grpc Normalize Benchmark

using System;
using System.Text.RegularExpressions;
using BenchmarkDotNet.Attributes;

namespace TestApp
{
    [MemoryDiagnoser]
    public class TextNormalizerBenchmark
    {
        private string _valueLowerCase = "headername";
        private string _valueUpperCase = "HeaderName";

        [Params("headername", "HeaderName")] 
        public string InputValue;

        private static readonly Regex ValidKeyRegex = new Regex("^[.a-z0-9_-]+$");

        [Benchmark(Baseline = true)]
        public void ToLower()
        {
            var normalized = InputValue.ToLowerInvariant();
            if (!ValidKeyRegex.IsMatch(normalized))
                throw new Exception();
        }

        [Benchmark]
        public void ToLowerNoRegex()
        {
            if (!IsValid(InputValue, out bool isLowercase))
                throw new Exception();

            string normalized;
            if (!isLowercase)
                normalized = InputValue.ToLowerInvariant();
            else
                normalized = InputValue;
        }

        private bool IsValid(string input, out bool isLowercase)
        {
            isLowercase = true;
            for (int i = 0; i < input.Length; i++)
            {
                char c = input[i];
                if ('a' <= c && c <= 'z'
                    || '0' <= c && c <= '9'
                    || c == '.' 
                    || c == '_' 
                    || c == '-')
                    continue;

                if ('A' <= c && c <= 'Z')
                {
                    isLowercase = false;
                    continue;
                }

                return false;
            }

            return true;
        }
    }
}