Codechange: Add VectorSaveLoadHandler to simplify handlers for vectors. (#13093)

This reduces the duplication needed for each saved complex vector.

src/saveload/company_sl.cpp

@@ -441,7 +441,7 @@ public:
 	void LoadCheck(CompanyProperties *c) const override { this->Load(c); }
 };
 
-class SlAllowListData : public DefaultSaveLoadHandler<SlAllowListData, CompanyProperties> {
+class SlAllowListData : public VectorSaveLoadHandler<SlAllowListData, CompanyProperties, std::string> {
 public:
 	struct KeyWrapper {
 		std::string key;
@@ -452,23 +452,7 @@ public:
 	};
 	inline const static SaveLoadCompatTable compat_description = {};
 
-	void Save(CompanyProperties *cprops) const override
+	std::vector<std::string> &GetVector(CompanyProperties *cprops) const override { return cprops->allow_list; }
-	{
-		SlSetStructListLength(cprops->allow_list.size());
-		for (std::string &str : cprops->allow_list) {
-			SlObject(&str, this->GetDescription());
-		}
-	}
-
-	void Load(CompanyProperties *cprops) const override
-	{
-		size_t num_keys = SlGetStructListLength(UINT32_MAX);
-		cprops->allow_list.clear();
-		cprops->allow_list.resize(num_keys);
-		for (std::string &str : cprops->allow_list) {
-			SlObject(&str, this->GetLoadDescription());
-		}
-	}
 
 	void LoadCheck(CompanyProperties *cprops) const override { this->Load(cprops); }
 };

src/saveload/industry_sl.cpp

@@ -19,7 +19,7 @@
 
 static OldPersistentStorage _old_ind_persistent_storage;
 
-class SlIndustryAccepted : public DefaultSaveLoadHandler<SlIndustryAccepted, Industry> {
+class SlIndustryAccepted : public VectorSaveLoadHandler<SlIndustryAccepted, Industry, Industry::AcceptedCargo, INDUSTRY_NUM_INPUTS> {
 public:
 	inline static const SaveLoad description[] = {
 		 SLE_VAR(Industry::AcceptedCargo, cargo, SLE_UINT8),
@@ -28,27 +28,9 @@ public:
 	};
 	inline const static SaveLoadCompatTable compat_description = _industry_accepts_sl_compat;
 
-	void Save(Industry *i) const override
+	std::vector<Industry::AcceptedCargo> &GetVector(Industry *i) const override { return i->accepted; }
-	{
-		SlSetStructListLength(i->accepted.size());
 
-		for (auto &a : i->accepted) {
+	/* Old array structure used by INDYChunkHandler for savegames before SLV_INDUSTRY_CARGO_REORGANISE. */
-			SlObject(&a, this->GetDescription());
-		}
-	}
-
-	void Load(Industry *i) const override
-	{
-		size_t len = SlGetStructListLength(INDUSTRY_NUM_INPUTS);
-
-		i->accepted.reserve(len);
-		for (size_t index = 0; index < len; ++index) {
-			auto &a = i->accepted.emplace_back();
-			SlObject(&a, this->GetLoadDescription());
-		}
-	}
-
-	/* Old array structure used for savegames before SLV_INDUSTRY_CARGO_REORGANISE. */
 	static inline std::array<CargoID, INDUSTRY_NUM_INPUTS> old_cargo;
 	static inline std::array<uint16_t, INDUSTRY_NUM_INPUTS> old_waiting;
 	static inline std::array<TimerGameEconomy::Date, INDUSTRY_NUM_INPUTS> old_last_accepted;
@@ -95,7 +77,7 @@ public:
 	}
 };
 
-class SlIndustryProduced : public DefaultSaveLoadHandler<SlIndustryProduced, Industry> {
+class SlIndustryProduced : public VectorSaveLoadHandler<SlIndustryProduced, Industry, Industry::ProducedCargo, INDUSTRY_NUM_OUTPUTS> {
 public:
 	inline static const SaveLoad description[] = {
 		 SLE_VAR(Industry::ProducedCargo, cargo, SLE_UINT8),
@@ -105,27 +87,9 @@ public:
 	};
 	inline const static SaveLoadCompatTable compat_description = _industry_produced_sl_compat;
 
-	void Save(Industry *i) const override
+	std::vector<Industry::ProducedCargo> &GetVector(Industry *i) const override { return i->produced; }
-	{
-		SlSetStructListLength(i->produced.size());
 
-		for (auto &p : i->produced) {
+	/* Old array structure used by INDYChunkHandler for savegames before SLV_INDUSTRY_CARGO_REORGANISE. */
-			SlObject(&p, this->GetDescription());
-		}
-	}
-
-	void Load(Industry *i) const override
-	{
-		size_t len = SlGetStructListLength(INDUSTRY_NUM_OUTPUTS);
-
-		i->produced.reserve(len);
-		for (size_t index = 0; index < len; ++index) {
-			auto &p = i->produced.emplace_back();
-			SlObject(&p, this->GetLoadDescription());
-		}
-	}
-
-	/* Old array structure used for savegames before SLV_INDUSTRY_CARGO_REORGANISE. */
 	static inline std::array<CargoID, INDUSTRY_NUM_OUTPUTS> old_cargo;
 	static inline std::array<uint16_t, INDUSTRY_NUM_OUTPUTS> old_waiting;
 	static inline std::array<uint8_t, INDUSTRY_NUM_OUTPUTS> old_rate;

src/saveload/saveload.h

@@ -1314,4 +1314,55 @@ inline void SlSkipBytes(size_t length)
 extern std::string _savegame_format;
 extern bool _do_autosave;
 
