card_game/src/lib.rs

@@ -719,16 +719,38 @@ where
 	where
 		S: serde::Serializer,
 	{
-		if let Some(state) = self.history.first() {
-			state.serialize(serializer)?;
+		struct History<'a, G: Game>(&'a [StateSnapshot<G>]);
+		impl<G: Game> serde::Serialize for History<'_, G>
+		where
+			G: serde::Serialize,
+			G::Instruction: serde::Serialize,
+		{
+			fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+			where
+				S: serde::Serializer,
+			{
+				let &History(history) = self;
+				use serde::ser::SerializeSeq;
+				let mut seq = serializer.serialize_seq(Some(history.len()))?;
+				for snapshot in history {
+					seq.serialize_element(&snapshot.instruction)?;
+				}
+				seq.end()
+			}
+		}
+
+		use serde::ser::SerializeMap;
+		let mut map = serializer.serialize_map(Some(2))?;
+		// serialize the initial state of the game.
+		// if there is history, it is the first snapshot's state,
+		// otherwise it is the current game state since there are no moves.
+		let state = if let Some(snapshot) = self.history.first() {
+			snapshot.state()
 		} else {
-			self.state.serialize(serializer)?;
-		}
-		use serde::ser::SerializeSeq;
-		let mut seq = serializer.serialize_seq(Some(self.history.len()))?;
-		for snapshot in &self.history {
-			seq.serialize_element(&snapshot.instruction)?;
-		}
-		seq.end()
+			&self.state
+		};
+		map.serialize_entry("state", state)?;
+		map.serialize_entry("history", &History(&self.history))?;
+		map.end()
 	}
 }