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Add zoned_time default constructor and,

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refine conversion from calendar types to sys_days and local_days.
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Howard Hinnant
2017-06-27 22:15:45 -04:00
parent 241551dd6c
commit 609dd49934
1 changed files with 27 additions and 28 deletions
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d0355r4.html
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@@ -60,8 +60,8 @@ Document number: D0355R4<br>
<ul>
<li><ins>Improve spec for operator-(const year_month& x, const year_month& y).</ins></li>
<li><ins>Refine constraints on conversions from calendar types to sys_days.</ins></li>
<li>Added issue concerning <code>zoned_time</code> default constructor.</li>
<li>Refine constraints on conversions from calendar types to sys_days.</li>
<li>Added <code>zoned_time</code> default constructor.</li>
<li>Correct minor type-o's.</li>
<li>Correct html bugs.</li>
</ul>
@@ -718,12 +718,6 @@ which is equal to <code>nullptr</code>.
</p>
</li>
<li>
<p>
Should <code>zoned_time</code> have a default constructor, and if so, what should its
value be?
</p>
</li>
</ol>
<a name="Wording"></a><h2>Proposed Wording</h2>
@@ -6748,15 +6742,18 @@ constexpr year_month_day::operator sys_days() const noexcept;
</p>
<p>
<i>Returns:</i> If <code>ok()</code>, returns a <code>sys_days</code>
holding a count of <code>days</code> before or since the
<code>sys_days</code> epoch. Otherwise returns a
holding a count of <code>days</code> from the <code>sys_days</code> epoch to
<code>*this</code> (a negative value if <code>*this</code> represents a date
prior to the <code>sys_days</code> epoch). Otherwise returns a
<code>sys_days</code> which is offset from
<code>sys_days{y_/m_/last}</code> by the number of <code>days</code>
<code>d_</code> is offset from <code>sys_days{y_/m_/last}.day()</code>.
</p>
<p>
<i>Remarks:</i> A <code>sys_days</code> which is converted to a <code>year_month_day</code>,
shall have the same value when converted back to a <code>sys_days</code>.
<i>Remarks:</i> A <code>sys_days</code> in the range
<code>[days{-12687428}, days{11248737}]</code> which is converted to a
<code>year_month_day</code>, shall have the same value when converted
back to a <code>sys_days</code>.
</p>
<p>
[<i>Example</i>:
@@ -6777,13 +6774,13 @@ constexpr explicit year_month_day::operator local_days() const noexcept;
<blockquote>
<p>
<i>Requires:</i> <code>ok() == true</code>.
<i>Requires:</i> <code>y_.ok() &amp;&amp; m_.ok() == true</code>.
</p>
<p>
<i>Effects:</i> Equivalent to:
</p>
<blockquote><pre>
return local_days{static_cast&lt;sys_days&gt;(*this).time_since_epoch()};
return local_days{sys_days{*this}.time_since_epoch()};
</pre></blockquote>
</blockquote>
@@ -7177,8 +7174,7 @@ constexpr year_month_day_last::operator sys_days() const noexcept;
<i>Requires:</i> <code>ok() == true</code>.
</p>
<p>
<i>Returns:</i> A <code>sys_days</code> which represents the date represented by
<code>*this</code>.
<i>Effects:</i> Equivalent to: <code>return sys_days{year()/month()/day()};</code>
</p>
</blockquote>
@@ -7191,11 +7187,8 @@ constexpr explicit year_month_day_last::operator local_days() const noexcept;
<i>Requires:</i> <code>ok() == true</code>.
</p>
<p>
<i>Effects:</i> Equivalent to:
<i>Effects:</i> Equivalent to: <code>return local_days{sys_days{*this}.time_since_epoch()};</code>
</p>
<blockquote><pre>
return local_days{static_cast&lt;sys_days&gt;(*this).time_since_epoch()};
</pre></blockquote>
</blockquote>
<pre>
@@ -7586,11 +7579,8 @@ constexpr explicit year_month_weekday::operator local_days() const noexcept;
<i>Requires:</i> <code>ok() == true</code>.
</p>
<p>
<i>Effects:</i> Equivalent to:
<i>Effects:</i> Equivalent to: <code>return local_days{sys_days{*this}.time_since_epoch()};</code>
</p>
<blockquote><pre>
return local_days{static_cast&lt;sys_days&gt;(*this).time_since_epoch()};
</pre></blockquote>
</blockquote>
<pre>
@@ -7920,11 +7910,8 @@ constexpr explicit year_month_weekday_last::operator local_days() const noexcept
<i>Requires:</i> <code>ok() == true</code>.
</p>
<p>
<i>Effects:</i> Equivalent to:
<i>Effects:</i> Equivalent to: <code>return local_days{sys_days{*this}.time_since_epoch()};</code>
</p>
<blockquote><pre>
return local_days{static_cast&lt;sys_days&gt;(*this).time_since_epoch()};
</pre></blockquote>
</blockquote>
<pre>
@@ -9671,6 +9658,7 @@ private:
sys_time&lt;duration&gt; tp_; // exposition only
public:
zoned_time();
zoned_time(const zoned_time&amp;) = default;
zoned_time&amp; operator=(const zoned_time&amp;) = default;
@@ -9734,6 +9722,17 @@ to a valid <code>time_zone</code>, and represents a point in time that exists
and is not ambiguous.
</p>
<pre>
zoned_time&lt;Duration&gt;::zoned_time();
</pre>
<blockquote>
<p>
<i>Effects:</i> Constructs a <code>zoned_time</code> <code>zt</code> such that
<code>zt.get_time_zone()-&gt;name() == "UTC"</code>, and
<code>zt.get_sys_time() == sys_seconds{}</code>.
</p>
</blockquote>
<pre>
zoned_time&lt;Duration&gt;::zoned_time(const zoned_time&amp;) = default;
zoned_time&lt;Duration&gt;&amp; zoned_time&lt;Duration&gt;::operator=(const zoned_time&amp;) = default;