UUIDv7: ctor accepts MonoTime as recommentded by IETF

Author: denizzzka

std/uuid.d

@@ -120,7 +120,7 @@ module std.uuid;
     assert(id.empty);
 }
 
-import core.time : dur;
+import core.time : dur, MonoTimeImpl;
 import std.datetime.systime : SysTime;
 import std.datetime : Clock, DateTime, UTC;
 import std.range.primitives;
@@ -323,21 +323,37 @@ public struct UUID
          *   random = UUID V7 has 74 bits of random data, which rounds to 10 ubyte's.
          *    If no random data is given, random data is generated.
          */
+        @safe pure this(TMonoTime)(TMonoTime timestamp, ubyte[10] random = generateV7RandomData())
+        if(isInstanceOf!(MonoTimeImpl, TMonoTime))
+        {
+            import std.datetime;
+
+            TMonoTime epochStart = TMonoTime.zero + unixTimeToStdTime(0).seconds;
+            ulong epoch = (timestamp - epochStart).total!"msecs";
+            this(epoch, random);
+        }
+
+        /// ditto
         @safe pure this(SysTime timestamp, ubyte[10] random = generateV7RandomData())
         {
             ulong epoch = (timestamp - SysTime.fromUnixTime(0)).total!"msecs";
-            this.data[6 .. $] = random[];
+            this(epoch, random);
+        }
 
-            this.data[0] = cast(ubyte)((epoch >> 40) & 0xFF);
-            this.data[1] = cast(ubyte)((epoch >> 32) & 0xFF);
-            this.data[2] = cast(ubyte)((epoch >> 24) & 0xFF);
-            this.data[3] = cast(ubyte)((epoch >> 16) & 0xFF);
-            this.data[4] = cast(ubyte)((epoch >> 8) & 0xFF);
-            this.data[5] = cast(ubyte)(epoch & 0xFF);
+        ///
+        @system unittest
+        {
+            import core.time : Duration;
+            import std.datetime;
 
-            // version and variant
-            this.data[6] = (this.data[6] & 0x0F) | 0x70;
-            this.data[8] = (this.data[8] & 0x3F) | 0x80;
+            MonoTime mt = MonoTime.currTime;
+            MonoTime mt_epoch_start = MonoTime.zero + unixTimeToStdTime(0).seconds;
+            Duration mt_dur = mt - mt_epoch_start;
+
+            UUID u = UUID(mt);
+            Duration u_dur = u.v7Milliseconds().msecs;
+
+            assert(u_dur == mt_dur, mt.toString() ~ " | " ~ u.toString());
         }
 
         ///
@@ -350,6 +366,22 @@ public struct UUID
             assert(o == st, st.toString() ~ " | " ~ o.toString());
         }
 
+        private @safe pure this(long epoch, ubyte[10] random)
+        {
+            this.data[6 .. $] = random[];
+
+            this.data[0] = cast(ubyte)((epoch >> 40) & 0xFF);
+            this.data[1] = cast(ubyte)((epoch >> 32) & 0xFF);
+            this.data[2] = cast(ubyte)((epoch >> 24) & 0xFF);
+            this.data[3] = cast(ubyte)((epoch >> 16) & 0xFF);
+            this.data[4] = cast(ubyte)((epoch >> 8) & 0xFF);
+            this.data[5] = cast(ubyte)(epoch & 0xFF);
+
+            // version and variant
+            this.data[6] = (this.data[6] & 0x0F) | 0x70;
+            this.data[8] = (this.data[8] & 0x3F) | 0x80;
+        }
+
         /**
          * <a name="UUID(string)"></a>
          * Parse a UUID from its canonical string form. An UUID in its
@@ -561,18 +593,23 @@ public struct UUID
          * returns, otherwise and UUIDParsingException is thrown.
          */
         SysTime v7Timestamp() const {
+            return SysTime(DateTime(1970, 1, 1), UTC()) + dur!"msecs"(v7Milliseconds());
+        }
+
+        /// ditto
+        ulong v7Milliseconds() const {
             if (this.uuidVersion != Version.timestampRandom)
             {
                 throw new UUIDParsingException("The UUID is not of version" ~
                     " v7 therefore no timestamp exist", 0);
             }
-            ulong milli = (cast(ulong)(this.data[0]) << 40) |
+
+            return (cast(ulong)(this.data[0]) << 40) |
                    (cast(ulong)(this.data[1]) << 32) |
                    (cast(ulong)(this.data[2]) << 24) |
                    (cast(ulong)(this.data[3]) << 16) |
                    (cast(ulong)(this.data[4]) << 8)  |
                    (cast(ulong)(this.data[5]));
-            return SysTime(DateTime(1970, 1, 1), UTC()) + dur!"msecs"(milli);
         }
 
         /**
@@ -1384,7 +1421,8 @@ if (isInputRange!RNG && isIntegral!(ElementType!RNG))
  */
 UUID timestampRandomUUID()
 {
-    return UUID(Clock.currTime());
+    import core.time : MonoTime;
+    return UUID(MonoTime.currTime);
 }
 
 ///