2007-11-14 Zoltan Varga <vargaz@gmail.com>

[mono.git] / mcs / class / corlib / System / Nullable.cs

diff --git a/mcs/class/corlib/System/Nullable.cs b/mcs/class/corlib/System/Nullable.cs
index 531d553cd8be2bf874c6158cd11c61ba651789cd..b981afb00596bb21fb9788cce4c8513c2a355adc 100644 (file)
--- a/mcs/class/corlib/System/Nullable.cs
+++ b/mcs/class/corlib/System/Nullable.cs
@@ -6,25 +6,85 @@
 // (C) 2004 Novell, Inc.
 //
 
+//
+// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
+//
+// Permission is hereby granted, free of charge, to any person obtaining
+// a copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to
+// permit persons to whom the Software is furnished to do so, subject to
+// the following conditions:
+// 
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//
+
 using System.Reflection;
-#if GENERICS
+#if NET_2_0
 using System.Collections.Generic;
 #endif
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+#if NET_2_0
+namespace System {
+#if NET_2_0
+       [ComVisible (true)]
+#endif
+       public static class Nullable {
+               public static int Compare<T> (Nullable<T> left, Nullable<T> right) where T: struct
+               {
+                       IComparable icomparable = left.value as IComparable;
+                       if (icomparable == null)
+                               throw new ArgumentException ("At least one object must implement IComparable.");
+                       if (left.has_value == false && right.has_value == false)
+                               return 0;
+                       if (!left.has_value)
+                               return -1;
+                       if (!right.has_value)
+                               return 1;
 
-#if GENERICS
-namespace System
-{
-       [CLSCompliant(false)]
-       public struct Nullable<T>
+                       return icomparable.CompareTo (right.value);
+               }
+
+               public static bool Equals<T> (Nullable <T> value1, Nullable<T> value2) where T: struct
+               {
+                       return value1.Equals (value2);
+               }
+
+               public static Type GetUnderlyingType (Type nullableType)
+               {
+                       if (nullableType == null)
+                               throw new ArgumentNullException ("nullableType");
+                       if (nullableType.IsGenericType && nullableType.GetGenericTypeDefinition () == typeof (Nullable<>))
+                               return nullableType.GetGenericArguments ()[0];
+                       else
+                               return null;
+               }
+       }
+
+       [Serializable]
+       public struct Nullable<T> where T: struct
        {
-               T value;
-               bool has_value;
+               #region Sync with runtime code
+               internal T value;
+               internal bool has_value;
+               #endregion
 
                public Nullable (T value)
                {
-                       this.value = value;
                        this.has_value = true;
+                       this.value = value;
                }
 
                public bool HasValue {
@@ -32,22 +92,90 @@ namespace System
                }
 
                public T Value {
-                       get { return value; }
+                       get { 
+                               if (!has_value)
+                                       throw new InvalidOperationException ("Nullable object must have a value.");
+                               
+                               return value; 
+                       }
+               }
+
+               public override bool Equals (object other)
+               {
+                       if (other == null)
+                               return has_value == false;
+                       if (!(other is Nullable<T>))
+                               return false;
+
+                       return Equals ((Nullable <T>) other);
+               }
+
+               bool Equals (Nullable<T> other)
+               {
+                       Nullable<T> no = (Nullable<T>) other;
+                       if (no.has_value != has_value)
+                               return false;
+
+                       if (has_value == false)
+                               return true;
+
+                       return no.value.Equals (value);
+               }
+
+               public override int GetHashCode ()
+               {
+                       if (!has_value)
+                               return 0;
+
+                       return value.GetHashCode ();
                }
 
                public T GetValueOrDefault ()
                {
-                       if (has_value)
-                               return value;
-                       return default (T);
+                       return GetValueOrDefault (default (T));
                }
 
                public T GetValueOrDefault (T def_value)
                {
-                       if (has_value)
+                       if (!has_value)
+                               return def_value;
+                       else
                                return value;
+               }
+
+               public override string ToString ()
+               {
+                       if (has_value)
+                               return value.ToString ();
                        else
-                               return def_value;
+                               return String.Empty;
+               }
+
+               public static implicit operator Nullable<T> (T value)
+               {
+                       return new Nullable<T> (value);
+               }
+
+               public static explicit operator T (Nullable<T> value)
+               {
+                       return value.Value;
+               }
+
+               // These are called by the JIT
+               // Ironicly, the C#  code is the same for these two,
+               // however, on the inside they do somewhat different things
+               static object Box (T? o)
+               {
+                       if (o == null)
+                               return null;
+                       return (T) o;
+               }
+               
+               static T? Unbox (object o)
+               {
+                       if (o == null)
+                               return null;
+                       return (T) o;
                }
        }
 }