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Expression tree cloner can now also create shallow field based clones

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git-svn-id: file:///srv/devel/repo-conversion/nusu@241 d2e56fa2-650e-0410-a79f-9358c0239efd
This commit is contained in:
Markus Ewald 2012-02-08 12:17:35 +00:00
parent e7d1c9720b
commit cd6cec42d3
8 changed files with 794 additions and 592 deletions
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6
Nuclex.Support (net-4.0).csproj
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@ -63,6 +63,12 @@
<Compile Include="Source\Cloning\CloneFactoryTest.cs" /> <Compile Include="Source\Cloning\CloneFactoryTest.cs" />
<Compile Include="Source\Cloning\CloningParameters.cs" /> <Compile Include="Source\Cloning\CloningParameters.cs" />
<Compile Include="Source\Cloning\ExpressionTreeCloner.cs" /> <Compile Include="Source\Cloning\ExpressionTreeCloner.cs" />
<Compile Include="Source\Cloning\ExpressionTreeCloner.FieldBased.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile>
<Compile Include="Source\Cloning\ExpressionTreeCloner.PropertyBased.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile>
<Compile Include="Source\Cloning\ExpressionTreeCloner.Test.cs"> <Compile Include="Source\Cloning\ExpressionTreeCloner.Test.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon> <DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile> </Compile>

6
Nuclex.Support (xna-4.0-phone7).csproj
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@ -94,6 +94,12 @@
<Compile Include="Source\Cloning\CloneFactoryTest.cs" /> <Compile Include="Source\Cloning\CloneFactoryTest.cs" />
<Compile Include="Source\Cloning\CloningParameters.cs" /> <Compile Include="Source\Cloning\CloningParameters.cs" />
<Compile Include="Source\Cloning\ExpressionTreeCloner.cs" /> <Compile Include="Source\Cloning\ExpressionTreeCloner.cs" />
<Compile Include="Source\Cloning\ExpressionTreeCloner.FieldBased.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile>
<Compile Include="Source\Cloning\ExpressionTreeCloner.PropertyBased.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile>
<Compile Include="Source\Cloning\ExpressionTreeCloner.Test.cs"> <Compile Include="Source\Cloning\ExpressionTreeCloner.Test.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon> <DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile> </Compile>

6
Nuclex.Support (xna-4.0-xbox360).csproj
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@ -105,6 +105,12 @@
<Compile Include="Source\Cloning\CloneFactoryTest.cs" /> <Compile Include="Source\Cloning\CloneFactoryTest.cs" />
<Compile Include="Source\Cloning\CloningParameters.cs" /> <Compile Include="Source\Cloning\CloningParameters.cs" />
<Compile Include="Source\Cloning\ExpressionTreeCloner.cs" /> <Compile Include="Source\Cloning\ExpressionTreeCloner.cs" />
<Compile Include="Source\Cloning\ExpressionTreeCloner.FieldBased.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile>
<Compile Include="Source\Cloning\ExpressionTreeCloner.PropertyBased.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile>
<Compile Include="Source\Cloning\ExpressionTreeCloner.Test.cs"> <Compile Include="Source\Cloning\ExpressionTreeCloner.Test.cs">
<DependentUpon>ExpressionTreeCloner.cs</DependentUpon> <DependentUpon>ExpressionTreeCloner.cs</DependentUpon>
</Compile> </Compile>

2
Source/Cloning/CloneFactoryTest.cs
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@ -123,6 +123,8 @@ namespace Nuclex.Support.Cloning {
HierarchicalReferenceType original, HierarchicalReferenceType clone, HierarchicalReferenceType original, HierarchicalReferenceType clone,
bool isDeepClone, bool isPropertyBasedClone bool isDeepClone, bool isPropertyBasedClone
) { ) {
Assert.AreNotSame(original, clone);
if(isPropertyBasedClone) { if(isPropertyBasedClone) {
Assert.AreEqual(0, clone.TestField); Assert.AreEqual(0, clone.TestField);
Assert.AreEqual(0, clone.ValueTypeField.TestField); Assert.AreEqual(0, clone.ValueTypeField.TestField);

579
Source/Cloning/ExpressionTreeCloner.FieldBased.cs Normal file
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@ -0,0 +1,579 @@
#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2010 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
#if !(XBOX360 || WINDOWS_PHONE)
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;
namespace Nuclex.Support.Cloning {
partial class ExpressionTreeCloner : ICloneFactory {
/// <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 field to be cloned and second when runner the matching
/// cloner for the field.
