/// <summary>
/// Generates state transfer expressions to copy a complex type.
/// </summary>
/// <param name="complexType">
/// Complex type that will be cloned.
/// </param>
/// <param name="source">
/// Variable expression for the original instance.
/// </param>
/// <param name="target">
/// Variable expression for the cloned instance.
/// </param>
/// <param name="expression">
/// Receives the generated transfer expressions.
/// </param>
private void GenerateFieldBasedComplexTypeTransferExpressions(Type complexType, Expression source, Expression target, ICollection <Expression> expression)
{
// Enumerate all of the type's fields and generate transfer expressions for each
ISet <FieldInfo> skipCloneFieldInfos;
IEnumerable <FieldInfo> fieldInfos = GetFieldInfosIncludingBaseClasses(complexType, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance, out skipCloneFieldInfos);
// For those field which skip deep copying, do shallow copying by assigning the field value from the source to the target
foreach (FieldInfo fieldInfo in skipCloneFieldInfos)
{
expression.Add(CloneExpressionHelper.CreateCopyFieldExpression(source, target, fieldInfo));
}
foreach (FieldInfo fieldInfo in fieldInfos)
{
Type fieldType = fieldInfo.FieldType;
if (IsTypePrimitiveOrString(fieldType))
{
expression.Add(CloneExpressionHelper.CreateCopyFieldExpression(source, target, 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.
this.GenerateFieldBasedComplexTypeTransferExpressions(fieldType, Expression.Field(source, fieldInfo), Expression.Field(target, fieldInfo), expression);
}
else
{
this.GenerateFieldBasedReferenceTypeTransferExpressions(source, target, expression, fieldInfo);
}
}
}
/// <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="expressions">
/// Receives the expression generated to transfer the values
/// </param>
/// <param name="fieldInfo">Reflection informations about the field being cloned</param>
private void GenerateFieldBasedReferenceTypeTransferExpressions(Expression original, Expression clone,
ICollection <Expression> expressions, FieldInfo fieldInfo)
{
// 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 fieldExpressions = new List <Expression>();
var fieldVariables = new List <ParameterExpression>();
var fieldType = fieldInfo.FieldType;
if (fieldType.IsArray)
{
Expression fieldClone = GenerateFieldBasedComplexArrayTransferExpressions(
fieldType,
fieldType.GetElementType(),
Expression.Field(original, fieldInfo),
fieldVariables,
fieldExpressions);
fieldExpressions.Add(CloneExpressionHelper.CreateSetFieldExpression(clone, fieldClone, fieldInfo));
}
else
{
fieldExpressions.Add(CloneExpressionHelper.CreateCopyComplexFieldExpression(original, clone,
fieldInfo, _objectDictionary));
}
expressions.Add(
Expression.IfThen(
Expression.NotEqual(Expression.Field(original, fieldInfo), Expression.Constant(null)),
Expression.Block(fieldVariables, fieldExpressions)));
}
/// <summary>
/// Generates state transfer expressions to copy a complex type
/// </summary>
/// <param name="complexType">Complex type that will be cloned</param>
/// <param name="source">Variable expression for the original instance</param>
/// <param name="target">Variable expression for the cloned instance</param>
/// <param name="expression">Receives the generated transfer expressions</param>
private void GenerateFieldBasedComplexTypeTransferExpressions(Type complexType, Expression source,
Expression target, ICollection <Expression> expression)
{
// Enumerate all of the type's fields and generate transfer expressions for each
ISet <FieldInfo> skipCloneFieldInfos;
var fieldInfos = GetFieldInfosIncludingBaseClasses(
complexType,
BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance,
out skipCloneFieldInfos);
// For those field which skip deep copying, do shallow copying by assigning the field value from the source to the target
foreach (var fieldInfo in skipCloneFieldInfos)
{
expression.Add(CloneExpressionHelper.CreateCopyFieldExpression(source, target, fieldInfo));
}
foreach (var fieldInfo in fieldInfos)
{
var fieldType = fieldInfo.FieldType;
if (fieldType.Equals(typeof(DataTable)))
{
expression.Add(CloneExpressionHelper.CreateCopyFieldExpression(source, target, fieldInfo));
}
else if (IsTypePrimitiveOrString(fieldType))
{
expression.Add(CloneExpressionHelper.CreateCopyFieldExpression(source, target, fieldInfo));
}
else if (fieldType.IsValueType)
{
GenerateFieldBasedComplexTypeTransferExpressions(fieldType, Expression.Field(source, fieldInfo),
Expression.Field(target, fieldInfo), expression);
}
else
{
GenerateFieldBasedReferenceTypeTransferExpressions(source, target, expression, fieldInfo);
}
}
}
/// <summary>
/// Generates state transfer expressions to copy an array of complex types.
