List InsertRange Span (#149)

Author: SimonCropp

api_list.include.md

@@ -50,6 +50,7 @@
 
  * `Void AddRange<T>(ReadOnlySpan<T>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.collectionextensions.addrange)
  * `Void CopyTo<T>(Span<T>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.collectionextensions.copyto?view=net-8.0)
+ * `Void InsertRange<T>(Int32, ReadOnlySpan<T>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.collectionextensions.insertrange)
 
 
 #### DateTime

readme.md

@@ -407,6 +407,7 @@ The class `Polyfill` includes the following extension methods:
 
  * `Void AddRange<T>(ReadOnlySpan<T>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.collectionextensions.addrange)
  * `Void CopyTo<T>(Span<T>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.collectionextensions.copyto?view=net-8.0)
+ * `Void InsertRange<T>(Int32, ReadOnlySpan<T>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.collectionextensions.insertrange)
 
 
 #### DateTime

src/Polyfill/Polyfill_List.cs

@@ -24,6 +24,23 @@ public static void AddRange<T>(this List<T> list, ReadOnlySpan<T> source)
         }
     }
 
+    /// <summary>Inserts the elements of a span into the <see cref="List{T}"/> at the specified index.</summary>
+    /// <typeparam name="T">The type of elements in the list.</typeparam>
+    /// <param name="list">The list into which the elements should be inserted.</param>
+    /// <param name="index">The zero-based index at which the new elements should be inserted.</param>
+    /// <param name="source">The span whose elements should be added to the <see cref="List{T}"/>.</param>
+    /// <exception cref="ArgumentNullException">The <paramref name="list"/> is null.</exception>
+    /// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is less than 0 or greater than <paramref name="list"/>'s <see cref="List{T}.Count"/>.</exception>
+    [Link("https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.collectionextensions.insertrange")]
+    public static void InsertRange<T>(this List<T> list, int index, ReadOnlySpan<T> source)
+    {
+        for (var i = 0; i < source.Length; i++)
+        {
+            var item = source[i];
+            list.Insert(i + index, item);
+        }
+    }
+
     /// <summary>Copies the entire <see cref="List{T}"/> to a span.</summary>
     /// <typeparam name="T">The type of elements in the list.</typeparam>
     /// <param name="list">The list from which the elements are copied.</param>

src/Tests/PolyfillTests_List.cs

@@ -9,6 +9,18 @@ public void ListAddRangeReadOnlySpan()
         Assert.AreEqual('b', list[1]);
     }
 
+    [Test]
+    public void ListInsertRangeReadOnlySpan()
+    {
+        var list = new List<char>
+        {
+            'a'
+        };
+        list.InsertRange(1, "bc".AsSpan());
+        Assert.AreEqual('b', list[1]);
+        Assert.AreEqual('c', list[2]);
+    }
+
     [Test]
     public void ListCopyToSpan()
     {