Added more comments and and done some minor refactoring
git-svn-id: file:///srv/devel/repo-conversion/nusu@238 d2e56fa2-650e-0410-a79f-9358c0239efd
This commit is contained in:
Markus Ewald
parent
28998dbdcf
commit
b2e484673d
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@ -208,21 +208,30 @@ namespace Nuclex.Support.Cloning {
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);
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}
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// Create a new (empty) array with the same dimensions and lengths as the original
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transferExpressions.Add(
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Expression.Assign(
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clone, Expression.NewArrayBounds(elementType, lengths)
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)
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);
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Expression innerLoop = null;
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// Initialize the indexer of the outer loop (indexers are initialized one up
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// in the loops (ie. before the loop using it begins), so we have to set this
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// one outside of the loop building code.
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transferExpressions.Add(
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Expression.Assign(indexes[0], Expression.Constant(0))
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);
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// We use a temporary variable to store the element
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ParameterExpression element = Expression.Variable(elementType);
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variables.Add(element);
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// Build the nested loops (one for each dimension) from the inside out
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Expression innerLoop = null;
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for(int index = dimensionCount - 1; index >= 0; --index) {
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var loopExpressions = new List<Expression>();
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// If we reached the end of the current array dimension, break the loop
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loopExpressions.Add(
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Expression.IfThen(
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Expression.GreaterThanOrEqual(indexes[index], lengths[index]),
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@ -231,6 +240,9 @@ namespace Nuclex.Support.Cloning {
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);
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if(innerLoop == null) {
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// The innermost loop clones an actual array element
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loopExpressions.Add(
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Expression.Assign(
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Expression.ArrayAccess(clone, indexes),
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@ -238,20 +250,26 @@ namespace Nuclex.Support.Cloning {
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)
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);
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} else {
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// Outer loops of any level just reset the inner loop's indexer and execute
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// the inner loop
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loopExpressions.Add(
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Expression.Assign(indexes[index + 1], Expression.Constant(0))
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);
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loopExpressions.Add(innerLoop);
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}
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// Each time we executed the loop instructions, increment the indexer
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loopExpressions.Add(Expression.PreIncrementAssign(indexes[index]));
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// Build the loop using the expressions recorded above
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innerLoop = Expression.Loop(
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Expression.Block(loopExpressions),
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labels[index]
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);
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}
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// After the loop builder has finished, the innerLoop variable contains
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// the entire hierarchy of nested loops, so add this to the clone expressions.
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transferExpressions.Add(innerLoop);
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return clone;
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@ -298,89 +316,111 @@ namespace Nuclex.Support.Cloning {
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transferExpressions
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);
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} else {
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// Reference types and arrays require special care because they can be null,
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// so gather the transfer expressions in a separate block for the null check
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Expression fieldClone;
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var fieldTransferExpressions = new List<Expression>();
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var fieldVariables = new List<ParameterExpression>();
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if(fieldType.IsArray) {
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// Arrays need to be cloned element-by-element
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Type elementType = fieldType.GetElementType();
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if(elementType.IsPrimitive || (elementType == typeof(string))) {
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// For primitive arrays, the Array.Clone() method is sufficient
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fieldClone = generatePrimitiveArrayTransferExpressions(
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fieldType,
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Expression.Field(original, fieldInfo),
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fieldVariables,
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fieldTransferExpressions
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);
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} else {
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// Arrays of complex types require manual cloning
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fieldClone = generateComplexArrayTransferExpressions(
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fieldType,
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Expression.Field(original, fieldInfo),
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fieldVariables,
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fieldTransferExpressions
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);
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}
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// Add the assignment to the transfer expressions. The array transfer expression
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// generator will either have set up a temporary variable to hold the array or
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// returned the conversion expression straight away
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fieldTransferExpressions.Add(
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Expression.Assign(Expression.Field(clone, fieldInfo), fieldClone)
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);
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} else {
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// Complex types are cloned by checking their actual, concrete type (fields
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// may be typed to an interface or base class) and requesting a cloner for that
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// type during runtime
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MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
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"getOrCreateDeepFieldBasedCloner",
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BindingFlags.NonPublic | BindingFlags.Static
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);
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MethodInfo getTypeMethodInfo = typeof(object).GetMethod("GetType");
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MethodInfo invokeMethodInfo = typeof(Func<object, object>).GetMethod("Invoke");
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// Generate expressions to do this:
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// clone.SomeField = getOrCreateDeepFieldBasedCloner(
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// original.SomeField.GetType()
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// ).Invoke(original.SomeField);
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fieldTransferExpressions.Add(
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Expression.Assign(
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Expression.Field(clone, fieldInfo),
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Expression.Convert(
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Expression.Call(
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Expression.Call(
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getOrCreateClonerMethodInfo,
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Expression.Call(
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Expression.Field(original, fieldInfo), getTypeMethodInfo
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)
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),
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invokeMethodInfo,
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Expression.Field(original, fieldInfo)
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),
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fieldType
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)
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)
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);
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}
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// Wrap up the generated array or complex reference type transfer expressions
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// in a null check so the field is skipped if it is not holding an instance.
