Add Encoding GetCharCount

Author: SimonCropp

apiCount.include.md

@@ -1 +1 @@
-**API count: 454**
+**API count: 455**

api_list.include.md

@@ -89,6 +89,7 @@
 
  * `int GetByteCount(Encoding, ReadOnlySpan<char>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getbytecount#system-text-encoding-getbytecount(system-readonlyspan((system-char))))
  * `int GetBytes(Encoding, ReadOnlySpan<char>, Span<byte>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getbytes#system-text-encoding-getbytes(system-readonlyspan((system-char))-system-span((system-byte))))
+ * `int GetCharCount(Encoding, ReadOnlySpan<byte>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getcharcount#system-text-encoding-getcharcount(system-readonlyspan((system-byte))))
  * `string GetString(Encoding, ReadOnlySpan<byte>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getstring#system-text-encoding-getstring(system-readonlyspan((system-byte))))
 
 

readme.md

@@ -12,7 +12,7 @@ The package targets `netstandard2.0` and is designed to support the following ru
  * `net5.0`, `net6.0`, `net7.0`, `net8.0`, `net9.0`
 
 
-**API count: 454**<!-- singleLineInclude: apiCount. path: /apiCount.include.md -->
+**API count: 455**<!-- singleLineInclude: apiCount. path: /apiCount.include.md -->
 
 
 **See [Milestones](../../milestones?state=closed) for release notes.**
@@ -558,6 +558,7 @@ The class `Polyfill` includes the following extension methods:
 
  * `int GetByteCount(Encoding, ReadOnlySpan<char>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getbytecount#system-text-encoding-getbytecount(system-readonlyspan((system-char))))
  * `int GetBytes(Encoding, ReadOnlySpan<char>, Span<byte>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getbytes#system-text-encoding-getbytes(system-readonlyspan((system-char))-system-span((system-byte))))
+ * `int GetCharCount(Encoding, ReadOnlySpan<byte>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getcharcount#system-text-encoding-getcharcount(system-readonlyspan((system-byte))))
  * `string GetString(Encoding, ReadOnlySpan<byte>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getstring#system-text-encoding-getstring(system-readonlyspan((system-byte))))
 
 

src/Polyfill/Polyfill_Encoding_GetCharCount.cs

@@ -0,0 +1,36 @@
+// <auto-generated />
+
+#pragma warning disable
+
+#if FeatureMemory
+
+namespace Polyfills;
+
+using System;
+
+using System.Runtime.InteropServices;
+using System.Text;
+
+static partial class Polyfill
+{
+#if NETCOREAPP2_0 || NETFRAMEWORK || NETSTANDARD2_0
+    /// <summary>
+    /// Calculates the number of characters produced by decoding the provided read-only byte span.
+    /// </summary>
+    /// <param name="chars">A read-only byte span to decode.</param>
+    /// <returns>The number of characters produced by decoding the byte span.</returns>
+    //Link: https://learn.microsoft.com/en-us/dotnet/api/system.text.encoding.getcharcount#system-text-encoding-getcharcount(system-readonlyspan((system-byte)))
+    public static int GetCharCount(this Encoding target, ReadOnlySpan<byte> bytes)
+    {
+        if (target is null)
+        {
+            throw new ArgumentNullException(nameof(target));
+        }
+
+        return target.GetCharCount(bytes.ToArray());
+    }
+#endif
+
+}
+
+#endif