protected internal override Expression VisitBinaryAssign(AssignBinaryCSharpExpression node)
{
var args = new List <object>();
if (node.IsLifted)
{
args.Add(new XAttribute(nameof(node.IsLifted), node.IsLifted));
}
if (node.IsLiftedToNull)
{
args.Add(new XAttribute(nameof(node.IsLiftedToNull), node.IsLiftedToNull));
}
if (node.Method != null)
{
args.Add(new XAttribute(nameof(node.Method), node.Method));
}
args.Add(new XElement(nameof(node.Left), Visit(node.Left)));
args.Add(new XElement(nameof(node.Right), Visit(node.Right)));
if (node.LeftConversion != null)
{
args.Add(new XElement(nameof(node.LeftConversion), Visit(node.LeftConversion)));
}
if (node.FinalConversion != null)
{
args.Add(new XElement(nameof(node.FinalConversion), Visit(node.FinalConversion)));
}
return(Push(node, args));
}
public AssignBinaryCSharpExpressionProxy(AssignBinaryCSharpExpression node)
{
_node = node;
}
protected internal virtual Expression VisitBinaryAssign(AssignBinaryCSharpExpression node)
{
return(node.Update(Visit(node.Left), VisitAndConvert(node.LeftConversion, nameof(VisitBinaryAssign)), Visit(node.Right), VisitAndConvert(node.FinalConversion, nameof(VisitBinaryAssign))));
}
private static AssignBinaryCSharpExpression MakeBinaryAssignCore(CSharpExpressionType binaryType, Expression left, Expression right, MethodInfo method, LambdaExpression finalConversion, LambdaExpression leftConversion)
{
Helpers.RequiresCanWrite(left, nameof(left));
RequiresCanRead(right, nameof(right));
// NB: We could return a BinaryExpression in case the lhs is not one of our index nodes, but it'd change
// the return type to Expression which isn't nice to consume. Also, the Update method would either
// have to change to return Expression or we should have an AssignBinary node to hold a Binary node
// underneath it. This said, a specialized layout for the case where the custom node trivially wraps
// a LINQ node could be useful (just make Left virtual).
if (binaryType != CSharpExpressionType.Assign)
{
var leftType = left.Type;
var rightType = right.Type;
if (leftType == typeof(string))
{
if (method == null)
{
if (binaryType == CSharpExpressionType.AddAssign || binaryType == CSharpExpressionType.AddAssignChecked)
{
if (rightType == typeof(string))
{
method = typeof(string).GetMethod(nameof(string.Concat), new[] { typeof(string), typeof(string) });
}
else
{
method = typeof(string).GetMethod(nameof(string.Concat), new[] { typeof(string), typeof(object) });
if (!TypeUtils1.AreReferenceAssignable(typeof(object), rightType))
{
// DESIGN: Should our factory do this our just reject the input?
right = Expression.Convert(right, typeof(object));
}
}
}
else
{
throw Error.InvalidCompoundAssignment(binaryType, typeof(string));
}
}
}
else if (typeof(MulticastDelegate).IsAssignableFrom(leftType))
{
if (leftType == typeof(MulticastDelegate))
{
throw Error.InvalidCompoundAssignmentWithOperands(binaryType, leftType, rightType);
}
// NB: This checks for assignment with variance checks in mind, e.g.
//
// Action<string> s = ...;
// Action<object> o = ...;
// s += o;
if (!TypeUtils1.AreReferenceAssignable(leftType, rightType))
{
throw Error.InvalidCompoundAssignmentWithOperands(binaryType, leftType, rightType);
}
if (method == null)
{
if (binaryType == CSharpExpressionType.AddAssign || binaryType == CSharpExpressionType.AddAssignChecked)
{
method = typeof(Delegate).GetMethod(nameof(Delegate.Combine), new[] { typeof(Delegate), typeof(Delegate) });
}
else if (binaryType == CSharpExpressionType.SubtractAssign || binaryType == CSharpExpressionType.SubtractAssignChecked)
{
method = typeof(Delegate).GetMethod(nameof(Delegate.Remove), new[] { typeof(Delegate), typeof(Delegate) });
}
else
{
throw Error.InvalidCompoundAssignment(binaryType, leftType);
}
if (finalConversion == null)
{
var resultParameter = Expression.Parameter(typeof(Delegate), "__result");
var convertResult = Expression.Convert(resultParameter, leftType);
finalConversion = Expression.Lambda(convertResult, resultParameter);
}
}
}
else if (IsCSharpSpecificCompoundNumeric(leftType))
{
// NB: If any of these are passed, we'll assume the types all line up. The call to
// the ValidateCustomBinaryAssign method below will check that's indeed the case.
if (method == null && leftConversion == null && finalConversion == null)
{
var isChecked = IsCheckedBinary(binaryType);
var isNullabeLeftType = leftType.IsNullableType();
var nonNullLeftType = leftType.GetNonNullableType();
var intermediateType = nonNullLeftType.IsEnum ? nonNullLeftType.GetEnumUnderlyingType() : typeof(int);
var leftParameter = Expression.Parameter(leftType, "__left");
var convertType = isNullabeLeftType ? typeof(Nullable <>).MakeGenericType(intermediateType) : intermediateType;
var convertLeft = isChecked ? Expression.ConvertChecked(leftParameter, convertType) : Expression.Convert(leftParameter, convertType);
leftConversion = Expression.Lambda(convertLeft, leftParameter);
var resultParameter = Expression.Parameter(convertType, "__result");
var convertResult = isChecked ? Expression.ConvertChecked(resultParameter, leftType) : Expression.Convert(resultParameter, leftType);
finalConversion = Expression.Lambda(convertResult, resultParameter);
if (rightType != convertType)
{
// DESIGN: Should our factory do this or just reject the input? On the one hand,
// C# allows e.g. byte += byte, so if this is a C#-specific API it may be
// reasonable for the user to expect such a tree can be built. On the
// other hand, it's very unlike the expression tree API to insert nodes
// on behalf of the user in the factories. Note that Roslyn often models
// conversions as properties on a node using a `Conversion` objects
// which would be handy to keep the shape from the tree isomorphic to the
// bound nodes in the compiler. Note though that the RHS of a compound
// assignment doesn't have such a conversion and the compiler will insert
// a convert node in this case, so this is really just a convenience in
// our factory method to mimic that behavior.
right = Expression.Convert(right, convertType);
}
}
}
}
return(AssignBinaryCSharpExpression.Make(binaryType, left, right, method, leftConversion, finalConversion));
}
public AssignBinaryCSharpExpressionProxy(AssignBinaryCSharpExpression node)
{
_node = node;
}
protected internal virtual Expression VisitBinaryAssign(AssignBinaryCSharpExpression node)
{
return node.Update(Visit(node.Left), VisitAndConvert(node.LeftConversion, nameof(VisitBinaryAssign)), Visit(node.Right), VisitAndConvert(node.FinalConversion, nameof(VisitBinaryAssign)));
}