All cloners are now able to clone objects without default constructors; began work on a property-based expression tree cloner

git-svn-id: file:///srv/devel/repo-conversion/nusu@243 d2e56fa2-650e-0410-a79f-9358c0239efd

Documents/Nuclex.Support.txt

@@ -26,3 +26,9 @@
   
   #endif
 
+
+Benchmark of cloners:
+
+  SerializationCloner took 13424 ms
+	ReflectionCloner took 2126 ms
+	ExpressionTreeCloner took 171 ms

Source/Cloning/CloneFactoryTest.cs

@@ -27,7 +27,7 @@ using NUnit.Framework;
 namespace Nuclex.Support.Cloning {
 
   /// <summary>Base class for unit tests verifying the clone factory</summary>
-  public abstract class CloneFactoryTest {
+  internal abstract class CloneFactoryTest {
 
     #region class TestReferenceType
 

Source/Cloning/ExpressionTreeCloner.FieldBased.cs

@@ -24,6 +24,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
 using System.Reflection;
+using System.Runtime.Serialization;
 
 namespace Nuclex.Support.Cloning {
 
@@ -60,7 +61,7 @@ namespace Nuclex.Support.Cloning {
         if(elementType.IsPrimitive || (elementType == typeof(string))) {
           // For primitive arrays, the Array.Clone() method is sufficient
           transferExpressions.Add(
-            generatePrimitiveArrayTransferExpressions(
+            generateFieldBasedPrimitiveArrayTransferExpressions(
               clonedType, original, variables, transferExpressions
             )
           );
@@ -75,7 +76,7 @@ namespace Nuclex.Support.Cloning {
 
           // Arrays of complex types require manual cloning
           transferExpressions.Add(
-            generateComplexArrayTransferExpressions(
+            generateFieldBasedComplexArrayTransferExpressions(
               clonedType, typedOriginal, variables, transferExpressions
             )
           );
@@ -87,7 +88,20 @@ namespace Nuclex.Support.Cloning {
         variables.Add(clone);
 
         // Give it a new instance of the type being cloned
-        transferExpressions.Add(Expression.Assign(clone, Expression.New(clonedType)));
+        MethodInfo getUninitializedObjectMethodInfo = typeof(FormatterServices).GetMethod(
+          "GetUninitializedObject", BindingFlags.Static | BindingFlags.Public
+        );
+        transferExpressions.Add(
+          Expression.Assign(
+            clone,
+            Expression.Convert(
+              Expression.Call(
+                getUninitializedObjectMethodInfo, Expression.Constant(clonedType)
+              ),
+              clonedType
+            )
+          )
+        );
 
         // To access the fields of the original type, we need it to be of the actual
         // type instead of an object, so perform a downcast
@@ -98,7 +112,7 @@ namespace Nuclex.Support.Cloning {
         );
 
         // Generate the expressions required to transfer the type field by field
-        generateComplexTypeTransferExpressions(
+        generateFieldBasedComplexTypeTransferExpressions(
           clonedType, typedOriginal, clone, variables, transferExpressions
         );
 
@@ -136,7 +150,7 @@ namespace Nuclex.Support.Cloning {
         transferExpressions.Add(original);
       } else if(clonedType.IsArray) {
         transferExpressions.Add(
-          generatePrimitiveArrayTransferExpressions(
+          generateFieldBasedPrimitiveArrayTransferExpressions(
             clonedType, original, variables, transferExpressions
           )
         );
@@ -201,7 +215,7 @@ namespace Nuclex.Support.Cloning {
     /// <param name="variables">Receives variables used by the transfer expressions</param>
     /// <param name="transferExpressions">Receives the generated transfer expressions</param>
     /// <returns>The variable holding the cloned array</returns>
-    private static Expression generatePrimitiveArrayTransferExpressions(
+    private static Expression generateFieldBasedPrimitiveArrayTransferExpressions(
       Type clonedType,
       Expression original,
       ICollection<ParameterExpression> variables,
@@ -224,7 +238,7 @@ namespace Nuclex.Support.Cloning {
     /// <param name="variables">Receives variables used by the transfer expressions</param>
     /// <param name="transferExpressions">Receives the generated transfer expressions</param>
     /// <returns>The variable holding the cloned array</returns>
-    private static ParameterExpression generateComplexArrayTransferExpressions(
+    private static ParameterExpression generateFieldBasedComplexArrayTransferExpressions(
       Type clonedType,
       Expression original,
       IList<ParameterExpression> variables,
@@ -310,7 +324,7 @@ namespace Nuclex.Support.Cloning {
             // Arrays of complex value types can be transferred by assigning all fields
             // of the source array element to the destination array element (cloning
             // any nested reference types appropriately)
-            generateComplexTypeTransferExpressions(
+            generateFieldBasedComplexTypeTransferExpressions(
               elementType,
               Expression.ArrayAccess(original, indexes),
               Expression.ArrayAccess(clone, indexes),
@@ -338,11 +352,11 @@ namespace Nuclex.Support.Cloning {
 
