Add iterative memento example

src/MememntoPattern/IterativeEmployee/Caretaker.cs

@@ -0,0 +1,50 @@
+using System.Collections.Generic;
+
+namespace MememntoPattern.IterativeEmployee
+{
+    /// <summary>
+    /// Caretaker
+    /// </summary>
+    public class Caretaker
+    {
+        EmployeeMemento initialMememento;
+        List<EmployeeMementoDiff> diffs;
+
+        public Caretaker()
+        {
+            diffs = new List<EmployeeMementoDiff>();
+            initialMememento = null;
+        }
+
+        public void Save(Employee emp)
+        {
+            EmployeeMemento memento = emp.Save();
+
+            if (initialMememento == null)
+                initialMememento = memento;
+            else            
+                diffs.Add(memento.GetDiffFor(GetLastSavedVersion()));            
+        }        
+
+        public void Revert(Employee emp)
+        {
+            EmployeeMemento em = GetLastSavedVersion();
+
+            if (diffs.Count > 0)
+                diffs.RemoveAt(diffs.Count - 1);
+
+            emp.Revert(em);
+        }
+
+        private EmployeeMemento GetLastSavedVersion()
+        {
+            var memento = initialMememento.Clone();
+            foreach (var diff in diffs)
+            {
+                memento.UpdateWithDelta(diff);
+            }
+
+            return memento;
+        }
+    }
+}

src/MememntoPattern/IterativeEmployee/Employee.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+
+namespace MememntoPattern.IterativeEmployee
+{
+    /// <summary>
+    /// Originator
+    /// </summary>
+    public class Employee
+    {
+        public string Name { get; set; }
+
+        public string Address { get; set; }
+
+        public List<string> Phones { get; set; }
+
+        public EmployeeMemento Save()
+        {
+            return new EmployeeMemento(Name, Address);
+        }
+
+        public void Revert(EmployeeMemento memento)
+        {
+            Name = memento.Name;
+
+            Address = memento.Address;
+        }
+    }
+}

src/MememntoPattern/IterativeEmployee/EmployeeIterativeExample.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace MememntoPattern.IterativeEmployee
+{
+    public class EmployeeIterativeExample
+    {
+        public void Run()
+        {
+            Caretaker caretaker = new Caretaker();
+            Employee e = new Employee();
+            e.Name = "Ghiuri";
+            e.Address = "Stairway to heaven";
+
+            Console.WriteLine("First saved address: {0}", e.Address);
+            caretaker.Save(e);
+
+            e.Address = "Highway to hell";
+
+            Console.WriteLine("Second saved address: {0}", e.Address);
+
+            caretaker.Save(e);
+
+            e.Address = "Home of the brave";
+
+            Console.WriteLine("Third saved address: {0}", e.Address);
+
+            caretaker.Save(e);
+
+            e.Address = "Somesing";
+
+            Console.WriteLine("Address before revert: {0}", e.Address);
+
+            caretaker.Revert(e);
+
+            Console.WriteLine("First reverted Address: {0}", e.Address);
+
+            caretaker.Revert(e);
+
+            Console.WriteLine("Second reverted Address: {0}", e.Address);
+
+            caretaker.Revert(e);
+
+            Console.WriteLine("Third reverted Address: {0}", e.Address);
+
+            caretaker.Revert(e);
+
+            Console.WriteLine("Forth reverted Address: {0}", e.Address);
+
+        }
+       
+    }
+}

src/MememntoPattern/IterativeEmployee/EmployeeMemento.cs

@@ -0,0 +1,51 @@
+namespace MememntoPattern.IterativeEmployee
+{
+    /// <summary>
+    /// Memento object
+    /// </summary>
+    public class EmployeeMemento : IIterativeMemento<EmployeeMemento, EmployeeMementoDiff>
+    {
+        public string Name { get; private set; }
+        public string Address { get; private set; }
+
+        public EmployeeMemento(string name, string address)
+        {
+            Name = name;
+            Address = address;
+        }
+
+        public EmployeeMementoDiff GetDiffFor(EmployeeMemento e)
+        {
+            EmployeeMementoDiff diff = new EmployeeMementoDiff();
+
+            if (Name != e.Name)
+                diff.UpdatedName = Name;
+
+            if (Address != e.Address)
+                diff.UpdatedAddress = Address;
+
+            return diff;
+        }
+
+        public void UpdateWithDelta(EmployeeMementoDiff diff)
+        {
+            if (diff.UpdatedName != null)
+                Name = diff.UpdatedName;
+
+            if (diff.UpdatedAddress != null)
+                Address = diff.UpdatedAddress;
+        }
+
+        public EmployeeMemento Clone()
+        {
+            return new EmployeeMemento(Name, Address);
+        }        
+    }
+
+    public class EmployeeMementoDiff
+    {
+        public string UpdatedName { get; set; }
+
+        public string UpdatedAddress { get; set; }
+    }
+}

src/MememntoPattern/IterativeEmployee/IIterativeMemento.cs

@@ -0,0 +1,9 @@
+namespace MememntoPattern.IterativeEmployee
+{
+    public interface IIterativeMemento<TMemento, TDiff>
+    {
+        TMemento Clone();
+        TDiff GetDiffFor(TMemento e);
+        void UpdateWithDelta(TDiff diff);
+    }
+}

src/MememntoPattern/MementoPatternExamples.cs

@@ -1,5 +1,6 @@
 using MememntoPattern.Employee;
 using MememntoPattern.EmployeeSerialized;
+using MememntoPattern.IterativeEmployee;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -28,6 +29,10 @@ namespace MememntoPattern
 
             GoToNextStep();
 
+            EmployeeIterativeExample empIterEx = new EmployeeIterativeExample();
+            empIterEx.Run();
+            GoToNextStep();
+
             Console.WriteLine(GetPitfalls());
         }