stdlib: Add RFC 3339 functions to module calendar

Functions for converting between RFC 3339 strings and system time
are added.

Options are lists, but we are considering using maps instead. If we
change, it will happen after Erlang/OTP 21.0-rc1 is released.

1 files changed, 70 insertions, 0 deletions

diff --git a/lib/stdlib/doc/src/calendar.xml b/lib/stdlib/doc/src/calendar.xml
index 0c4a30ce16..8f2b6b747a 100644
--- a/lib/stdlib/doc/src/calendar.xml
+++ b/lib/stdlib/doc/src/calendar.xml
@@ -317,6 +317,30 @@
     </func>
 
     <func>
+      <name name="rfc3339_to_system_time" arity="1"/>
+      <name name="rfc3339_to_system_time" arity="2"/>
+      <fsummary>Convert from RFC 3339 timestamp to system time.</fsummary>
+      <type name="rfc3339_string"/>
+      <type name="rfc3339_time_unit"/>
+      <desc>
+	<p>Converts an RFC 3339 timestamp into system time.</p>
+	<p>Valid option:</p>
+	<taglist>
+	  <tag><c>{unit, Unit}</c></tag>
+	  <item><p>The time unit of the return value.
+	    The default is <c>second</c>.</p>
+	  </item>
+	</taglist>
+        <pre>
+1> <input>calendar:rfc3339_to_system_time("2018-02-01T16:17:58+01:00").</input>
+1517498278
+2> <input>calendar:rfc3339_to_system_time("2018-02-01 15:18:02.088Z",
+   [{unit, nanosecond}]).</input>
+1517498282088000000</pre>
+      </desc>
+    </func>
+
+    <func>
       <name name="seconds_to_daystime" arity="1"/>
       <fsummary>Compute days and time from seconds.</fsummary>
       <desc>
@@ -347,6 +371,52 @@
     </func>
 
     <func>
+      <name name="system_time_to_rfc3339" arity="1"/>
+      <name name="system_time_to_rfc3339" arity="2"/>
+      <fsummary>Convert from system to RFC 3339 timestamp.</fsummary>
+      <type name="offset"/>
+      <type name="rfc3339_string"/>
+      <type name="rfc3339_time_unit"/>
+      <desc>
+	<p>Converts a system time into RFC 3339 timestamp.</p>
+	<p>Valid options:</p>
+	<taglist>
+	  <tag><c>{offset, Offset}</c></tag>
+	  <item><p>The offset, either a string or an integer, to be
+	    included in the formatted string.
+	    An empty string, which is the default, is interpreted
+	    as local time. A non-empty string is included as is.
+	    The time unit of the integer is the same as the one
+	    of <c><anno>Time</anno></c>.</p>
+	  </item>
+	  <tag><c>{time_designator, Character}</c></tag>
+	  <item><p>The character used as time designator, that is,
+	    the date and time separator. The default is <c>$T</c>.</p>
+	  </item>
+	  <tag><c>{unit, Unit}</c></tag>
+	  <item><p>The time unit of <c><anno>Time</anno></c>. The
+	    default is <c>second</c>. If some other unit is given
+	    (<c>millisecond</c>, <c>microsecond</c>, or
+	    <c>nanosecond</c>), the formatted string includes a
+	    fraction of a second.</p>
+	  </item>
+	</taglist>
+        <pre>
+1> <input>calendar:system_time_to_rfc3339(erlang:system_time(second)).</input>
+"2018-04-23T14:56:28+02:00"
+2> <input>calendar:system_time_to_rfc3339(erlang:system_time(second),
+   [{offset, "-02:00"}]).</input>
+"2018-04-23T10:56:52-02:00"
+3> <input>calendar:system_time_to_rfc3339(erlang:system_time(second),
+   [{offset, -7200}]).</input>
+"2018-04-23T10:57:05-02:00"
+4> <input>calendar:system_time_to_rfc3339(erlang:system_time(millisecond),
+   [{unit, millisecond}, {time_designator, $\s}, {offset, "Z"}]).</input>
+"2018-04-23 12:57:20.482Z"</pre>
+      </desc>
+    </func>
+
+    <func>
       <name name="system_time_to_universal_time" arity="2"/>
       <fsummary>Convert system time to universal date and time.</fsummary>
       <desc>