Method GenerateBuildTrainList

src/build_vehicle_gui.cpp:1379–1447

Figure out what train EngineIDs to put in the list */

	/* Figure out what train EngineIDs to put in the list */
	void GenerateBuildTrainList(GUIEngineList &list)
	{
		FlatSet<EngineID> variants;
		EngineID sel_id = EngineID::Invalid();
		size_t num_engines = 0;

		list.clear();

		BadgeTextFilter btf(this->string_filter, GSF_TRAINS);
		BadgeDropdownFilter bdf(this->badge_filter_choices);

		/* Make list of all available train engines and wagons.
		 * Also check to see if the previously selected engine is still available,
		 * and if not, reset selection to EngineID::Invalid(). This could be the case
		 * when engines become obsolete and are removed */
		for (const Engine *e : Engine::IterateType(VEH_TRAIN)) {
			if (!this->show_hidden_engines && e->IsVariantHidden(_local_company)) continue;
			EngineID eid = e->index;
			const RailVehicleInfo *rvi = &e->VehInfo<RailVehicleInfo>();

			if (this->filter.railtype != INVALID_RAILTYPE && !HasPowerOnRail(rvi->railtypes, this->filter.railtype)) continue;
			if (!IsEngineBuildable(eid, VEH_TRAIN, _local_company)) continue;

			/* Filter now! So num_engines and num_wagons is valid */
			if (!FilterSingleEngine(eid)) continue;

			if (!bdf.Filter(e->badges)) continue;

			/* Filter by name or NewGRF extra text */
			if (!FilterByText(e) && !btf.Filter(e->badges)) continue;

			list.emplace_back(eid, e->info.variant_id, e->display_flags, 0);

			if (rvi->railveh_type != RAILVEH_WAGON) num_engines++;

			/* Add all parent variants of this engine to the variant list */
			EngineID parent = e->info.variant_id;
			while (parent != EngineID::Invalid() && variants.insert(parent).second) {
				parent = Engine::Get(parent)->info.variant_id;
			}

			if (eid == this->sel_engine) sel_id = eid;
		}

		/* ensure primary engine of variant group is in list */
		for (const auto &variant : variants) {
			if (std::ranges::find(list, variant, &GUIEngineListItem::engine_id) == list.end()) {
				const Engine *e = Engine::Get(variant);
				list.emplace_back(variant, e->info.variant_id, e->display_flags | EngineDisplayFlag::Shaded, 0);
				if (e->VehInfo<RailVehicleInfo>().railveh_type != RAILVEH_WAGON) num_engines++;
			}
		}

		this->SelectEngine(sel_id);

		/* invalidate cached values for name sorter - engine names could change */
		_last_engine[0] = _last_engine[1] = EngineID::Invalid();