System.Xml.XmlBaseWriter.StartAttribute C# (CSharp) Méthode

        private void StartAttribute(ref string prefix, string localName, string ns, XmlDictionaryString xNs)
        {
            if (IsClosed)
                ThrowClosed();

            if (_writeState == WriteState.Attribute)
                WriteEndAttribute();

            if (localName == null || (localName.Length == 0 && prefix != "xmlns"))
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException(nameof(localName)));

            if (_writeState != WriteState.Element)
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(SR.Format(SR.XmlInvalidWriteState, "WriteStartAttribute", WriteState.ToString())));

            if (prefix == null)
            {
                if (ns == xmlnsNamespace && localName != "xmlns")
                    prefix = "xmlns";
                else if (ns == xmlNamespace)
                    prefix = "xml";
                else
                    prefix = string.Empty;
            }

            // Normalize a (prefix,localName) of (null, "xmlns") to ("xmlns", string.Empty).
            if (prefix.Length == 0 && localName == "xmlns")
            {
                prefix = "xmlns";
                localName = string.Empty;
            }

            _isXmlnsAttribute = false;
            _isXmlAttribute = false;
            if (prefix == "xml")
            {
                if (ns != null && ns != xmlNamespace)
                    throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.Format(SR.XmlPrefixBoundToNamespace, "xml", xmlNamespace, ns), nameof(ns)));
                _isXmlAttribute = true;
                _attributeValue = string.Empty;
                _attributeLocalName = localName;
            }
            else if (prefix == "xmlns")
            {
                if (ns != null && ns != xmlnsNamespace)
                    throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.Format(SR.XmlPrefixBoundToNamespace, "xmlns", xmlnsNamespace, ns), nameof(ns)));
                _isXmlnsAttribute = true;
                _attributeValue = string.Empty;
                _attributeLocalName = localName;
            }
            else if (ns == null)
            {
                // A null namespace means the namespace of the given prefix.
                if (prefix.Length == 0)
                {
                    // An empty prefix on an attribute means no namespace (not the default namespace)
                    ns = string.Empty;
                }
                else
                {
                    ns = _nsMgr.LookupNamespace(prefix);

                    if (ns == null)
                        throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.Format(SR.XmlUndefinedPrefix, prefix), nameof(prefix)));
                }
            }
            else if (ns.Length == 0)
            {
                // An empty namespace means no namespace; prefix must be empty
                if (prefix.Length != 0)
                    throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.Format(SR.XmlEmptyNamespaceRequiresNullPrefix), nameof(prefix)));
            }
            else if (prefix.Length == 0)
            {
                // No prefix specified - try to find a prefix corresponding to the given namespace
                prefix = _nsMgr.LookupAttributePrefix(ns);

                // If we didn't find anything with the right namespace, generate one.
                if (prefix == null)
                {
                    // Watch for special values
                    if (ns.Length == xmlnsNamespace.Length && ns == xmlnsNamespace)
                        throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.Format(SR.XmlSpecificBindingNamespace, "xmlns", ns)));
                    if (ns.Length == xmlNamespace.Length && ns == xmlNamespace)
                        throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.Format(SR.XmlSpecificBindingNamespace, "xml", ns)));

                    prefix = GeneratePrefix(ns, xNs);
                }
            }
            else
            {
                _nsMgr.AddNamespaceIfNotDeclared(prefix, ns, xNs);
            }
            _writeState = WriteState.Attribute;
        }