undo/redo for setting special number

src/scenedit/scen.actions.cpp

@@ -2807,7 +2807,12 @@ void set_special(location spot_hit) {
 		// Edit the node of the encounter already on the space
 		if(specials[x] == spot_hit && specials[x].spec >= 0) {
 			int spec = edit_special_num(editing_town ? 2 : 1,specials[x].spec);
-			if(spec >= 0) specials[x].spec = spec;
+			if(spec >= 0 && spec != specials[x].spec){
+				undo_list.add(action_ptr(new aSetSpecial(spot_hit, specials[x].spec, spec)));
+				// TODO if create/edit was used, add those actions
+				update_edit_menu();
+				specials[x].spec = spec;
+			}
 			return;
 		}
 	for(short x = 0; x <= specials.size(); x++) {

src/scenedit/scen.undo.cpp

@@ -90,6 +90,24 @@ bool aPlaceEraseSpecial::redo_me() {
 	return true;
 }
 
+bool aSetSpecial::undo_me() {
+	cArea* cur_area = get_current_area();
+	auto& specials = cur_area->special_locs;
+	for(spec_loc_t& special : specials){
+		if(special == area.where) special.spec = old_num;
+	}
+	return true;
+}
+
+bool aSetSpecial::redo_me() {
+	cArea* cur_area = get_current_area();
+	auto& specials = cur_area->special_locs;
+	for(spec_loc_t& special : specials){
+		if(special == area.where) special.spec = new_num;
+	}
+	return true;
+}
+
 aCreateDeleteTown::aCreateDeleteTown(bool create, cTown* t)
 	: cAction(create ? "Create Town" : "Delete Last Town", !create)
 	, theTown(t)

src/scenedit/scen.undo.hpp

@@ -76,6 +76,17 @@ private:
 	bool editing_town;
 };
 
+/// Action that sets the number of an existing special encounter
+class aSetSpecial : public cTerrainAction {
+	short old_num;
+	short new_num;
+	bool undo_me() override;
+	bool redo_me() override;
+public:
+	aSetSpecial(location where, short old_num, short new_num) :
+		cTerrainAction("Edit Special Encounter", where), old_num(old_num), new_num(new_num) {}
+};
+
 /// Action which modifies terrain tiles (i.e. paintbrush, pencil, eraser)
 class aDrawTerrain : public cTerrainAction {
 public: