System.Xml.Xsl.Runtime.XsltFunctions.SubstringBefore C# (CSharp) Method

        public static string SubstringBefore(string s1, string s2)
        {
            if (s2.Length == 0) { return s2; }
            //int idx = collation.IndexOf(s1, s2);
            int idx = s_compareInfo.IndexOf(s1, s2, CompareOptions.Ordinal);
            return (idx < 1) ? string.Empty : s1.Substring(0, idx);
        }