| public ContextForMemberLookup ( ) : Microsoft.CSharp.RuntimeBinder.Semantics.Declaration | ||
| return | Microsoft.CSharp.RuntimeBinder.Semantics.Declaration | |
private bool TryVarianceAdjustmentToGetAccessibleType(CSemanticChecker semanticChecker, BindingContext bindingContext, AggregateType typeSrc, out CType typeDst)
{
Debug.Assert(typeSrc != null);
Debug.Assert(typeSrc.isInterfaceType() || typeSrc.isDelegateType());
typeDst = null;
AggregateSymbol aggSym = typeSrc.GetOwningAggregate();
AggregateType aggOpenType = aggSym.getThisType();
if (!semanticChecker.CheckTypeAccess(aggOpenType, bindingContext.ContextForMemberLookup()))
{
// if the aggregate symbol itself is not accessible, then forget it, there is no
// variance that will help us arrive at an accessible type.
return false;
}
TypeArray typeArgs = typeSrc.GetTypeArgsThis();
TypeArray typeParams = aggOpenType.GetTypeArgsThis();
CType[] newTypeArgsTemp = new CType[typeArgs.size];
for (int i = 0; i < typeArgs.size; i++)
{
if (semanticChecker.CheckTypeAccess(typeArgs.Item(i), bindingContext.ContextForMemberLookup()))
{
// we have an accessible argument, this position is not a problem.
newTypeArgsTemp[i] = typeArgs.Item(i);
continue;
}
if (!typeArgs.Item(i).IsRefType() || !typeParams.Item(i).AsTypeParameterType().Covariant)
{
// This guy is inaccessible, and we are not going to be able to vary him, so we need to fail.
return false;
}
CType intermediateTypeArg;
if (GetBestAccessibleType(semanticChecker, bindingContext, typeArgs.Item(i), out intermediateTypeArg))
{
// now we either have a value type (which must be accessible due to the above
// check, OR we have an inaccessible type (which must be a ref type). In either
// case, the recursion worked out and we are OK to vary this argument.
newTypeArgsTemp[i] = intermediateTypeArg;
continue;
}
else
{
Debug.Assert(false, "GetBestAccessibleType unexpectedly failed on a type that was used as a type parameter");
return false;
}
}
TypeArray newTypeArgs = semanticChecker.getBSymmgr().AllocParams(typeArgs.size, newTypeArgsTemp);
CType intermediateType = this.GetAggregate(aggSym, typeSrc.outerType, newTypeArgs);
// All type arguments were varied successfully, which means now we must be accessible. But we could
// have violated constraints. Let's check that out.
if (!TypeBind.CheckConstraints(semanticChecker, null/*ErrorHandling*/, intermediateType, CheckConstraintsFlags.NoErrors))
{
return false;
}
typeDst = intermediateType;
Debug.Assert(semanticChecker.CheckTypeAccess(typeDst, bindingContext.ContextForMemberLookup()));
return true;
}
private bool TryArrayVarianceAdjustmentToGetAccessibleType(CSemanticChecker semanticChecker, BindingContext bindingContext, ArrayType typeSrc, out CType typeDst)
{
Debug.Assert(typeSrc != null);
typeDst = null;
// We are here because we have an array type with an inaccessible element type. If possible,
// we should create a new array type that has an accessible element type for which a
// conversion exists.
CType elementType = typeSrc.GetElementType();
if (!elementType.IsRefType())
{
// Covariant array conversions exist for reference types only.
return false;
}
CType intermediateType;
if (GetBestAccessibleType(semanticChecker, bindingContext, elementType, out intermediateType))
{
typeDst = this.GetArray(intermediateType, typeSrc.rank);
Debug.Assert(semanticChecker.CheckTypeAccess(typeDst, bindingContext.ContextForMemberLookup()));
return true;
}
return false;
}
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
// RUNTIME BINDER ONLY CHANGE
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
internal bool GetBestAccessibleType(CSemanticChecker semanticChecker, BindingContext bindingContext, CType typeSrc, out CType typeDst)
{
// This method implements the "best accessible type" algorithm for determining the type
// of untyped arguments in the runtime binder. It is also used in method type inference
// to fix type arguments to types that are accessible.
// The new type is returned in an out parameter. The result will be true (and the out param
// non-null) only when the algorithm could find a suitable accessible type.
Debug.Assert(semanticChecker != null);
Debug.Assert(bindingContext != null);
Debug.Assert(typeSrc != null);
typeDst = null;
if (semanticChecker.CheckTypeAccess(typeSrc, bindingContext.ContextForMemberLookup()))
{
// If we already have an accessible type, then use it. This is the terminal point of the recursion.
typeDst = typeSrc;
return true;
}
// These guys have no accessibility concerns.
Debug.Assert(!typeSrc.IsVoidType() && !typeSrc.IsErrorType() && !typeSrc.IsTypeParameterType());
if (typeSrc.IsParameterModifierType() || typeSrc.IsPointerType())
{
// We cannot vary these.
return false;
}
CType intermediateType;
if ((typeSrc.isInterfaceType() || typeSrc.isDelegateType()) && TryVarianceAdjustmentToGetAccessibleType(semanticChecker, bindingContext, typeSrc.AsAggregateType(), out intermediateType))
{
// If we have an interface or delegate type, then it can potentially be varied by its type arguments
// to produce an accessible type, and if that's the case, then return that.
// Example: IEnumerable<PrivateConcreteFoo> --> IEnumerable<PublicAbstractFoo>
typeDst = intermediateType;
Debug.Assert(semanticChecker.CheckTypeAccess(typeDst, bindingContext.ContextForMemberLookup()));
return true;
}
if (typeSrc.IsArrayType() && TryArrayVarianceAdjustmentToGetAccessibleType(semanticChecker, bindingContext, typeSrc.AsArrayType(), out intermediateType))
{
// Similarly to the interface and delegate case, arrays are covariant in their element type and
// so we can potentially produce an array type that is accessible.
// Example: PrivateConcreteFoo[] --> PublicAbstractFoo[]
typeDst = intermediateType;
Debug.Assert(semanticChecker.CheckTypeAccess(typeDst, bindingContext.ContextForMemberLookup()));
return true;
}
if (typeSrc.IsNullableType())
{
// We have an inaccessible nullable type, which means that the best we can do is System.ValueType.
typeDst = this.GetOptPredefAgg(PredefinedType.PT_VALUE).getThisType();
Debug.Assert(semanticChecker.CheckTypeAccess(typeDst, bindingContext.ContextForMemberLookup()));
return true;
}
if (typeSrc.IsArrayType())
{
// We have an inaccessible array type for which we could not earlier find a better array type
// with a covariant conversion, so the best we can do is System.Array.
typeDst = this.GetReqPredefAgg(PredefinedType.PT_ARRAY).getThisType();
Debug.Assert(semanticChecker.CheckTypeAccess(typeDst, bindingContext.ContextForMemberLookup()));
return true;
}
Debug.Assert(typeSrc.IsAggregateType());
if (typeSrc.IsAggregateType())
{
// We have an AggregateType, so recurse on its base class.
AggregateType aggType = typeSrc.AsAggregateType();
AggregateType baseType = aggType.GetBaseClass();
if (baseType == null)
{
// This happens with interfaces, for instance. But in that case, the
// conversion to object does exist, is an implicit reference conversion,
// and so we will use it.
baseType = this.GetReqPredefAgg(PredefinedType.PT_OBJECT).getThisType();
}
return GetBestAccessibleType(semanticChecker, bindingContext, baseType, out typeDst);
}
return false;
}
