AnsiParser improvement (dotnet#39729)

Jacksondr5 · Aug 10, 2020 · 211b72d · 211b72d
1 parent 402e551
commit 211b72d
Showing 1 changed file with 11 additions and 10 deletions.
diff --git a/src/libraries/Microsoft.Extensions.Logging.Console/src/AnsiParser.cs b/src/libraries/Microsoft.Extensions.Logging.Console/src/AnsiParser.cs
@@ -3,6 +3,7 @@
 
 using System;
 using System.IO;
+using System.Runtime.CompilerServices;
 
 namespace Microsoft.Extensions.Logging.Console
 {
@@ -47,6 +48,7 @@ public void Parse(string message)
         {
             int startIndex = -1;
             int length = 0;
+            int escapeCode;
             ConsoleColor? foreground = null;
             ConsoleColor? background = null;
             var span = message.AsSpan();
@@ -59,12 +61,10 @@ public void Parse(string message)
                 {
                     if (span[i + 3] == 'm')
                     {
-#if NETCOREAPP
-                        if (ushort.TryParse(span.Slice(i + 2, length: 1), out ushort escapeCode))
-#else
-                        if (ushort.TryParse(span.Slice(i + 2, length: 1).ToString(), out ushort escapeCode))
-#endif
+                        // Example: \x1B[1m
+                        if (IsDigit(span[i + 2]))
                         {
+                            escapeCode = (int)(span[i + 2] - '0');
                             if (startIndex != -1)
                             {
                                 _onParseWrite(message, startIndex, length, background, foreground);
@@ -79,12 +79,10 @@ public void Parse(string message)
                     }
                     else if (span.Length >= i + 5 && span[i + 4] == 'm')
                     {
-#if NETCOREAPP
-                        if (ushort.TryParse(span.Slice(i + 2, length: 2), out ushort escapeCode))
-#else
-                        if (ushort.TryParse(span.Slice(i + 2, length: 2).ToString(), out ushort escapeCode))
-#endif
+                        // Example: \x1B[40m
+                        if (IsDigit(span[i + 2]) && IsDigit(span[i + 3]))
                         {
+                            escapeCode = (int)(span[i + 2] - '0') * 10 + (int)(span[i + 3] - '0');
                             if (startIndex != -1)
                             {
                                 _onParseWrite(message, startIndex, length, background, foreground);
@@ -128,6 +126,9 @@ public void Parse(string message)
             }
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static bool IsDigit(char c) => (uint)(c - '0') <= ('9' - '0');
+
         internal const string DefaultForegroundColor = "\x1B[39m\x1B[22m"; // reset to default foreground color
         internal const string DefaultBackgroundColor = "\x1B[49m"; // reset to the background color