From 85becd241533fccf8ec534a41fd148168cd59f9c Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Wed, 20 Apr 2022 19:27:06 +0100
Subject: [PATCH] Add Array.Fill

---
 X10D.Tests/src/Core/ArrayTests.cs           | 23 +++++++++-
 X10D/src/ArrayExtensions/ArrayExtensions.cs | 49 ++++++++++++++++++++-
 2 files changed, 69 insertions(+), 3 deletions(-)

diff --git a/X10D.Tests/src/Core/ArrayTests.cs b/X10D.Tests/src/Core/ArrayTests.cs
index 3b12420..8bd6533 100644
--- a/X10D.Tests/src/Core/ArrayTests.cs
+++ b/X10D.Tests/src/Core/ArrayTests.cs
@@ -15,8 +15,7 @@ public class ArrayTests
         args.Clear();
 
         int[] comparison = Enumerable.Repeat(0, args.Length).ToArray();
-        CollectionAssert.AreEqual(args, comparison, $"{string.Join(", ", args)} is not equal to" +
-                                                    $"{string.Join(", ", comparison)}. ");
+        CollectionAssert.AreEqual(args, comparison);
     }
 
     [TestMethod]
@@ -25,4 +24,24 @@ public class ArrayTests
         int[]? array = null;
         Assert.ThrowsException<ArgumentNullException>(array!.Clear);
     }
+
+    [TestMethod]
+    [DataRow]
+    [DataRow(1)]
+    [DataRow(1, 2, 3)]
+    [DataRow(1, 2, 3, 4, 5)]
+    public void Fill(params int[] args)
+    {
+        args.Fill(1);
+
+        int[] comparison = Enumerable.Repeat(1, args.Length).ToArray();
+        CollectionAssert.AreEqual(args, comparison);
+    }
+
+    [TestMethod]
+    public void FillNull()
+    {
+        int[]? array = null;
+        Assert.ThrowsException<ArgumentNullException>(() => array!.Fill(0));
+    }
 }
diff --git a/X10D/src/ArrayExtensions/ArrayExtensions.cs b/X10D/src/ArrayExtensions/ArrayExtensions.cs
index 6f454dc..8968adc 100644
--- a/X10D/src/ArrayExtensions/ArrayExtensions.cs
+++ b/X10D/src/ArrayExtensions/ArrayExtensions.cs
@@ -53,7 +53,7 @@ public static class ArrayExtensions
         {
             end = array.Length - end;
         }
-        
+
         array.Clear(index, end - index);
     }
 
@@ -86,4 +86,51 @@ public static class ArrayExtensions
 
         Array.Clear(array, index, length);
     }
+
+    /// <summary>
+    ///     Assigns the given value to each element of the array.
+    /// </summary>
+    /// <param name="array">The array to be filled.</param>
+    /// <param name="value">The value to assign to each array element.</param>
+    /// <typeparam name="T">The type of the elements in the array.</typeparam>
+    /// <exception cref="ArgumentNullException"><paramref name="array" /> is <see langword="null" />.</exception>
+    public static void Fill<T>(this T?[] array, T value)
+    {
+        if (array is null)
+        {
+            throw new ArgumentNullException(nameof(array));
+        }
+
+        if (array.Length == 0)
+        {
+            return;
+        }
+
+        Array.Fill(array, value);
+    }
+
+    /// <summary>
+    ///     Assigns the given value to the elements of the array which are within the range of <paramref name="startIndex" />
+    ///     (inclusive) and the next <paramref name="count" /> number of indices.
+    /// </summary>
+    /// <param name="array">The array to be filled.</param>
+    /// <param name="value">The value to assign to each array element.</param>
+    /// <param name="startIndex">A 32-bit integer that represents the index in the array at which filling begins.</param>
+    /// <param name="count">The number of elements to fill.</param>
+    /// <typeparam name="T">The type of the elements in the array.</typeparam>
+    /// <exception cref="ArgumentNullException"><paramref name="array" /> is <see langword="null" />.</exception>
+    public static void Fill<T>(this T?[] array, T value, int startIndex, int count)
+    {
+        if (array is null)
+        {
+            throw new ArgumentNullException(nameof(array));
+        }
+
+        if (count == 0 || array.Length == 0)
+        {
+            return;
+        }
+
+        Array.Fill(array, value, startIndex, count);
+    }
 }