private function _translateInput($char)
    {
        if        (strpos(self::QUERY_WHITE_SPACE_CHARS,    $char) !== false) { return self::IN_WHITE_SPACE;
        } else if (strpos(self::QUERY_SYNT_CHARS,           $char) !== false) { return self::IN_SYNT_CHAR;
        } else if (strpos(self::QUERY_MUTABLE_CHARS,        $char) !== false) { return self::IN_MUTABLE_CHAR;
        } else if (strpos(self::QUERY_LEXEMEMODIFIER_CHARS, $char) !== false) { return self::IN_LEXEME_MODIFIER;
        } else if (strpos(self::QUERY_ASCIIDIGITS_CHARS,    $char) !== false) { return self::IN_ASCII_DIGIT;
        } else if ($char === '"' ) { return self::IN_QUOTE;
        } else if ($char === '.' ) { return self::IN_DECIMAL_POINT;
        } else if ($char === '\\') { return self::IN_ESCAPE_CHAR;
        } else                                                                { return self::IN_CHAR;
        }
    }