               Type nestedElementType = elementType.GetElementType();
               if(nestedElementType.IsPrimitive || (nestedElementType == typeof(string))) {
-                clonedElement = generatePrimitiveArrayTransferExpressions(
+                clonedElement = generateFieldBasedPrimitiveArrayTransferExpressions(
                   elementType, originalElement, nestedVariables, nestedTransferExpressions
                 );
               } else {
-                clonedElement = generateComplexArrayTransferExpressions(
+                clonedElement = generateFieldBasedComplexArrayTransferExpressions(
                   elementType, originalElement, nestedVariables, nestedTransferExpressions
                 );
               }
@@ -427,7 +441,7 @@ namespace Nuclex.Support.Cloning {
     /// <param name="clone">Variable expression for the cloned instance</param>
     /// <param name="variables">Receives variables used by the transfer expressions</param>
     /// <param name="transferExpressions">Receives the generated transfer expressions</param>
-    private static void generateComplexTypeTransferExpressions(
+    private static void generateFieldBasedComplexTypeTransferExpressions(
       Type clonedType, // Actual, concrete type (not declared type)
       Expression original, // Expected to be an object
       Expression clone,	// As actual, concrete type
@@ -454,7 +468,7 @@ namespace Nuclex.Support.Cloning {
         } else if(fieldType.IsValueType) {
           // A nested value type is part of the parent and will have its fields directly
           // assigned without boxing, new instance creation or anything like that.
-          generateComplexTypeTransferExpressions(
+          generateFieldBasedComplexTypeTransferExpressions(
             fieldType,
             Expression.Field(original, fieldInfo),
             Expression.Field(clone, fieldInfo),
@@ -462,7 +476,7 @@ namespace Nuclex.Support.Cloning {
             transferExpressions
           );
         } else {
-          generateReferenceTypeTransferExpressions(
+          generateFieldBasedReferenceTypeTransferExpressions(
             original, clone, transferExpressions, fieldInfo, fieldType
           );
         }
@@ -479,7 +493,7 @@ namespace Nuclex.Support.Cloning {
     /// </param>
     /// <param name="fieldInfo">Reflection informations about the field being cloned</param>
     /// <param name="fieldType">Type of the field being cloned</param>
-    private static void generateReferenceTypeTransferExpressions(
+    private static void generateFieldBasedReferenceTypeTransferExpressions(
       Expression original,
       Expression clone,
       ICollection<Expression> transferExpressions,
@@ -498,7 +512,7 @@ namespace Nuclex.Support.Cloning {
         Type elementType = fieldType.GetElementType();
         if(elementType.IsPrimitive || (elementType == typeof(string))) {
           // For primitive arrays, the Array.Clone() method is sufficient
-          fieldClone = generatePrimitiveArrayTransferExpressions(
+          fieldClone = generateFieldBasedPrimitiveArrayTransferExpressions(
             fieldType,
             Expression.Field(original, fieldInfo),
             fieldVariables,
@@ -506,7 +520,7 @@ namespace Nuclex.Support.Cloning {
           );
         } else {
           // Arrays of complex types require manual cloning
-          fieldClone = generateComplexArrayTransferExpressions(
+          fieldClone = generateFieldBasedComplexArrayTransferExpressions(
             fieldType,
             Expression.Field(original, fieldInfo),
             fieldVariables,

Source/Cloning/ExpressionTreeCloner.PropertyBased.cs

@@ -21,7 +21,6 @@ License along with this library
 #if !(XBOX360 || WINDOWS_PHONE)
 
