Function IsSafeWaitingPosition

src/pbs.cpp:381–416

* Determine whether a certain track on a tile is a safe position to end a path. * * @param v the vehicle to test for * @param tile The tile * @param trackdir The trackdir to test * @param include_line_end Should end-of-line tiles be considered safe? * @param forbid_90deg Don't allow trains to make 90 degree turns * @return True if it is a safe position */

 * @return True if it is a safe position
 */
bool IsSafeWaitingPosition(const Train *v, TileIndex tile, Trackdir trackdir, bool include_line_end, bool forbid_90deg)
{
	if (IsRailDepotTile(tile)) return true;

	if (IsTileType(tile, MP_RAILWAY)) {
		/* For non-pbs signals, stop on the signal tile. */
		if (HasSignalOnTrackdir(tile, trackdir) && !IsPbsSignal(GetSignalType(tile, TrackdirToTrack(trackdir)))) return true;
	}

	/* Check next tile. For performance reasons, we check for 90 degree turns ourself. */
	CFollowTrackRail ft(v, GetAllCompatibleRailTypes(v->railtypes));

	/* End of track? */
	if (!ft.Follow(tile, trackdir)) {
		/* Last tile of a terminus station is a safe position. */
		if (include_line_end) return true;
	}

	/* Check for reachable tracks. */
	ft.new_td_bits &= DiagdirReachesTrackdirs(ft.exitdir);
	if (Rail90DegTurnDisallowed(GetTileRailType(ft.old_tile), GetTileRailType(ft.new_tile), forbid_90deg)) ft.new_td_bits &= ~TrackdirCrossesTrackdirs(trackdir);
	if (ft.new_td_bits == TRACKDIR_BIT_NONE) return include_line_end;

	if (ft.new_td_bits != TRACKDIR_BIT_NONE && KillFirstBit(ft.new_td_bits) == TRACKDIR_BIT_NONE) {
		Trackdir td = FindFirstTrackdir(ft.new_td_bits);
		/* PBS signal on next trackdir? Safe position. */
		if (HasPbsSignalOnTrackdir(ft.new_tile, td)) return true;
		/* One-way PBS signal against us? Safe if end-of-line is allowed. */
		if (IsTileType(ft.new_tile, MP_RAILWAY) && HasSignalOnTrackdir(ft.new_tile, ReverseTrackdir(td)) &&
				GetSignalType(ft.new_tile, TrackdirToTrack(td)) == SIGTYPE_PBS_ONEWAY) {
			return include_line_end;
		}
	}

	return false;
}

/**
 * Check if a safe position is free.