Function CommitVehicleListOrderChanges

src/newgrf_engine.cpp:1375–1413

* Determine default engine sorting and execute recorded ListOrderChanges from AlterVehicleListOrder. */

 * Determine default engine sorting and execute recorded ListOrderChanges from AlterVehicleListOrder.
 */
void CommitVehicleListOrderChanges()
{
	/* Build a list of EngineIDs. EngineIDs are sequential from 0 up to the number of pool items with no gaps. */
	std::vector<EngineID> ordering(Engine::GetNumItems());
	std::iota(std::begin(ordering), std::end(ordering), EngineID::Begin());

	/* Pre-sort engines by scope-grfid and local index */
	std::ranges::sort(ordering, EnginePreSort);

	/* Apply Insertion-Sort operations */
	for (const ListOrderChange &loc : _list_order_changes) {
		EngineID source = loc.engine;

		Engine *engine_source = Engine::Get(source);
		if (engine_source->grf_prop.local_id == loc.target) continue;

		EngineID target = _engine_mngr.GetID(engine_source->type, loc.target, engine_source->grf_prop.grfid);
		if (target == EngineID::Invalid()) continue;

		auto it_source = std::ranges::find(ordering, source);
		auto it_target = std::ranges::find(ordering, target);

		assert(it_source != std::end(ordering) && it_target != std::end(ordering));
		assert(it_source != it_target);

		/* Move just this item to before the target. */
		Slide(it_source, std::next(it_source), it_target);
	}

	/* Store final sort-order */
	for (uint16_t index = 0; const EngineID &eid : ordering) {
		Engine::Get(eid)->list_position = index;
		++index;
	}

	/* Clear out the queue */
	_list_order_changes.clear();
	_list_order_changes.shrink_to_fit();
}

/**
 * Fill the grf_cache of the given vehicle.