/// </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> createDeepFieldBasedCloner(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(
generatePrimitiveArrayTransferExpressions(
clonedType, original, variables, transferExpressions
)
);
} else {
// 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
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(
generateComplexArrayTransferExpressions(
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 fields 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 field by field
generateComplexTypeTransferExpressions(
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>Compiles a method that creates a shallow 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>
private static Func<object, object> createShallowFieldBasedCloner(Type clonedType) {
ParameterExpression original = Expression.Parameter(typeof(object), "original");
var transferExpressions = new List<Expression>();
var variables = new List<ParameterExpression>();
if(clonedType.IsPrimitive || clonedType.IsValueType || (clonedType == typeof(string))) {
// Primitives and strings are copied on direct assignment
transferExpressions.Add(original);
} else if(clonedType.IsArray) {
transferExpressions.Add(
generatePrimitiveArrayTransferExpressions(
clonedType, original, 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);
// 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
ParameterExpression typedOriginal = Expression.Variable(clonedType);
variables.Add(typedOriginal);
transferExpressions.Add(
Expression.Assign(typedOriginal, Expression.Convert(original, clonedType))
);
// Give it a new instance of the type being cloned
transferExpressions.Add(Expression.Assign(clone, Expression.New(clonedType)));
// Enumerate all of the type's fields and generate transfer expressions for each
FieldInfo[] fieldInfos = clonedType.GetFields(
BindingFlags.Public | BindingFlags.NonPublic |
BindingFlags.Instance | BindingFlags.FlattenHierarchy
);
for(int index = 0; index < fieldInfos.Length; ++index) {
FieldInfo fieldInfo = fieldInfos[index];
transferExpressions.Add(
Expression.Assign(
Expression.Field(clone, fieldInfo),
Expression.Field(typedOriginal, fieldInfo)
)
);
}
// 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 generatePrimitiveArrayTransferExpressions(
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 generateComplexArrayTransferExpressions(
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))
);
// We use a temporary variable to store the element
ParameterExpression element = Expression.Variable(elementType);
variables.Add(element);
// 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 fields
// of the source array element to the destination array element (cloning
// any nested reference types appropriately)
generateComplexTypeTransferExpressions(
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 fields 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 = generatePrimitiveArrayTransferExpressions(
elementType, originalElement, nestedVariables, nestedTransferExpressions
);
} else {
clonedElement = generateComplexArrayTransferExpressions(
elementType, originalElement, nestedVariables, nestedTransferExpressions
);
}
nestedTransferExpressions.Add(
Expression.Assign(Expression.ArrayAccess(clone, indexes), clonedElement)
);
} else {
// Complex types are cloned by checking their actual, concrete type (fields
// may be typed to an interface or base class) and requesting a cloner for that
// type during runtime
MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
"getOrCreateDeepFieldBasedCloner",
BindingFlags.NonPublic | BindingFlags.Static
);
MethodInfo getTypeMethodInfo = typeof(object).GetMethod("GetType");
MethodInfo invokeMethodInfo = typeof(Func<object, object>).GetMethod("Invoke");
// Generate expressions to do this:
// clone.SomeField = getOrCreateDeepFieldBasedCloner(
// original.SomeField.GetType()
// ).Invoke(original.SomeField);
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 generateComplexTypeTransferExpressions(
