code refactoring: fix memory leaks, code style, etc.

memento/Memento.cpp

@@ -16,19 +16,21 @@
  * stores internal state of the Originator object and protects
  * against access by objects other than the originator
  */
-class Memento {
+class Memento
+{
 private:
   // accessible only to Originator
   friend class Originator;
-
-  Memento(int s)
-    : state(s) {}
-
-  void setState(int s) {
+  
+  Memento( const int s ) : state( s ) {}
+  
+  void setState( const int s )
+  {
     state = s;
   }
-
-  int getState() {
+  
+  int getState()
+  {
     return state;
   }
   // ...
@@ -43,25 +45,30 @@ private:
  * creates a memento containing a snapshot of its current internal
  * state and uses the memento to restore its internal state
  */
-class Originator {
+class Originator
+{
 public:
   // implemented only for printing purpose
-  void setState(int s) {
+  void setState( const int s )
+  {
     std::cout << "Set state to " << s << "." << std::endl;
     state = s;
   }
-
+  
   // implemented only for printing purpose
-  int getState() {
+  int getState()
+  {
     return state;
   }
-
-  void setMemento(Memento *m) {
+  
+  void setMemento( Memento* const m )
+  {
     state = m->getState();
   }
-
-  Memento *createMemento() {
-    return new Memento(state);
+  
+  Memento *createMemento()
+  {
+    return new Memento( state );
   }
 
 private:
@@ -73,55 +80,68 @@ private:
  * CareTaker
  * is responsible for the memento's safe keeping
  */
-class CareTaker {
+class CareTaker
+{
 public:
-  CareTaker(Originator *o)
-    : originator(o) {}
-
-  ~CareTaker() {
-    for (unsigned int i = 0; i < history.size(); i++) {
-      delete history.at(i);
+  CareTaker( Originator* const o ) : originator( o ) {}
+  
+  ~CareTaker()
+  {
+    for ( unsigned int i = 0; i < history.size(); i++ )
+    {
+      delete history.at( i );
     }
     history.clear();
   }
-
-  void save() {
-    std::cout << "Save state." << std::endl;;
-    history.push_back(originator->createMemento());
+  
+  void save()
+  {
+    std::cout << "Save state." << std::endl;
+    history.push_back( originator->createMemento() );
   }
-
-  void undo() {
-    std::cout << "Undo state." << std::endl;;
-    originator->setMemento(history.back());
+  
+  void undo()
+  {
+    if ( history.empty() )
+    {
+      std::cout << "Unable to undo state." << std::endl;
+      return;
+    }
+    
+    Memento *m = history.back();
+    originator->setMemento( m );
+    std::cout << "Undo state." << std::endl;
+    
     history.pop_back();
+    delete m;
   }
   // ...
 
 private:
   Originator *originator;
-  std::vector<Memento *> history;
+  std::vector<Memento*> history;
   // ...
 };
 
 
 int main()
 {
-  Originator *originator = new Originator;
-  CareTaker *caretaker = new CareTaker(originator);
-
-  originator->setState(1);
+  Originator *originator = new Originator();
+  CareTaker *caretaker = new CareTaker( originator );
+  
+  originator->setState( 1 );
   caretaker->save();
-
-  originator->setState(2);
+  
+  originator->setState( 2 );
   caretaker->save();
-
-  originator->setState(3);
+  
+  originator->setState( 3 );
   caretaker->undo();
-
+  
   std::cout << "Actual state is " << originator->getState() << "." << std::endl;
-
+  
   delete originator;
   delete caretaker;
-
+  
   return 0;
 }