Parsing Problem

From: jwwillcox2003 (jwwillcox2003_at_[hidden])
Date: 2003-08-18 12:50:17

struct usmtf : public grammar<usmtf>
{
    template <typename ScannerT>

    struct definition
    {
        definition(usmtf const& self)
        {
            message = mainText;

            exerciseSet = !eol_p >> str_p("EXER")[do_print("EXER")] 
>> ch_p('/') >> *(field >> ch_p('/')) >> ch_p('/');
            messageIdentifierSet = str_p("MSGID")[do_print("MSGID")] 
>> ch_p('/') >> *(field >> ch_p('/')) >> ch_p('/');

            field =
                lexeme_d
                [
                    +(upper_p - ch_p('/') - eol_p)
                ];

            mainText = exerciseSet >> eol_p >> messageIdentifierSet 
>> end_p;
        };
    
        rule<ScannerT> message, mainText,
             exerciseSet, messageIdentifierSet, field;

        rule<ScannerT> const& start() const { return message; }
    };
};

Using this grammar above, it will parse 
EXER/EE/FF//MSGID//
using
   mainText = exerciseSet >> messageIdentifierSet >> end_p;

However, I want it to parse
EXER/EE/FF//
MSGID//

and 
    mainText = exerciseSet >> eol_p >> messageIdentifierSet >> end_p;
does not work.   Why?  How do I parse what I want?