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -30,7 +29,476 @@ namespace Nuclex.Support.Cloning {
 
   partial class ExpressionTreeCloner : ICloneFactory {
 
-    // Not implement yet...
+#if false
+
+    /// <summary>Compiles a method that creates a deep clone of an object</summary>
+    /// <param name="clonedType">Type for which a clone method will be created</param>
+    /// <returns>A method that clones an object of the provided type</returns>
+    /// <remarks>
+    ///   <para>
+    ///     The 'null' check is supposed to take place before running the cloner. This
+    ///     avoids having redundant 'null' checks on nested types - first before calling
+    ///     GetType() on the property to be cloned and second when runner the matching
+    ///     cloner for the property.
+    ///   </para>
+    ///   <para>
+    ///     This design also enables the cloning of nested value types (which can never
+    ///     be null) without any null check whatsoever.
+    ///   </para>
+    /// </remarks>
+    private static Func<object, object> createDeepPropertyBasedCloner(Type clonedType) {
+      ParameterExpression original = Expression.Parameter(typeof(object), "original");
+
+      var transferExpressions = new List<Expression>();
+      var variables = new List<ParameterExpression>();
+
+      if(clonedType.IsPrimitive || (clonedType == typeof(string))) {
+        // Primitives and strings are copied on direct assignment
+        transferExpressions.Add(original);
+      } else if(clonedType.IsArray) {
+        // Arrays need to be cloned element-by-element
+        Type elementType = clonedType.GetElementType();
+
+        if(elementType.IsPrimitive || (elementType == typeof(string))) {
+          // For primitive arrays, the Array.Clone() method is sufficient
+          transferExpressions.Add(
+            generatePropertyBasedPrimitiveArrayTransferExpressions(
+              clonedType, original, variables, transferExpressions
+            )
+          );
+        } else {
+          // To access the propertys of the original type, we need it to be of the actual
+          // type instead of an object, so perform a downcast
+          ParameterExpression typedOriginal = Expression.Variable(clonedType);
+          variables.Add(typedOriginal);
+          transferExpressions.Add(
+            Expression.Assign(typedOriginal, Expression.Convert(original, clonedType))
+          );
+
+          // Arrays of complex types require manual cloning
+          transferExpressions.Add(
+            generatePropertyBasedComplexArrayTransferExpressions(
+              clonedType, typedOriginal, variables, transferExpressions
+            )
+          );
+        }
+      } else {
+        // We need a variable to hold the clone because due to the assignments it
+        // won't be last in the block when we're finished
+        ParameterExpression clone = Expression.Variable(clonedType);
+        variables.Add(clone);
+
+        // Give it a new instance of the type being cloned
+        transferExpressions.Add(Expression.Assign(clone, Expression.New(clonedType)));
+
+        // To access the propertys of the original type, we need it to be of the actual
+        // type instead of an object, so perform a downcast
+        ParameterExpression typedOriginal = Expression.Variable(clonedType);
+        variables.Add(typedOriginal);
+        transferExpressions.Add(
+          Expression.Assign(typedOriginal, Expression.Convert(original, clonedType))
+        );
+
+        // Generate the expressions required to transfer the type property by property
+        generatePropertyBasedComplexTypeTransferExpressions(
+          clonedType, typedOriginal, clone, variables, transferExpressions
+        );
+
+        // Make sure the clone is the last thing in the block to set the return value
+        transferExpressions.Add(clone);
+      }
+
+      // Turn all transfer expressions into a single block if necessary
+      Expression resultExpression;
+      if((transferExpressions.Count == 1) && (variables.Count == 0)) {
+        resultExpression = transferExpressions[0];
+      } else {
+        resultExpression = Expression.Block(variables, transferExpressions);
+      }
+
+      // Value types require manual boxing
+      if(clonedType.IsValueType) {
+        resultExpression = Expression.Convert(resultExpression, typeof(object));
+      }
+
+      return Expression.Lambda<Func<object, object>>(resultExpression, original).Compile();
+    }
+
+    /// <summary>
+    ///   Generates state transfer expressions to copy an array of primitive types
+    /// </summary>
+    /// <param name="clonedType">Type of array that will be cloned</param>
+    /// <param name="original">Variable expression for the original array</param>
+    /// <param name="variables">Receives variables used by the transfer expressions</param>
+    /// <param name="transferExpressions">Receives the generated transfer expressions</param>
+    /// <returns>The variable holding the cloned array</returns>
+    private static Expression generatePropertyBasedPrimitiveArrayTransferExpressions(
+      Type clonedType,
+      Expression original,
+      ICollection<ParameterExpression> variables,
+      ICollection<Expression> transferExpressions
+    ) {
