internal interface IXamlCodeCompletionContext
{
bool IsAvailable { get; }
TextRange PrefixRange { get; } // invoke here
IList<ILookupItem> EvaluateLookupItems();
}

internal class XamlCodeCompletionContext<T> : IXamlCodeCompletionContext, IElementPointerFactory where T : class, ICompleteableReference {}

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