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transferExpressions.Add(
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Expression.IfThen(
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Expression.NotEqual(
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Expression.Field(original, fieldInfo), Expression.Constant(null)
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),
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Expression.Block(fieldVariables, fieldTransferExpressions)
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)
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generateReferenceTypeTransferExpressions(
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original, clone, transferExpressions, fieldInfo, fieldType
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);
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}
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}
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}
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/// <summary>
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/// Generates the expressions to transfer a reference type (array or class)
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/// </summary>
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/// <param name="original">Original value that will be cloned</param>
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/// <param name="clone">Variable that will receive the cloned value</param>
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/// <param name="transferExpressions">
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/// Receives the expression generated to transfer the values
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/// </param>
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/// <param name="fieldInfo">Reflection informations about the field being cloned</param>
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/// <param name="fieldType">Type of the field being cloned</param>
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private static void generateReferenceTypeTransferExpressions(
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Expression original,
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Expression clone,
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ICollection<Expression> transferExpressions,
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FieldInfo fieldInfo,
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Type fieldType
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) {
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// Reference types and arrays require special care because they can be null,
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// so gather the transfer expressions in a separate block for the null check
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var fieldTransferExpressions = new List<Expression>();
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var fieldVariables = new List<ParameterExpression>();
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if(fieldType.IsArray) {
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// Arrays need to be cloned element-by-element
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Expression fieldClone;
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Type elementType = fieldType.GetElementType();
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if(elementType.IsPrimitive || (elementType == typeof(string))) {
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// For primitive arrays, the Array.Clone() method is sufficient
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fieldClone = generatePrimitiveArrayTransferExpressions(
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fieldType,
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Expression.Field(original, fieldInfo),
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fieldVariables,
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fieldTransferExpressions
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);
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} else {
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// Arrays of complex types require manual cloning
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fieldClone = generateComplexArrayTransferExpressions(
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fieldType,
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Expression.Field(original, fieldInfo),
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fieldVariables,
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fieldTransferExpressions
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);
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}
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// Add the assignment to the transfer expressions. The array transfer expression
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// generator will either have set up a temporary variable to hold the array or
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// returned the conversion expression straight away
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fieldTransferExpressions.Add(
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Expression.Assign(Expression.Field(clone, fieldInfo), fieldClone)
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);
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} else {
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// Complex types are cloned by checking their actual, concrete type (fields
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// may be typed to an interface or base class) and requesting a cloner for that
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// type during runtime
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MethodInfo getOrCreateClonerMethodInfo = typeof(ExpressionTreeCloner).GetMethod(
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"getOrCreateDeepFieldBasedCloner",
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BindingFlags.NonPublic | BindingFlags.Static
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);
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MethodInfo getTypeMethodInfo = typeof(object).GetMethod("GetType");
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MethodInfo invokeMethodInfo = typeof(Func<object, object>).GetMethod("Invoke");
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// Generate expressions to do this:
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// clone.SomeField = getOrCreateDeepFieldBasedCloner(
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// original.SomeField.GetType()
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// ).Invoke(original.SomeField);
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fieldTransferExpressions.Add(
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Expression.Assign(
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Expression.Field(clone, fieldInfo),
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Expression.Convert(
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Expression.Call(
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Expression.Call(
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getOrCreateClonerMethodInfo,
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Expression.Call(
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Expression.Field(original, fieldInfo), getTypeMethodInfo
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)
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),
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invokeMethodInfo,
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Expression.Field(original, fieldInfo)
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),
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fieldType
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)
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)
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);
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}
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// Wrap up the generated array or complex reference type transfer expressions
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// in a null check so the field is skipped if it is not holding an instance.
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transferExpressions.Add(
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Expression.IfThen(
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Expression.NotEqual(
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Expression.Field(original, fieldInfo), Expression.Constant(null)
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),
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Expression.Block(fieldVariables, fieldTransferExpressions)
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)
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);
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}
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/// <summary>Compiles a method that creates a clone of an object</summary>
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/// <param name="clonedType">Type for which a clone method will be created</param>
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/// <returns>A method that clones an object of the provided type</returns>
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