nuclex-shared-dotnet/Nuclex.Support
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Expression tree cloner now transfers the fields of structures (of any nesting level)

Browse Source 
git-svn-id: file:///srv/devel/repo-conversion/nusu@234 d2e56fa2-650e-0410-a79f-9358c0239efd
This commit is contained in:
Markus Ewald 2012-02-06 08:43:23 +00:00
parent 3267e399ee
commit 62d0c6611c
2 changed files with 65 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Source/Cloning/ExpressionTreeCloner.Test.cs
View File

@ -137,7 +137,7 @@ namespace Nuclex.Support.Cloning {
[Test]
public void DeepFieldBasedClonesOfValueTypesCanBeMade() {
HierarchicalValueType original = CreateValueType();
//HierarchicalValueType clone = this.cloneFactory.DeepClone(original, false);
HierarchicalValueType clone = this.cloneFactory.DeepClone(original, false);
//VerifyClone(ref original, ref clone, isDeepClone: true, isPropertyBasedClone: false);
}

128
Source/Cloning/ExpressionTreeCloner.cs
View File

@ -146,36 +146,19 @@ 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 generatePrimitiveArrayTransferExpressions(
private static Expression generatePrimitiveArrayTransferExpressions(
Type clonedType,
Expression original,
ICollection<ParameterExpression> variables,
ICollection<Expression> transferExpressions
) {
// We need a temporary variable because the IfThen expression is not suitable
// for returning values
ParameterExpression clone = Expression.Variable(typeof(object));
variables.Add(clone);
// If the array referenced by 'original' is not null, call Array.Clone() on it
// and assign the result to our temporary variable
MethodInfo arrayCloneMethodInfo = typeof(Array).GetMethod("Clone");
transferExpressions.Add(
Expression.IfThen(
Expression.NotEqual(original, Expression.Constant(null)),
Expression.Assign(
clone,
Expression.Convert(
return Expression.Convert(
Expression.Call(
Expression.Convert(original, typeof(Array)), arrayCloneMethodInfo
),
clonedType
)
)
)
);
return clone;
}
/// <summary>
@ -192,8 +175,7 @@ namespace Nuclex.Support.Cloning {
IList<ParameterExpression> variables,
ICollection<Expression> transferExpressions
) {
// We need a temporary variable because the IfThen expression is not suitable
// for returning values
// We need a temporary variable in order to transfer the elements of the array
ParameterExpression clone = Expression.Variable(clonedType);
variables.Add(clone);
ParameterExpression typedOriginal = Expression.Variable(clonedType);
@ -290,8 +272,6 @@ namespace Nuclex.Support.Cloning {
}
}
// Only execute the array transfer expressions if the array is not null
transferExpressions.Add(
Expression.IfThen(
@ -306,21 +286,16 @@ namespace Nuclex.Support.Cloning {
/// <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>
/// <returns>The variable holding the cloned array</returns>
private static ParameterExpression generateComplexTypeTransferExpressions(
Type clonedType,
Expression original,
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
) {
// Create a variable to hold the clone and begin by assigning a new instance of
// the cloned type to it.
ParameterExpression clone = Expression.Variable(clonedType);
variables.Add(clone);
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);
@ -348,14 +323,19 @@ namespace Nuclex.Support.Cloning {
)
);
} else if(fieldType.IsValueType) {
// TODO: Copy field without null check
generateComplexTypeTransferExpressions(
fieldType,
Expression.Field(typedOriginal, fieldInfo),
Expression.Field(clone, fieldInfo),
variables,
transferExpressions
);
} else {
var fieldTransferExpressions = new List<Expression>();
var fieldVariables = new List<ParameterExpression>();
Expression fieldClone;
if(fieldType.IsArray) {
/*
Type elementType = fieldType.GetElementType();
if(elementType.IsPrimitive || (elementType == typeof(string))) {
fieldClone = generatePrimitiveArrayTransferExpressions(
@ -372,9 +352,10 @@ namespace Nuclex.Support.Cloning {
fieldTransferExpressions
);
}
*/
fieldClone = Expression.Field(typedOriginal, fieldInfo);
fieldTransferExpressions.Add(fieldClone);
fieldTransferExpressions.Add(
Expression.Assign(Expression.Field(clone, fieldInfo), fieldClone)
);
} else {
MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
"getOrCreateDeepFieldBasedCloner",
@ -414,8 +395,6 @@ namespace Nuclex.Support.Cloning {
}
}
return clone;
}
/// <summary>Compiles a method that creates a clone of an object</summary>
@ -431,44 +410,59 @@ namespace Nuclex.Support.Cloning {
// Primitives and strings are copied on direct assignment
transferExpressions.Add(original);
} else if(clonedType.IsArray) {
ParameterExpression clone;
// Arrays need to be cloned element-by-element
Type elementType = clonedType.GetElementType();
if(elementType.IsPrimitive || (elementType == typeof(string))) {
clone = generatePrimitiveArrayTransferExpressions(
clonedType, original, variables, transferExpressions
);
} else {
clone = generateComplexArrayTransferExpressions(
clonedType, original, variables, transferExpressions
);
}
transferExpressions.Add(clone);
//clone = original;
} else {
if(elementType.IsPrimitive || (elementType == typeof(string))) {
// For primitive arrays, the Array.Clone() method is sufficient
transferExpressions.Add(
generateComplexTypeTransferExpressions(
generatePrimitiveArrayTransferExpressions(
clonedType, original, variables, transferExpressions
)
);
} else {
// Arrays of complex types require manual cloning
transferExpressions.Add(
generateComplexArrayTransferExpressions(
clonedType, original, variables, transferExpressions
)
);
}
Expression<Func<object, object>> expression;
if(variables.Count > 0) {
expression = Expression.Lambda<Func<object, object>>(
Expression.Block(variables, transferExpressions), original
);
} else if(transferExpressions.Count == 1) {
expression = Expression.Lambda<Func<object, object>>(
transferExpressions[0], original
);
} else {
expression = Expression.Lambda<Func<object, object>>(
Expression.Block(transferExpressions), original
// 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)));
// Generate the expressions required to transfer the type field by field
generateComplexTypeTransferExpressions(
clonedType, original, 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));
}
Expression<Func<object, object>> expression = Expression.Lambda<Func<object, object>>(
resultExpression, original
);
return expression.Compile();
}