+      MethodInfo arrayCloneMethodInfo = typeof(Array).GetMethod("Clone");
+      return Expression.Convert(
+        Expression.Call(
+          Expression.Convert(original, typeof(Array)), arrayCloneMethodInfo
+        ),
+        clonedType
+      );
+    }
+
+    /// <summary>
+    ///   Generates state transfer expressions to copy an array of complex types
+    /// </summary>
+    /// <param name="clonedType">Type of array that will be cloned</param>
+    /// <param name="original">Variable expression for the original array</param>
+    /// <param name="variables">Receives variables used by the transfer expressions</param>
+    /// <param name="transferExpressions">Receives the generated transfer expressions</param>
+    /// <returns>The variable holding the cloned array</returns>
+    private static ParameterExpression generatePropertyBasedComplexArrayTransferExpressions(
+      Type clonedType,
+      Expression original,
+      IList<ParameterExpression> variables,
+      ICollection<Expression> transferExpressions
+    ) {
+      // We need a temporary variable in order to transfer the elements of the array
+      ParameterExpression clone = Expression.Variable(clonedType);
+      variables.Add(clone);
+
+      int dimensionCount = clonedType.GetArrayRank();
+      int baseVariableIndex = variables.Count;
+      Type elementType = clonedType.GetElementType();
+
+      var lengths = new List<ParameterExpression>();
+      var indexes = new List<ParameterExpression>();
+      var labels = new List<LabelTarget>();
+
+      // Retrieve the length of each of the array's dimensions
+      MethodInfo arrayGetLengthMethodInfo = typeof(Array).GetMethod("GetLength");
+      for(int index = 0; index < dimensionCount; ++index) {
+
+        // Obtain the length of the array in the current dimension
+        lengths.Add(Expression.Variable(typeof(int)));
+        variables.Add(lengths[index]);
+        transferExpressions.Add(
+          Expression.Assign(
+            lengths[index],
+            Expression.Call(
+              original, arrayGetLengthMethodInfo, Expression.Constant(index)
+            )
+          )
+        );
+
+        // Set up a variable to index the array in this dimension
+        indexes.Add(Expression.Variable(typeof(int)));
+        variables.Add(indexes[index]);
+
+        // Also set up a label than can be used to break out of the dimension's
+        // transfer loop
+        labels.Add(Expression.Label());
+
+      }
+
+      // Create a new (empty) array with the same dimensions and lengths as the original
+      transferExpressions.Add(
+        Expression.Assign(clone, Expression.NewArrayBounds(elementType, lengths))
+      );
+
+      // Initialize the indexer of the outer loop (indexers are initialized one up
+      // in the loops (ie. before the loop using it begins), so we have to set this
+      // one outside of the loop building code.
+      transferExpressions.Add(
+        Expression.Assign(indexes[0], Expression.Constant(0))
+      );
+
+      // Build the nested loops (one for each dimension) from the inside out
+      Expression innerLoop = null;
+      for(int index = dimensionCount - 1; index >= 0; --index) {
+        var loopVariables = new List<ParameterExpression>();
+        var loopExpressions = new List<Expression>();
+
+        // If we reached the end of the current array dimension, break the loop
+        loopExpressions.Add(
+          Expression.IfThen(
+            Expression.GreaterThanOrEqual(indexes[index], lengths[index]),
+            Expression.Break(labels[index])
+          )
+        );
+
+        if(innerLoop == null) {
+          // The innermost loop clones an actual array element
+
+          if(elementType.IsPrimitive || (elementType == typeof(string))) {
+            // Primitive array elements can be copied by simple assignment. This case
+            // should not occur since Array.Clone() should be used instead.
+            loopExpressions.Add(
+              Expression.Assign(
+                Expression.ArrayAccess(clone, indexes),
+                Expression.ArrayAccess(original, indexes)
+              )
+            );
+          } else if(elementType.IsValueType) {
+            // Arrays of complex value types can be transferred by assigning all propertys
+            // of the source array element to the destination array element (cloning
+            // any nested reference types appropriately)
+            generatePropertyBasedComplexTypeTransferExpressions(
+              elementType,
+              Expression.ArrayAccess(original, indexes),
+              Expression.ArrayAccess(clone, indexes),
+              variables,
+              loopExpressions
+            );
+
+          } else {
+            // Arrays of reference types need to be cloned by creating a new instance
+            // of the reference type and then transferring the propertys over
+            ParameterExpression originalElement = Expression.Variable(elementType);
+            loopVariables.Add(originalElement);
+
+            loopExpressions.Add(
+              Expression.Assign(originalElement, Expression.ArrayAccess(original, indexes))
+            );
+
+            var nestedVariables = new List<ParameterExpression>();
+            var nestedTransferExpressions = new List<Expression>();
+