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 fields and generate transfer expressions for each
FieldInfo[] fieldInfos = clonedType.GetFields(
BindingFlags.Public | BindingFlags.NonPublic |
BindingFlags.Instance | BindingFlags.FlattenHierarchy
);
for(int index = 0; index < fieldInfos.Length; ++index) {
FieldInfo fieldInfo = fieldInfos[index];
Type fieldType = fieldInfo.FieldType;
if(fieldType.IsPrimitive || (fieldType == typeof(string))) {
// Primitive types and strings can be transferred by simple assignment
transferExpressions.Add(
Expression.Assign(
Expression.Field(clone, fieldInfo),
Expression.Field(original, fieldInfo)
)
);
} 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(
fieldType,
Expression.Field(original, fieldInfo),
Expression.Field(clone, fieldInfo),
variables,
transferExpressions
);
} else {
generateReferenceTypeTransferExpressions(
original, clone, transferExpressions, fieldInfo, fieldType
);
}
}
}
/// <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="fieldInfo">Reflection informations about the field being cloned</param>
/// <param name="fieldType">Type of the field being cloned</param>
private static void generateReferenceTypeTransferExpressions(
Expression original,
Expression clone,
ICollection<Expression> transferExpressions,
FieldInfo fieldInfo,
Type fieldType
) {
// 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 fieldTransferExpressions = new List<Expression>();
var fieldVariables = new List<ParameterExpression>();
if(fieldType.IsArray) {
// Arrays need to be cloned element-by-element
Expression fieldClone;
Type elementType = fieldType.GetElementType();
if(elementType.IsPrimitive || (elementType == typeof(string))) {
// For primitive arrays, the Array.Clone() method is sufficient
fieldClone = generatePrimitiveArrayTransferExpressions(
fieldType,
Expression.Field(original, fieldInfo),
fieldVariables,
fieldTransferExpressions
);
} else {
// Arrays of complex types require manual cloning
fieldClone = generateComplexArrayTransferExpressions(
fieldType,
Expression.Field(original, fieldInfo),
fieldVariables,
fieldTransferExpressions
);
}
// 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
fieldTransferExpressions.Add(
Expression.Assign(Expression.Field(clone, fieldInfo), fieldClone)
);
} else {
// Complex types are cloned by checking their actual, concrete type (fields
// may be typed to an interface or base class) and requesting a cloner for that
// type during runtime
MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
"getOrCreateDeepFieldBasedCloner",
BindingFlags.NonPublic | BindingFlags.Static
);
MethodInfo getTypeMethodInfo = typeof(object).GetMethod("GetType");
MethodInfo invokeMethodInfo = typeof(Func<object, object>).GetMethod("Invoke");
// Generate expressions to do this:
// clone.SomeField = getOrCreateDeepFieldBasedCloner(
// original.SomeField.GetType()
// ).Invoke(original.SomeField);
fieldTransferExpressions.Add(
Expression.Assign(
Expression.Field(clone, fieldInfo),
Expression.Convert(
Expression.Call(
Expression.Call(
getOrCreateClonerMethodInfo,
Expression.Call(
Expression.Field(original, fieldInfo), getTypeMethodInfo
)
),
invokeMethodInfo,
Expression.Field(original, fieldInfo)
),
fieldType
)
)
);
}
// Wrap up the generated array or complex reference type transfer expressions
// in a null check so the field is skipped if it is not holding an instance.
transferExpressions.Add(
Expression.IfThen(
Expression.NotEqual(
Expression.Field(original, fieldInfo), Expression.Constant(null)
),
Expression.Block(fieldVariables, fieldTransferExpressions)
)
);
}
}
} // namespace Nuclex.Support.Cloning
#endif // !(XBOX360 || WINDOWS_PHONE)

39
Source/Cloning/ExpressionTreeCloner.PropertyBased.cs Normal file
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@ -0,0 +1,39 @@
#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2010 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
#if !(XBOX360 || WINDOWS_PHONE)
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;
namespace Nuclex.Support.Cloning {
partial class ExpressionTreeCloner : ICloneFactory {
// Not implement yet...
