Function GetBestFittingSubType

src/vehicle_gui.cpp:600–661

* Get the best fitting subtype when 'cloning'/'replacing' \a v_from with \a v_for. * All articulated parts of both vehicles are tested to find a possibly shared subtype. * For \a v_for only vehicle refittable to \a dest_cargo_type are considered. * @param v_from the vehicle to match the subtype from * @param v_for the vehicle to get the subtype for * @param dest_cargo_type Destination cargo

 * @return the best sub type
 */
uint8_t GetBestFittingSubType(Vehicle *v_from, Vehicle *v_for, CargoType dest_cargo_type)
{
	v_from = v_from->GetFirstEnginePart();
	v_for = v_for->GetFirstEnginePart();

	/* Create a list of subtypes used by the various parts of v_for */
	static std::vector<StringID> subtypes;
	subtypes.clear();
	for (; v_from != nullptr; v_from = v_from->HasArticulatedPart() ? v_from->GetNextArticulatedPart() : nullptr) {
		const Engine *e_from = v_from->GetEngine();
		if (!e_from->CanCarryCargo() || !e_from->info.callback_mask.Test(VehicleCallbackMask::CargoSuffix)) continue;
		include(subtypes, GetCargoSubtypeText(v_from));
	}

	uint8_t ret_refit_cyc = 0;
	bool success = false;
	if (!subtypes.empty()) {
		/* Check whether any articulated part is refittable to 'dest_cargo_type' with a subtype listed in 'subtypes' */
		for (Vehicle *v = v_for; v != nullptr; v = v->HasArticulatedPart() ? v->GetNextArticulatedPart() : nullptr) {
			const Engine *e = v->GetEngine();
			if (!e->CanCarryCargo() || !e->info.callback_mask.Test(VehicleCallbackMask::CargoSuffix)) continue;
			if (!HasBit(e->info.refit_mask, dest_cargo_type) && v->cargo_type != dest_cargo_type) continue;

			CargoType old_cargo_type = v->cargo_type;
			uint8_t old_cargo_subtype = v->cargo_subtype;

			/* Set the 'destination' cargo */
			v->cargo_type = dest_cargo_type;

			/* Cycle through the refits */
			for (uint refit_cyc = 0; refit_cyc < MAX_REFIT_CYCLE; refit_cyc++) {
				v->cargo_subtype = refit_cyc;

				/* Make sure we don't pick up anything cached. */
				v->First()->InvalidateNewGRFCache();
				v->InvalidateNewGRFCache();

				StringID subtype = GetCargoSubtypeText(v);
				if (subtype == STR_EMPTY) break;

				if (std::ranges::find(subtypes, subtype) == subtypes.end()) continue;

				/* We found something matching. */
				ret_refit_cyc = refit_cyc;
				success = true;
				break;
			}

			/* Reset the vehicle's cargo type */
			v->cargo_type    = old_cargo_type;
			v->cargo_subtype = old_cargo_subtype;

			/* Make sure we don't taint the vehicle. */
			v->First()->InvalidateNewGRFCache();
			v->InvalidateNewGRFCache();

			if (success) break;
		}