Codechange: Build station and depot vehicle lists from shared order lists. (#11676)

The brings some performance advantages:

* No need to iterate all vehicles and check for primary vehicle as only vehicles that can have orders are listed.
* Shared orders only need to be tested once instead of for each vehicle sharing them.
* Vehicle tests only need to be performed on the first shared vehicle instead of all.

src/CMakeLists.txt

@@ -510,6 +510,7 @@ add_files(
     vehiclelist.cpp
     vehiclelist.h
     vehiclelist_cmd.h
+    vehiclelist_func.h
     viewport.cpp
     viewport_cmd.h
     viewport_func.h

src/script/api/script_vehiclelist.cpp

@@ -14,6 +14,7 @@
 #include "script_station.hpp"
 #include "../../depot_map.h"
 #include "../../vehicle_base.h"
+#include "../../vehiclelist_func.h"
 #include "../../train.h"
 #include "../../core/backup_type.hpp"
 #include <../squirrel/sqvm.h>
@@ -111,16 +112,12 @@ ScriptVehicleList_Station::ScriptVehicleList_Station(StationID station_id)
 
 	bool is_deity = ScriptCompanyMode::IsDeity();
 	CompanyID owner = ScriptObject::GetCompany();
-	for (const Vehicle *v : Vehicle::Iterate()) {
-		if ((v->owner == owner || is_deity) && v->IsPrimaryVehicle()) {
-			for (const Order *order : v->Orders()) {
-				if ((order->IsType(OT_GOTO_STATION) || order->IsType(OT_GOTO_WAYPOINT)) && order->GetDestination() == station_id) {
-					this->AddItem(v->index);
-					break;
-				}
-			}
-		}
-	}
+
+	FindVehiclesWithOrder(
+		[is_deity, owner](const Vehicle *v) { return is_deity || v->owner == owner; },
+		[station_id](const Order *order) { return (order->IsType(OT_GOTO_STATION) || order->IsType(OT_GOTO_WAYPOINT)) && order->GetDestination() == station_id; },
+		[this](const Vehicle *v) { this->AddItem(v->index); }
+	);
 }
 
 ScriptVehicleList_Depot::ScriptVehicleList_Depot(TileIndex tile)
@@ -162,16 +159,12 @@ ScriptVehicleList_Depot::ScriptVehicleList_Depot(TileIndex tile)
 
 	bool is_deity = ScriptCompanyMode::IsDeity();
 	CompanyID owner = ScriptObject::GetCompany();
-	for (const Vehicle *v : Vehicle::Iterate()) {
-		if ((v->owner == owner || is_deity) && v->IsPrimaryVehicle() && v->type == type) {
-			for (const Order *order : v->Orders()) {
-				if (order->IsType(OT_GOTO_DEPOT) && order->GetDestination() == dest) {
-					this->AddItem(v->index);
-					break;
-				}
-			}
-		}
-	}
+
+	FindVehiclesWithOrder(
+		[is_deity, owner, type](const Vehicle *v) { return (is_deity || v->owner == owner) && v->type == type; },
+		[dest](const Order *order) { return order->IsType(OT_GOTO_DEPOT) && order->GetDestination() == dest; },
+		[this](const Vehicle *v) { this->AddItem(v->index); }
+	);
 }
 
 ScriptVehicleList_SharedOrders::ScriptVehicleList_SharedOrders(VehicleID vehicle_id)

src/vehiclelist.cpp

@@ -10,6 +10,7 @@
 #include "stdafx.h"
 #include "train.h"
 #include "vehiclelist.h"
+#include "vehiclelist_func.h"
 #include "group.h"
 
 #include "safeguards.h"
@@ -116,17 +117,11 @@ bool GenerateVehicleSortList(VehicleList *list, const VehicleListIdentifier &vli
 
 	switch (vli.type) {
 		case VL_STATION_LIST:
-			for (const Vehicle *v : Vehicle::Iterate()) {
-				if (v->type == vli.vtype && v->IsPrimaryVehicle()) {
-					for (const Order *order : v->Orders()) {
-						if ((order->IsType(OT_GOTO_STATION) || order->IsType(OT_GOTO_WAYPOINT) || order->IsType(OT_IMPLICIT))
-								&& order->GetDestination() == vli.index) {
-							list->push_back(v);
-							break;
-						}
-					}
-				}
-			}
+			FindVehiclesWithOrder(
+				[&vli](const Vehicle *v) { return v->type == vli.vtype; },
+				[&vli](const Order *order) { return (order->IsType(OT_GOTO_STATION) || order->IsType(OT_GOTO_WAYPOINT) || order->IsType(OT_IMPLICIT)) && order->GetDestination() == vli.index; },
+				[&list](const Vehicle *v) { list->push_back(v); }
+			);
 			break;
 
 		case VL_SHARED_ORDERS: {
@@ -161,16 +156,11 @@ bool GenerateVehicleSortList(VehicleList *list, const VehicleListIdentifier &vli
 			break;
 
 		case VL_DEPOT_LIST:
-			for (const Vehicle *v : Vehicle::Iterate()) {
-				if (v->type == vli.vtype && v->IsPrimaryVehicle()) {
-					for (const Order *order : v->Orders()) {
-						if (order->IsType(OT_GOTO_DEPOT) && !(order->GetDepotActionType() & ODATFB_NEAREST_DEPOT) && order->GetDestination() == vli.index) {
-							list->push_back(v);
-							break;
-						}
-					}
-				}
-			}
+			FindVehiclesWithOrder(
+				[&vli](const Vehicle *v) { return v->type == vli.vtype; },
+				[&vli](const Order *order) { return order->IsType(OT_GOTO_DEPOT) && !(order->GetDepotActionType() & ODATFB_NEAREST_DEPOT) && order->GetDestination() == vli.index; },
+				[&list](const Vehicle *v) { list->push_back(v); }
+			);
 			break;
 
 		default: return false;

src/vehiclelist_func.h

@@ -0,0 +1,46 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file vehiclelist_func.h Functions and type for generating vehicle lists. */
+
+#ifndef VEHICLELIST_FUNC_H
+#define VEHICLELIST_FUNC_H
+
+#include "order_base.h"
+#include "vehicle_base.h"
+
+/**
+ * Find vehicles matching an order.
+ * This can be used, e.g. to find all vehicles that stop at a particular station.
+ * @param veh_pred Vehicle selection predicate. This is called only for the first vehicle using the order list.
+ * @param ord_pred Order selection predicate.
+ * @param veh_func Called for each vehicle that matches both vehicle and order predicates.
+ **/
+template <class VehiclePredicate, class OrderPredicate, class VehicleFunc>
+void FindVehiclesWithOrder(VehiclePredicate veh_pred, OrderPredicate ord_pred, VehicleFunc veh_func)
+{
+	for (const OrderList *orderlist : OrderList::Iterate()) {
+
+		/* We assume all vehicles sharing an order list match the condition. */
+		const Vehicle *v = orderlist->GetFirstSharedVehicle();
+		if (!veh_pred(v)) continue;
+
+		/* Vehicle is a candidate, search for a matching order. */
+		for (const Order *order = orderlist->GetFirstOrder(); order != nullptr; order = order->next) {
+
+			if (!ord_pred(order)) continue;
+
+			/* An order matches, we can add all shared vehicles to the list. */
+			for (; v != nullptr; v = v->NextShared()) {
+				veh_func(v);
+			}
+			break;
+		}
+	}
+}
+
+#endif /* VEHICLELIST_FUNC_H */