delete last town is just the inverse of create town

rsrc/dialogs/delete-town-confirm.xml

@@ -8,12 +8,11 @@
 	<text top='6' left='49' width='271' height='66'>
 		You are about to delete the last town in your scenario's town list
 		(so if you have 10 towns in your scenario, the tenth will disappear).
-		This change will immediately be saved, and can't be undone.
 	</text>
-	<text top='127' left='49' width='268' height='14'>Are you sure you want to do this?</text>
 	<text top='73' left='49' width='276' height='53'>
 		Make sure to remove all outdoor entrances to the deleted town,
 		as well as all references to it in special encounters.
 		Failure to do so will result in scenario run-time errors.
 	</text>
+	<text top='127' left='49' width='268' height='14'>Are you sure you want to do this?</text>
 </dialog>

src/scenedit/scen.townout.cpp

@@ -48,6 +48,7 @@ extern cUndoList undo_list;
 extern std::string help_text_rsrc;
 extern bool editing_town;
 extern bool last_shift_continuous;
+extern void update_edit_menu();
 
 const char *day_str_1[] = {"Unused","Day creature appears","Day creature disappears",
 	"Unused","Unused","Unused","Unused","Unused","Unused"};
@@ -1671,7 +1672,8 @@ bool new_town() {
 		for(short j = 0; j < town->max_dim; j++)
 			town->terrain(i,j) = preset;
 
-	undo_list.add(action_ptr(new aNewTown(scenario.towns.back())));
+	undo_list.add(action_ptr(new aCreateDeleteTown(true, scenario.towns.back())));
+	update_edit_menu();
 	change_made = true;
 	
 	return true;
@@ -1679,9 +1681,10 @@ bool new_town() {
 
 // before calling this, be sure to do all checks to make sure it's safe.
 void delete_last_town() {
-	cTown* last_town = scenario.towns.back();
+	undo_list.add(action_ptr(new aCreateDeleteTown(false, scenario.towns.back())));
+	update_edit_menu();
+
 	scenario.towns.pop_back();
-	delete last_town;
 	change_made = true;
 }
 

src/scenedit/scen.undo.cpp

@@ -14,6 +14,7 @@ extern cArea* get_current_area();
 extern void start_town_edit();
 extern void start_out_edit();
 extern void redraw_screen();
+extern void set_current_town(int,bool first_restore = false);
 
 cTerrainAction::cTerrainAction(std::string name, short town_num, location where) : cAction(name) {
 	area.is_town = true;
@@ -72,24 +73,25 @@ bool aEraseSpecial::redo_me() {
 	return true;
 }
 
-aNewTown::aNewTown(cTown* t)
+aCreateDeleteTown::aCreateDeleteTown(bool create, cTown* t)
-	: cAction("Add Town")
+	: cAction(create ? "Create Town" : "Delete Last Town", !create)
 	, theTown(t)
 {}
 
-bool aNewTown::undo_me() {
+bool aCreateDeleteTown::undo_me() {
 	scenario.towns.resize(scenario.towns.size() - 1);
-	cur_town = min(cur_town, scenario.towns.size() - 1);
+	set_current_town(min(cur_town, scenario.towns.size() - 1));
 	return true;
 }
 
-bool aNewTown::redo_me() {
+bool aCreateDeleteTown::redo_me() {
 	scenario.towns.push_back(theTown);
+	set_current_town(scenario.towns.size() - 1);
 	return true;
 }
 
-aNewTown::~aNewTown() {
+aCreateDeleteTown::~aCreateDeleteTown() {
-	if(!isDone()) delete theTown;
+	if(isDone() == reversed) delete theTown;
 }
 
 bool aDrawTerrain::undo_me() {

src/scenedit/scen.undo.hpp

@@ -19,7 +19,7 @@ struct ter_change_t {
 
 typedef std::map<location,ter_change_t,loc_compare> stroke_ter_changes_t;
 
-// Action that modified town or outdoor terrain, so we should show the modified area when undoing or redoing
+// Action that modified something in town or outdoor terrain, so we should show the modified area when undoing or redoing
 class cTerrainAction : public cAction {
 public:
 	cTerrainAction(std::string name, short town_num, location where);
@@ -35,16 +35,7 @@ private:
 	area_ref_t area;
 };
 
-/// Represents the action of adding a new town to the end of the list
+/// Action that erased a special encounter from a spot
-class aNewTown : public cAction {
-	class cTown* theTown;
-	bool undo_me() override;
-	bool redo_me() override;
-public:
-	aNewTown(class cTown* t);
-	~aNewTown();
-};
-
 class aEraseSpecial : public cTerrainAction {
 public:
 	aEraseSpecial(spec_loc_t special) : cTerrainAction("Erase Special Encounter", special), for_redo(special) {}
@@ -55,6 +46,7 @@ private:
 	bool editing_town;
 };
 
+/// Action which modifies terrain tiles (i.e. paintbrush, pencil, eraser)
 class aDrawTerrain : public cTerrainAction {
 public:
 	aDrawTerrain(std::string name, stroke_ter_changes_t stroke_changes) :
@@ -66,4 +58,16 @@ private:
 	const stroke_ter_changes_t changes;
 };
 
+/// Action which adds a new town to the end of the list, or deletes the last one
+class aCreateDeleteTown : public cAction {
+	bool created;
+	class cTown* theTown;
+	bool undo_me() override;
+	bool redo_me() override;
+public:
+	aCreateDeleteTown(bool create, class cTown* t);
+	~aCreateDeleteTown();
+};
+
+
 #endif

src/tools/undo.cpp

@@ -23,13 +23,13 @@ cAction::~cAction() {}
 
 void cAction::undo() {
 	UNDO_LOG("Undoing " + actname);
-	if(done && undo_me())
+	if(done && reversed ? redo_me() : undo_me())
 		done = false;
 }
 
 void cAction::redo() {
 	UNDO_LOG("Redoing " + actname);
-	if(!done && redo_me())
+	if(!done && reversed ? undo_me() : redo_me())
 		done = true;
 }
 

src/tools/undo.hpp

@@ -23,7 +23,9 @@ class cAction {
 protected:
 	/// Construct a named action
 	/// @param name The name of the action to show in the Edit menu
-	cAction(std::string name) : actname(name) {}
+	cAction(std::string name, bool reversed = false) : actname(name), reversed(reversed) {}
+	/// For actions that have an inverse, this flag inverts the action implementation (i.e. create/delete)
+	bool reversed = true;
 public:
 	/// Undoes this action if it has not already been undone.
 	/// If it has already been undone, does nothing.