examples:
//
// // A unique civil time
// const auto jan01 = lax.At(absl::CivilSecond(2011, 1, 1, 0, 0, 0));
// // jan01.kind == TimeZone::TimeInfo::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
// const auto mar13 = lax.At(absl::CivilSecond(2011, 3, 13, 2, 15, 0));
// // mar13.kind == TimeZone::TimeInfo::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
// const auto nov06 = lax.At(absl::CivilSecond(2011, 11, 6, 1, 15, 0));
// // nov06.kind == TimeZone::TimeInfo::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
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_);
}
private:
friend bool operator==(TimeZone a, TimeZone b) { return a.cz_ == b.cz_; }
friend bool operator!=(TimeZone a, TimeZone b) { return a.cz_ != b.cz_; }
friend std::ostream& operator<<(std::ostream& os, TimeZone tz) {
return os << tz.name();
}
time_internal::cctz::time_zone cz_;
};
// LoadTimeZone()
//
// Loads the named zone. May perform I/O on the initial load of the named
// zone. If the name is invalid, or some other kind of error occurs, returns
// `false` and `*tz` is set to the UTC time zone.
inline bool LoadTimeZone(const std::string& name, TimeZone* tz) {
if (name == "localtime") {
*tz = TimeZone(time_internal::cctz::local_time_zone());
return true;
}
time_internal::cctz::time_zone cz;
const bool b = time_internal::cctz::load_time_zone(name, &cz);
*tz = TimeZone(cz);
return b;
}
// FixedTimeZone()
//
// Returns a TimeZone 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., no offset) instead.
inline TimeZone FixedTimeZone(int seconds) {
return TimeZone(
time_internal::cctz::fixed_time_zone(std::chrono::seconds(seconds)));
}
// UTCTimeZone()
//
// Convenience method returning the UTC time zone.
inline TimeZone UTCTimeZone() {
return TimeZone(time_internal::cctz::utc_time_zone());
}
// LocalTimeZone()
//
// Convenience method returning the local time zone, or UTC if there is
// no configured local zone. Warning: Be wary of using LocalTimeZone(),
// and particularly so in a server process, as the zone configured for the
// local machine should be irrelevant. Prefer an explicit zone name.
inline TimeZone LocalTimeZone() {
return TimeZone(time_internal::cctz::local_time_zone());
}
// ToCivilSecond()
// ToCivilMinute()
// ToCivilHour()
// ToCivilDay()
// ToCivilMonth()
// ToCivilYear()
//
// Helpers for TimeZone::At(Time) to return particularly aligned civil times.
//
// Example:
//
// absl::Time t = ...;
// absl::TimeZone tz = ...;
// const auto cd = absl::ToCivilDay(t, tz);
inline CivilSecond ToCivilSecond(Time t, TimeZone tz) {
return tz.At(t).cs; // already a CivilSecond
}
inline CivilMinute ToCivilMinute(Time t, TimeZone tz) {
return CivilMinute(tz.At(t).cs);
}
inline CivilHour ToCivilHour(Time t, TimeZone tz) {
return CivilHour(tz.At(t).cs);
}
inline CivilDay ToCivilDay(Time t, TimeZone tz) {
return CivilDay(tz.At(t).cs);
}
inline CivilMonth ToCivilMonth(Time t, TimeZone tz) {
return CivilMonth(tz.At(t).cs);
}
inline CivilYear ToCivilYear(Time t, TimeZone tz) {
return CivilYear(tz.At(t).cs);
}
// FromCivil()
//
// Helper for TimeZone::At(CivilSecond) that provides "order-preserving
// semantics." If the civil time maps to a unique time, that time is
// returned. If the civil time is repeated in the given time zone, the
// time using the pre-transition offset is returned. Otherwise, the
// civil time is skipped in the given time zone, and the transition time
// is returned. This means that for any two civil times, ct1 and ct2,
// (ct1 < ct2) => (FromCivil(ct1) <= FromCivil(ct2)), the equal case
// being when two non-existent civil times map to the same transition time.
//
// Note: Accepts civil times of any alignment.
inline Time FromCivil(CivilSecond ct, TimeZone tz) {
const auto ti = tz.At(ct);
if (ti.kind == TimeZone::TimeInfo::SKIPPED) return ti.trans;
return ti.pre;
}
// TimeConversion
//
// An `absl::TimeConversion` represents the conversion of year, month, day,
// hour, minute, and second values (i.e., a civil time), in a particular
// `absl::TimeZone`, to a time instant (an absolute time), as returned by
// `absl::ConvertDateTime()`. Lecacy version of `absl::TimeZone::TimeInfo`.
