XmlDeclaration.cs

using System.Text;

namespace System.Xml
{
    public class XmlDeclaration : XmlLinkedNode
    {
        private const string YES = "yes";

        private const string NO = "no";

        private string version;

        private string encoding;

        private string standalone;

        public string Version
        {
            get
            {
                return version;
            }
            internal set
            {
                version = value;
            }
        }

        public string Encoding
        {
            get
            {
                return encoding;
            }
            set
            {
                encoding = ((value == null) ? string.Empty : value);
            }
        }

        public string Standalone
        {
            get
            {
                return standalone;
            }
            set
            {
                if (value == null)
                {
                    standalone = string.Empty;
                    return;
                }
                if (value.Length == 0 || value == "yes" || value == "no")
                {
                    standalone = value;
                    return;
                }
                throw new ArgumentException(Res.GetString("Xdom_standalone", value));
            }
        }

        public override string Value
        {
            get
            {
                return InnerText;
            }
            set
            {
                InnerText = value;
            }
        }

        public override string InnerText
        {
            get
            {
                StringBuilder stringBuilder = new StringBuilder("version=\"" + Version + "\"");
                if (Encoding.Length > 0)
                {
                    stringBuilder.Append(" encoding=\"");
                    stringBuilder.Append(Encoding);
                    stringBuilder.Append("\"");
                }
                if (Standalone.Length > 0)
                {
                    stringBuilder.Append(" standalone=\"");
                    stringBuilder.Append(Standalone);
                    stringBuilder.Append("\"");
                }
                return stringBuilder.ToString();
            }
            set
            {
                string text = null;
                string text2 = null;
                string text3 = null;
                string text4 = Encoding;
                string text5 = Standalone;
                string text6 = Version;
                XmlLoader.ParseXmlDeclarationValue(value, out text, out text2, out text3);
                try
                {
                    if (text != null && !IsValidXmlVersion(text))
                    {
                        throw new ArgumentException(Res.GetString("Xdom_Version"));
                    }
                    Version = text;
                    if (text2 != null)
                    {
                        Encoding = text2;
                    }
                    if (text3 != null)
                    {
                        Standalone = text3;
                    }
                }
                catch
                {
                    Encoding = text4;
                    Standalone = text5;
                    Version = text6;
                    throw;
                }
            }
        }

        public override string Name => "xml";

        public override string LocalName => Name;

        public override XmlNodeType NodeType => XmlNodeType.XmlDeclaration;

        protected internal XmlDeclaration(string version, string encoding, string standalone, XmlDocument doc)
            : base(doc)
        {
            if (!IsValidXmlVersion(version))
            {
                throw new ArgumentException(Res.GetString("Xdom_Version"));
            }
            if (standalone != null && standalone.Length > 0 && standalone != "yes" && standalone != "no")
            {
                throw new ArgumentException(Res.GetString("Xdom_standalone", standalone));
            }
            Encoding = encoding;
            Standalone = standalone;
            Version = version;
        }

        public override XmlNode CloneNode(bool deep)
        {
            return OwnerDocument.CreateXmlDeclaration(Version, Encoding, Standalone);
        }

        public override void WriteTo(XmlWriter w)
        {
            w.WriteProcessingInstruction(Name, InnerText);
        }

        public override void WriteContentTo(XmlWriter w)
        {
        }

        private bool IsValidXmlVersion(string ver)
        {
            if (ver.Length >= 3 && ver[0] == '1' && ver[1] == '.')
            {
                return XmlCharType.IsOnlyDigits(ver, 2, ver.Length - 2);
            }
            return false;
        }
    }
}