From Jason Turner

[time.cal.ymwd]

C++17 → C++20 7.7 KB 254 lines
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  1. tmp/tmpds4g19cc/{from.md → to.md} +251 -0
tmp/tmpds4g19cc/{from.md → to.md} RENAMED
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+ ### Class `year_month_weekday` <a id="time.cal.ymwd">[[time.cal.ymwd]]</a>
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+
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+ #### Overview <a id="time.cal.ymwd.overview">[[time.cal.ymwd.overview]]</a>
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+
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+ ``` cpp
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+ namespace std::chrono {
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+ class year_month_weekday {
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+ chrono::year y_; // exposition only
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+ chrono::month m_; // exposition only
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+ chrono::weekday_indexed wdi_; // exposition only
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+
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+ public:
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+ year_month_weekday() = default;
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+ constexpr year_month_weekday(const chrono::year& y, const chrono::month& m,
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+ const chrono::weekday_indexed& wdi) noexcept;
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+ constexpr year_month_weekday(const sys_days& dp) noexcept;
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+ constexpr explicit year_month_weekday(const local_days& dp) noexcept;
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+
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+ constexpr year_month_weekday& operator+=(const months& m) noexcept;
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+ constexpr year_month_weekday& operator-=(const months& m) noexcept;
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+ constexpr year_month_weekday& operator+=(const years& y) noexcept;
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+ constexpr year_month_weekday& operator-=(const years& y) noexcept;
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+
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+ constexpr chrono::year year() const noexcept;
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+ constexpr chrono::month month() const noexcept;
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+ constexpr chrono::weekday weekday() const noexcept;
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+ constexpr unsigned index() const noexcept;
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+ constexpr chrono::weekday_indexed weekday_indexed() const noexcept;
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+
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+ constexpr operator sys_days() const noexcept;
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+ constexpr explicit operator local_days() const noexcept;
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+ constexpr bool ok() const noexcept;
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+ };
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+ }
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+ ```
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+
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+ `year_month_weekday` represents a specific year, month, and nᵗʰ weekday
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+ of the month. `year_month_weekday` is a field-based time point with a
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+ resolution of `days`.
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+
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+ [*Note 1*: `year_month_weekday` supports `years`- and `months`-oriented
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+ arithmetic, but not `days`-oriented arithmetic. For the latter, there is
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+ a conversion to `sys_days`, which efficiently supports `days`-oriented
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+ arithmetic. — *end note*]
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+
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+ `year_month_weekday` meets the *Cpp17EqualityComparable* (
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+ [[cpp17.equalitycomparable]]) requirements.
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+
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+ `year_month_weekday` is a trivially copyable and standard-layout class
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+ type.
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+
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+ #### Member functions <a id="time.cal.ymwd.members">[[time.cal.ymwd.members]]</a>
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+
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+ ``` cpp
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+ constexpr year_month_weekday(const chrono::year& y, const chrono::month& m,
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+ const chrono::weekday_indexed& wdi) noexcept;
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+ ```
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+
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+ *Effects:* Initializes `y_` with `y`, `m_` with `m`, and `wdi_` with
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+ `wdi`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday(const sys_days& dp) noexcept;
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+ ```
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+
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+ *Effects:* Constructs an object of type `year_month_weekday` which
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+ corresponds to the date represented by `dp`.
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+
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+ *Remarks:* For any value `ymdl` of type `year_month_weekday` for which
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+ `ymdl.ok()` is `true`, `ymdl == year_month_weekday{sys_days{ymdl}}` is
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+ `true`.
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+
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+ ``` cpp
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+ constexpr explicit year_month_weekday(const local_days& dp) noexcept;
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+ ```
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+
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+ *Effects:* Equivalent to constructing with
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+ `sys_days{dp.time_since_epoch()}`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday& operator+=(const months& m) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Effects:* `*this = *this + m`.
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+
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+ *Returns:* `*this`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday& operator-=(const months& m) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Effects:* `*this = *this - m`.
