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Document clock_cast for local_time.

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Document clock_time_conversion<D, local_t> calling D::from_local
and clock_time_conversion<locat_t, S> calling S::to_local.

To avoid ambiguities addes:
* clock_time_conversion<local_t, local_t> - idenitity
* clock_time_conversion<local_t, utc_clock> - same as default (utc_clock::to_local)
* clock_time_conversion<utc_clock, local_t> - same as default (utc_clock::from_local)

In addition, as std::chrono::system_clock cannot be edited, added:
* clock_time_conversion<local_t, std::chrono::system_clock> - assumes same epoch
* clock_time_conversion<std::chrono::system_clock, local_t> - assumes same epoch
This commit is contained in:
Howard Hinnant
2018-06-11 15:16:42 -04:00
parent 0543e00b88
commit 8fbeb9ac4f
1 changed files with 267 additions and 1 deletions
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268
tz.html
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@@ -26,7 +26,7 @@
<br/>
<br/>
<a href="mailto:howard.hinnant@gmail.com">Howard E. Hinnant</a><br/>
2018-06-02<br/>
2018-06-11<br/>
</address>
<hr/>
<h1 align=center>Time Zone Database Parser</h1>
@@ -2690,6 +2690,16 @@ public:
static
utc_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
from_sys(const sys_time&lt;Duration&gt;&amp;);
template &lt;class Duration&gt;
static
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
to_local(const utc_time&lt;Duration&gt;&amp;);
template &lt;class Duration&gt;
static
utc_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
from_local(const local_time&lt;Duration&gt;&amp;);
};
template &lt;class Duration&gt;
@@ -2756,6 +2766,30 @@ second insertion), then the conversion counts that leap second as inserted.
</p>
</blockquote>
<pre>
template &lt;class Duration&gt;
static
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
utc_clock::to_local(const utc_time&lt;Duration&gt;&amp; u);
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>local_time&lt;Duration&gt;{to_sys(u).time_since_epoch()}</code>.
</p>
</blockquote>
<pre>
template &lt;class Duration&gt;
static
utc_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
utc_clock::from_local(const local_time&lt;Duration&gt;&amp; t);
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>from_sys(sys_time&lt;Duration&gt;{t.time_since_epoch()})</code>.
</p>
</blockquote>
<pre>
template &lt;class CharT, class Traits, class Duration&gt;
std::basic_ostream&lt;class CharT, class Traits&gt;&amp;
@@ -2896,6 +2930,16 @@ public:
static
tai_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
from_utc(const utc_time&lt;Duration&gt;&amp;) noexcept;
template &lt;class Duration&gt;
static
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
to_local(const tai_time&lt;Duration&gt;&amp;) noexcept;
template &lt;class Duration&gt;
static
tai_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
from_local(const local_time&lt;Duration&gt;&amp;) noexcept;
};
template &lt;class Duration&gt;
@@ -2958,6 +3002,32 @@ tai_clock::from_utc(const utc_time&lt;Duration&gt;&amp; t) noexcept;
</p>
</blockquote>
<pre>
template &lt;class Duration&gt;
static
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
tai_clock::to_local(const tai_time&lt;Duration&gt;&amp; t) noexcept;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>local_time&lt;Duration&gt;{t.time_since_epoch()} -
(local_days{1970_y/January/1} - local_days{1958_y/January/1})</code>.
</p>
</blockquote>
<pre>
template &lt;class Duration&gt;
static
tai_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
tai_clock::from_local(const local_time&lt;Duration&gt;&amp; t) noexcept;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>tai_time&lt;Duration&gt;{t.time_since_epoch()} +
(local_days{1970_y/January/1} - local_days{1958_y/January/1})</code>.
</p>
</blockquote>
<pre>
template &lt;class CharT, class Traits, class Duration&gt;
std::basic_ostream&lt;class CharT, class Traits&gt;&amp;
@@ -3041,6 +3111,16 @@ public:
static
gps_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
from_utc(const utc_time&lt;Duration&gt;&amp;) noexcept;
template &lt;class Duration&gt;
static
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
to_local(const gps_time&lt;Duration&gt;&amp;) noexcept;
template &lt;class Duration&gt;
static
gps_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
from_local(const local_time&lt;Duration&gt;&amp;) noexcept;
};
template &lt;class Duration&gt;
@@ -3102,6 +3182,32 @@ gps_clock::from_utc(const utc_time&lt;Duration&gt;&amp; t) noexcept;
</p>
</blockquote>
<pre>
template &lt;class Duration&gt;
static
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
gps_clock::to_local(const gps_time&lt;Duration&gt;&amp; t) noexcept;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>local_time&lt;Duration&gt;{t.time_since_epoch()} +
