System.Xml.XmlBaseWriter.NamespaceManager.LookupAttributePrefix C# (CSharp) Méthode

            public string LookupAttributePrefix(string ns)
            {
                if (_lastNameSpace != null && _lastNameSpace.Uri == ns && _lastNameSpace.Prefix.Length != 0)
                    return _lastNameSpace.Prefix;

                int nsCount = _nsCount;
                for (int i = nsCount - 1; i >= _nsTop; i--)
                {
                    Namespace nameSpace = _namespaces[i];

                    if (object.ReferenceEquals(nameSpace.Uri, ns))
                    {
                        string prefix = nameSpace.Prefix;
                        if (prefix.Length != 0)
                        {
                            // Make sure that the prefix refers to the namespace in scope
                            bool declared = false;
                            for (int j = i + 1; j < nsCount; j++)
                            {
                                if (_namespaces[j].Prefix == prefix)
                                {
                                    declared = true;
                                    break;
                                }
                            }
                            if (!declared)
                            {
                                _lastNameSpace = nameSpace;
                                return prefix;
                            }
                        }
                    }
                }
                for (int i = nsCount - 1; i >= _nsTop; i--)
                {
                    Namespace nameSpace = _namespaces[i];
                    if (nameSpace.Uri == ns)
                    {
                        string prefix = nameSpace.Prefix;
                        if (prefix.Length != 0)
                        {
                            // Make sure that the prefix refers to the namespace in scope
                            bool declared = false;
                            for (int j = i + 1; j < nsCount; j++)
                            {
                                if (_namespaces[j].Prefix == prefix)
                                {
                                    declared = true;
                                    break;
                                }
                            }
                            if (!declared)
                            {
                                _lastNameSpace = nameSpace;
                                return prefix;
                            }
                        }
                    }
                }
                if (ns.Length == 0)
                    return string.Empty;
                return null;
            }