Regex feedback

Author: JamesNK

src/Shared/ConsoleLogs/TimestampParser.cs

@@ -9,16 +9,14 @@ namespace Aspire.Dashboard.ConsoleLogs;
 
 internal static partial class TimestampParser
 {
-    private static readonly Regex s_rfc3339RegEx = GenerateRfc3339RegEx();
-
     public static bool TryParseConsoleTimestamp(string text, [NotNullWhen(true)] out TimestampParserResult? result)
     {
-        var match = s_rfc3339RegEx.Match(text);
+        // Regex is cached inside the method.
+        var match = GenerateRfc3339RegEx().Match(text);
 
         if (match.Success)
         {
             var span = text.AsSpan();
-            var timestamp = span[match.Index..(match.Index + match.Length)];
 
             ReadOnlySpan<char> content;
             if (match.Index + match.Length >= span.Length)
@@ -36,6 +34,7 @@ public static bool TryParseConsoleTimestamp(string text, [NotNullWhen(true)] out
                 }
             }
 
+            var timestamp = match.ValueSpan;
             result = new(content.ToString(), DateTimeOffset.Parse(timestamp.ToString(), CultureInfo.InvariantCulture));
             return true;
         }
@@ -45,34 +44,24 @@ public static bool TryParseConsoleTimestamp(string text, [NotNullWhen(true)] out
     }
 
     // Regular Expression for an RFC3339 timestamp, including RFC3339Nano
-    //
-    // Example timestamps:
-    // 2023-10-02T12:56:35.123456789Z
-    // 2023-10-02T13:56:35.123456789+10:00
-    // 2023-10-02T13:56:35.123456789-10:00
-    // 2023-10-02T13:56:35.123456789Z10:00
-    // 2023-10-02T13:56:35.123456Z
-    // 2023-10-02T13:56:35Z
-    //
-    // Explanation:
-    // ^                                                   - Starts the string
-    // (?:\\d{4})                                          - Four digits for the year
-    // -                                                   - Separator for the date
-    // (?:0[1-9]|1[0-2])                                   - Two digits for the month, restricted to 01-12
-    // -                                                   - Separator for the date
-    // (?:0[1-9]|[12][0-9]|3[01])                          - Two digits for the day, restricted to 01-31
-    // [T ]                                                - Literal, separator between date and time, either a T or a space
-    // (?:[01][0-9]|2[0-3])                                - Two digits for the hour, restricted to 00-23
-    // :                                                   - Separator for the time
-    // (?:[0-5][0-9])                                      - Two digits for the minutes, restricted to 00-59
-    // :                                                   - Separator for the time
-    // (?:[0-5][0-9])                                      - Two digits for the seconds, restricted to 00-59
-    // (?:\\.\\d{1,9})                                     - A period and up to nine digits for the partial seconds
-    // Z                                                   - Literal, same as +00:00
-    // (?:[Z+-](?:[01][0-9]|2[0-3]):(?:[0-5][0-9]))        - Time Zone offset, in the form ZHH:MM or +HH:MM or -HH:MM
-    //
-    // Note: (?:) is a non-capturing group, since we don't care about the values, we are just interested in whether or not there is a match
-    [GeneratedRegex("^(?:\\d{4})-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12][0-9]|3[01])T(?:[01][0-9]|2[0-3]):(?:[0-5][0-9]):(?:[0-5][0-9])(?:\\.\\d{1,9})?(?:Z|(?:[Z+-](?:[01][0-9]|2[0-3]):(?:[0-5][0-9])))?")]
+    [GeneratedRegex("""
+        ^                                          # Starts the string
+        \d{4}                                      # Four digits for the year
+        -                                          # Separator for the date
+        (0[1-9]|1[0-2])                            # Two digits for the month, restricted to 01-12
+        -                                          # Separator for the date
+        (0[1-9]|[12][0-9]|3[01])                   # Two digits for the day, restricted to 01-31
+        [T ]                                       # Literal, separator between date and time, either a T or a space
+        ([01][0-9]|2[0-3])                         # Two digits for the hour, restricted to 00-23
+        :                                          # Separator for the time
+        ([0-5][0-9])                               # Two digits for the minutes, restricted to 00-59
+        :                                          # Separator for the time
+        [0-5][0-9]                                 # Two digits for the seconds, restricted to 00-59
+        \.\d{1,9}                                  # A period and up to nine digits for the partial seconds
+        Z                                          # Literal, same as +00:00
+        [Z+-]([01][0-9]|2[0-3]):[0-5][0-9]         # Time Zone offset, in the form ZHH:MM or +HH:MM or -HH:MM
+        """,
+        RegexOptions.ExplicitCapture | RegexOptions.CultureInvariant | RegexOptions.IgnorePatternWhitespace)]
     private static partial Regex GenerateRfc3339RegEx();
 
     public readonly record struct TimestampParserResult(string ModifiedText, DateTimeOffset Timestamp);