265 /************************************************************************

   266  * Engine Replacement stuff

   267  ************************************************************************/

   268 

   269 struct EngineRenew;

   270 /**

   271  * Memory pool for engine renew elements. DO NOT USE outside of engine.c. Is

   272  * placed here so the only exception to this rule, the saveload code, can use

   273  * it.

   274  */

   275 DECLARE_OLD_POOL(EngineRenew, EngineRenew, 3, 8000)

   276 

   277 /**

   278  * Struct to store engine replacements. DO NOT USE outside of engine.c. Is

   279  * placed here so the only exception to this rule, the saveload code, can use

   280  * it.

   281  */

   282 struct EngineRenew : PoolItem<EngineRenew, EngineRenewID, &_EngineRenew_pool> {

   283 	EngineID from;

   284 	EngineID to;

   285 	EngineRenew *next;

   286 	GroupID group_id;

   287 

   288 	EngineRenew(EngineID from = INVALID_ENGINE, EngineID to = INVALID_ENGINE) : from(from), to(to), next(NULL) {}

   289 	~EngineRenew() { this->from = INVALID_ENGINE; }

   290 

   291 	inline bool IsValid() const { return this->from != INVALID_ENGINE; }

   292 };

   293 

   294 #define FOR_ALL_ENGINE_RENEWS_FROM(er, start) for (er = GetEngineRenew(start); er != NULL; er = (er->index + 1U < GetEngineRenewPoolSize()) ? GetEngineRenew(er->index + 1U) : NULL) if (er->IsValid())

   295 #define FOR_ALL_ENGINE_RENEWS(er) FOR_ALL_ENGINE_RENEWS_FROM(er, 0)

   296 

   297 

   298 /**

   299  * A list to group EngineRenew directives together (such as per-player).

   300  */

   301 typedef EngineRenew* EngineRenewList;

   302 

   303 /**

   304  * Remove all engine replacement settings for the player.

   305  * @param  erl The renewlist for a given player.

   306  * @return The new renewlist for the player.

   307  */

   308 void RemoveAllEngineReplacement(EngineRenewList *erl);

   309 

   310 /**

   311  * Retrieve the engine replacement in a given renewlist for an original engine type.

   312  * @param  erl The renewlist to search in.

   313  * @param  engine Engine type to be replaced.

   314  * @return The engine type to replace with, or INVALID_ENGINE if no

   315  * replacement is in the list.

   316  */

   317 EngineID EngineReplacement(EngineRenewList erl, EngineID engine, GroupID group);

   318 

   319 /**

   320  * Add an engine replacement to the given renewlist.

   321  * @param erl The renewlist to add to.

   322  * @param old_engine The original engine type.

   323  * @param new_engine The replacement engine type.

   324  * @param flags The calling command flags.

   325  * @return 0 on success, CMD_ERROR on failure.

   326  */

   327 CommandCost AddEngineReplacement(EngineRenewList *erl, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags);

   328 

   329 /**

   330  * Remove an engine replacement from a given renewlist.

   331  * @param erl The renewlist from which to remove the replacement

   332  * @param engine The original engine type.

   333  * @param flags The calling command flags.

   334  * @return 0 on success, CMD_ERROR on failure.

   335  */

   336 CommandCost RemoveEngineReplacement(EngineRenewList *erl, EngineID engine, GroupID group, uint32 flags);

   337 

   338 /** When an engine is made buildable or is removed from being buildable, add/remove it from the build/autoreplace lists

   339  * @param type The type of engine

   340  */

   341 void AddRemoveEngineFromAutoreplaceAndBuildWindows(VehicleType type);

   342