public override void WriteStartAttribute()

in src/Shared/Compat/XmlTextWriter.cs [487:598]
96 lines of code
39 McCabe index (conditional complexity)

        public override  void WriteStartAttribute(string prefix, string localName, string ns) {
            try {
                AutoComplete(Token.StartAttribute);
 
                this.specialAttr = SpecialAttr.None;
                if (this.namespaces) {
 
                    if (prefix != null && prefix.Length == 0) {
                        prefix = null;
                    }
 
                    if (ns == XmlReservedNs.NsXmlNs && prefix == null && localName != "xmlns") {
                        prefix = "xmlns";
                    }
 
                    if (prefix == "xml") {
                        if (localName == "lang") {
                            this.specialAttr = SpecialAttr.XmlLang;
                        }
                        else if (localName == "space") {
                            this.specialAttr = SpecialAttr.XmlSpace;
                        }
                        /* bug54408. to be fwd compatible we need to treat xml prefix as reserved
                        and not really insist on a specific value. Who knows in the future it
                        might be OK to say xml:blabla
                        else {
                            throw new ArgumentException(Res.GetString(Res.Xml_InvalidPrefix));
                        }*/
                    }
                    else if (prefix == "xmlns") {
 
                        if (XmlReservedNs.NsXmlNs != ns && ns != null) {
                            throw new ArgumentException("Xml_XmlnsBelongsToReservedNs");
                        }
                        if (localName == null || localName.Length == 0) {
                            localName = prefix;
                            prefix = null;
                            this.prefixForXmlNs = null;
                        }
                        else {
                            this.prefixForXmlNs = localName;
                        }
                        this.specialAttr = SpecialAttr.XmlNs;
                    }
                    else if (prefix == null && localName == "xmlns") {
                        if (XmlReservedNs.NsXmlNs != ns && ns != null) {
                            // add the below line back in when DOM is fixed
                            throw new ArgumentException("Xml_XmlnsBelongsToReservedNs");
                        }
                        this.specialAttr = SpecialAttr.XmlNs;
                        this.prefixForXmlNs = null;
                    }
                    else {
                        if (ns == null) {
                            // use defined prefix
                            if (prefix != null && (LookupNamespace(prefix) == -1)) {
                                throw new ArgumentException("Xml_UndefPrefix");
                            }
                        }
                        else if (ns.Length == 0) {
                            // empty namespace require null prefix
                            prefix = string.Empty;
                        }
                        else { // ns.Length != 0
                            VerifyPrefixXml(prefix, ns);
                            if (prefix != null && LookupNamespaceInCurrentScope(prefix) != -1) {
                                prefix = null;
                            }
                            // Now verify prefix validity
                            string definedPrefix = FindPrefix(ns);
                            if (definedPrefix != null && (prefix == null || prefix == definedPrefix)) {
                                prefix = definedPrefix;
                            }
                            else {
                                if (prefix == null) {
                                    prefix = GeneratePrefix(); // need a prefix if
                                }
                                PushNamespace(prefix, ns, false);
                            }
                        }
                    }
                    if (prefix != null && prefix.Length != 0) {
                        textWriter.Write(prefix);
                        textWriter.Write(':');
                    }
                }
                else {
                    if ((ns != null && ns.Length != 0) || (prefix != null && prefix.Length != 0)) {
                        throw new ArgumentException("Xml_NoNamespaces");
                    }
                    if (localName == "xml:lang") {
                        this.specialAttr = SpecialAttr.XmlLang;
                    }
                    else if (localName == "xml:space") {
                        this.specialAttr = SpecialAttr.XmlSpace;
                    }
                }
                xmlEncoder.StartAttribute(this.specialAttr != SpecialAttr.None);
 
                textWriter.Write(localName);
                textWriter.Write('=');
                if (this.curQuoteChar != this.quoteChar) {
                    this.curQuoteChar = this.quoteChar;
                    xmlEncoder.QuoteChar = this.quoteChar;
                }
                textWriter.Write(this.curQuoteChar);
            }
            catch {
                currentState = State.Error;
                throw;
            }
        }