Codechange: Use vehicle tile hash to build depot vehicle list. (#12186)

This avoids iterating the entire vehicle pool.

src/vehiclelist.cpp

@@ -9,6 +9,7 @@
 
 #include "stdafx.h"
 #include "train.h"
+#include "vehicle_func.h"
 #include "vehiclelist.h"
 #include "vehiclelist_func.h"
 #include "group.h"
@@ -59,6 +60,39 @@ bool VehicleListIdentifier::UnpackIfValid(uint32_t data)
 	return result;
 }
 
+/** Data for building a depot vehicle list. */
+struct BuildDepotVehicleListData
+{
+	VehicleList *engines; ///< Pointer to list to add vehicles to.
+	VehicleList *wagons; ///< Pointer to list to add wagons to (can be nullptr).
+	VehicleType type; ///< Type of vehicle.
+	bool individual_wagons; ///< If true add every wagon to \a wagons which is not attached to an engine. If false only add the first wagon of every row.
+};
+
+/**
+ * Add vehicles to a depot vehicle list.
+ * @param v The found vehicle.
+ * @param data The depot vehicle list data.
+ * @return Always nullptr.
+ */
+static Vehicle *BuildDepotVehicleListProc(Vehicle *v, void *data)
+{
+	auto bdvld = static_cast<BuildDepotVehicleListData *>(data);
+	if (v->type != bdvld->type || !v->IsInDepot()) return nullptr;
+
+	if (bdvld->type == VEH_TRAIN) {
+		const Train *t = Train::From(v);
+		if (t->IsArticulatedPart() || t->IsRearDualheaded()) return nullptr;
+		if (bdvld->wagons != nullptr && t->First()->IsFreeWagon()) {
+			if (bdvld->individual_wagons || t->IsFreeWagon()) bdvld->wagons->push_back(t);
+			return nullptr;
+		}
+	}
+
+	if (v->IsPrimaryVehicle()) bdvld->engines->push_back(v);
+	return nullptr;
+};
+
 /**
  * Generate a list of vehicles inside a depot.
  * @param type    Type of vehicle
@@ -72,32 +106,8 @@ void BuildDepotVehicleList(VehicleType type, TileIndex tile, VehicleList *engine
 	engines->clear();
 	if (wagons != nullptr && wagons != engines) wagons->clear();
 
-	for (const Vehicle *v : Vehicle::Iterate()) {
-		/* General tests for all vehicle types */
-		if (v->type != type) continue;
-		if (v->tile != tile) continue;
-
-		switch (type) {
-			case VEH_TRAIN: {
-				const Train *t = Train::From(v);
-				if (t->IsArticulatedPart() || t->IsRearDualheaded()) continue;
-				if (!t->IsInDepot()) continue;
-				if (wagons != nullptr && t->First()->IsFreeWagon()) {
-					if (individual_wagons || t->IsFreeWagon()) wagons->push_back(t);
-					continue;
-				}
-				if (!t->IsPrimaryVehicle()) continue;
-				break;
-			}
-
-			default:
-				if (!v->IsPrimaryVehicle()) continue;
-				if (!v->IsInDepot()) continue;
-				break;
-		}
-
-		engines->push_back(v);
-	}
+	BuildDepotVehicleListData bdvld{engines, wagons, type, individual_wagons};
+	FindVehicleOnPos(tile, &bdvld, BuildDepotVehicleListProc);
 
 	/* Ensure the lists are not wasting too much space. If the lists are fresh
 	 * (i.e. built within a command) then this will actually do nothing. */