public override Symbol DoAction()

in lang/csharp/src/apache/main/IO/JsonDecoder.cs [616:707]
83 lines of code
21 McCabe index (conditional complexity)

        public override Symbol DoAction(Symbol input, Symbol top)
        {
            if (top is Symbol.FieldAdjustAction)
            {
                Symbol.FieldAdjustAction fa = (Symbol.FieldAdjustAction)top;
                string name = fa.FName;
                if (currentReorderBuffer != null)
                {
                    IList<JsonElement> node = currentReorderBuffer.SavedFields[name];
                    if (node != null)
                    {
                        currentReorderBuffer.SavedFields.Remove(name);
                        currentReorderBuffer.OrigParser = reader;
                        reader = MakeParser(node);
                        return null;
                    }
                }

                if (reader.TokenType == JsonToken.PropertyName)
                {
                    do
                    {
                        string fn = Convert.ToString(reader.Value);
                        reader.Read();
                        if (name.Equals(fn) || (fa.Aliases != null && fa.Aliases.Contains(fn)))
                        {
                            return null;
                        }
                        else
                        {
                            if (currentReorderBuffer == null)
                            {
                                currentReorderBuffer = new ReorderBuffer();
                            }

                            currentReorderBuffer.SavedFields[fn] = GetValueAsTree(reader);
                        }
                    } while (reader.TokenType == JsonToken.PropertyName);

                    throw new AvroTypeException("Expected field name not found: " + fa.FName);
                }
            }
            else if (top == Symbol.FieldEnd)
            {
                if (currentReorderBuffer != null && currentReorderBuffer.OrigParser != null)
                {
                    reader = currentReorderBuffer.OrigParser;
                    currentReorderBuffer.OrigParser = null;
                }
            }
            else if (top == Symbol.RecordStart)
            {
                if (reader.TokenType == JsonToken.StartObject)
                {
                    reader.Read();
                    reorderBuffers.Push(currentReorderBuffer);
                    currentReorderBuffer = null;
                }
                else
                {
                    throw TypeError("record-start");
                }
            }
            else if (top == Symbol.RecordEnd || top == Symbol.UnionEnd)
            {
                // AVRO-2034 advance to the end of our object
                while (reader.TokenType != JsonToken.EndObject)
                {
                    reader.Read();
                }

                if (top == Symbol.RecordEnd)
                {
                    if (currentReorderBuffer != null && currentReorderBuffer.SavedFields.Count > 0)
                    {
                        throw TypeError("Unknown fields: " + currentReorderBuffer.SavedFields.Keys
                            .Aggregate((x, y) => x + ", " + y));
                    }

                    currentReorderBuffer = reorderBuffers.Pop();
                }

                // AVRO-2034 advance beyond the end object for the next record.
                reader.Read();
            }
            else
            {
                throw new AvroTypeException("Unknown action symbol " + top);
            }

            return null;
        }