}
} // namespace Nuclex.Support.Cloning
#endif // !(XBOX360 || WINDOWS_PHONE)

207
Source/Cloning/ExpressionTreeCloner.Test.cs
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@ -27,131 +27,128 @@ using NUnit.Framework;
namespace Nuclex.Support.Cloning { namespace Nuclex.Support.Cloning {
/// <summary>Unit Test for the expression tree-based cloner</summary> /// <summary>Unit Test for the expression tree-based cloner</summary>
[TestFixture] [TestFixture]
public class ExpressionTreeClonerTest : CloneFactoryTest { public class ExpressionTreeClonerTest : CloneFactoryTest {
/// <summary>Initializes a new unit test suite for the reflection cloner</summary> /// <summary>Initializes a new unit test suite for the reflection cloner</summary>
public ExpressionTreeClonerTest() { public ExpressionTreeClonerTest() {
this.cloneFactory = new ExpressionTreeCloner(); this.cloneFactory = new ExpressionTreeCloner();
} }
/// <summary>Verifies that clones of primitive types can be created</summary> /// <summary>Verifies that clones of primitive types can be created</summary>
[Test] [Test]
public void PrimitiveTypesCanBeCloned() { public void PrimitiveTypesCanBeCloned() {
int original = 12345; int original = 12345;
int clone = this.cloneFactory.DeepClone(original, false); int clone = this.cloneFactory.DeepClone(original, false);
Assert.AreEqual(original, clone); Assert.AreEqual(original, clone);
} }
/// <summary>Verifies that shallow clones of arrays can be made</summary> /// <summary>Verifies that shallow clones of arrays can be made</summary>
[Test] [Test]
public void ReferenceTypesCanBeCloned() { public void ReferenceTypesCanBeCloned() {
var original = new TestReferenceType() { TestField = 123, TestProperty = 456 }; var original = new TestReferenceType() { TestField = 123, TestProperty = 456 };
TestReferenceType clone = this.cloneFactory.DeepClone(original, false); TestReferenceType clone = this.cloneFactory.DeepClone(original, false);
Assert.AreNotSame(original, clone); Assert.AreNotSame(original, clone);
Assert.AreEqual(original.TestField, clone.TestField); Assert.AreEqual(original.TestField, clone.TestField);
Assert.AreEqual(original.TestProperty, clone.TestProperty); Assert.AreEqual(original.TestProperty, clone.TestProperty);
} }
/// <summary>Verifies that shallow clones of arrays can be made</summary> /// <summary>Verifies that shallow clones of arrays can be made</summary>
[Test] [Test]
public void PrimitiveArraysCanBeCloned() { public void PrimitiveArraysCanBeCloned() {
var original = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 }; var original = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
int[] clone = this.cloneFactory.DeepClone(original, false); int[] clone = this.cloneFactory.DeepClone(original, false);
Assert.AreNotSame(original, clone); Assert.AreNotSame(original, clone);
CollectionAssert.AreEqual(original, clone); CollectionAssert.AreEqual(original, clone);
} }
#if false /// <summary>Verifies that shallow clones of arrays can be made</summary>
/// <summary>Verifies that shallow clones of arrays can be made</summary> [Test]
[Test] public void ShallowClonesOfArraysCanBeMade() {
public void ShallowClonesOfArraysCanBeMade() { var original = new TestReferenceType[] {
var original = new TestReferenceType[] {
new TestReferenceType() { TestField = 123, TestProperty = 456 } new TestReferenceType() { TestField = 123, TestProperty = 456 }
}; };
TestReferenceType[] clone = this.cloneFactory.ShallowClone(original, false); TestReferenceType[] clone = this.cloneFactory.ShallowClone(original, false);
Assert.AreSame(original[0], clone[0]); Assert.AreSame(original[0], clone[0]);
} }
#endif
/// <summary>Verifies that deep clones of arrays can be made</summary> /// <summary>Verifies that deep clones of arrays can be made</summary>
[Test] [Test]
public void DeepClonesOfArraysCanBeMade() { public void DeepClonesOfArraysCanBeMade() {
var original = new TestReferenceType[,] { var original = new TestReferenceType[,] {
{ {
new TestReferenceType() { TestField = 123, TestProperty = 456 } new TestReferenceType() { TestField = 123, TestProperty = 456 }
} }
}; };
TestReferenceType[,] clone = this.cloneFactory.DeepClone(original, false); TestReferenceType[,] clone = this.cloneFactory.DeepClone(original, false);
Assert.AreNotSame(original[0, 0], clone[0, 0]); Assert.AreNotSame(original[0, 0], clone[0, 0]);
Assert.AreEqual(original[0, 0].TestField, clone[0, 0].TestField); Assert.AreEqual(original[0, 0].TestField, clone[0, 0].TestField);
Assert.AreEqual(original[0, 0].TestProperty, clone[0, 0].TestProperty); Assert.AreEqual(original[0, 0].TestProperty, clone[0, 0].TestProperty);
} }
/// <summary>Verifies that deep clones of a generic list can be made</summary> /// <summary>Verifies that deep clones of a generic list can be made</summary>
[Test] [Test]
public void GenericListsCanBeCloned() { public void GenericListsCanBeCloned() {
var original = new List<int>(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 }); var original = new List<int>(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 });
List<int> clone = this.cloneFactory.DeepClone(original, false); List<int> clone = this.cloneFactory.DeepClone(original, false);
