mcs/class/corlib/System/DBNull.cs

   1 //
   2 // System.DBNull.cs
   3 //
   4 // Authors:
   5 //   Duncan Mak (duncan@ximian.com)
   6 //   Ben Maurer (bmaurer@users.sourceforge.net)
   7 //
   8 // (C) 2002 Ximian, Inc. http://www.ximian.com
   9 // (C) 2003 Ben Maurer
  10 //
  11
  12 //
  13 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  14 //
  15 // Permission is hereby granted, free of charge, to any person obtaining
  16 // a copy of this software and associated documentation files (the
  17 // "Software"), to deal in the Software without restriction, including
  18 // without limitation the rights to use, copy, modify, merge, publish,
  19 // distribute, sublicense, and/or sell copies of the Software, and to
  20 // permit persons to whom the Software is furnished to do so, subject to
  21 // the following conditions:
  22 //
  23 // The above copyright notice and this permission notice shall be
  24 // included in all copies or substantial portions of the Software.
  25 //
  26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  33 //
  34
  35 using System.Runtime.Serialization;
  36
  37 namespace System
  38 {
  39         [Serializable]
  40         public sealed class DBNull : ISerializable, IConvertible
  41         {
  42                 // Fields
  43                 public static readonly DBNull Value = new DBNull ();
  44
  45                 // Private constructor
  46                 private DBNull ()
  47                 {
  48                 }
  49
  50                 private DBNull (SerializationInfo info, StreamingContext context)
  51                 {
  52                         throw new NotSupportedException ();
  53                 }
  54
  55                 // Methods
  56                 public void GetObjectData (SerializationInfo info, StreamingContext context)
  57                 {
  58                         UnitySerializationHolder.GetDBNullData (this, info, context);
  59                 }
  60
  61                 public TypeCode GetTypeCode ()
  62                 {
  63                         return TypeCode.DBNull;
  64                 }
  65
  66                 bool IConvertible.ToBoolean (IFormatProvider provider)
  67                 {
  68                         throw new InvalidCastException ();
  69                 }
  70
  71                 byte IConvertible.ToByte (IFormatProvider provider)
  72                 {
  73                         throw new InvalidCastException ();
  74                 }
  75
  76                 char IConvertible.ToChar (IFormatProvider provider)
  77                 {
  78                         throw new InvalidCastException ();
  79                 }
  80
  81                 DateTime IConvertible.ToDateTime (IFormatProvider provider)
  82                 {
  83                         throw new InvalidCastException ();
  84                 }
  85
  86                 decimal IConvertible.ToDecimal (IFormatProvider provider)
  87                 {
  88                         throw new InvalidCastException ();
  89                 }
  90
  91                 double IConvertible.ToDouble (IFormatProvider provider)
  92                 {
  93                         throw new InvalidCastException ();
  94                 }
  95
  96                 short IConvertible.ToInt16 (IFormatProvider provider)
  97                 {
  98                         throw new InvalidCastException ();
  99                 }
 100
 101                 int IConvertible.ToInt32 (IFormatProvider provider)
 102                 {
 103                         throw new InvalidCastException ();
 104                 }
 105
 106                 long IConvertible.ToInt64 (IFormatProvider provider)
 107                 {
 108                         throw new InvalidCastException ();
 109                 }
 110
 111                 sbyte IConvertible.ToSByte (IFormatProvider provider)
 112                 {
 113                         throw new InvalidCastException ();
 114                 }
 115
 116                 float IConvertible.ToSingle (IFormatProvider provider)
 117                 {
 118                         throw new InvalidCastException ();
 119                 }
 120
 121                 object IConvertible.ToType (Type type, IFormatProvider provider)
 122                 {
 123                         if (type == typeof (string))
 124                                 return String.Empty;
 125                         throw new InvalidCastException ();
 126                 }
 127
 128                 ushort IConvertible.ToUInt16 (IFormatProvider provider)
 129                 {
 130                         throw new InvalidCastException ();
 131                 }
 132
 133                 uint IConvertible.ToUInt32 (IFormatProvider provider)
 134                 {
 135                         throw new InvalidCastException ();
 136                 }
 137
 138                 ulong IConvertible.ToUInt64 (IFormatProvider provider)
 139                 {
 140                         throw new InvalidCastException ();
 141                 }
 142
 143                 public override string ToString ()
 144                 {
 145                         return String.Empty;
 146                 }
 147
 148                 public string ToString (IFormatProvider provider)
 149                 {
 150                         return String.Empty;
 151                 }
 152         }
 153 }