+/**
+ * Default handler for saving/loading a vector to/from disk.
+ *
+ * This handles a few common things for handlers, meaning the actual handler
+ * needs less code.
+ *
+ * @tparam TImpl The class initializing this template.
+ * @tparam TObject The class of the object using this SaveLoadHandler.
+ * @tparam TElementType The type of the elements contained within the vector.
+ * @tparam MAX_LENGTH maximum number of elements to load.
+ */
+template <class TImpl, class TObject, class TElementType, size_t MAX_LENGTH = UINT32_MAX>
+class VectorSaveLoadHandler : public DefaultSaveLoadHandler<TImpl, TObject> {
+public:
+	/**
+	 * Get instance of vector to load/save.
+	 * @param object Object containing vector.
+	 * @returns Vector to load/save.
+	 */
+	virtual std::vector<TElementType> &GetVector(TObject *object) const = 0;
+
+	/**
+	 * Get number of elements to load into vector.
+	 * @returns Number of elements to load into the vector.
+	 * @note This is only overridden if the number of elements comes from a different location due to savegame changes.
+	 */
+	virtual size_t GetLength() const { return SlGetStructListLength(MAX_LENGTH); }
+
+	void Save(TObject *object) const override
+	{
+		auto &vector = this->GetVector(object);
+		SlSetStructListLength(vector.size());
+
+		for (auto &item : vector) {
+			SlObject(&item, this->GetDescription());
+		}
+	}
+
+	void Load(TObject *object) const override
+	{
+		auto &vector = this->GetVector(object);
+		size_t count = this->GetLength();
+
+		vector.reserve(count);
+		while (count-- > 0) {
+			auto &item = vector.emplace_back();
+			SlObject(&item, this->GetLoadDescription());
+		}
+	}
+};
+
 #endif /* SAVELOAD_H */

src/saveload/station_sl.cpp

@@ -201,7 +201,7 @@ static void SwapPackets(GoodsEntry *ge)
 }
 
 template <typename T>
-class SlStationSpecList : public DefaultSaveLoadHandler<SlStationSpecList<T>, BaseStation> {
+class SlStationSpecList : public VectorSaveLoadHandler<SlStationSpecList<T>, BaseStation, SpecMapping<T>> {
 public:
 	inline static const SaveLoad description[] = {
 		SLE_CONDVAR(SpecMapping<T>, grfid,    SLE_UINT32,                SLV_27,                    SL_MAX_VERSION),
@@ -212,25 +212,11 @@ public:
 
 	static inline uint8_t last_num_specs; ///< Number of specs of the last loaded station.
 
-	void Save(BaseStation *bst) const override
+	std::vector<SpecMapping<T>> &GetVector(BaseStation *bst) const override { return GetStationSpecList<T>(bst); }
-	{
-		auto &speclist = GetStationSpecList<T>(bst);
-		SlSetStructListLength(speclist.size());
-		for (auto &sm : speclist) {
-			SlObject(&sm, this->GetDescription());
-		}
-	}
 
-	void Load(BaseStation *bst) const override
+	size_t GetLength() const override
 	{
-		size_t num_specs = IsSavegameVersionBefore(SLV_SAVELOAD_LIST_LENGTH) ? last_num_specs : SlGetStructListLength(UINT8_MAX);
+		return IsSavegameVersionBefore(SLV_SAVELOAD_LIST_LENGTH) ? last_num_specs : SlGetStructListLength(UINT8_MAX);
-
-		auto &speclist = GetStationSpecList<T>(bst);
-		speclist.reserve(num_specs);
-		for (size_t index = 0; index < num_specs; ++index) {
-			auto &sm = speclist.emplace_back();
-			SlObject(&sm, this->GetLoadDescription());
-		}
 	}
 };
 
@@ -518,7 +504,7 @@ struct STNSChunkHandler : ChunkHandler {
 	}
 };
 
-class SlRoadStopTileData : public DefaultSaveLoadHandler<SlRoadStopTileData, BaseStation> {
+class SlRoadStopTileData : public VectorSaveLoadHandler<SlRoadStopTileData, BaseStation, RoadStopTileData> {
 public:
 	inline static const SaveLoad description[] = {
 	    SLE_VAR(RoadStopTileData, tile,            SLE_UINT32),
@@ -527,22 +513,7 @@ public:
 	};
 	inline const static SaveLoadCompatTable compat_description = {};
 
-	void Save(BaseStation *bst) const override
+	std::vector<RoadStopTileData> &GetVector(BaseStation *bst) const override { return bst->custom_roadstop_tile_data; }
-	{
-		SlSetStructListLength(bst->custom_roadstop_tile_data.size());
-		for (uint i = 0; i < bst->custom_roadstop_tile_data.size(); i++) {
-			SlObject(&bst->custom_roadstop_tile_data[i], this->GetDescription());
-		}
-	}
-
-	void Load(BaseStation *bst) const override
-	{
-		uint32_t num_tiles = (uint32_t)SlGetStructListLength(UINT32_MAX);
-		bst->custom_roadstop_tile_data.resize(num_tiles);
-		for (uint i = 0; i < num_tiles; i++) {
-			SlObject(&bst->custom_roadstop_tile_data[i], this->GetLoadDescription());
-		}
-	}
 };
 
 /**