XmlNodeType.cs

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using System;
using System.IO;
using System.Xml;

using Deveel.Data.Sql.Objects;
using Deveel.Data.Types;

namespace Deveel.Data.Xml {
    public sealed class XmlNodeType : SqlType {
        public XmlNodeType()
            : base("XMLNODE", SqlTypeCode.Type) {
        }

        static XmlNodeType() {
            XmlType = new XmlNodeType();
        }

        public static SqlType XmlType { get; private set; }

        public override object ConvertTo(ISqlObject obj, Type destType) {
            var xmlNode = obj as SqlXmlNode;
            if (xmlNode == null || xmlNode.IsNull)
                return null;

            if (destType == typeof (string))
                return xmlNode.ToString();
            if (destType == typeof (XmlNode))
                return xmlNode.ToXmlNode();
            if (destType == typeof (byte[]))
                return xmlNode.ToBytes();

            return base.ConvertTo(obj, destType);
        }

        public override ISqlObject DeserializeObject(Stream stream) {
            return base.DeserializeObject(stream);
        }

        public override void SerializeObject(Stream stream, ISqlObject obj) {
            base.SerializeObject(stream, obj);
        }

        public override bool CanCastTo(SqlType destType) {
            return destType is StringType ||
                   destType is BinaryType;
        }

        public override DataObject CastTo(DataObject value, SqlType destType) {
            var xmlNode = value.Value as SqlXmlNode;
            if (xmlNode == null)
                return DataObject.Null(this);

            var destTypeCode = destType.TypeCode;
            switch (destTypeCode) {
                case SqlTypeCode.String:
                case SqlTypeCode.VarChar:
                case SqlTypeCode.LongVarChar:
                    // TODO: more advanced casting...
                    return DataObject.String(xmlNode.ToSqlString());
                case SqlTypeCode.Binary:
                case SqlTypeCode.LongVarBinary:
                case SqlTypeCode.VarBinary:
                    // TODO: more advanced casting...
                    return DataObject.Binary(xmlNode.ToSqlBinary());
                default:
                    throw new InvalidCastException(String.Format("Cannot cast XML node to type '{0}'.", destType));
            }
        }
    }
}