System.Runtime.Serialization.Json.XmlJsonWriter.WriteStartElement C# (CSharp) Method

        public override void WriteStartElement(string prefix, string localName, string ns)
        {
            if (localName == null)
            {
                throw new ArgumentNullException(nameof(localName));
            }
            if (localName.Length == 0)
            {
                throw new ArgumentException(SR.JsonInvalidLocalNameEmpty, nameof(localName));
            }
            if (!string.IsNullOrEmpty(prefix))
            {
                if (string.IsNullOrEmpty(ns) || !TrySetWritingNameWithMapping(localName, ns))
                {
                    throw new ArgumentException(SR.Format(SR.JsonPrefixMustBeNullOrEmpty, prefix), nameof(prefix));
                }
            }
            if (!string.IsNullOrEmpty(ns))
            {
                if (!TrySetWritingNameWithMapping(localName, ns))
                {
                    throw new ArgumentException(SR.Format(SR.JsonNamespaceMustBeEmpty, ns), nameof(ns));
                }
            }
            if (IsClosed)
            {
                ThrowClosed();
            }
            if (HasOpenAttribute)
            {
                throw new XmlException(SR.Format(SR.JsonOpenAttributeMustBeClosedFirst, "WriteStartElement"));
            }
            if ((_nodeType != JsonNodeType.None) && _depth == 0)
            {
                throw new XmlException(SR.JsonMultipleRootElementsNotAllowedOnWriter);
            }

            switch (_nodeType)
            {
                case JsonNodeType.None:
                    {
                        if (!localName.Equals(JsonGlobals.rootString))
                        {
                            throw new XmlException(SR.Format(SR.JsonInvalidRootElementName, localName, JsonGlobals.rootString));
                        }
                        EnterScope(JsonNodeType.Element);
                        break;
                    }
                case JsonNodeType.Element:
                    {
                        if ((_dataType != JsonDataType.Array) && (_dataType != JsonDataType.Object))
                        {
                            throw new XmlException(SR.JsonNodeTypeArrayOrObjectNotSpecified);
                        }
                        if (_indent)
                        {
                            WriteNewLine();
                            WriteIndent();
                        }
                        if (!IsWritingCollection)
                        {
                            if (_nameState != NameState.IsWritingNameWithMapping)
                            {
                                WriteJsonElementName(localName);
                            }
                        }
                        else if (!localName.Equals(JsonGlobals.itemString))
                        {
                            throw new XmlException(SR.Format(SR.JsonInvalidItemNameForArrayElement, localName, JsonGlobals.itemString));
                        }
                        EnterScope(JsonNodeType.Element);
                        break;
                    }
                case JsonNodeType.EndElement:
                    {
                        if (_endElementBuffer)
                        {
                            _nodeWriter.WriteText(JsonGlobals.MemberSeparatorChar);
                        }
                        if (_indent)
                        {
                            WriteNewLine();
                            WriteIndent();
                        }
                        if (!IsWritingCollection)
                        {
                            if (_nameState != NameState.IsWritingNameWithMapping)
                            {
                                WriteJsonElementName(localName);
                            }
                        }
                        else if (!localName.Equals(JsonGlobals.itemString))
                        {
                            throw new XmlException(SR.Format(SR.JsonInvalidItemNameForArrayElement, localName, JsonGlobals.itemString));
                        }
                        EnterScope(JsonNodeType.Element);
                        break;
                    }
                default:
                    throw new XmlException(SR.JsonInvalidStartElementCall);
            }

            _isWritingDataTypeAttribute = false;
            _isWritingServerTypeAttribute = false;
            _isWritingXmlnsAttribute = false;
            _wroteServerTypeAttribute = false;
            _serverTypeValue = null;
            _dataType = JsonDataType.None;
            _nodeType = JsonNodeType.Element;
        }