Merge pull request #5207 from smoogipoo/nullable-support

Add IsNull()/IsNotNull() helper extensions

osu.Framework/Extensions/ObjectExtensions/ObjectExtensions.cs

@@ -1,10 +1,11 @@
 // Copyright (c) ppy Pty Ltd <[email protected]>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-using System.Diagnostics;
-
 #nullable enable
 
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+
 namespace osu.Framework.Extensions.ObjectExtensions
 {
     /// <summary>
@@ -27,5 +28,15 @@ public static T AsNonNull<T>(this T? obj)
             Debug.Assert(obj != null);
             return obj;
         }
+
+        /// <summary>
+        /// If the given object is null.
+        /// </summary>
+        public static bool IsNull<T>([NotNullWhen(false)] this T obj) => ReferenceEquals(obj, null);
+
+        /// <summary>
+        /// <c>true</c> if the given object is not null, <c>false</c> otherwise.
+        /// </summary>
+        public static bool IsNotNull<T>([NotNullWhen(true)] this T obj) => !ReferenceEquals(obj, null);
     }
 }