# HG changeset patch
# User alberth <alberth@openttd.org>
# Date 2010-03-07 20:44:05
# Node ID 6075f6397e6ffe1903e5777f62f2bbf3444123b4
# Parent  811d443d9452131fb6c0a99a27646568fb04278b

(svn r19372) -Codechange: CheckTileOwnership() returns a CommandCost.

diff --git a/src/company_cmd.cpp b/src/company_cmd.cpp
--- a/src/company_cmd.cpp
+++ b/src/company_cmd.cpp
@@ -266,20 +266,19 @@ bool CheckOwnership(Owner owner, TileInd
  * the given tile.  If that isn't the case an
  * appropriate error will be given.
  * @param tile the tile to check.
- * @return true iff it's owned by the current company.
+ * @return A succeeded command iff it's owned by the current company, else a failed command.
  */
-bool CheckTileOwnership(TileIndex tile)
+CommandCost CheckTileOwnership(TileIndex tile)
 {
 	Owner owner = GetTileOwner(tile);
 
 	assert(owner < OWNER_END);
 
-	if (owner == _current_company) return true;
-	_error_message = STR_ERROR_OWNED_BY;
+	if (owner == _current_company) return CommandCost();
 
 	/* no need to get the name of the owner unless we're the local company (saves some time) */
 	if (IsLocalCompany()) GetNameOfOwner(owner, tile);
-	return false;
+	return_cmd_error(STR_ERROR_OWNED_BY);
 }
 
 static void GenerateCompanyName(Company *c)
diff --git a/src/functions.h b/src/functions.h
--- a/src/functions.h
+++ b/src/functions.h
@@ -25,7 +25,7 @@ bool CheckCompanyHasMoney(CommandCost &c
 void SubtractMoneyFromCompany(CommandCost cost);
 void SubtractMoneyFromCompanyFract(CompanyID company, CommandCost cost);
 bool CheckOwnership(Owner owner, TileIndex tile = 0);
-bool CheckTileOwnership(TileIndex tile);
+CommandCost CheckTileOwnership(TileIndex tile);
 
 /* misc functions */
 /**
diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -366,13 +366,15 @@ CommandCost CmdBuildSingleRail(TileIndex
 
 	switch (GetTileType(tile)) {
 		case MP_RAILWAY: {
-			if (!CheckTileOwnership(tile)) return CMD_ERROR;
+			CommandCost ret = CheckTileOwnership(tile);
+			ret.SetGlobalErrorMessage();
+			if (ret.Failed()) return ret;
 
 			if (!IsPlainRail(tile)) return CMD_ERROR;
 
 			if (!IsCompatibleRail(GetRailType(tile), railtype)) return_cmd_error(STR_ERROR_IMPOSSIBLE_TRACK_COMBINATION);
 
-			CommandCost ret = CheckTrackCombination(tile, trackbit, flags);
+			ret = CheckTrackCombination(tile, trackbit, flags);
 			if (ret.Succeeded()) ret = EnsureNoTrainOnTrack(tile, track);
 			ret.SetGlobalErrorMessage();
 			if (ret.Failed()) return ret;
@@ -514,11 +516,14 @@ CommandCost CmdRemoveSingleRail(TileInde
 
 	switch (GetTileType(tile)) {
 		case MP_ROAD: {
-			if (!IsLevelCrossing(tile) ||
-					GetCrossingRailBits(tile) != trackbit ||
-					(_current_company != OWNER_WATER && !CheckTileOwnership(tile))) {
-				return CMD_ERROR;
+			if (!IsLevelCrossing(tile) || GetCrossingRailBits(tile) != trackbit) return CMD_ERROR;
+
+			if (_current_company != OWNER_WATER) {
+				CommandCost ret = CheckTileOwnership(tile);
+				ret.SetGlobalErrorMessage();
+				if (ret.Failed()) return ret;
 			}
+
 			if (!(flags & DC_BANKRUPT)) {
 				CommandCost ret = EnsureNoVehicleOnGround(tile);
 				ret.SetGlobalErrorMessage();
@@ -539,7 +544,13 @@ CommandCost CmdRemoveSingleRail(TileInde
 		case MP_RAILWAY: {
 			TrackBits present;
 
