- Added `GetCharCountImpl` tests, fixed handling of empty strings

- Added ifdef to remove `Deconstruct` extension on everything except `NETSTANDARD2_0`

LLama.Unittest/EncodingExtensionsTests.cs

@@ -16,6 +16,15 @@ namespace LLama.Unittest
             Assert.True(chars[..count].SequenceEqual(str));
         }
 
+        private static void GetCharCountTest(string str)
+        {
+            var bytes = Encoding.UTF8.GetBytes(str);
+
+            var count = EncodingExtensions.GetCharCountImpl(Encoding.UTF8, bytes);
+
+            Assert.Equal(str.Length, count);
+        }
+
         [Fact]
         public void GetCharsEmptyString()
         {
@@ -33,5 +42,23 @@ namespace LLama.Unittest
         {
             GetCharsTest("猫坐在垫子上");
         }
+
+        [Fact]
+        public void GetCharCountEmptyString()
+        {
+            GetCharCountTest("");
+        }
+
+        [Fact]
+        public void GetCharCountString()
+        {
+            GetCharCountTest("Hello World");
+        }
+
+        [Fact]
+        public void GetCharCountChineseString()
+        {
+            GetCharCountTest("猫坐在垫子上");
+        }
     }
 }

LLama/Extensions/EncodingExtensions.cs

@@ -35,6 +35,9 @@ internal static class EncodingExtensions
 
     internal static int GetCharCountImpl(Encoding encoding, ReadOnlySpan<byte> bytes)
     {
+        if (bytes.Length == 0)
+            return 0;
+
         unsafe
         {
             fixed (byte* bytePtr = bytes)

LLama/Extensions/KeyValuePairExtensions.cs

@@ -5,8 +5,9 @@ namespace LLama.Extensions
     /// <summary>
     /// Extensions to the KeyValuePair struct
     /// </summary>
-    public static class KeyValuePairExtensions
+    internal static class KeyValuePairExtensions
     {
+#if NETSTANDARD2_0
         /// <summary>
         /// Deconstruct a KeyValuePair into it's constituent parts.
         /// </summary>
@@ -20,5 +21,6 @@ namespace LLama.Extensions
             first = pair.Key;
             second = pair.Value;
         }
+#endif
     }
 }