XmlDeclaration.cs

Go to the documentation of this file.

using System.Diagnostics.CodeAnalysis;
using System.Text;
 
namespace System.Xml;
 
public class XmlDeclaration : XmlLinkedNode
{
    private string _version;
 
    private string _encoding;
 
    private string _standalone;
 
    public string Version
    {
        get
        {
            return _version;
        }
        [MemberNotNull("_version")]
        internal set
        {
            _version = value;
        }
    }
 
    public string Encoding
    {
        get
        {
            return _encoding;
        }
        [MemberNotNull("_encoding")]
        [param: AllowNull]
        set
        {
            _encoding = ((value == null) ? string.Empty : value);
        }
    }
 
    public string Standalone
    {
        get
        {
            return _standalone;
        }
        [MemberNotNull("_standalone")]
        [param: AllowNull]
        set
        {
            if (value == null)
            {
                _standalone = string.Empty;
                return;
            }
            if (value.Length == 0 || value == "yes" || value == "no")
            {
                _standalone = value;
                return;
            }
            throw new ArgumentException(System.SR.Format(System.SR.Xdom_standalone, value));
        }
    }
 
    public override string? Value
    {
        get
        {
            return InnerText;
        }
        set
        {
            InnerText = value;
        }
    }
 
    public override string InnerText
    {
        get
        {
            StringBuilder stringBuilder = System.Text.StringBuilderCache.Acquire();
            stringBuilder.Append("version=\"");
            stringBuilder.Append(Version);
            stringBuilder.Append('"');
            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 System.Text.StringBuilderCache.GetStringAndRelease(stringBuilder);
        }
        set
        {
            string version = null;
            string encoding = null;
            string standalone = null;
            string encoding2 = Encoding;
            string standalone2 = Standalone;
            string version2 = Version;
            XmlLoader.ParseXmlDeclarationValue(value, out version, out encoding, out standalone);
            try
            {
                if (version != null && !IsValidXmlVersion(version))
                {
                    throw new ArgumentException(System.SR.Xdom_Version);
                }
                Version = version;
                if (encoding != null)
                {
                    Encoding = encoding;
                }
                if (standalone != null)
                {
                    Standalone = standalone;
                }
            }
            catch
            {
                Encoding = encoding2;
                Standalone = standalone2;
                Version = version2;
                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(System.SR.Xdom_Version);
        }
        if (standalone != null && standalone.Length > 0 && standalone != "yes" && standalone != "no")
        {
            throw new ArgumentException(System.SR.Format(System.SR.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;
    }
}