private static bool CanCastToClass(this TypeDesc thisType, TypeDesc otherType, StackOverflowProtect protect)
{
TypeDesc curType = thisType;
if (curType.IsInterface && otherType.IsObject)
{
return(true);
}
// If the target type has variant type parameters, we take a slower path
if (curType.HasVariance)
{
// First chase inheritance hierarchy until we hit a class that only differs in its instantiation
do
{
if (curType == otherType)
{
return(true);
}
if (curType.CanCastByVarianceToInterfaceOrDelegate(otherType, protect))
{
return(true);
}
curType = curType.BaseType;
}while (curType != null);
}
else
{
// If there are no variant type parameters, just chase the hierarchy
// Allow curType to be nullable, which means this method
// will additionally return true if curType is Nullable<T> && (
// currType == otherType
// OR otherType is System.ValueType or System.Object)
// Always strip Nullable from the otherType, if present
if (otherType.IsNullable && !curType.IsNullable)
{
return(thisType.CanCastTo(otherType.Instantiation[0]));
}
do
{
if (curType == otherType)
{
return(true);
}
curType = curType.BaseType;
} while (curType != null);
}
return(false);
}
private static bool CanCastToInterface(this TypeDesc thisType, TypeDesc otherType, StackOverflowProtect protect)
{
if (!otherType.HasVariance)
{
return(thisType.CanCastToNonVariantInterface(otherType, protect));
}
else
{
if (thisType.CanCastByVarianceToInterfaceOrDelegate(otherType, protect))
{
return(true);
}
foreach (var interfaceType in thisType.RuntimeInterfaces)
{
if (interfaceType.CanCastByVarianceToInterfaceOrDelegate(otherType, protect))
{
return(true);
}
}
}
return(false);
}