System.ComponentModel.TypeDescriptor.PipelineAttributeFilter C# (CSharp) Method

        private static ICollection PipelineAttributeFilter(int pipelineType, ICollection members, Attribute[] filter, object instance, IDictionary cache)
        {
            Debug.Assert(pipelineType != PIPELINE_ATTRIBUTES, "PipelineAttributeFilter is not supported for attributes");

            IList list = members as ArrayList;

            if (filter == null || filter.Length == 0)
            {
                return members;
            }

            // Now, check our cache.  The cache state is only valid
            // if the data coming into us is read-only.  If it is read-write,
            // that means something higher in the pipeline has already changed
            // it so we must recompute anyway.
            //
            if (cache != null && (list == null || list.IsReadOnly))
            {
                AttributeFilterCacheItem filterCache = cache[s_pipelineAttributeFilterKeys[pipelineType]] as AttributeFilterCacheItem;
                if (filterCache != null && filterCache.IsValid(filter))
                {
                    return filterCache.FilteredMembers;
                }
            }

            // Our cache did not contain the correct state, so generate it.
            //
            if (list == null || list.IsReadOnly)
            {
                list = new ArrayList(members);
            }

            ArrayList filterResult = FilterMembers(list, filter);
            if (filterResult != null) list = filterResult;

            // And, if we have a cache, store the updated state into it for future reference.
            //
            if (cache != null)
            {
                ICollection cacheValue;

                switch (pipelineType)
                {
                    case PIPELINE_PROPERTIES:
                        PropertyDescriptor[] propArray = new PropertyDescriptor[list.Count];
                        list.CopyTo(propArray, 0);
                        cacheValue = new PropertyDescriptorCollection(propArray, true);
                        break;

                    case PIPELINE_EVENTS:
                        EventDescriptor[] eventArray = new EventDescriptor[list.Count];
                        list.CopyTo(eventArray, 0);
                        cacheValue = new EventDescriptorCollection(eventArray, true);
                        break;

                    default:
                        Debug.Fail("unknown pipeline type");
                        cacheValue = null;
                        break;
                }

                AttributeFilterCacheItem filterCache = new AttributeFilterCacheItem(filter, cacheValue);
                cache[s_pipelineAttributeFilterKeys[pipelineType]] = filterCache;
            }

            return list;
        }