// Stolen from the guts of MEF ConventionBuilder code,
// implements the default type selection logic of
// ConventionBuilder.ForTypesDerivedFrom<T>()
internal static bool IsDescendentOf(Type type, Type baseType)
{
if (type == baseType || type == typeof(object) || type == null)
{
return(false);
}
TypeInfo typeInfo1 = type.GetTypeInfo();
TypeInfo typeInfo2 = baseType.GetTypeInfo();
if (typeInfo1.IsGenericTypeDefinition)
{
return(MefExtensions.IsGenericDescendentOf(typeInfo1, typeInfo2));
}
return(typeInfo2.IsAssignableFrom(typeInfo1));
}
// Stolen from the guts of MEF ConventionBuilder code,
// supports the default type selection logic of
// ConventionBuilder.ForTypesDerivedFrom<T>()
internal static bool IsGenericDescendentOf(TypeInfo openType, TypeInfo baseType)
{
if (openType.BaseType == null)
{
return(false);
}
if (openType.BaseType == baseType.AsType())
{
return(true);
}
foreach (Type type in openType.ImplementedInterfaces)
{
if (type.IsConstructedGenericType && type.GetGenericTypeDefinition() == baseType.AsType())
{
return(true);
}
}
return(MefExtensions.IsGenericDescendentOf(IntrospectionExtensions.GetTypeInfo(openType.BaseType), baseType));
}
/// <summary>
/// Evaluates whether a candidate type is a provider type.
/// </summary>
/// <remarks>
/// The default implementation simply tests if the candidate type
/// is a qualified descendent of the TProv provider type.
/// <para>
/// Subclasses may add, or replace with, other conditions such as testing
/// for the presence of a particular class-level custom attribute or
/// testing for the presence of other features of the class definition
/// such as a qualifying constructor signature.
/// </para>
/// </remarks>
protected bool MatchProviderType(Type candidate)
{
return(MefExtensions.IsDescendentOf(candidate, typeof(TProv)));
}
/// <summary>
/// Evaluates whether a candidate type is a provider type.
/// </summary>
/// <remarks>
/// The default implementation simply tests if the candidate type
/// is a qualified descendent of the TExt provider type and is
/// decorated with a custom attribute of type TAtt.
/// </remarks>
protected bool MatchProviderType(Type candidate)
{
return(MefExtensions.IsDescendentOf(candidate, typeof(TExt)) &&
candidate.GetTypeInfo().GetCustomAttribute <TAtt>() != null);
}