CollectionAssert.AreEqual(original, clone); CollectionAssert.AreEqual(original, clone);
} }
/// <summary>Verifies that deep clones of a generic dictionary can be made</summary> /// <summary>Verifies that deep clones of a generic dictionary can be made</summary>
[Test] [Test]
public void GenericDictionariesCanBeCloned() { public void GenericDictionariesCanBeCloned() {
var original = new Dictionary<int, string>(); var original = new Dictionary<int, string>();
original.Add(1, "one"); original.Add(1, "one");
Dictionary<int, string> clone = this.cloneFactory.DeepClone(original, false); Dictionary<int, string> clone = this.cloneFactory.DeepClone(original, false);
Assert.AreEqual("one", clone[1]); Assert.AreEqual("one", clone[1]);
} }
#if false /// <summary>
/// <summary> /// Verifies that a field-based shallow clone of a value type can be performed
/// Verifies that a field-based shallow clone of a value type can be performed /// </summary>
/// </summary> [Test]
[Test] public void ShallowFieldBasedClonesOfValueTypesCanBeMade() {
public void ShallowFieldBasedClonesOfValueTypesCanBeMade() { HierarchicalValueType original = CreateValueType();
HierarchicalValueType original = CreateValueType(); HierarchicalValueType clone = this.cloneFactory.ShallowClone(original, false);
HierarchicalValueType clone = this.cloneFactory.ShallowClone(original, false); VerifyClone(ref original, ref clone, isDeepClone: false, isPropertyBasedClone: false);
VerifyClone(ref original, ref clone, isDeepClone: false, isPropertyBasedClone: false); }
}
/// <summary> /// <summary>
/// Verifies that a field-based shallow clone of a reference type can be performed /// Verifies that a field-based shallow clone of a reference type can be performed
/// </summary> /// </summary>
[Test] [Test]
public void ShallowFieldBasedClonesOfReferenceTypesCanBeMade() { public void ShallowFieldBasedClonesOfReferenceTypesCanBeMade() {
HierarchicalReferenceType original = CreateReferenceType(); HierarchicalReferenceType original = CreateReferenceType();
HierarchicalReferenceType clone = this.cloneFactory.ShallowClone(original, false); HierarchicalReferenceType clone = this.cloneFactory.ShallowClone(original, false);
VerifyClone(original, clone, isDeepClone: false, isPropertyBasedClone: false); VerifyClone(original, clone, isDeepClone: false, isPropertyBasedClone: false);
} }
#endif
/// <summary>
/// Verifies that a field-based deep clone of a value type can be performed
/// </summary>
[Test]
public void DeepFieldBasedClonesOfValueTypesCanBeMade() {
HierarchicalValueType original = CreateValueType();
HierarchicalValueType clone = this.cloneFactory.DeepClone(original, false);
VerifyClone(ref original, ref clone, isDeepClone: true, isPropertyBasedClone: false);
}
/// <summary> /// <summary>
/// Verifies that a field-based deep clone of a reference type can be performed /// Verifies that a field-based deep clone of a value type can be performed
/// </summary> /// </summary>
[Test] [Test]
public void DeepFieldBasedClonesOfReferenceTypesCanBeMade() { public void DeepFieldBasedClonesOfValueTypesCanBeMade() {
HierarchicalReferenceType original = CreateReferenceType(); HierarchicalValueType original = CreateValueType();
HierarchicalReferenceType clone = this.cloneFactory.DeepClone(original, false); HierarchicalValueType clone = this.cloneFactory.DeepClone(original, false);
VerifyClone(original, clone, isDeepClone: true, isPropertyBasedClone: false); VerifyClone(ref original, ref clone, isDeepClone: true, isPropertyBasedClone: false);
} }
/// <summary>
/// Verifies that a field-based deep clone of a reference type can be performed
/// </summary>
[Test]
public void DeepFieldBasedClonesOfReferenceTypesCanBeMade() {
HierarchicalReferenceType original = CreateReferenceType();
HierarchicalReferenceType clone = this.cloneFactory.DeepClone(original, false);
VerifyClone(original, clone, isDeepClone: true, isPropertyBasedClone: false);
}
#if false #if false
/// <summary> /// <summary>
@ -197,10 +194,10 @@ namespace Nuclex.Support.Cloning {
} }
#endif #endif
/// <summary>Clone factory being tested</summary> /// <summary>Clone factory being tested</summary>
private ICloneFactory cloneFactory; private ICloneFactory cloneFactory;
} }
} // namespace Nuclex.Support.Cloning } // namespace Nuclex.Support.Cloning

541
Source/Cloning/ExpressionTreeCloner.cs
View File

@ -28,25 +28,16 @@ using System.Reflection;
namespace Nuclex.Support.Cloning { namespace Nuclex.Support.Cloning {
/// <summary>An action that takes its arguments as references to a structure</summary>
/// <typeparam name="TFirst">Type of the first argument to the method</typeparam>
/// <typeparam name="TSecond">Type of the second argument to the method</typeparam>
/// <param name="first">First argument to the method</param>
/// <param name="second">Second argument to the method</param>
public delegate void ReferenceAction<TFirst, TSecond>(ref TFirst first, ref TSecond second)
where TFirst : struct
where TSecond : struct;
/// <summary> /// <summary>
/// Cloning factory which uses expression trees to improve performance when cloning /// Cloning factory which uses expression trees to improve performance when cloning
/// is a high-frequency action. /// is a high-frequency action.
