private IEnumerable <BsonDocument> Filter(FilterDefinition <TDocument> filter)
        {
            var documentSerializer = BsonSerializer.SerializerRegistry.GetSerializer <TDocument>();
            var filterBson         = filter.Render(documentSerializer, BsonSerializer.SerializerRegistry);

            var parsedFilter = _filterParser.Parse(filterBson);

            return(_documents.Where(parsedFilter.Filter));
        }
 private IEnumerable <BsonDocument> Filter(FilterDefinition <TDocument> filter)
 {
     return(_documents.Where(RenderFilterDefinition(filter).Filter));
 }