4 // Martin Baulig (martin@ximian.com)
5 // Marek Safar (marek.safar@gmail.com)
7 // (C) 2004 Novell, Inc.
11 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
13 // Permission is hereby granted, free of charge, to any person obtaining
14 // a copy of this software and associated documentation files (the
15 // "Software"), to deal in the Software without restriction, including
16 // without limitation the rights to use, copy, modify, merge, publish,
17 // distribute, sublicense, and/or sell copies of the Software, and to
18 // permit persons to whom the Software is furnished to do so, subject to
19 // the following conditions:
21 // The above copyright notice and this permission notice shall be
22 // included in all copies or substantial portions of the Software.
24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
33 using System
.Reflection
;
34 using System
.Collections
.Generic
;
35 using System
.Runtime
.CompilerServices
;
36 using System
.Runtime
.InteropServices
;
41 public static class Nullable
{
46 public static int Compare
<T
> (T
? value1
, T
? value2
) where T
: struct
48 if (value1
.has_value
) {
49 if (!value2
.has_value
)
52 return Comparer
<T
>.Default
.Compare (value1
.value, value2
.value);
55 return value2
.has_value
? -1 : 0;
61 public static bool Equals
<T
> (T
? value1
, T
? value2
) where T
: struct
63 if (value1
.has_value
!= value2
.has_value
)
66 if (!value1
.has_value
)
69 return EqualityComparer
<T
>.Default
.Equals (value1
.value, value2
.value);
72 public static Type
GetUnderlyingType (Type nullableType
)
74 if (nullableType
== null)
75 throw new ArgumentNullException ("nullableType");
76 if (nullableType
.IsGenericType
&& nullableType
.GetGenericTypeDefinition () == typeof (Nullable
<>))
77 return nullableType
.GetGenericArguments ()[0];
84 public struct Nullable
<T
> where T
: struct
86 #region Sync with runtime code
88 internal bool has_value
;
91 public Nullable (T
value)
93 this.has_value
= true;
97 public bool HasValue
{
98 get { return has_value; }
104 throw new InvalidOperationException ("Nullable object must have a value.");
110 public override bool Equals (object other
)
113 return has_value
== false;
114 if (!(other
is Nullable
<T
>))
117 return Equals ((Nullable
<T
>) other
);
120 bool Equals (Nullable
<T
> other
)
122 if (other
.has_value
!= has_value
)
125 if (has_value
== false)
128 return other
.value.Equals (value);
131 public override int GetHashCode ()
136 return value.GetHashCode ();
139 public T
GetValueOrDefault ()
141 return has_value
? value : default (T
);
144 public T
GetValueOrDefault (T defaultValue
)
146 return has_value
? value : defaultValue
;
149 public override string ToString ()
152 return value.ToString ();
157 public static implicit operator Nullable
<T
> (T
value)
159 return new Nullable
<T
> (value);
162 public static explicit operator T (Nullable
<T
> value)
168 // These are called by the JIT
170 #pragma warning disable 169
172 // JIT implementation of box valuetype System.Nullable`1<T>
174 static object Box (T
? o
)
182 static T
? Unbox (object o
)
188 #pragma warning restore 169