/// </summary>
/// <param name="arrayType">
/// Type of array that will be cloned.
/// </param>
/// <param name="elementType">
/// Type of the elements of the array.
/// </param>
/// <param name="originalArray">
/// Variable expression for the original array.
/// </param>
/// <param name="arrayVariables">
/// Receives variables used by the transfer expressions.
/// </param>
/// <param name="arrayExpressions">
/// Receives the generated transfer expressions.
/// </param>
/// <returns>
/// The variable holding the cloned array.
/// </returns>
private ParameterExpression GenerateFieldBasedComplexArrayTransferExpressions(Type arrayType, Type elementType, Expression originalArray, ICollection <ParameterExpression> arrayVariables, ICollection <Expression> arrayExpressions)
{
// We need a temporary variable in order to transfer the elements of the array
ParameterExpression arrayClone = Expression.Variable(arrayType);
arrayVariables.Add(arrayClone);
int dimensionCount = arrayType.GetArrayRank();
List <ParameterExpression> lengths = new List <ParameterExpression>();
List <ParameterExpression> indexes = new List <ParameterExpression>();
List <LabelTarget> labels = new List <LabelTarget>();
// Retrieve the length of each of the array's dimensions
for (int index = 0; index < dimensionCount; ++index)
{
// Obtain the length of the array in the current dimension
lengths.Add(Expression.Variable(typeof(int)));
arrayVariables.Add(lengths[index]);
arrayExpressions.Add(Expression.Assign(lengths[index], Expression.Call(originalArray, ArrayGetLengthMethodInfo, Expression.Constant(index))));
// Set up a variable to index the array in this dimension
indexes.Add(Expression.Variable(typeof(int)));
arrayVariables.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
arrayExpressions.Add(Expression.Assign(arrayClone, 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.
arrayExpressions.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)
{
List <ParameterExpression> loopVariables = new List <ParameterExpression>();
List <Expression> loopExpressions = new List <Expression>
{
Expression.IfThen(Expression.GreaterThanOrEqual(indexes[index], lengths[index]), Expression.Break(labels[index]))
};
// If we reached the end of the current array dimension, break the loop
if (innerLoop == null)
{
// The innermost loop clones an actual array element
if (IsTypePrimitiveOrString(elementType))
{
loopExpressions.Add(Expression.Assign(Expression.ArrayAccess(arrayClone, indexes), Expression.ArrayAccess(originalArray, indexes)));
}
else if (elementType.IsValueType)
{
this.GenerateFieldBasedComplexTypeTransferExpressions(elementType, Expression.ArrayAccess(originalArray, indexes), Expression.ArrayAccess(arrayClone, indexes), loopExpressions);
}
else
{
List <ParameterExpression> nestedVariables = new List <ParameterExpression>();
List <Expression> nestedExpressions = 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)
{
Type nestedElementType = elementType.GetElementType();
Expression clonedElement = IsTypePrimitiveOrString(nestedElementType)
? GenerateFieldBasedPrimitiveArrayTransferExpressions(elementType, Expression.ArrayAccess(originalArray, indexes))
: this.GenerateFieldBasedComplexArrayTransferExpressions(elementType, nestedElementType, Expression.ArrayAccess(originalArray, indexes), nestedVariables, nestedExpressions);
nestedExpressions.Add(Expression.Assign(Expression.ArrayAccess(arrayClone, indexes), clonedElement));
}
else
{
nestedExpressions.Add(CloneExpressionHelper.CreateCopyComplexArrayTypeFieldExpression(Expression.ArrayAccess(originalArray, indexes), Expression.ArrayAccess(arrayClone, indexes), elementType, this._objectDictionary));
}
// 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(Expression.ArrayAccess(originalArray, indexes), Expression.Constant(null)),
Expression.Block(nestedVariables, nestedExpressions)));
}
}
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.
arrayExpressions.Add(innerLoop);
return(arrayClone);
}
