From Jason Turner

[time.zone.leap]

C++17 → C++20 4.2 KB 171 lines
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Archived: C++17 | C++20
Markdown: C++17 | C++20
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  1. tmp/tmpionx4ywe/{from.md → to.md} +168 -0
tmp/tmpionx4ywe/{from.md → to.md} RENAMED
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+ ### Class `leap_second` <a id="time.zone.leap">[[time.zone.leap]]</a>
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+
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+ #### Overview <a id="time.zone.leap.overview">[[time.zone.leap.overview]]</a>
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+
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+ ``` cpp
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+ namespace std::chrono {
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+ class leap_second {
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+ public:
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+ leap_second(const leap_second&) = default;
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+ leap_second& operator=(const leap_second&) = default;
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+
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+ // unspecified additional constructors
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+
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+ constexpr sys_seconds date() const noexcept;
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+ constexpr seconds value() const noexcept;
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+ };
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+ }
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+ ```
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+
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+ Objects of type `leap_second` representing the date and value of the
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+ leap second insertions are constructed and stored in the time zone
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+ database when initialized.
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+
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+ [*Example 1*:
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+
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+ ``` cpp
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+ for (auto& l : get_tzdb().leap_seconds)
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+ if (l <= 2018y/March/17d)
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+ cout << l.date() << ": " << l.value() << '\n';
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+ ```
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+
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+ Produces the output:
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+
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+ ``` cpp
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+ 1972-07-01 00:00:00: 1s
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+ 1973-01-01 00:00:00: 1s
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+ 1974-01-01 00:00:00: 1s
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+ 1975-01-01 00:00:00: 1s
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+ 1976-01-01 00:00:00: 1s
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+ 1977-01-01 00:00:00: 1s
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+ 1978-01-01 00:00:00: 1s
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+ 1979-01-01 00:00:00: 1s
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+ 1980-01-01 00:00:00: 1s
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+ 1981-07-01 00:00:00: 1s
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+ 1982-07-01 00:00:00: 1s
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+ 1983-07-01 00:00:00: 1s
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+ 1985-07-01 00:00:00: 1s
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+ 1988-01-01 00:00:00: 1s
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+ 1990-01-01 00:00:00: 1s
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+ 1991-01-01 00:00:00: 1s
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+ 1992-07-01 00:00:00: 1s
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+ 1993-07-01 00:00:00: 1s
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+ 1994-07-01 00:00:00: 1s
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+ 1996-01-01 00:00:00: 1s
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+ 1997-07-01 00:00:00: 1s
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+ 1999-01-01 00:00:00: 1s
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+ 2006-01-01 00:00:00: 1s
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+ 2009-01-01 00:00:00: 1s
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+ 2012-07-01 00:00:00: 1s
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+ 2015-07-01 00:00:00: 1s
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+ 2017-01-01 00:00:00: 1s
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+ ```
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+
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+ — *end example*]
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+
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+ #### Member functions <a id="time.zone.leap.members">[[time.zone.leap.members]]</a>
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+
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+ ``` cpp
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+ constexpr sys_seconds date() const noexcept;
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+ ```
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+
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+ *Returns:* The date and time at which the leap second was inserted.
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+
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+ ``` cpp
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+ constexpr seconds value() const noexcept;
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+ ```
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+
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+ *Returns:* `+1s` to indicate a positive leap second or `-1s` to indicate
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+ a negative leap second.
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+
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+ [*Note 1*: All leap seconds inserted up through 2019 were positive leap
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+ seconds. — *end note*]
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+
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+ #### Non-member functions <a id="time.zone.leap.nonmembers">[[time.zone.leap.nonmembers]]</a>
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+
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+ ``` cpp
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+ constexpr bool operator==(const leap_second& x, const leap_second& y) noexcept;
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+ ```
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+
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+ *Returns:* `x.date() == y.date()`.
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+
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+ ``` cpp
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+ constexpr strong_ordering operator<=>(const leap_second& x, const leap_second& y) noexcept;
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+ ```
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+
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+ *Returns:* `x.date() <=> y.date()`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator==(const leap_second& x, const sys_time<Duration>& y) noexcept;
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+ ```
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+
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+ *Returns:* `x.date() == y`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator<(const leap_second& x, const sys_time<Duration>& y) noexcept;
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+ ```
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+
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+ *Returns:* `x.date() < y`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator<(const sys_time<Duration>& x, const leap_second& y) noexcept;
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+ ```
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+
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+ *Returns:* `x < y.date()`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator>(const leap_second& x, const sys_time<Duration>& y) noexcept;
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+ ```
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+
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+ *Returns:* `y < x`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator>(const sys_time<Duration>& x, const leap_second& y) noexcept;
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+ ```
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+
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+ *Returns:* `y < x`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator<=(const leap_second& x, const sys_time<Duration>& y) noexcept;
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+ ```
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+
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+ *Returns:* `!(y < x)`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator<=(const sys_time<Duration>& x, const leap_second& y) noexcept;
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+ ```
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+
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+ *Returns:* `!(y < x)`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator>=(const leap_second& x, const sys_time<Duration>& y) noexcept;
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+ ```
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+
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+ *Returns:* `!(x < y)`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ constexpr bool operator>=(const sys_time<Duration>& x, const leap_second& y) noexcept;
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+ ```
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+
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+ *Returns:* `!(x < y)`.
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+
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+ ``` cpp
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+ template<class Duration>
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+ requires three_way_comparable_with<sys_seconds, sys_time<Duration>>
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+ constexpr auto operator<=>(const leap_second& x, const sys_time<Duration>& y) noexcept;
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+ ```
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+
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+ *Returns:* `x.date() <=> y`.
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+