//
// Deprecated. Use `absl::TimeZone::TimeInfo`.
struct
TimeConversion {
Time pre; // time calculated using the pre-transition offset
Time trans; // when the civil-time discontinuity occurred
Time post; // time calculated using the post-transition offset
enum Kind {
UNIQUE, // the civil time was singular (pre == trans == post)
SKIPPED, // the civil time did not exist
REPEATED, // the civil time was ambiguous
};
Kind kind;
bool normalized; // input values were outside their valid ranges
};
// ConvertDateTime()
//
// Legacy version of `absl::TimeZone::At(absl::CivilSecond)` that takes
// the civil time as six, separate values (YMDHMS).
//
// The input month, day, hour, minute, and second values can be outside
// of their valid ranges, in which case they will be "normalized" during
// the conversion.
//
// Example:
//
// // "October 32" normalizes to "November 1".
// absl::TimeConversion tc =
// absl::ConvertDateTime(2013, 10, 32, 8, 30, 0, lax);
// // tc.kind == TimeConversion::UNIQUE && tc.normalized == true
// // absl::ToCivilDay(tc.pre, tz).month() == 11
// // absl::ToCivilDay(tc.pre, tz).day() == 1
//
// Deprecated. Use `absl::TimeZone::At(CivilSecond)`.
TimeConversion ConvertDateTime(int64_t year, int mon, int day, int hour,
int min, int sec, TimeZone tz);
// FromDateTime()
//
// A convenience wrapper for `absl::ConvertDateTime()` that simply returns
// the "pre" `absl::Time`. That is, the unique result, or the instant that
// is correct using the pre-transition offset (as if the transition never
// happened).
//
// Example:
//
// absl::Time t = absl::FromDateTime(2017, 9, 26, 9, 30, 0, lax);
// // t = 2017-09-26 09:30:00 -0700
//
// Deprecated. Use `absl::FromCivil(CivilSecond, TimeZone)`. Note that the
// behavior of `FromCivil()` differs from `FromDateTime()` for skipped civil
// times. If you care about that see `absl::TimeZone::At(absl::CivilSecond)`.
inline Time FromDateTime(int64_t year, int mon, int day, int hour,
int min, int sec, TimeZone tz) {
return ConvertDateTime(year, mon, day, hour, min, sec, tz).pre;
}
// FromTM()
//
// Converts the `tm_year`, `tm_mon`, `tm_mday`, `tm_hour`, `tm_min`, and
// `tm_sec` fields to an `absl::Time` using the given time zone. See ctime(3)
// for a description of the expected values of the tm fields. If the indicated
// time instant is not unique (see `absl::TimeZone::At(absl::CivilSecond)`
// above), the `tm_isdst` field is consulted to select the desired instant
// (`tm_isdst` > 0 means DST, `tm_isdst` == 0 means no DST, `tm_isdst` < 0
// means use the post-transition offset).
Time FromTM(const struct tm& tm, TimeZone tz);
// ToTM()
//
// Converts the given `absl::Time` to a struct tm using the given time zone.
// See ctime(3) for a description of the values of the tm fields.
struct tm ToTM(Time t, TimeZone tz);
// RFC3339_full
// RFC3339_sec
//
// FormatTime()/ParseTime() format specifiers for RFC3339 date/time strings,
// with trailing zeros trimmed or with fractional seconds omitted altogether.
//
// Note that RFC3339_sec[] matches an ISO 8601 extended format for date and
// time with UTC offset. Also note the use of "%Y": RFC3339 mandates that
// years have exactly four digits, but we allow them to take their natural
// width.
extern const char RFC3339_full[]; // %Y-%m-%dT%H:%M:%E*S%Ez
extern const char RFC3339_sec[]; // %Y-%m-%dT%H:%M:%S%Ez
// RFC1123_full
// RFC1123_no_wday
//
// FormatTime()/ParseTime() format specifiers for RFC1123 date/time strings.
extern const char RFC1123_full[]; // %a, %d %b %E4Y %H:%M:%S %z
extern const char RFC1123_no_wday[]; // %d %b %E4Y %H:%M:%S %z
// FormatTime()
//
// Formats the given `absl::Time` in the `absl::TimeZone` 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.
