Codechange: unify creation of diagonal/orthogonal iterator using smart pointers

src/landscape.cpp

@@ -758,7 +758,7 @@ std::tuple<CommandCost, Money> CmdClearArea(DoCommandFlag flags, TileIndex tile,
 	const Company *c = (flags & (DC_AUTO | DC_BANKRUPT)) ? nullptr : Company::GetIfValid(_current_company);
 	int limit = (c == nullptr ? INT32_MAX : GB(c->clear_limit, 16, 16));
 
-	TileIterator *iter = diagonal ? (TileIterator *)new DiagonalTileIterator(tile, start_tile) : new OrthogonalTileIterator(tile, start_tile);
+	std::unique_ptr<TileIterator> iter = TileIterator::Create(tile, start_tile, diagonal);
 	for (; *iter != INVALID_TILE; ++(*iter)) {
 		TileIndex t = *iter;
 		CommandCost ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags & ~DC_EXEC, t);
@@ -774,7 +774,6 @@ std::tuple<CommandCost, Money> CmdClearArea(DoCommandFlag flags, TileIndex tile,
 		if (flags & DC_EXEC) {
 			money -= ret.GetCost();
 			if (ret.GetCost() > 0 && money < 0) {
-				delete iter;
 				return { cost, ret.GetCost() };
 			}
 			Command<CMD_LANDSCAPE_CLEAR>::Do(flags, t);
@@ -794,7 +793,6 @@ std::tuple<CommandCost, Money> CmdClearArea(DoCommandFlag flags, TileIndex tile,
 		cost.AddCost(ret);
 	}
 
-	delete iter;
 	return { had_success ? cost : last_error, 0 };
 }
 

src/object_cmd.cpp

@@ -402,7 +402,7 @@ CommandCost CmdBuildObjectArea(DoCommandFlag flags, TileIndex tile, TileIndex st
 	const Company *c = Company::GetIfValid(_current_company);
 	int limit = (c == nullptr ? INT32_MAX : GB(c->build_object_limit, 16, 16));
 
-	TileIterator *iter = diagonal ? (TileIterator *)new DiagonalTileIterator(tile, start_tile) : new OrthogonalTileIterator(tile, start_tile);
+	std::unique_ptr<TileIterator> iter = TileIterator::Create(tile, start_tile, diagonal);
 	for (; *iter != INVALID_TILE; ++(*iter)) {
 		TileIndex t = *iter;
 		CommandCost ret = Command<CMD_BUILD_OBJECT>::Do(flags & ~DC_EXEC, t, type, view);
@@ -426,7 +426,6 @@ CommandCost CmdBuildObjectArea(DoCommandFlag flags, TileIndex tile, TileIndex st
 		cost.AddCost(ret);
 	}
 
-	delete iter;
 	return had_success ? cost : last_error;
 }
 

src/rail_cmd.cpp

@@ -1548,7 +1548,7 @@ CommandCost CmdConvertRail(DoCommandFlag flags, TileIndex tile, TileIndex area_s
 	CommandCost error = CommandCost(STR_ERROR_NO_SUITABLE_RAILROAD_TRACK); // by default, there is no track to convert.
 	bool found_convertible_track = false; // whether we actually did convert some track (see bug #7633)
 
-	TileIterator *iter = diagonal ? (TileIterator *)new DiagonalTileIterator(area_start, area_end) : new OrthogonalTileIterator(area_start, area_end);
+	std::unique_ptr<TileIterator> iter = TileIterator::Create(area_start, area_end, diagonal);
 	for (; (tile = *iter) != INVALID_TILE; ++(*iter)) {
 		TileType tt = GetTileType(tile);
 
@@ -1745,7 +1745,6 @@ CommandCost CmdConvertRail(DoCommandFlag flags, TileIndex tile, TileIndex area_s
 		}
 	}
 
-	delete iter;
 	return found_convertible_track ? cost : error;
 }
 

src/terraform_cmd.cpp

@@ -361,7 +361,7 @@ std::tuple<CommandCost, Money, TileIndex> CmdLevelLand(DoCommandFlag flags, Tile
 	if (limit == 0) return { CommandCost(STR_ERROR_TERRAFORM_LIMIT_REACHED), 0, INVALID_TILE };
 
 	TileIndex error_tile = INVALID_TILE;
-	TileIterator *iter = diagonal ? (TileIterator *)new DiagonalTileIterator(tile, start_tile) : new OrthogonalTileIterator(tile, start_tile);
+	std::unique_ptr<TileIterator> iter = TileIterator::Create(tile, start_tile, diagonal);
 	for (; *iter != INVALID_TILE; ++(*iter)) {
 		TileIndex t = *iter;
 		uint curh = TileHeight(t);
@@ -379,7 +379,6 @@ std::tuple<CommandCost, Money, TileIndex> CmdLevelLand(DoCommandFlag flags, Tile
 			if (flags & DC_EXEC) {
 				money -= ret.GetCost();
 				if (money < 0) {
-					delete iter;
 					return { cost, ret.GetCost(), error_tile };
 				}
 				Command<CMD_TERRAFORM_LAND>::Do(flags, t, SLOPE_N, curh <= h);
@@ -403,7 +402,6 @@ std::tuple<CommandCost, Money, TileIndex> CmdLevelLand(DoCommandFlag flags, Tile
 		if (limit <= 0) break;
 	}
 
-	delete iter;
 	CommandCost cc_ret = had_success ? cost : last_error;
 	return { cc_ret, 0, cc_ret.Succeeded() ? tile : error_tile };
 }

src/tilearea.cpp

@@ -280,3 +280,18 @@ TileIterator &DiagonalTileIterator::operator++()
 	if (this->b_max == this->b_cur) this->tile = INVALID_TILE;
 	return *this;
 }
+
+/**
+ * Create either an OrthogonalTileIterator or DiagonalTileIterator given the diagonal parameter.
+ * @param corner1 Tile from where to begin iterating.
+ * @param corner2 Tile where to end the iterating.
+ * @param diagonal Whether to create a DiagonalTileIterator or OrthogonalTileIterator.
+ * @return unique_ptr to the allocated TileIterator.
+ */
+/* static */ std::unique_ptr<TileIterator> TileIterator::Create(TileIndex corner1, TileIndex corner2, bool diagonal)
+{
+	if (diagonal) {
+		return std::make_unique<DiagonalTileIterator>(corner1, corner2);
+	}
+	return std::make_unique<OrthogonalTileIterator>(corner1, corner2);
+}

src/tilearea_type.h

@@ -177,6 +177,8 @@ public:
 	{
 		return this->tile != rhs;
 	}
+
+	static std::unique_ptr<TileIterator> Create(TileIndex corner1, TileIndex corner2, bool diagonal);
 };
 
 /** Iterator to iterate over a tile area (rectangle) of the map. */

src/water_cmd.cpp

@@ -445,13 +445,7 @@ CommandCost CmdBuildCanal(DoCommandFlag flags, TileIndex tile, TileIndex start_t
 
 	CommandCost cost(EXPENSES_CONSTRUCTION);
 
-	std::unique_ptr<TileIterator> iter;
-	if (diagonal) {
-		iter = std::make_unique<DiagonalTileIterator>(tile, start_tile);
-	} else {
-		iter = std::make_unique<OrthogonalTileIterator>(tile, start_tile);
-	}
-
+	std::unique_ptr<TileIterator> iter = TileIterator::Create(tile, start_tile, diagonal);
 	for (; *iter != INVALID_TILE; ++(*iter)) {
 		TileIndex current_tile = *iter;
 		CommandCost ret;