+            // A nested array should be cloned by directly creating a new array (not invoking
+            // a cloner) since you cannot derive from an array
+            if(elementType.IsArray) {
+              Expression clonedElement;
+
+              Type nestedElementType = elementType.GetElementType();
+              if(nestedElementType.IsPrimitive || (nestedElementType == typeof(string))) {
+                clonedElement = generatePropertyBasedPrimitiveArrayTransferExpressions(
+                  elementType, originalElement, nestedVariables, nestedTransferExpressions
+                );
+              } else {
+                clonedElement = generatePropertyBasedComplexArrayTransferExpressions(
+                  elementType, originalElement, nestedVariables, nestedTransferExpressions
+                );
+              }
+              nestedTransferExpressions.Add(
+                Expression.Assign(Expression.ArrayAccess(clone, indexes), clonedElement)
+              );
+            } else {
+              // Complex types are cloned by checking their actual, concrete type (propertys
+              // may be typed to an interface or base class) and requesting a cloner for that
+              // type during runtime
+              MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
+                "getOrCreateDeepPropertyBasedCloner",
+                BindingFlags.NonPublic | BindingFlags.Static
+              );
+              MethodInfo getTypeMethodInfo = typeof(object).GetMethod("GetType");
+              MethodInfo invokeMethodInfo = typeof(Func<object, object>).GetMethod("Invoke");
+
+              // Generate expressions to do this:
+              //   clone.SomeProperty = getOrCreateDeepPropertyBasedCloner(
+              //     original.SomeProperty.GetType()
+              //   ).Invoke(original.SomeProperty);
+              nestedTransferExpressions.Add(
+                Expression.Assign(
+                  Expression.ArrayAccess(clone, indexes),
+                  Expression.Convert(
+                    Expression.Call(
+                      Expression.Call(
+                        getOrCreateClonerMethodInfo,
+                        Expression.Call(originalElement, getTypeMethodInfo)
+                      ),
+                      invokeMethodInfo,
+                      originalElement
+                    ),
+                    elementType
+                  )
+                )
+              );
+            }
+
+            // Whether array-in-array of reference-type-in-array, we need a null check before
+            // doing anything to avoid NullReferenceExceptions for unset members
+            loopExpressions.Add(
+              Expression.IfThen(
+                Expression.NotEqual(originalElement, Expression.Constant(null)),
+                Expression.Block(
+                  nestedVariables,
+                  nestedTransferExpressions
+                )
+              )
+            );
+          }
+
+        } else {
+          // Outer loops of any level just reset the inner loop's indexer and execute
+          // the inner loop
+          loopExpressions.Add(
+            Expression.Assign(indexes[index + 1], Expression.Constant(0))
+          );
+          loopExpressions.Add(innerLoop);
+        }
+
+        // Each time we executed the loop instructions, increment the indexer
+        loopExpressions.Add(Expression.PreIncrementAssign(indexes[index]));
+
+        // Build the loop using the expressions recorded above
+        innerLoop = Expression.Loop(
+          Expression.Block(loopVariables, loopExpressions),
+          labels[index]
+        );
+      }
+
+      // After the loop builder has finished, the innerLoop variable contains
+      // the entire hierarchy of nested loops, so add this to the clone expressions.
+      transferExpressions.Add(innerLoop);
+
+      return clone;
+    }
+
+    /// <summary>Generates state transfer expressions to copy a complex type</summary>
+    /// <param name="clonedType">Complex type that will be cloned</param>
+    /// <param name="original">Variable expression for the original instance</param>
+    /// <param name="clone">Variable expression for the cloned instance</param>
+    /// <param name="variables">Receives variables used by the transfer expressions</param>
+    /// <param name="transferExpressions">Receives the generated transfer expressions</param>
+    private static void generatePropertyBasedComplexTypeTransferExpressions(
+      Type clonedType, // Actual, concrete type (not declared type)
+      Expression original, // Expected to be an object
+      Expression clone,	// As actual, concrete type
+      IList<ParameterExpression> variables,
+      ICollection<Expression> transferExpressions
+    ) {
+      // Enumerate all of the type's propertys and generate transfer expressions for each
+      PropertyInfo[] propertyInfos = clonedType.GetProperties(
+        BindingFlags.Public | BindingFlags.NonPublic |
+        BindingFlags.Instance | BindingFlags.FlattenHierarchy
+      );
+      for(int index = 0; index < propertyInfos.Length; ++index) {
+        PropertyInfo propertyInfo = propertyInfos[index];
+        Type propertyType = propertyInfo.PropertyType;
+
+        if(propertyType.IsPrimitive || (propertyType == typeof(string))) {