//
// We recommend that format strings include the UTC offset (%z, %Ez, or %E*z)
// so that the result uniquely identifies a time instant.
//
// Example:
//
// absl::CivilSecond cs(2013, 1, 2, 3, 4, 5);
// absl::Time t = absl::FromCivil(cs, lax);
// std::string f = absl::FormatTime("%H:%M:%S", t, lax); // "03:04:05"
// f = absl::FormatTime("%H:%M:%E3S", t, lax); // "03:04:05.000"
//
// Note: If the given `absl::Time` is `absl::InfiniteFuture()`, the returned
// string will be exactly "infinite-future". If the given `absl::Time` is
// `absl::InfinitePast()`, the returned string will be exactly "infinite-past".
// In both cases the given format string and `absl::TimeZone` are ignored.
//
std::string FormatTime(const std::string& format, Time t, TimeZone tz);
// Convenience functions that format the given time using the RFC3339_full
// format. The first overload uses the provided TimeZone, while the second
// uses LocalTimeZone().
std::string FormatTime(Time t, TimeZone tz);
std::string FormatTime(Time t);
// Output stream operator.
inline std::ostream& operator<<(std::ostream& os, Time t) {
return os << FormatTime(t);
}
// ParseTime()
//
// Parses an input string according to the provided format string and
// returns the corresponding `absl::Time`. Uses strftime()-like formatting
// options, with the same extensions as FormatTime(), 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 an absl::Time
// that represents "1970-01-01 15:45:00.0 +0000".
//
// Note that since ParseTime() returns time instants, it makes the most sense
// to parse fully-specified date/time strings that include a UTC offset (%z,
// %Ez, or %E*z).
//
// Note also that `absl::ParseTime()` 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 `absl::CivilSecond` does. For example,
// it is an error to parse the date "Oct 32, 2013" because 32 is out of range.
//
// A leap 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 and assigning an error message
// to the "err" out param if it is non-null.
//
// Note: If the input string is exactly "infinite-future", the returned
// `absl::Time` will be `absl::InfiniteFuture()` and `true` will be returned.
// If the input string is "infinite-past", the returned `absl::Time` will be
// `absl::InfinitePast()` and `true` will be returned.
//
bool ParseTime(const std::string& format, const std::string& input, Time* time,
std::string* err);
// Like ParseTime() above, but if the format string does not contain a UTC
// offset specification (%z/%Ez/%E*z) then the input is interpreted in the
// given TimeZone. This means that the input, by itself, does not identify a
// unique instant. Being time-zone dependent, it also admits the possibility
// of ambiguity or non-existence, in which case the "pre" time (as defined
// by TimeZone::TimeInfo) is returned. For these reasons we recommend that
// all date/time strings include a UTC offset so they're context independent.
bool ParseTime(const std::string& format, const std::string& input, TimeZone tz,
Time* time, std::string* err);
// ============================================================================
// Implementation Details Follow
// ============================================================================
namespace time_internal {
// Creates a Duration with a given representation.
// REQUIRES: hi,lo is a valid representation of a Duration as specified
// in time/duration.cc.
constexpr Duration MakeDuration(int64_t hi, uint32_t lo = 0) {
return Duration(hi, lo);
}
constexpr Duration MakeDuration(int64_t hi, int64_t lo) {
return MakeDuration(hi, static_cast<uint32_t>(lo));
}
// Make a Duration value from a floating-point number, as long as that number
// is in the range [ 0 .. numeric_limits<int64_t>::max ), that is, as long as
// it's positive and can be converted to int64_t without risk of UB.
inline Duration MakePosDoubleDuration(double n) {
const int64_t int_secs = static_cast<int64_t>(n);
const uint32_t ticks =
static_cast<uint32_t>((n - int_secs) * kTicksPerSecond + 0.5);
return ticks < kTicksPerSecond
? MakeDuration(int_secs, ticks)
: MakeDuration(int_secs + 1, ticks - kTicksPerSecond);
}
// Creates a normalized Duration from an almost-normalized (sec,ticks)
// pair. sec may be positive or negative. ticks must be in the range
// -kTicksPerSecond < *ticks < kTicksPerSecond. If ticks is negative it
// will be normalized to a positive value in the resulting Duration.
constexpr Duration MakeNormalizedDuration(int64_t sec, int64_t ticks) {
return (ticks < 0) ? MakeDuration(sec - 1, ticks + kTicksPerSecond)
: MakeDuration(sec, ticks);
}
// Provide access to the Duration representation.
constexpr int64_t GetRepHi(Duration d) { return d.rep_hi_; }
constexpr uint32_t GetRepLo(Duration d) { return d.rep_lo_; }
// Returns true iff d is positive or negative infinity.
constexpr bool IsInfiniteDuration(Duration d) { return GetRepLo(d) == ~0U; }
// Returns an infinite Duration with the opposite sign.
