internal static ConversionClass ClassifyPredefinedCLRConversion(Type TargetType, Type SourceType)
{
if (TargetType == SourceType)
{
return(ConversionClass.Identity);
}
if (Symbols.IsRootObjectType(TargetType) || Symbols.IsOrInheritsFrom(SourceType, TargetType))
{
return(ConversionClass.Widening);
}
if (Symbols.IsRootObjectType(SourceType) || Symbols.IsOrInheritsFrom(TargetType, SourceType))
{
return(ConversionClass.Narrowing);
}
if (Symbols.IsInterface(SourceType))
{
if ((Symbols.IsClass(TargetType) || Symbols.IsArrayType(TargetType)) || Symbols.IsGenericParameter(TargetType))
{
return(ConversionClass.Narrowing);
}
if (Symbols.IsInterface(TargetType))
{
return(ConversionClass.Narrowing);
}
if (!Symbols.IsValueType(TargetType))
{
return(ConversionClass.Narrowing);
}
if (Symbols.Implements(TargetType, SourceType))
{
return(ConversionClass.Narrowing);
}
return(ConversionClass.None);
}
if (Symbols.IsInterface(TargetType))
{
if (Symbols.IsArrayType(SourceType))
{
return(ClassifyCLRArrayToInterfaceConversion(TargetType, SourceType));
}
if (Symbols.IsValueType(SourceType))
{
if (Symbols.Implements(SourceType, TargetType))
{
return(ConversionClass.Widening);
}
return(ConversionClass.None);
}
if (Symbols.IsClass(SourceType))
{
if (Symbols.Implements(SourceType, TargetType))
{
return(ConversionClass.Widening);
}
return(ConversionClass.Narrowing);
}
}
if (Symbols.IsEnum(SourceType) || Symbols.IsEnum(TargetType))
{
if (Symbols.GetTypeCode(SourceType) != Symbols.GetTypeCode(TargetType))
{
return(ConversionClass.None);
}
if (Symbols.IsEnum(TargetType))
{
return(ConversionClass.Narrowing);
}
return(ConversionClass.Widening);
}
if (Symbols.IsGenericParameter(SourceType))
{
if (!Symbols.IsClassOrInterface(TargetType))
{
return(ConversionClass.None);
}
foreach (Type type2 in Symbols.GetInterfaceConstraints(SourceType))
{
switch (ClassifyPredefinedConversion(TargetType, type2))
{
case ConversionClass.Widening:
case ConversionClass.Identity:
return(ConversionClass.Widening);
}
}
Type classConstraint = Symbols.GetClassConstraint(SourceType);
if (classConstraint != null)
{
switch (ClassifyPredefinedConversion(TargetType, classConstraint))
{
case ConversionClass.Widening:
case ConversionClass.Identity:
return(ConversionClass.Widening);
}
}
return(Interaction.IIf <ConversionClass>(Symbols.IsInterface(TargetType), ConversionClass.Narrowing, ConversionClass.None));
}
if (Symbols.IsGenericParameter(TargetType))
{
Type derived = Symbols.GetClassConstraint(TargetType);
if ((derived != null) && Symbols.IsOrInheritsFrom(derived, SourceType))
{
return(ConversionClass.Narrowing);
}
return(ConversionClass.None);
}
if ((Symbols.IsArrayType(SourceType) && Symbols.IsArrayType(TargetType)) && (SourceType.GetArrayRank() == TargetType.GetArrayRank()))
{
return(ClassifyCLRConversionForArrayElementTypes(TargetType.GetElementType(), SourceType.GetElementType()));
}
return(ConversionClass.None);
}