In JavaScriptEngineSwitcher.ChakraCore improved a performance of the UnicodeToAnsi method of EncodingHelpers class

Author: Taritsyn

src/JavaScriptEngineSwitcher.ChakraCore/Helpers/EncodingHelpers.cs

@@ -25,7 +25,11 @@ public static string UnicodeToAnsi(string value, out int byteCount)
 			string result;
 			int valueLength = value.Length;
 			Encoding utf8Encoding = Encoding.UTF8;
+#if NETFULL
+			Encoding ansiEncoding = Encoding.Default;
+#else
 			Encoding ansiEncoding = Encoding.GetEncoding(0);
+#endif
 
 			var byteArrayPool = ArrayPool<byte>.Shared;
 			int bufferLength = utf8Encoding.GetByteCount(value);
@@ -34,7 +38,7 @@ public static string UnicodeToAnsi(string value, out int byteCount)
 
 			try
 			{
-#if NET471 || NETSTANDARD || NETCOREAPP2_1
+#if NET45 || NET471 || NETSTANDARD || NETCOREAPP2_1
 				result = ConvertStringInternal(utf8Encoding, ansiEncoding, value, valueLength, buffer, bufferLength);
 #else
 				utf8Encoding.GetBytes(value, 0, valueLength, buffer, 0);
@@ -50,7 +54,7 @@ public static string UnicodeToAnsi(string value, out int byteCount)
 
 			return result;
 		}
-#if NET471 || NETSTANDARD || NETCOREAPP2_1
+#if NET45 || NET471 || NETSTANDARD || NETCOREAPP2_1
 
 		private static unsafe string ConvertStringInternal(Encoding srcEncoding, Encoding dstEncoding, string s,
 			int charCount, byte[] bytes, int byteCount)
@@ -59,10 +63,37 @@ private static unsafe string ConvertStringInternal(Encoding srcEncoding, Encodin
 			fixed (byte* pBytes = bytes)
 			{
 				srcEncoding.GetBytes(pString, charCount, pBytes, byteCount);
+#if NET471 || NETSTANDARD || NETCOREAPP2_1
 				string result = dstEncoding.GetString(pBytes, byteCount);
 
 				return result;
 			}
+#else
+			}
+
+			int resultLength = dstEncoding.GetCharCount(bytes, 0, byteCount);
+			var charArrayPool = ArrayPool<char>.Shared;
+			char[] resultChars = charArrayPool.Rent(resultLength + 1);
+			resultChars[resultLength] = '\0';
+
+			string result;
+
+			try
+			{
+				fixed (byte* pBytes = bytes)
+				fixed (char* pResultChars = resultChars)
+				{
+					dstEncoding.GetChars(pBytes, byteCount, pResultChars, resultLength);
+					result = new string(pResultChars, 0, resultLength);
+				}
+			}
+			finally
+			{
+				charArrayPool.Return(resultChars);
+			}
+
+			return result;
+#endif
 		}
 #endif
 	}

src/JavaScriptEngineSwitcher.ChakraCore/JavaScriptEngineSwitcher.ChakraCore.csproj

@@ -22,9 +22,7 @@ This package does not contain the native implementations of ChakraCore. Therefor
  * JavaScriptEngineSwitcher.ChakraCore.Native.osx-x64</Description>
 		<PackageIconUrl>https://raw.githubusercontent.com/Taritsyn/JavaScriptEngineSwitcher/master/Icons/JavaScriptEngineSwitcher_ChakraCore_Logo128x128.png</PackageIconUrl>
 		<PackageTags>JavaScriptEngineSwitcher;JavaScript;ECMAScript;ChakraCore</PackageTags>
-		<PackageReleaseNotes>1. Reduced a memory consumption in cases, where not used the embedding of objects and types;
-2. Fixed a wrong implementation of destruction of the embedded delegates;
-3. Accelerated a conversion of script types to host types.</PackageReleaseNotes>
+		<PackageReleaseNotes>Improved a performance of the `UnicodeToAnsi` method of `EncodingHelpers` class.</PackageReleaseNotes>
 	</PropertyGroup>
 
 	<Import Project="../../build/common.props" />

src/JavaScriptEngineSwitcher.ChakraCore/readme.txt

@@ -30,10 +30,7 @@
    =============
    RELEASE NOTES
    =============
-  1. Reduced a memory consumption in cases, where not used the embedding of objects
-     and types;
-  2. Fixed a wrong implementation of destruction of the embedded delegates;
-  3. Accelerated a conversion of script types to host types.
+   Improved a performance of the `UnicodeToAnsi` method of `EncodingHelpers` class.
 
    =============
    DOCUMENTATION