Some preliminary support for object erase. But this will need a major refactor to split basic map data from in-game data.

lib/mapObjects/CGHeroInstance.cpp

@@ -1403,6 +1403,11 @@ void CGHeroInstance::afterAddToMap(CMap * map)
 	if(ID == Obj::HERO)
 		map->heroesOnMap.push_back(this);
 }
+void CGHeroInstance::afterRemoveFromMap(CMap* map)
+{
+	if (ID == Obj::HERO)
+		vstd::erase_if_present(map->heroesOnMap, this);
+}
 
 void CGHeroInstance::setHeroTypeName(const std::string & identifier)
 {

lib/mapObjects/CGHeroInstance.h

@@ -268,6 +268,7 @@ public:
 	std::string getObjectName() const override;
 
 	void afterAddToMap(CMap * map) override;
+	void afterRemoveFromMap(CMap* map) override;
 
 	void updateFrom(const JsonNode & data) override;
 

lib/mapObjects/CGTownInstance.cpp

@@ -1441,6 +1441,12 @@ void CGTownInstance::afterAddToMap(CMap * map)
 		map->towns.push_back(this);
 }
 
+void CGTownInstance::afterRemoveFromMap(CMap* map)
+{
+	if (ID == Obj::TOWN)
+		vstd::erase_if_present(map->towns, this);
+}
+
 void CGTownInstance::reset()
 {
 	CGTownInstance::merchantArtifacts.clear();

lib/mapObjects/CGTownInstance.h

@@ -342,6 +342,7 @@ public:
 	std::string getObjectName() const override;
 
 	void afterAddToMap(CMap * map) override;
+	void afterRemoveFromMap(CMap* map);
 	static void reset();
 
 	inline bool isBattleOutsideTown(const CGHeroInstance * defendingHero) const

lib/mapObjects/CObjectHandler.cpp

@@ -385,6 +385,11 @@ void CGObjectInstance::afterAddToMap(CMap * map)
 	//nothing here
 }
 
+void CGObjectInstance::afterRemoveFromMap(CMap* map)
+{
+	//nothing here
+}
+
 void CGObjectInstance::serializeJsonOptions(JsonSerializeFormat & handler)
 {
 	//nothing here

lib/mapObjects/CObjectHandler.h

@@ -197,6 +197,7 @@ public:
 	void setProperty(ui8 what, ui32 val) override final;
 
 	virtual void afterAddToMap(CMap * map);
+	virtual void afterRemoveFromMap(CMap* map);
 
 	///Entry point of binary (de-)serialization
 	template <typename Handler> void serialize(Handler &h, const int version)

lib/mapObjects/MiscObjects.cpp

@@ -1425,6 +1425,9 @@ void CGArtifact::blockingDialogAnswered(const CGHeroInstance *hero, ui32 answer)
 
 void CGArtifact::afterAddToMap(CMap * map)
 {
+	//Artifacts from map objects are never removed
+	//FIXME: This should be revertible in map editor
+
 	if(ID == Obj::SPELL_SCROLL && storedArtifact && storedArtifact->id.getNum() < 0)
         map->addNewArtifactInstance(storedArtifact);
 }

lib/mapping/CMap.cpp

@@ -594,6 +594,7 @@ void CMap::addNewArtifactInstance(CArtifactInstance * art)
 
 void CMap::eraseArtifactInstance(CArtifactInstance * art)
 {
+	//TODO: handle for artifacts removed in map editor
 	assert(artInstances[art->id.getNum()] == art);
 	artInstances[art->id.getNum()].dellNull();
 }
@@ -604,6 +605,20 @@ void CMap::addNewQuestInstance(CQuest* quest)
 	quests.push_back(quest);
 }
 
+void CMap::removeQuestInstance(CQuest* quest)
+{
+	//TODO: should be called only by map editor.
+	//During game, completed quests or quests from removed objects stay forever
+
+	//Shift indexes
+	auto iter = std::next(quests.begin(), quest->qid);
+	iter = quests.erase(iter);
+	for (int i = quest->qid; iter != quests.end(); ++i, ++iter)
+	{
+		(*iter)->qid = i;
+	}
+}
+
 void CMap::setUniqueInstanceName(CGObjectInstance* obj)
 {
 	//this gives object unique name even if objects are removed later
@@ -632,7 +647,6 @@ void CMap::addNewObject(CGObjectInstance * obj)
 	addBlockVisTiles(obj);
 
 	//TODO: how about deafeated heroes recruited again?
-	//TODO: How about objects restored with map editor?
 
 	obj->afterAddToMap(this);
 }
@@ -657,15 +671,7 @@ void CMap::removeObject(CGObjectInstance * obj)
 		(*iter)->id = ObjectInstanceID(i);
 	}
 	
-	auto iterTown = std::find(towns.begin(), towns.end(), obj);
-	if(iterTown != towns.end())
-		towns.erase(iterTown);
-	auto iterHero = std::find(allHeroes.begin(), allHeroes.end(), obj);
-	if(iterHero != allHeroes.end())
-		allHeroes.erase(iterHero);
-	iterHero = std::find(heroesOnMap.begin(), heroesOnMap.end(), obj);
-	if(iterHero != heroesOnMap.end())
-		heroesOnMap.erase(iterHero);
+	obj->afterRemoveFromMap(this);
 
 	//TOOD: Clean artifact instances (mostly worn by hero?) and quests related to this object
 }

lib/mapping/CMap.h

@@ -361,6 +361,7 @@ public:
 	void eraseArtifactInstance(CArtifactInstance * art);
 
 	void addNewQuestInstance(CQuest * quest);
+	void removeQuestInstance(CQuest* quest);
 
 	void setUniqueInstanceName(CGObjectInstance* obj);
 	///Use only this method when creating new map object instances