/// </summary> /// </summary>
public class ExpressionTreeCloner : ICloneFactory { public partial class ExpressionTreeCloner : ICloneFactory {
/// <summary>Initializes the static members of the expression tree cloner</summary> /// <summary>Initializes the static members of the expression tree cloner</summary>
static ExpressionTreeCloner() { static ExpressionTreeCloner() {
shallowCloners = new ConcurrentDictionary<Type, Func<object, object>>(); shallowFieldBasedCloners = new ConcurrentDictionary<Type, Func<object, object>>();
deepCloners = new ConcurrentDictionary<Type, Func<object, object>>(); deepFieldBasedCloners = new ConcurrentDictionary<Type, Func<object, object>>();
} }
/// <summary> /// <summary>
@ -87,7 +78,17 @@ namespace Nuclex.Support.Cloning {
public static TCloned ShallowClone<TCloned>( public static TCloned ShallowClone<TCloned>(
TCloned objectToClone, bool usePropertyBasedClone TCloned objectToClone, bool usePropertyBasedClone
) { ) {
throw new NotImplementedException("Not implemented yet"); object objectToCloneAsObject = objectToClone;
if(objectToCloneAsObject == null) {
return default(TCloned);
}
if(usePropertyBasedClone) {
throw new NotImplementedException("Not implemented yet");
} else {
Func<object, object> cloner = getOrCreateShallowFieldBasedCloner(typeof(TCloned));
return (TCloned)cloner(objectToCloneAsObject);
}
} }
/// <summary> /// <summary>
@ -121,478 +122,6 @@ namespace Nuclex.Support.Cloning {
return ExpressionTreeCloner.ShallowClone<TCloned>(objectToClone, usePropertyBasedClone); return ExpressionTreeCloner.ShallowClone<TCloned>(objectToClone, usePropertyBasedClone);
} }
/// <summary>
/// Retrieves the existing clone method for the specified type or compiles one if
/// none exists for the type yet
/// </summary>
/// <param name="clonedType">Type for which a clone method will be retrieved</param>
/// <returns>The clone method for the specified type</returns>
private static Func<object, object> getOrCreateDeepFieldBasedCloner(Type clonedType) {
Func<object, object> cloner;
if(!deepCloners.TryGetValue(clonedType, out cloner)) {
cloner = createDeepFieldBasedCloner(clonedType);
deepCloners.TryAdd(clonedType, cloner);
}
return cloner;
}
/// <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 generatePrimitiveArrayTransferExpressions(
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 generateComplexArrayTransferExpressions(
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) {
lengths.Add(Expression.Variable(typeof(int)));
variables.Add(lengths[index]);
indexes.Add(Expression.Variable(typeof(int)));
variables.Add(indexes[index]);
labels.Add(Expression.Label());
transferExpressions.Add(
Expression.Assign(
lengths[index],
Expression.Call(
original, arrayGetLengthMethodInfo, Expression.Constant(index)
)
)
);
}
// 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))
);
// We use a temporary variable to store the element
ParameterExpression element = Expression.Variable(elementType);
variables.Add(element);
// 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))) {
loopExpressions.Add(
Expression.Assign(
Expression.ArrayAccess(clone, indexes),
Expression.ArrayAccess(original, indexes)
)
);
} else if(elementType.IsValueType) {
generateComplexTypeTransferExpressions(
elementType,
Expression.ArrayAccess(original, indexes),
Expression.ArrayAccess(clone, indexes),
variables,
loopExpressions
);
} else {
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>();
if(elementType.IsArray) {
Expression clonedElement;
Type nestedElementType = elementType.GetElementType();
if(nestedElementType.IsPrimitive || (nestedElementType == typeof(string))) {
clonedElement = generatePrimitiveArrayTransferExpressions(
elementType, originalElement, nestedVariables, nestedTransferExpressions
);
} else {
clonedElement = generateComplexArrayTransferExpressions(
elementType, originalElement, nestedVariables, nestedTransferExpressions
);
}
nestedTransferExpressions.Add(
Expression.Assign(Expression.ArrayAccess(clone, indexes), clonedElement)
);
} else {
// Complex types are cloned by checking their actual, concrete type (fields
// may be typed to an interface or base class) and requesting a cloner for that
// type during runtime
MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
"getOrCreateDeepFieldBasedCloner",
BindingFlags.NonPublic | BindingFlags.Static
);
MethodInfo getTypeMethodInfo = typeof(object).GetMethod("GetType");
MethodInfo invokeMethodInfo = typeof(Func<object, object>).GetMethod("Invoke");
// Generate expressions to do this:
// clone.SomeField = getOrCreateDeepFieldBasedCloner(
// original.SomeField.GetType()
// ).Invoke(original.SomeField);
nestedTransferExpressions.Add(
Expression.Assign(
Expression.ArrayAccess(clone, indexes),
Expression.Convert(
Expression.Call(
Expression.Call(
getOrCreateClonerMethodInfo,
Expression.Call(originalElement, getTypeMethodInfo)
),
invokeMethodInfo,
originalElement
),
elementType
)
)
);
}
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 generateComplexTypeTransferExpressions(
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 fields and generate transfer expressions for each
FieldInfo[] fieldInfos = clonedType.GetFields(
BindingFlags.Public | BindingFlags.NonPublic |
BindingFlags.Instance | BindingFlags.FlattenHierarchy
);
for(int index = 0; index < fieldInfos.Length; ++index) {
FieldInfo fieldInfo = fieldInfos[index];
Type fieldType = fieldInfo.FieldType;
if(fieldType.IsPrimitive || (fieldType == typeof(string))) {
// Primitive types and strings can be transferred by simple assignment
transferExpressions.Add(
Expression.Assign(
Expression.Field(clone, fieldInfo),
Expression.Field(original, fieldInfo)
)
);
} 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(
fieldType,
Expression.Field(original, fieldInfo),
Expression.Field(clone, fieldInfo),
variables,
transferExpressions
);
} else {
generateReferenceTypeTransferExpressions(
original, clone, transferExpressions, fieldInfo, fieldType
);
}
}
}
/// <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="fieldInfo">Reflection informations about the field being cloned</param>
/// <param name="fieldType">Type of the field being cloned</param>
private static void generateReferenceTypeTransferExpressions(
Expression original,
Expression clone,
ICollection<Expression> transferExpressions,
FieldInfo fieldInfo,
Type fieldType
) {
// 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 fieldTransferExpressions = new List<Expression>();
var fieldVariables = new List<ParameterExpression>();
if(fieldType.IsArray) {
// Arrays need to be cloned element-by-element
Expression fieldClone;
Type elementType = fieldType.GetElementType();
if(elementType.IsPrimitive || (elementType == typeof(string))) {
// For primitive arrays, the Array.Clone() method is sufficient
fieldClone = generatePrimitiveArrayTransferExpressions(
fieldType,
Expression.Field(original, fieldInfo),
fieldVariables,
fieldTransferExpressions
);
} else {
// Arrays of complex types require manual cloning
fieldClone = generateComplexArrayTransferExpressions(
fieldType,
Expression.Field(original, fieldInfo),
fieldVariables,
fieldTransferExpressions
);
}
// 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
fieldTransferExpressions.Add(
Expression.Assign(Expression.Field(clone, fieldInfo), fieldClone)
);
} else {
// Complex types are cloned by checking their actual, concrete type (fields
// may be typed to an interface or base class) and requesting a cloner for that
// type during runtime
MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
"getOrCreateDeepFieldBasedCloner",
BindingFlags.NonPublic | BindingFlags.Static
);
MethodInfo getTypeMethodInfo = typeof(object).GetMethod("GetType");
MethodInfo invokeMethodInfo = typeof(Func<object, object>).GetMethod("Invoke");
// Generate expressions to do this:
// clone.SomeField = getOrCreateDeepFieldBasedCloner(
// original.SomeField.GetType()
// ).Invoke(original.SomeField);
fieldTransferExpressions.Add(
Expression.Assign(
Expression.Field(clone, fieldInfo),
Expression.Convert(
Expression.Call(
Expression.Call(
getOrCreateClonerMethodInfo,
Expression.Call(
Expression.Field(original, fieldInfo), getTypeMethodInfo
)
),
invokeMethodInfo,
Expression.Field(original, fieldInfo)
),
fieldType
)
)
);
}
// Wrap up the generated array or complex reference type transfer expressions
// in a null check so the field is skipped if it is not holding an instance.
