Method ClearDriveThrough

src/roadstop.cpp:122–197

* Prepare for removal of this stop; update other neighbouring stops * if needed. Also update the length etc. */

 * if needed. Also update the length etc.
 */
void RoadStop::ClearDriveThrough()
{
	assert(this->entries != nullptr);

	RoadStopType rst = GetRoadStopType(this->xy);
	Axis axis = GetDriveThroughStopAxis(this->xy);
	TileIndexDiff offset = TileOffsByAxis(axis);

	/* Information about the tile north of us */
	TileIndex north_tile = this->xy - offset;
	bool north = IsDriveThroughRoadStopContinuation(this->xy, north_tile);
	RoadStop *rs_north = north ? RoadStop::GetByTile(north_tile, rst) : nullptr;

	/* Information about the tile south of us */
	TileIndex south_tile = this->xy + offset;
	bool south = IsDriveThroughRoadStopContinuation(this->xy, south_tile);
	RoadStop *rs_south = south ? RoadStop::GetByTile(south_tile, rst) : nullptr;

	/* Must only be cleared after we determined which neighbours are
	 * part of our little entry 'queue' */
	DoClearSquare(this->xy);

	if (north) {
		/* There is a tile to the north, so we can't clear ourselves. */
		if (south) {
			/* There are more southern tiles too, they must be split;
			 * first make the new southern 'base' */
			rs_south->status.Set(RoadStopStatusFlag::BaseEntry);
			rs_south->entries = new Entries();

			/* Keep track of the base because we need it later on */
			RoadStop *rs_south_base = rs_south;
			TileIndex base_tile = south_tile;

			/* Make all (even more) southern stops part of the new entry queue */
			for (south_tile += offset; IsDriveThroughRoadStopContinuation(base_tile, south_tile); south_tile += offset) {
				rs_south = RoadStop::GetByTile(south_tile, rst);
				rs_south->entries = rs_south_base->entries;
			}

			/* Find the other end; the northern most tile */
			for (; IsDriveThroughRoadStopContinuation(base_tile, north_tile); north_tile -= offset) {
				rs_north = RoadStop::GetByTile(north_tile, rst);
			}

			/* We have to rebuild the entries because we cannot easily determine
			 * how full each part is. So instead of keeping and maintaining a list
			 * of vehicles and using that to 'rebuild' the occupied state we just
			 * rebuild it from scratch as that removes lots of maintenance code
			 * for the vehicle list and it's faster in real games as long as you
			 * do not keep split and merge road stop every tick by the millions. */
			rs_south_base->entries->east.Rebuild(rs_south_base);
			rs_south_base->entries->west.Rebuild(rs_south_base);

			assert(rs_north->status.Test(RoadStopStatusFlag::BaseEntry));
			rs_north->entries->east.Rebuild(rs_north);
			rs_north->entries->west.Rebuild(rs_north);
		} else {