private Expr GenerateUserDefinedConversion(ExprUserDefinedConversion pExpr, Expr pArgument)
{
Expr pCastCall = pExpr.UserDefinedCall;
Expr pCastArgument = pExpr.Argument;
Expr pConversionSource;
if (!isEnumToDecimalConversion(pArgument.Type, pExpr.Type) &&
IsNullableValueAccess(pCastArgument, pArgument))
{
// We have an implicit conversion of nullable CType to the value CType, generate a convert node for it.
pConversionSource = GenerateValueAccessConversion(pArgument);
}
else
{
ExprCall call = pCastCall as ExprCall;
Expr pUDConversion = call?.PConversions;
if (pUDConversion != null)
{
if (pUDConversion is ExprCall convCall)
{
Expr pUDConversionArgument = convCall.OptionalArguments;
if (IsNullableValueAccess(pUDConversionArgument, pArgument))
{
pConversionSource = GenerateValueAccessConversion(pArgument);
}
else
{
pConversionSource = Visit(pUDConversionArgument);
}
return(GenerateConversionWithSource(pConversionSource, pCastCall.Type, call.isChecked()));
}
// This can happen if we have a UD conversion from C to, say, int,
// and we have an explicit cast to decimal?. The conversion should
// then be bound as two chained user-defined conversions.
Debug.Assert(pUDConversion is ExprUserDefinedConversion);
// Just recurse.
return(GenerateUserDefinedConversion((ExprUserDefinedConversion)pUDConversion, pArgument));
}
pConversionSource = Visit(pCastArgument);
}
return(GenerateUserDefinedConversion(pCastArgument, pExpr.Type, pConversionSource, pExpr.UserDefinedCallMethod));
}
protected override Expr VisitCALL(ExprCall expr)
{
Debug.Assert(expr != null);
switch (expr.NullableCallLiftKind)
{
default:
break;
case NullableCallLiftKind.NullableIntermediateConversion:
case NullableCallLiftKind.NullableConversion:
case NullableCallLiftKind.NullableConversionConstructor:
return(GenerateConversion(expr.OptionalArguments, expr.Type, expr.isChecked()));
case NullableCallLiftKind.NotLiftedIntermediateConversion:
case NullableCallLiftKind.UserDefinedConversion:
return(GenerateUserDefinedConversion(expr.OptionalArguments, expr.Type, expr.MethWithInst));
}
if (expr.MethWithInst.Meth().IsConstructor())
{
return(GenerateConstructor(expr));
}
ExprMemberGroup memberGroup = expr.MemberGroup;
if (memberGroup.IsDelegate)
{
return(GenerateDelegateInvoke(expr));
}
Expr pObject;
if (expr.MethWithInst.Meth().isStatic || expr.MemberGroup.OptionalObject == null)
{
pObject = GetExprFactory().CreateNull();
}
else
{
pObject = expr.MemberGroup.OptionalObject;
// If we have, say, an int? which is the object of a call to ToString
// then we do NOT want to generate ((object)i).ToString() because that
// will convert a null-valued int? to a null object. Rather what we want
// to do is box it to a ValueType and call ValueType.ToString.
//
// To implement this we say that if the object of the call is an implicit boxing cast
// then just generate the object, not the cast. If the cast is explicit in the
// source code then it will be an EXPLICITCAST and we will visit it normally.
//
// It might be better to rewrite the expression tree API so that it
// can handle in the general case all implicit boxing conversions. Right now it
// requires that all arguments to a call that need to be boxed be explicitly boxed.
if (pObject != null && pObject is ExprCast cast && cast.IsBoxingCast)
{
pObject = cast.Argument;
}
pObject = Visit(pObject);
}
Expr methodInfo = GetExprFactory().CreateMethodInfo(expr.MethWithInst);
Expr args = GenerateArgsList(expr.OptionalArguments);
Expr Params = GenerateParamsArray(args, PredefinedType.PT_EXPRESSION);
PREDEFMETH pdm = PREDEFMETH.PM_EXPRESSION_CALL;
Debug.Assert(!expr.MethWithInst.Meth().isVirtual || expr.MemberGroup.OptionalObject != null);
return(GenerateCall(pdm, pObject, methodInfo, Params));
}