(svn r11011) -Fix [FS#1129]: GetFirstVehicleInChain did change the game state while being marked const.

-Codechange: do not brute force determine the first vehicle in the chain or previous vehicle, but do it by properly accounting the previous and first pointers when updating the next pointer. This gives a performance increase of about 15% when there are a lot of vehicles in the game.

1 files changed, 6 insertions, 6 deletions

diff --git a/src/autoreplace_cmd.cpp b/src/autoreplace_cmd.cpp
index 606a60126..08638a903 100644
--- a/src/autoreplace_cmd.cpp
+++ b/src/autoreplace_cmd.cpp
@@ -52,7 +52,7 @@ static void MoveVehicleCargo(Vehicle *dest, Vehicle *source)
 	 * the complete train, which is without the weight of cargo we just
 	 * moved back into some (of the) new wagon(s).
 	 */
-	if (dest->type == VEH_TRAIN) TrainConsistChanged(dest->first);
+	if (dest->type == VEH_TRAIN) TrainConsistChanged(dest->First());
 }
 
 static bool VerifyAutoreplaceRefitForOrders(const Vehicle *v, const EngineID engine_type)
@@ -61,7 +61,7 @@ static bool VerifyAutoreplaceRefitForOrders(const Vehicle *v, const EngineID eng
 	const Vehicle *u;
 
 	if (v->type == VEH_TRAIN) {
-		u = GetFirstVehicleInChain(v);
+		u = v->First();
 	} else {
 		u = v;
 	}
@@ -104,7 +104,7 @@ static CargoID GetNewCargoTypeForReplace(Vehicle *v, EngineID engine_type)
 
 	/* the old engine didn't have cargo capacity, but the new one does
 	 * now we will figure out what cargo the train is carrying and refit to fit this */
-	v = GetFirstVehicleInChain(v);
+	v = v->First();
 	do {
 		if (v->cargo_cap == 0) continue;
 		/* Now we found a cargo type being carried on the train and we will see if it is possible to carry to this one */
@@ -200,9 +200,9 @@ static CommandCost ReplaceVehicle(Vehicle **w, byte flags, Money total_cost)
 			 * sell the old engine in a moment
 			 */
 			/* Get the vehicle in front of the one we move out */
-			Vehicle *front = GetPrevVehicleInChain(old_v);
+			Vehicle *front = old_v->Previous();
 			/* If the vehicle in front is the rear end of a dualheaded engine, then we need to use the one in front of that one */
-			if (IsMultiheaded(front) && !IsTrainEngine(front)) front = GetPrevVehicleInChain(front);
+			if (IsMultiheaded(front) && !IsTrainEngine(front)) front = front->Previous();
 			/* Now we move the old one out of the train */
 			DoCommand(0, (INVALID_VEHICLE << 16) | old_v->index, 0, DC_EXEC, CMD_MOVE_RAIL_VEHICLE);
 			/* Add the new vehicle */
@@ -236,7 +236,7 @@ static CommandCost ReplaceVehicle(Vehicle **w, byte flags, Money total_cost)
 			}
 		}
 		/* We are done setting up the new vehicle. Now we move the cargo from the old one to the new one */
-		MoveVehicleCargo(new_v->type == VEH_TRAIN ? GetFirstVehicleInChain(new_v) : new_v, old_v);
+		MoveVehicleCargo(new_v->type == VEH_TRAIN ? new_v->First() : new_v, old_v);
 
 		// Get the name of the old vehicle if it has a custom name.
 		if (!IsCustomName(old_v->string_id)) {