Change: Expose NewGRF classes and specs as spans and simplify iteration.

This replaces some index-based loops with range loops.

src/airport_gui.cpp

@@ -241,8 +241,8 @@ class BuildAirportWindow : public PickerWindowBase {
 	{
 		DropDownList list;
 
-		for (uint i = 0; i < AirportClass::GetClassCount(); i++) {
-			list.push_back(MakeDropDownListStringItem(AirportClass::Get((AirportClassID)i)->name, i));
+		for (const auto &cls : AirportClass::Classes()) {
+			list.push_back(MakeDropDownListStringItem(cls.name, cls.Index()));
 		}
 
 		return list;
@@ -322,8 +322,8 @@ public:
 		switch (widget) {
 			case WID_AP_CLASS_DROPDOWN: {
 				Dimension d = {0, 0};
-				for (uint i = 0; i < AirportClass::GetClassCount(); i++) {
-					d = maxdim(d, GetStringBoundingBox(AirportClass::Get((AirportClassID)i)->name));
+				for (const auto &cls : AirportClass::Classes()) {
+					d = maxdim(d, GetStringBoundingBox(cls.name));
 				}
 				d.width += padding.width;
 				d.height += padding.height;
@@ -546,14 +546,12 @@ public:
 		if (change_class) {
 			/* If that fails, select the first available airport
 			 * from the first class where airports are available. */
-			for (AirportClassID j = APC_BEGIN; j < AirportClass::GetClassCount(); j++) {
-				AirportClass *apclass = AirportClass::Get(j);
-				for (uint i = 0; i < apclass->GetSpecCount(); i++) {
-					const AirportSpec *as = apclass->GetSpec(i);
+			for (const auto &cls : AirportClass::Classes()) {
+				for (const auto &as : cls.Specs()) {
 					if (as->IsAvailable()) {
-						_selected_airport_class = j;
-						this->vscroll->SetCount(apclass->GetSpecCount());
-						this->SelectOtherAirport(i);
+						_selected_airport_class = cls.Index();
+						this->vscroll->SetCount(cls.GetSpecCount());
+						this->SelectOtherAirport(as->GetIndex());
 						return;
 					}
 				}

src/newgrf_class.h

@@ -38,6 +38,18 @@ public:
 	/* Public constructor as emplace_back needs access. */
 	NewGRFClass(uint32_t global_id, StringID name) : global_id(global_id), name(name) { }
 
+	/**
+	 * Get read-only span of specs of this class.
+	 * @return Read-only span of specs.
+	 */
+	std::span<Tspec * const> Specs() const { return this->spec; }
+
+	/**
+	 * Get read-only span of all classes of this type.
+	 * @return Read-only span of classes.
+	 */
+	static std::span<NewGRFClass<Tspec, Tid, Tmax> const> Classes() { return NewGRFClass::classes; }
+
 	void Insert(Tspec *spec);
 
 	Tid Index() const { return static_cast<Tid>(std::distance(&*std::cbegin(NewGRFClass::classes), this)); }

src/newgrf_roadstop.cpp

@@ -465,13 +465,12 @@ void TriggerRoadStopRandomisation(Station *st, TileIndex tile, RoadStopRandomTri
  */
 bool GetIfNewStopsByType(RoadStopType rs, RoadType roadtype)
 {
-	for (uint i = 0; i < RoadStopClass::GetClassCount(); i++) {
+	for (const auto &cls : RoadStopClass::Classes()) {
 		/* Ignore the waypoint class. */
-		if (i == ROADSTOP_CLASS_WAYP) continue;
-		const RoadStopClass *roadstopclass = RoadStopClass::Get((RoadStopClassID)i);
+		if (cls.Index() == ROADSTOP_CLASS_WAYP) continue;
 		/* Ignore the default class with only the default station. */
-		if (i == ROADSTOP_CLASS_DFLT && roadstopclass->GetSpecCount() == 1) continue;
-		if (GetIfClassHasNewStopsByType(roadstopclass, rs, roadtype)) return true;
+		if (cls.Index() == ROADSTOP_CLASS_DFLT && cls.GetSpecCount() == 1) continue;
+		if (GetIfClassHasNewStopsByType(&cls, rs, roadtype)) return true;
 	}
 	return false;
 }
@@ -485,8 +484,8 @@ bool GetIfNewStopsByType(RoadStopType rs, RoadType roadtype)
  */
 bool GetIfClassHasNewStopsByType(const RoadStopClass *roadstopclass, RoadStopType rs, RoadType roadtype)
 {
-	for (uint j = 0; j < roadstopclass->GetSpecCount(); j++) {
-		if (GetIfStopIsForType(roadstopclass->GetSpec(j), rs, roadtype)) return true;
+	for (const auto spec : roadstopclass->Specs()) {
+		if (GetIfStopIsForType(spec, rs, roadtype)) return true;
 	}
 	return false;
 }

