5 // Duncan Mak (duncan@ximian.com)
6 // Ben Maurer (bmaurer@users.sourceforge.net)
8 // (C) 2002 Ximian, Inc. http://www.ximian.com
13 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
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:
23 // The above copyright notice and this permission notice shall be
24 // included in all copies or substantial portions of the Software.
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.
35 using System.Runtime.Serialization;
36 using System.Runtime.InteropServices;
44 public sealed class DBNull : ISerializable, IConvertible
47 public static readonly DBNull Value = new DBNull ();
49 // Private constructor
54 private DBNull (SerializationInfo info, StreamingContext context)
56 throw new NotSupportedException ();
60 public void GetObjectData (SerializationInfo info, StreamingContext context)
62 UnitySerializationHolder.GetDBNullData (this, info, context);
65 public TypeCode GetTypeCode ()
67 return TypeCode.DBNull;
70 bool IConvertible.ToBoolean (IFormatProvider provider)
72 throw new InvalidCastException ();
75 byte IConvertible.ToByte (IFormatProvider provider)
77 throw new InvalidCastException ();
80 char IConvertible.ToChar (IFormatProvider provider)
82 throw new InvalidCastException ();
85 DateTime IConvertible.ToDateTime (IFormatProvider provider)
87 throw new InvalidCastException ();
90 decimal IConvertible.ToDecimal (IFormatProvider provider)
92 throw new InvalidCastException ();
95 double IConvertible.ToDouble (IFormatProvider provider)
97 throw new InvalidCastException ();
100 short IConvertible.ToInt16 (IFormatProvider provider)
102 throw new InvalidCastException ();
105 int IConvertible.ToInt32 (IFormatProvider provider)
107 throw new InvalidCastException ();
110 long IConvertible.ToInt64 (IFormatProvider provider)
112 throw new InvalidCastException ();
115 sbyte IConvertible.ToSByte (IFormatProvider provider)
117 throw new InvalidCastException ();
120 float IConvertible.ToSingle (IFormatProvider provider)
122 throw new InvalidCastException ();
125 object IConvertible.ToType (Type type, IFormatProvider provider)
127 if (type == typeof (string))
129 throw new InvalidCastException ();
132 ushort IConvertible.ToUInt16 (IFormatProvider provider)
134 throw new InvalidCastException ();
137 uint IConvertible.ToUInt32 (IFormatProvider provider)
139 throw new InvalidCastException ();
142 ulong IConvertible.ToUInt64 (IFormatProvider provider)
144 throw new InvalidCastException ();
147 public override string ToString ()
152 public string ToString (IFormatProvider provider)