// REQUIRES: IsInfiniteDuration(d)
constexpr Duration OppositeInfinity(Duration d) {
return GetRepHi(d) < 0
? MakeDuration((std::numeric_limits<int64_t>::max)(), ~0U)
: MakeDuration((std::numeric_limits<int64_t>::min)(), ~0U);
}
// Returns (-n)-1 (equivalently -(n+1)) without avoidable overflow.
constexpr int64_t NegateAndSubtractOne(int64_t n) {
// Note: Good compilers will optimize this expression to ~n when using
// a two's-complement representation (which is required for int64_t).
return (n < 0) ? -(n + 1) : (-n) - 1;
}
// Map between a Time and a Duration since the Unix epoch. Note that these
// functions depend on the above mentioned choice of the Unix epoch for the
// Time representation (and both need to be Time friends). Without this
// knowledge, we would need to add-in/subtract-out UnixEpoch() respectively.
constexpr Time FromUnixDuration(Duration d) { return Time(d); }
constexpr Duration ToUnixDuration(Time t) { return t.rep_; }
template <std::intmax_t N>
constexpr Duration FromInt64(int64_t v, std::ratio<1, N>) {
static_assert(0 < N && N <= 1000 * 1000 * 1000, "Unsupported ratio");
// Subsecond ratios cannot overflow.
return MakeNormalizedDuration(
v / N, v % N * kTicksPerNanosecond * 1000 * 1000 * 1000 / N);
}
constexpr Duration FromInt64(int64_t v, std::ratio<60>) {
return (v <= (std::numeric_limits<int64_t>::max)() / 60 &&
v >= (std::numeric_limits<int64_t>::min)() / 60)
? MakeDuration(v * 60)
: v > 0 ? InfiniteDuration() : -InfiniteDuration();
}
constexpr Duration FromInt64(int64_t v, std::ratio<3600>) {
return (v <= (std::numeric_limits<int64_t>::max)() / 3600 &&
v >= (std::numeric_limits<int64_t>::min)() / 3600)
? MakeDuration(v * 3600)
: v > 0 ? InfiniteDuration() : -InfiniteDuration();
}
// IsValidRep64<T>(0) is true if the expression `int64_t{std::declval<T>()}` is
// valid. That is, if a T can be assigned to an int64_t without narrowing.
template <typename T>
constexpr auto IsValidRep64(int)
-> decltype(int64_t{std::declval<T>()}, bool()) {
return true;
}
template <typename T>
constexpr auto IsValidRep64(char) -> bool {
return false;
}
// Converts a std::chrono::duration to an absl::Duration.
template <typename Rep, typename Period>
constexpr Duration FromChrono(const std::chrono::duration<Rep, Period>& d) {
static_assert(IsValidRep64<Rep>(0), "duration::rep is invalid");
return FromInt64(int64_t{d.count()}, Period{});
}
template <typename Ratio>
int64_t ToInt64(Duration d, Ratio) {
// Note: This may be used on MSVC, which may have a system_clock period of
// std::ratio<1, 10 * 1000 * 1000>
return ToInt64Seconds(d * Ratio::den / Ratio::num);
}
// Fastpath implementations for the 6 common duration units.
inline int64_t ToInt64(Duration d, std::nano) {
return ToInt64Nanoseconds(d);
}
inline int64_t ToInt64(Duration d, std::micro) {
return ToInt64Microseconds(d);
}
inline int64_t ToInt64(Duration d, std::milli) {
return ToInt64Milliseconds(d);
}
inline int64_t ToInt64(Duration d, std::ratio<1>) {
return ToInt64Seconds(d);
}
inline int64_t ToInt64(Duration d, std::ratio<60>) {
return ToInt64Minutes(d);
}
inline int64_t ToInt64(Duration d, std::ratio<3600>) {
return ToInt64Hours(d);
}
// Converts an absl::Duration to a chrono duration of type T.
