Add LuaTable.SetNil()

Author: Quahu

src/Laylua.Tests/Tests/Library/Entities/Table/LuaTableTests.cs

@@ -144,6 +144,21 @@ public void GetValueOrDefault_MissingNullableInt_DefaultValue_ReturnsDefaultValu
         Assert.That(missingValue, Is.EqualTo(42));
     }
 
+    [Test]
+    public void SetNil_ExistingValue_OverwritesItToNil()
+    {
+        // Arrange
+        using var table = Lua.CreateTable();
+
+        // Act
+        table.SetValue("Value", 1);
+        table.SetNil("Value");
+        var value = table.GetValueOrDefault<string, int?>("Value");
+
+        // Assert
+        Assert.That(value, Is.Null);
+    }
+
     [Test]
     public void Count_ReturnsValidCount()
     {

src/Laylua/Library/Entities/Reference/Table/LuaTable.cs

@@ -393,6 +393,29 @@ public void SetValue<TKey, TValue>(TKey key, TValue? value)
         }
     }
 
+    /// <summary>
+    ///     Sets a nil value with the given key in the table.
+    /// </summary>
+    /// <param name="key"> The key of the value to set. </param>
+    /// <typeparam name="TKey"> The type of the key. </typeparam>
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    public void SetNil<TKey>(TKey key)
+        where TKey : notnull
+    {
+        ThrowIfInvalid();
+
+        Lua.Stack.EnsureFreeCapacity(3);
+
+        var L = Lua.GetStatePointer();
+        using (Lua.Stack.SnapshotCount())
+        {
+            PushValue(this);
+            Lua.Stack.Push(key);
+            Lua.Stack.PushNil();
+            lua_settable(L, -3);
+        }
+    }
+
     /// <summary>
     ///     Clears this table by setting all values to nil.
     /// </summary>