Update headers, docs, and add IsNullOrEmpty for arrays

Updated file headers for consistency and correct dates. Clarified XML docs for AsMemento in Action extensions. Added IsNullOrEmpty extension for nullable arrays and improved array extension documentation. Renamed IBinaryInteger extension file header for accuracy.

Author: cerebrate

Arkane.Core/Extensions/ExtensionMethods-System-Action.cs

@@ -7,7 +7,7 @@
 // 
 // Copyright Arkane Systems 2012-2026.  All rights reserved.
 // 
-// Created: 2026-04-06 9:27 AM
+// Created: 2026-04-07 10:27 PM
 
 #endregion
 
@@ -37,10 +37,13 @@ public static partial class ExtensionMethods
   extension (Action @this)
   {
     /// <summary>
-    ///   Creates an <see cref="IDisposable" /> that will execute the specified <see cref="Action" /> when it is
+    ///   Creates an <see cref="IDisposable" /> <see cref="T:ArkaneSystems.Arkane.Memento" /> that will execute the specified
+    ///   <see cref="Action" /> when it is
     ///   disposed.
     /// </summary>
-    /// <returns>An <see cref="IDisposable" /> implemented by a <see cref="T:ArkaneSystems.Arkane.Memento" />.</returns>
+    /// <returns>
+    ///   An <see cref="IDisposable" /> implemented by a <see cref="T:ArkaneSystems.Arkane.Memento" />.
+    /// </returns>
     [PublicAPI]
     public IDisposable AsMemento () => new Memento (@this);
 

Arkane.Core/Extensions/ExtensionMethods-System-Array.cs

@@ -7,7 +7,7 @@
 // 
 // Copyright Arkane Systems 2012-2026.  All rights reserved.
 // 
-// Created: 2026-04-06 6:26 PM
+// Created: 2026-04-07 10:31 AM
 
 #endregion
 
@@ -29,6 +29,11 @@ public static partial class ExtensionMethods
 {
   #region Nested type: $extension
 
+  /// <summary>
+  ///   Extension methods for <see cref="Array" />.  Note that these are not extension methods for
+  ///   <see cref="System.Array" />, but rather for any array type, such as <c>int[]</c>, <c>string[,]</c>, etc.
+  /// </summary>
+  /// <param name="this">The array instance.</param>
   extension (Array @this)
   {
     /// <summary>
@@ -57,5 +62,19 @@ public Type GetElementType ()
     }
   }
 
+  /// <summary>
+  ///   Extension methods for nullable array types.
+  /// </summary>
+  /// <param name="this"></param>
+  extension (Array? @this)
+  {
+    /// <summary>
+    ///   Determines whether the specified array is null or has a length of zero.
+    /// </summary>
+    /// <returns>true if the array is null or empty; otherwise, false.</returns>
+    [PublicAPI]
+    public bool IsNullOrEmpty () => (@this == null) || (@this.Length == 0);
+  }
+
   #endregion
 }

Arkane.Core/Extensions/ExtensionMethods-System-Numerics-IBinaryInteger.cs

@@ -1,13 +1,13 @@
 #region header
 
-// Arkane.Core - ExtensionMethods-System-IBinaryInteger.cs
+// Arkane.Core - ExtensionMethods-System-Numerics-IBinaryInteger.cs
 // 
 // Alistair J. R. Young
 // Arkane Systems
 // 
 // Copyright Arkane Systems 2012-2026.  All rights reserved.
 // 
-// Created: 2026-04-05 11:04 PM
+// Created: 2026-04-07 10:31 AM
 
 #endregion