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+
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+ *Returns:* `*this`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday& operator+=(const years& y) noexcept;
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+ ```
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+
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+ *Effects:* `*this = *this + y`.
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+
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+ *Returns:* `*this`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday& operator-=(const years& y) noexcept;
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+ ```
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+
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+ *Effects:* `*this = *this - y`.
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+
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+ *Returns:* `*this`.
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+
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+ ``` cpp
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+ constexpr chrono::year year() const noexcept;
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+ ```
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+
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+ *Returns:* `y_`.
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+
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+ ``` cpp
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+ constexpr chrono::month month() const noexcept;
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+ ```
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+
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+ *Returns:* `m_`.
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+
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+ ``` cpp
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+ constexpr chrono::weekday weekday() const noexcept;
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+ ```
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+
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+ *Returns:* `wdi_.weekday()`.
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+
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+ ``` cpp
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+ constexpr unsigned index() const noexcept;
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+ ```
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+
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+ *Returns:* `wdi_.index()`.
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+
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+ ``` cpp
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+ constexpr chrono::weekday_indexed weekday_indexed() const noexcept;
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+ ```
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+
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+ *Returns:* `wdi_`.
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+
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+ ``` cpp
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+ constexpr operator sys_days() const noexcept;
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+ ```
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+
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+ *Returns:* If `y_.ok() && m_.ok() && wdi_.weekday().ok()`, returns a
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+ `sys_days` that represents the date `(index() - 1) * 7` days after the
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+ first `weekday()` of `year()/month()`. If `index()` is 0 the returned
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+ `sys_days` represents the date 7 days prior to the first `weekday()` of
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+ `year()/month()`. Otherwise the returned value is unspecified.
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+
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+ ``` cpp
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+ constexpr explicit operator local_days() const noexcept;
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+ ```
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+
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+ *Returns:* `local_days{sys_days{*this}.time_since_epoch()}`.
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+
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+ ``` cpp
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+ constexpr bool ok() const noexcept;
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+ ```
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+
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+ *Returns:* If any of `y_.ok()`, `m_.ok()`, or `wdi_.ok()` is `false`,
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+ returns `false`. Otherwise, if `*this` represents a valid date, returns
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+ `true`. Otherwise, returns `false`.
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+
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+ #### Non-member functions <a id="time.cal.ymwd.nonmembers">[[time.cal.ymwd.nonmembers]]</a>
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+
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+ ``` cpp
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+ constexpr bool operator==(const year_month_weekday& x, const year_month_weekday& y) noexcept;
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+ ```
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+
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+ *Returns:*
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+
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+ ``` cpp
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+ x.year() == y.year() && x.month() == y.month() && x.weekday_indexed() == y.weekday_indexed()
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+ ```
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+
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+ ``` cpp
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+ constexpr year_month_weekday operator+(const year_month_weekday& ymwd, const months& dm) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Returns:* `(ymwd.year() / ymwd.month() + dm) / ymwd.weekday_indexed()`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday operator+(const months& dm, const year_month_weekday& ymwd) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Returns:* `ymwd + dm`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday operator-(const year_month_weekday& ymwd, const months& dm) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Returns:* `ymwd + (-dm)`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday operator+(const year_month_weekday& ymwd, const years& dy) noexcept;
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+ ```
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+
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+ *Returns:* `{ymwd.year()+dy, ymwd.month(), ymwd.weekday_indexed()}`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday operator+(const years& dy, const year_month_weekday& ymwd) noexcept;
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+ ```
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+
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+ *Returns:* `ymwd + dy`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday operator-(const year_month_weekday& ymwd, const years& dy) noexcept;
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+ ```
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+
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+ *Returns:* `ymwd + (-dy)`.
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+
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+ ``` cpp
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+ template<class charT, class traits>
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+ basic_ostream<charT, traits>&
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+ operator<<(basic_ostream<charT, traits>& os, const year_month_weekday& ymwd);
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ return os << format(os.getloc(), STATICALLY-WIDEN<charT>("{}/{}/{}"),
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+ ymwd.year(), ymwd.month(), ymwd.weekday_indexed());
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+ ```
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+