transferExpressions.Add(
Expression.IfThen(
Expression.NotEqual(
Expression.Field(original, fieldInfo), Expression.Constant(null)
),
Expression.Block(fieldVariables, fieldTransferExpressions)
)
);
}
/// <summary>Compiles a method that creates a 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 field to be cloned and second when runner the matching
/// cloner for the field.
/// </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> createDeepFieldBasedCloner(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(
generatePrimitiveArrayTransferExpressions(
clonedType, original, variables, transferExpressions
)
);
} else {
// 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
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(
generateComplexArrayTransferExpressions(
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 fields 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 field by field
generateComplexTypeTransferExpressions(
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();
}
#if false #if false
/// <summary> /// <summary>
/// Transfers the state of one object into another, creating clones of referenced objects /// Transfers the state of one object into another, creating clones of referenced objects
@ -651,10 +180,48 @@ namespace Nuclex.Support.Cloning {
#endif #endif
/// <summary>
/// Retrieves the existing clone method for the specified type or compiles one if
/// none exists for the type yet
/// </summary>
/// <param name="clonedType">Type for which a clone method will be retrieved</param>
/// <returns>The clone method for the specified type</returns>
private static Func<object, object> getOrCreateShallowFieldBasedCloner(Type clonedType) {
Func<object, object> cloner;
if(!shallowFieldBasedCloners.TryGetValue(clonedType, out cloner)) {
cloner = createShallowFieldBasedCloner(clonedType);
shallowFieldBasedCloners.TryAdd(clonedType, cloner);
}
return cloner;
}
/// <summary>
/// Retrieves the existing clone method for the specified type or compiles one if
/// none exists for the type yet
/// </summary>
/// <param name="clonedType">Type for which a clone method will be retrieved</param>
/// <returns>The clone method for the specified type</returns>
private static Func<object, object> getOrCreateDeepFieldBasedCloner(Type clonedType) {
Func<object, object> cloner;
if(!deepFieldBasedCloners.TryGetValue(clonedType, out cloner)) {
cloner = createDeepFieldBasedCloner(clonedType);
deepFieldBasedCloners.TryAdd(clonedType, cloner);
}
return cloner;
}
/// <summary>Compiled cloners that perform shallow clone operations</summary> /// <summary>Compiled cloners that perform shallow clone operations</summary>
private static ConcurrentDictionary<Type, Func<object, object>> shallowCloners; private static ConcurrentDictionary<Type, Func<object, object>> shallowFieldBasedCloners;
/// <summary>Compiled cloners that perform deep clone operations</summary> /// <summary>Compiled cloners that perform deep clone operations</summary>
private static ConcurrentDictionary<Type, Func<object, object>> deepCloners; private static ConcurrentDictionary<Type, Func<object, object>> deepFieldBasedCloners;
/// <summary>Compiled cloners that perform shallow clone operations</summary>
private static ConcurrentDictionary<Type, Func<object, object>> shallowPropertyBasedCloners;
/// <summary>Compiled cloners that perform deep clone operations</summary>
private static ConcurrentDictionary<Type, Func<object, object>> deepPropertyBasedCloners;
} }