+          // Primitive types and strings can be transferred by simple assignment
+          transferExpressions.Add(
+            Expression.Assign(
+              Expression.Property(clone, propertyInfo),
+              Expression.Property(original, propertyInfo)
+            )
+          );
+        } else if(propertyType.IsValueType) {
+          // A nested value type is part of the parent and will have its propertys directly
+          // assigned without boxing, new instance creation or anything like that.
+          generatePropertyBasedComplexTypeTransferExpressions(
+            propertyType,
+            Expression.Property(original, propertyInfo),
+            Expression.Property(clone, propertyInfo),
+            variables,
+            transferExpressions
+          );
+        } else {
+          generatePropertyBasedReferenceTypeTransferExpressions(
+            original, clone, transferExpressions, propertyInfo, propertyType
+          );
+        }
+      }
+    }
+
+    /// <summary>
+    ///   Generates the expressions to transfer a reference type (array or class)
+    /// </summary>
+    /// <param name="original">Original value that will be cloned</param>
+    /// <param name="clone">Variable that will receive the cloned value</param>
+    /// <param name="transferExpressions">
+    ///   Receives the expression generated to transfer the values
+    /// </param>
+    /// <param name="propertyInfo">Reflection informations about the property being cloned</param>
+    /// <param name="propertyType">Type of the property being cloned</param>
+    private static void generatePropertyBasedReferenceTypeTransferExpressions(
+      Expression original,
+      Expression clone,
+      ICollection<Expression> transferExpressions,
+      PropertyInfo propertyInfo,
+      Type propertyType
+    ) {
+      // Reference types and arrays require special care because they can be null,
+      // so gather the transfer expressions in a separate block for the null check
+      var propertyTransferExpressions = new List<Expression>();
+      var propertyVariables = new List<ParameterExpression>();
+
+      if(propertyType.IsArray) {
+        // Arrays need to be cloned element-by-element
+        Expression propertyClone;
+
+        Type elementType = propertyType.GetElementType();
+        if(elementType.IsPrimitive || (elementType == typeof(string))) {
+          // For primitive arrays, the Array.Clone() method is sufficient
+          propertyClone = generatePropertyBasedPrimitiveArrayTransferExpressions(
+            propertyType,
+            Expression.Property(original, propertyInfo),
+            propertyVariables,
+            propertyTransferExpressions
+          );
+        } else {
+          // Arrays of complex types require manual cloning
+          propertyClone = generatePropertyBasedComplexArrayTransferExpressions(
+            propertyType,
+            Expression.Property(original, propertyInfo),
+            propertyVariables,
+            propertyTransferExpressions
+          );
+        }
+
+        // Add the assignment to the transfer expressions. The array transfer expression
+        // generator will either have set up a temporary variable to hold the array or
+        // returned the conversion expression straight away
+        propertyTransferExpressions.Add(
+          Expression.Assign(Expression.Property(clone, propertyInfo), propertyClone)
+        );
+      } else {
+        // Complex types are cloned by checking their actual, concrete type (propertys
+        // may be typed to an interface or base class) and requesting a cloner for that
+        // type during runtime
+        MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
+          "getOrCreateDeepPropertyBasedCloner",
+          BindingFlags.NonPublic | BindingFlags.Static
+        );
+        MethodInfo getTypeMethodInfo = typeof(object).GetMethod("GetType");
+        MethodInfo invokeMethodInfo = typeof(Func<object, object>).GetMethod("Invoke");
+
+        // Generate expressions to do this:
+        //   clone.SomeProperty = getOrCreateDeepPropertyBasedCloner(
+        //     original.SomeProperty.GetType()
+        //   ).Invoke(original.SomeProperty);
+        propertyTransferExpressions.Add(
+          Expression.Assign(
+            Expression.Property(clone, propertyInfo),
+            Expression.Convert(
+              Expression.Call(
+                Expression.Call(
+                  getOrCreateClonerMethodInfo,
+                  Expression.Call(
+                    Expression.Property(original, propertyInfo), getTypeMethodInfo
+                  )
+                ),
+                invokeMethodInfo,
+                Expression.Property(original, propertyInfo)
+              ),
+              propertyType
+            )
+          )
+        );
+      }
+
+      // Wrap up the generated array or complex reference type transfer expressions
+      // in a null check so the property is skipped if it is not holding an instance.
+      transferExpressions.Add(
+        Expression.IfThen(
+          Expression.NotEqual(
+            Expression.Property(original, propertyInfo), Expression.Constant(null)
+          ),
+          Expression.Block(propertyVariables, propertyTransferExpressions)
+        )
+      );
+    }
+
+#endif
 
