Function CmdRemoveSingleSignal

src/rail_cmd.cpp:1458–1511

* Remove signals * @param flags operation to perform * @param tile coordinates where signal is being deleted from * @param track track-orientation * @return the cost of this operation or an error */

 * @return the cost of this operation or an error
 */
CommandCost CmdRemoveSingleSignal(DoCommandFlags flags, TileIndex tile, Track track)
{
	if (!ValParamTrackOrientation(track) || !IsPlainRailTile(tile) || !HasTrack(tile, track)) {
		return CommandCost(STR_ERROR_THERE_IS_NO_RAILROAD_TRACK);
	}
	if (!HasSignalOnTrack(tile, track)) {
		return CommandCost(STR_ERROR_THERE_ARE_NO_SIGNALS);
	}

	/* Only water can remove signals from anyone */
	if (_current_company != OWNER_WATER) {
		CommandCost ret = CheckTileOwnership(tile);
		if (ret.Failed()) return ret;
	}

	/* Do it? */
	if (flags.Test(DoCommandFlag::Execute)) {
		Train *v = nullptr;
		if (HasReservedTracks(tile, TrackToTrackBits(track))) {
			v = GetTrainForReservation(tile, track);
		} else if (IsPbsSignal(GetSignalType(tile, track))) {
			/* PBS signal, might be the end of a path reservation. */
			Trackdir td = TrackToTrackdir(track);
			for (int i = 0; v == nullptr && i < 2; i++, td = ReverseTrackdir(td)) {
				/* Only test the active signal side. */
				if (!HasSignalOnTrackdir(tile, ReverseTrackdir(td))) continue;
				TileIndex next = TileAddByDiagDir(tile, TrackdirToExitdir(td));
				TrackBits tracks = TrackdirBitsToTrackBits(TrackdirReachesTrackdirs(td));
				if (HasReservedTracks(next, tracks)) {
					v = GetTrainForReservation(next, TrackBitsToTrack(GetReservedTrackbits(next) & tracks));
				}
			}
		}
		Company::Get(GetTileOwner(tile))->infrastructure.signal -= CountBits(GetPresentSignals(tile));
		SetPresentSignals(tile, GetPresentSignals(tile) & ~SignalOnTrack(track));
		Company::Get(GetTileOwner(tile))->infrastructure.signal += CountBits(GetPresentSignals(tile));
		DirtyCompanyInfrastructureWindows(GetTileOwner(tile));

		/* removed last signal from tile? */
		if (GetPresentSignals(tile) == 0) {
			SetSignalStates(tile, 0);
			SetHasSignals(tile, false);
			SetSignalVariant(tile, INVALID_TRACK, SIG_ELECTRIC); // remove any possible semaphores
		}

		AddTrackToSignalBuffer(tile, track, GetTileOwner(tile));
		YapfNotifyTrackLayoutChange(tile, track);
		if (v != nullptr) TryPathReserve(v, false);

		MarkTileDirtyByTile(tile);
	}

	return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_CLEAR_SIGNALS]);
}

/**
 * Remove signals on a stretch of track.