class StringExtensions
{

        private const char kSlugSeparatorChar = '-';

        public static string Slugify(this string str)
        {
            if (string.IsNullOrWhiteSpace(str))
                return string.Empty;

            // https://referencesource.microsoft.com/#mscorlib/system/text/stringbuildercache.cs
            var sb = StringBuilderCache.Acquire(str.Length * 2);
            foreach (var chr in str)
            {
                AddToCharBuffer(chr, ref sb);
            }

            // Create the resulting string and clear the character array buffer
            if (sb.Length > 0 && sb[^1] == kSlugSeparatorChar)
                sb.Length -= 1;

            // Done
            var result = StringBuilderCache.GetStringAndRelease(sb);
            return result;
        }

        private static void AddToCharBuffer(in char chr, ref StringBuilder builder)
        {
            if (chr == 0x00)
                return;

            // Determine whether the character represents a lowercase letter or a digit character
            if (chr >= 97 && chr <= 122 || char.IsDigit(chr))
            {
                // Lowercase letters or digits
                builder.Append(chr);
                return;
            }

            // Determine whether the character represents an uppercase letter
            if (chr >= 65 && chr <= 90)
            {
                // Uppercase letters
                builder.Append(char.ToLowerInvariant(chr));
                return;
            }

            // Only append separator if another character has already been added and
            // prevent adding two or more separators in a row
            if (builder.Length == 0 || builder[^1] == kSlugSeparatorChar)
                return;

            builder.Append(kSlugSeparatorChar);
        }
}