(local_days{1980_y/January/Sunday[1]} - local_days{1970_y/January/1})</code>.
</p>
</blockquote>
<pre>
template &lt;class Duration&gt;
static
gps_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
gps_clock::from_local(const local_time&lt;Duration&gt;&amp; t) noexcept;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>local_time&lt;Duration&gt;{t.time_since_epoch()} -
(local_days{1980_y/January/Sunday[1]} - local_days{1970_y/January/1})</code>.
</p>
</blockquote>
<pre>
template &lt;class CharT, class Traits, class Duration&gt;
std::basic_ostream&lt;class CharT, class Traits&gt;&amp;
@@ -3312,6 +3418,26 @@ operator()(const utc_time&lt;Duration&gt;&amp; t) const;
</p>
</blockquote>
<pre>
template &lt;&gt;
struct clock_time_conversion&lt;local_t, local_t&gt;
{
template &lt;class Duration&gt;
local_time&lt;Duration&gt;
operator()(const local_time&lt;Duration&gt;&amp; t) const;
};
template &lt;class Duration&gt;
local_time&lt;Duration&gt;
operator()(const local_time&lt;Duration&gt;&amp; t) const;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>t</code>.
</p>
</blockquote>
<pre>
// system_clock &lt;-&gt; utc_clock
</pre>
@@ -3356,6 +3482,94 @@ operator()(const utc_time&lt;Duration&gt;&amp; t) const;
</p>
</blockquote>
<pre>
// system_clock &lt;-&gt; local_t
</pre>
<pre>
template &lt;&gt;
struct clock_time_conversion&lt;local_t, std::chrono::system_clock&gt;
{
template &lt;class Duration&gt;
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
operator()(const sys_time&lt;Duration&gt;&amp; t) const;
};
template &lt;class Duration&gt;
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
operator()(const sys_time&lt;Duration&gt;&amp; t) const;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>local_time&lt;Duration&gt;{t.time_since_epoch()}</code>.
</p>
</blockquote>
<pre>
template &lt;&gt;
struct clock_time_conversion&lt;std::chrono::system_clock, local_t&gt;
{
template &lt;class Duration&gt;
sys_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
operator()(const local_t&lt;Duration&gt;&amp; t) const;
};
template &lt;class Duration&gt;
sys_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
operator()(const local_t&lt;Duration&gt;&amp; t) const;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>sys_time&lt;Duration&gt;{t.time_since_epoch()}</code>.
</p>
</blockquote>
<pre>
// utc_clock &lt;-&gt; local_t
</pre>
<pre>
template &lt;&gt;
struct clock_time_conversion&lt;local_t, utc_clock&gt;
{
template &lt;class Duration&gt;
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
operator()(const utc_time&lt;Duration&gt;&amp; t) const;
};
template &lt;class Duration&gt;
local_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
operator()(const utc_time&lt;Duration&gt;&amp; t) const;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>utc_clock::to_local(t)</code>.
</p>
</blockquote>
<pre>
template &lt;&gt;
struct clock_time_conversion&lt;utc_clock, local_t&gt;
{
template &lt;class Duration&gt;
utc_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
operator()(const local_t&lt;Duration&gt;&amp; t) const;
};
template &lt;class Duration&gt;
utc_time&lt;std::common_type_t&lt;Duration, std::chrono::seconds&gt;&gt;
operator()(const local_t&lt;Duration&gt;&amp; t) const;
</pre>
<blockquote>
<p>
<i>Returns:</i> <code>utc_clock::from_local(t)</code>.
</p>
</blockquote>
<pre>
// Clock &lt;-&gt; system_clock
</pre>
@@ -3477,6 +3691,58 @@ operator()(const utc_time&lt;Duration&gt;&amp; t) const
</p>
</blockquote>
<pre>
// Clock &lt;-&gt; local_t
</pre>
<pre>
template &lt;class SourceClock&gt;
struct clock_time_conversion&lt;local_t, SourceClock&gt;
{
template &lt;class Duration&gt;
auto
operator()(const std::chrono::time_point&lt;SourceClock, Duration&gt;&amp; t) const
-&gt; decltype(SourceClock::to_local(t));
};
template &lt;class Duration&gt;
auto
operator()(const std::chrono::time_point&lt;SourceClock, Duration&gt;&amp; t) const
-&gt; decltype(SourceClock::to_local(t));
</pre>
<blockquote>
<p>
<i>Remarks:</i> This function does not participate in overload resolution unless
<code>SourceClock::to_local(t)</code> is well formed. If
<code>SourceClock::to_local(t)</code> does not return
<code>local_time&lt;<i>some duration</i>&gt;</code> the program is ill-formed.
</p>
<p>
<i>Returns:</i> <code>SourceClock::to_local(t)</code>.
</p>
</blockquote>
<pre>
template &lt;class Duration&gt;
auto
operator()(const local_time&lt;Duration&gt;&amp; t) const
-&gt; decltype(DestClock::from_local(t));
</pre>
<blockquote>
<p>
<i>Remarks:</i> This function does not participate in overload resolution unless
<code>DestClock::from_local(t)</code> is well formed. If
<code>DestClock::from_local(t)</code> does not return
<code>time_point&lt;DestClock, <i>some duration</i>&gt;</code> the program is ill-formed.
<code></code>.
</p>
<p>
<i>Returns:</i> <code>DestClock::from_local(t)</code>.
</p>
</blockquote>
<pre>
// clock_cast
</pre>