System.Xml.ValidateNames.ParseNameTestThrow C# (CSharp) Method

        internal static void ParseNameTestThrow(string s, out string prefix, out string localName)
        {
            int len, lenLocal, offset;

            if (s.Length != 0 && s[0] == '*')
            {
                // '*' as a NameTest
                prefix = localName = null;
                len = 1;
            }
            else
            {
                // Parse NCName (may be prefix, may be local name)
                len = ParseNCName(s, 0);
                if (len != 0)
                {
                    // Non-empty NCName, so look for colon if there are any characters left
                    localName = s.Substring(0, len);
                    if (len < s.Length && s[len] == ':')
                    {
                        // First NCName was prefix, so look for local name part
                        prefix = localName;
                        offset = len + 1;
                        if (offset < s.Length && s[offset] == '*')
                        {
                            // '*' as a local name part, add 2 to len for colon and star
                            localName = null;
                            len += 2;
                        }
                        else
                        {
                            lenLocal = ParseNCName(s, offset);
                            if (lenLocal != 0)
                            {
                                // Local name part found, so increase total NameTest length
                                localName = s.Substring(offset, lenLocal);
                                len += lenLocal + 1;
                            }
                        }
                    }
                    else
                    {
                        prefix = string.Empty;
                    }
                }
                else
                {
                    // Make the compiler happy
                    prefix = localName = null;
                }
            }

            if (len == 0 || len != s.Length)
            {
                // If the string is not a valid NameTest, then throw
                ThrowInvalidName(s, 0, len);
            }
        }