-			if (!IsPlainRail(tile) || (_current_company != OWNER_WATER && !CheckTileOwnership(tile))) return CMD_ERROR;
+			if (!IsPlainRail(tile)) return CMD_ERROR;
+
+			if (_current_company != OWNER_WATER) {
+				CommandCost ret = CheckTileOwnership(tile);
+				ret.SetGlobalErrorMessage();
+				if (ret.Failed()) return ret;
+			}
 
 			CommandCost ret = EnsureNoTrainOnTrack(tile, track);
 			ret.SetGlobalErrorMessage();
@@ -906,7 +917,9 @@ CommandCost CmdBuildSingleSignal(TileInd
 	/* Protect against invalid signal copying */
 	if (p2 != 0 && (p2 & SignalOnTrack(track)) == 0) return CMD_ERROR;
 
-	if (!CheckTileOwnership(tile)) return CMD_ERROR;
+	ret = CheckTileOwnership(tile);
+	ret.SetGlobalErrorMessage();
+	if (ret.Failed()) return ret;
 
 	{
 		/* See if this is a valid track combination for signals, (ie, no overlap) */
@@ -1265,7 +1278,11 @@ CommandCost CmdRemoveSingleSignal(TileIn
 	if (ret.Failed()) return ret;
 
 	/* Only water can remove signals from anyone */
-	if (_current_company != OWNER_WATER && !CheckTileOwnership(tile)) return CMD_ERROR;
+	if (_current_company != OWNER_WATER) {
+		CommandCost ret = CheckTileOwnership(tile);
+		ret.SetGlobalErrorMessage();
+		if (ret.Failed()) return ret;
+	}
 
 	/* Do it? */
 	if (flags & DC_EXEC) {
@@ -1398,7 +1415,11 @@ CommandCost CmdConvertRail(TileIndex til
 			if (type == totype || (_settings_game.vehicle.disable_elrails && totype == RAILTYPE_RAIL && type == RAILTYPE_ELECTRIC)) continue;
 
 			/* Trying to convert other's rail */
-			if (!CheckTileOwnership(tile)) continue;
+			CommandCost ret = CheckTileOwnership(tile);
+			if (ret.Failed()) {
+				ret.SetGlobalErrorMessage();
+				continue;
+			}
 
 			SmallVector<Train *, 2> vehicles_affected;
 
@@ -1527,8 +1548,11 @@ CommandCost CmdConvertRail(TileIndex til
 
 static CommandCost RemoveTrainDepot(TileIndex tile, DoCommandFlag flags)
 {
-	if (!CheckTileOwnership(tile) && _current_company != OWNER_WATER)
-		return CMD_ERROR;
+	if (_current_company != OWNER_WATER) {
+		CommandCost ret = CheckTileOwnership(tile);
+		ret.SetGlobalErrorMessage();
+		if (ret.Failed()) return ret;
+	}
 
 	CommandCost ret = EnsureNoVehicleOnGround(tile);
 	ret.SetGlobalErrorMessage();
diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -911,7 +911,11 @@ CommandCost CmdBuildRoadDepot(TileIndex 
 
 static CommandCost RemoveRoadDepot(TileIndex tile, DoCommandFlag flags)
 {
-	if (!CheckTileOwnership(tile) && _current_company != OWNER_WATER) return CMD_ERROR;
+	if (_current_company != OWNER_WATER) {
+		CommandCost ret = CheckTileOwnership(tile);
+		ret.SetGlobalErrorMessage();
+		if (ret.Failed()) return ret;
+	}
 
 	CommandCost ret = EnsureNoVehicleOnGround(tile);
 	ret.SetGlobalErrorMessage();
diff --git a/src/tunnelbridge_cmd.cpp b/src/tunnelbridge_cmd.cpp
--- a/src/tunnelbridge_cmd.cpp
+++ b/src/tunnelbridge_cmd.cpp
@@ -587,7 +587,9 @@ static inline bool CheckAllowRemoveTunne
 			if (HasBit(rts, ROADTYPE_TRAM)) tram_owner = GetRoadOwner(tile, ROADTYPE_TRAM);
 
