Function FollowTrainReservation

src/pbs.cpp:289–322

* Follow a train reservation to the last tile. * * @param v the vehicle * @param train_on_res Is set to a train we might encounter * @returns The last tile of the reservation or the current train tile if no reservation present. */

 * @returns The last tile of the reservation or the current train tile if no reservation present.
 */
PBSTileInfo FollowTrainReservation(const Train *v, Vehicle **train_on_res)
{
	assert(v->type == VEH_TRAIN);

	TileIndex tile = v->tile;
	Trackdir  trackdir = v->GetVehicleTrackdir();

	if (IsRailDepotTile(tile) && !GetDepotReservationTrackBits(tile)) return PBSTileInfo(tile, trackdir, false);

	FindTrainOnTrackInfo ftoti;
	ftoti.res = FollowReservation(v->owner, GetAllCompatibleRailTypes(v->railtypes), tile, trackdir);
	ftoti.res.okay = IsSafeWaitingPosition(v, ftoti.res.tile, ftoti.res.trackdir, true, _settings_game.pf.forbid_90_deg);
	if (train_on_res != nullptr) {
		CheckTrainsOnTrack(ftoti, ftoti.res.tile);
		if (ftoti.best != nullptr) *train_on_res = ftoti.best->First();
		if (*train_on_res == nullptr && IsRailStationTile(ftoti.res.tile)) {
			/* The target tile is a rail station. The track follower
			 * has stopped on the last platform tile where we haven't
			 * found a train. Also check all previous platform tiles
			 * for a possible train. */
			TileIndexDiff diff = TileOffsByDiagDir(TrackdirToExitdir(ReverseTrackdir(ftoti.res.trackdir)));
			for (TileIndex st_tile = ftoti.res.tile + diff; *train_on_res == nullptr && IsCompatibleTrainStationTile(st_tile, ftoti.res.tile); st_tile += diff) {
				CheckTrainsOnTrack(ftoti, st_tile);
				if (ftoti.best != nullptr) *train_on_res = ftoti.best->First();
			}
		}
		if (*train_on_res == nullptr && IsTileType(ftoti.res.tile, MP_TUNNELBRIDGE)) {
			/* The target tile is a bridge/tunnel, also check the other end tile. */
			CheckTrainsOnTrack(ftoti, GetOtherTunnelBridgeEnd(ftoti.res.tile));
			if (ftoti.best != nullptr) *train_on_res = ftoti.best->First();
		}
	}
	return ftoti.res;
}

/**
 * Find the train which has reserved a specific path.