   }
 

Source/Cloning/ExpressionTreeCloner.Test.cs

@@ -29,7 +29,7 @@ namespace Nuclex.Support.Cloning {
 
   /// <summary>Unit Test for the expression tree-based cloner</summary>
   [TestFixture]
-	public class ExpressionTreeClonerTest : CloneFactoryTest {
+  internal class ExpressionTreeClonerTest : CloneFactoryTest {
 
     /// <summary>Initializes a new unit test suite for the reflection cloner</summary>
     public ExpressionTreeClonerTest() {

Source/Cloning/ReflectionCloner.Test.cs

@@ -29,7 +29,7 @@ namespace Nuclex.Support.Cloning {
 
   /// <summary>Unit Test for the reflection-based cloner</summary>
   [TestFixture]
-  public class ReflectionClonerTest : CloneFactoryTest {
+  internal class ReflectionClonerTest : CloneFactoryTest {
 
     /// <summary>Initializes a new unit test suite for the reflection cloner</summary>
     public ReflectionClonerTest() {

Source/Cloning/ReflectionCloner.cs

@@ -20,6 +20,7 @@ License along with this library
 
 using System;
 using System.Reflection;
+using System.Runtime.Serialization;
 
 namespace Nuclex.Support.Cloning {
 
@@ -119,7 +120,7 @@ namespace Nuclex.Support.Cloning {
     /// <returns>A clone of the original instance</returns>
     private static object shallowCloneComplexFieldBased(object original) {
       Type originalType = original.GetType();
-      object clone = Activator.CreateInstance(originalType);
+			object clone = FormatterServices.GetUninitializedObject(originalType);
 
       FieldInfo[] fieldInfos = originalType.GetFields(
         BindingFlags.Public | BindingFlags.NonPublic |
@@ -196,7 +197,7 @@ namespace Nuclex.Support.Cloning {
     /// <returns>A clone of the original instance</returns>
     private static object deepCloneComplexFieldBased(object original) {
       Type originalType = original.GetType();
-      object clone = Activator.CreateInstance(originalType);
+			object clone = FormatterServices.GetUninitializedObject(originalType);
 
       FieldInfo[] fieldInfos = originalType.GetFields(
         BindingFlags.Public | BindingFlags.NonPublic |

Source/Cloning/SerializationCloner.Test.cs

@@ -29,7 +29,7 @@ namespace Nuclex.Support.Cloning {
 
   /// <summary>Unit Test for the binary serializer-based cloner</summary>
   [TestFixture]
-  public class SerializationClonerTest : CloneFactoryTest {
+  internal class SerializationClonerTest : CloneFactoryTest {
 
     /// <summary>Initializes a new unit test suite for the reflection cloner</summary>
     public SerializationClonerTest() {