 			/* We can remove unowned road and if the town allows it */
-			if (road_owner == OWNER_TOWN && !(_settings_game.construction.extra_dynamite || _cheats.magic_bulldozer.value)) return CheckTileOwnership(tile);
+			if (road_owner == OWNER_TOWN && !(_settings_game.construction.extra_dynamite || _cheats.magic_bulldozer.value)) {
+				return CheckTileOwnership(tile).Succeeded();
+			}
 			if (road_owner == OWNER_NONE || road_owner == OWNER_TOWN) road_owner = _current_company;
 			if (tram_owner == OWNER_NONE) tram_owner = _current_company;
 
diff --git a/src/unmovable_cmd.cpp b/src/unmovable_cmd.cpp
--- a/src/unmovable_cmd.cpp
+++ b/src/unmovable_cmd.cpp
@@ -175,7 +175,11 @@ CommandCost CmdPurchaseLandArea(TileInde
 CommandCost CmdSellLandArea(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
 {
 	if (!IsOwnedLandTile(tile)) return CMD_ERROR;
-	if (!CheckTileOwnership(tile) && _current_company != OWNER_WATER) return CMD_ERROR;
+	if (_current_company != OWNER_WATER) {
+		CommandCost ret = CheckTileOwnership(tile);
+		ret.SetGlobalErrorMessage();
+		if (ret.Failed()) return ret;
+	}
 
 	CommandCost ret = EnsureNoVehicleOnGround(tile);
 	ret.SetGlobalErrorMessage();
@@ -500,7 +504,11 @@ static void ChangeTileOwner_Unmovable(Ti
 static CommandCost TerraformTile_Unmovable(TileIndex tile, DoCommandFlag flags, uint z_new, Slope tileh_new)
 {
 	/* Owned land remains unsold */
-	if (IsOwnedLand(tile) && CheckTileOwnership(tile)) return CommandCost();
+	if (IsOwnedLand(tile)) {
+		CommandCost ret = CheckTileOwnership(tile);
+		ret.SetGlobalErrorMessage();
+		if (ret.Succeeded()) return CommandCost();
+	}
 
 	if (AutoslopeEnabled() && (IsStatue(tile) || IsCompanyHQ(tile))) {
 		if (!IsSteepSlope(tileh_new) && (z_new + GetSlopeMaxZ(tileh_new) == GetTileMaxZ(tile))) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -168,7 +168,10 @@ void MakeWaterKeepingClass(TileIndex til
 static CommandCost RemoveShipDepot(TileIndex tile, DoCommandFlag flags)
 {
 	if (!IsShipDepot(tile)) return CMD_ERROR;
-	if (!CheckTileOwnership(tile)) return CMD_ERROR;
+
+	CommandCost ret = CheckTileOwnership(tile);
+	ret.SetGlobalErrorMessage();
+	if (ret.Failed()) return ret;
 
 	TileIndex tile2 = GetOtherShipDepotTile(tile);
 
@@ -244,10 +247,14 @@ static CommandCost RemoveShiplift(TileIn
 {
 	TileIndexDiff delta = TileOffsByDiagDir(GetLockDirection(tile));
 
-	if (!CheckTileOwnership(tile) && GetTileOwner(tile) != OWNER_NONE) return CMD_ERROR;
+	if (GetTileOwner(tile) != OWNER_NONE) {
+		CommandCost ret = CheckTileOwnership(tile);
+		ret.SetGlobalErrorMessage();
+		if (ret.Failed()) return ret;
+	}
 
 	/* make sure no vehicle is on the tile. */
-	CommandCost ret = EnsureNoVehicleOnGround(tile);
+	ret = EnsureNoVehicleOnGround(tile);
 	if (ret.Succeeded()) ret = EnsureNoVehicleOnGround(tile + delta);
 	if (ret.Succeeded()) ret = EnsureNoVehicleOnGround(tile - delta);
 	ret.SetGlobalErrorMessage();
@@ -361,7 +368,11 @@ static CommandCost ClearTile_Water(TileI
 			ret.SetGlobalErrorMessage();
 			if (ret.Failed()) return ret;
 
-			if (GetTileOwner(tile) != OWNER_WATER && GetTileOwner(tile) != OWNER_NONE && !CheckTileOwnership(tile)) return CMD_ERROR;
+			if (GetTileOwner(tile) != OWNER_WATER && GetTileOwner(tile) != OWNER_NONE) {
+				CommandCost ret = CheckTileOwnership(tile);
+				ret.SetGlobalErrorMessage();
+				if (ret.Failed()) return ret;
+			}
 
 			if (flags & DC_EXEC) {
 				DoClearSquare(tile);