template <typename T>
T ToChronoDuration(Duration d) {
using Rep = typename T::rep;
using Period = typename T::period;
static_assert(IsValidRep64<Rep>(0), "duration::rep is invalid");
if (time_internal::IsInfiniteDuration(d))
return d < ZeroDuration() ? (T::min)() : (T::max)();
const auto v = ToInt64(d, Period{});
if (v > (std::numeric_limits<Rep>::max)()) return (T::max)();
if (v < (std::numeric_limits<Rep>::min)()) return (T::min)();
return T{v};
}
} // namespace time_internal
constexpr Duration Nanoseconds(int64_t n) {
return time_internal::FromInt64(n, std::nano{});
}
constexpr Duration Microseconds(int64_t n) {
return time_internal::FromInt64(n, std::micro{});
}
constexpr Duration Milliseconds(int64_t n) {
return time_internal::FromInt64(n, std::milli{});
}
constexpr Duration Seconds(int64_t n) {
return time_internal::FromInt64(n, std::ratio<1>{});
}
constexpr Duration Minutes(int64_t n) {
return time_internal::FromInt64(n, std::ratio<60>{});
}
constexpr Duration Hours(int64_t n) {
return time_internal::FromInt64(n, std::ratio<3600>{});
}
constexpr bool operator<(Duration lhs, Duration rhs) {
return time_internal::GetRepHi(lhs) != time_internal::GetRepHi(rhs)
? time_internal::GetRepHi(lhs) < time_internal::GetRepHi(rhs)
: time_internal::GetRepHi(lhs) ==
(std::numeric_limits<int64_t>::min)()
? time_internal::GetRepLo(lhs) + 1 <
time_internal::GetRepLo(rhs) + 1
: time_internal::GetRepLo(lhs) <
time_internal::GetRepLo(rhs);
}
constexpr bool operator==(Duration lhs, Duration rhs) {
return time_internal::GetRepHi(lhs) == time_internal::GetRepHi(rhs) &&
time_internal::GetRepLo(lhs) == time_internal::GetRepLo(rhs);
}
constexpr Duration operator-(Duration d) {
// This is a little interesting because of the special cases.
//
// If rep_lo_ is zero, we have it easy; it's safe to negate rep_hi_, we're
// dealing with an integral number of seconds, and the only special case is
// the maximum negative finite duration, which can't be negated.
//
// Infinities stay infinite, and just change direction.
//
// Finally we're in the case where rep_lo_ is non-zero, and we can borrow
// a second's worth of ticks and avoid overflow (as negating int64_t-min + 1
// is safe).
return time_internal::GetRepLo(d) == 0
? time_internal::GetRepHi(d) ==
(std::numeric_limits<int64_t>::min)()
? InfiniteDuration()
: time_internal::MakeDuration(-time_internal::GetRepHi(d))
: time_internal::IsInfiniteDuration(d)
? time_internal::OppositeInfinity(d)
: time_internal::MakeDuration(
time_internal::NegateAndSubtractOne(
time_internal::GetRepHi(d)),
time_internal::kTicksPerSecond -
time_internal::GetRepLo(d));
}
constexpr Duration InfiniteDuration() {
return time_internal::MakeDuration((std::numeric_limits<int64_t>::max)(),
~0U);
}
constexpr Duration FromChrono(const std::chrono::nanoseconds& d) {
return time_internal::FromChrono(d);
}
constexpr Duration FromChrono(const std::chrono::microseconds& d) {
return time_internal::FromChrono(d);
}
constexpr Duration FromChrono(const std::chrono::milliseconds& d) {
return time_internal::FromChrono(d);
}
constexpr Duration FromChrono(const std::chrono::seconds& d) {
return time_internal::FromChrono(d);
}
constexpr Duration FromChrono(const std::chrono::minutes& d) {
return time_internal::FromChrono(d);
}
constexpr Duration FromChrono(const std::chrono::hours& d) {
return time_internal::FromChrono(d);
}
constexpr Time FromUnixNanos(int64_t ns) {
return time_internal::FromUnixDuration(Nanoseconds(ns));
}
constexpr Time FromUnixMicros(int64_t us) {
return time_internal::FromUnixDuration(Microseconds(us));
}
constexpr Time FromUnixMillis(int64_t ms) {
return time_internal::FromUnixDuration(Milliseconds(ms));
}
constexpr Time FromUnixSeconds(int64_t s) {
return time_internal::FromUnixDuration(Seconds(s));
}
constexpr Time FromTimeT(time_t t) {
return time_internal::FromUnixDuration(Seconds(t));
}
} // namespace absl
#endif // ABSL_TIME_TIME_H_