src/object_gui.cpp

@@ -145,10 +145,9 @@ public:
 
 		this->object_classes.clear();
 
-		for (uint i = 0; i < ObjectClass::GetClassCount(); i++) {
-			ObjectClass *objclass = ObjectClass::Get((ObjectClassID)i);
-			if (objclass->GetUISpecCount() == 0) continue; // Is this needed here?
-			object_classes.push_back((ObjectClassID)i);
+		for (const auto &cls : ObjectClass::Classes()) {
+			if (cls.GetUISpecCount() == 0) continue; // Is this needed here?
+			object_classes.push_back(cls.Index());
 		}
 
 		this->object_classes.Filter(this->string_filter);

src/rail_gui.cpp

@@ -1109,15 +1109,11 @@ public:
 
 		this->station_classes.clear();
 
-		for (uint i = 0; i < StationClass::GetClassCount(); i++) {
-			StationClassID station_class_id = (StationClassID)i;
-			if (station_class_id == StationClassID::STAT_CLASS_WAYP) {
-				// Skip waypoints.
-				continue;
-			}
-			StationClass *station_class = StationClass::Get(station_class_id);
-			if (station_class->GetUISpecCount() == 0) continue;
-			station_classes.push_back(station_class_id);
+		for (const auto &cls : StationClass::Classes()) {
+			/* Skip waypoints. */
+			if (cls.Index() == STAT_CLASS_WAYP) continue;
+			if (cls.GetUISpecCount() == 0) continue;
+			station_classes.push_back(cls.Index());
 		}
 
 		if (_railstation.newstations) {

src/road_gui.cpp

@@ -1201,7 +1201,7 @@ public:
 		this->FinishInitNested(TRANSPORT_ROAD);
 
 		this->window_class = (rs == ROADSTOP_BUS) ? WC_BUS_STATION : WC_TRUCK_STATION;
-		if (!newstops || _roadstop_gui_settings.roadstop_class >= (int)RoadStopClass::GetClassCount()) {
+		if (!newstops || _roadstop_gui_settings.roadstop_class >= RoadStopClass::GetClassCount()) {
 			/* There's no new stops available or the list has reduced in size.
 			 * Now, set the default road stops as selected. */
 			_roadstop_gui_settings.roadstop_class = ROADSTOP_CLASS_DFLT;
@@ -1264,14 +1264,10 @@ public:
 
 		this->roadstop_classes.clear();
 
-		for (uint i = 0; i < RoadStopClass::GetClassCount(); i++) {
-			RoadStopClassID rs_id = (RoadStopClassID)i;
-			if (rs_id == ROADSTOP_CLASS_WAYP) {
-				// Skip waypoints.
-				continue;
-			}
-			RoadStopClass *rs_class = RoadStopClass::Get(rs_id);
-			if (GetIfClassHasNewStopsByType(rs_class, this->roadStopType, _cur_roadtype)) this->roadstop_classes.push_back(rs_id);
+		for (const auto &cls : RoadStopClass::Classes()) {
+			/* Skip waypoints. */
+			if (cls.Index() == ROADSTOP_CLASS_WAYP) continue;
+			if (GetIfClassHasNewStopsByType(&cls, this->roadStopType, _cur_roadtype)) this->roadstop_classes.push_back(cls.Index());
 		}
 
 		if (this->ShowNewStops()) {