Problems with optional expression and parsing error position - c++

Question

I'm trying to write my first boost spirit parser for a specific messaging format and I encountered some problems. The boost library version used is 1.49.0!
#include <iostream>
#include <sstream>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/support_multi_pass.hpp>
#include <boost/spirit/include/classic_position_iterator.hpp>
#include <boost/fusion/adapted/struct/adapt_struct.hpp>
namespace qi = boost::spirit::qi;
struct message
{
std::string title;
std::string sender;
std::string receiver;
unsigned int seqNo;
std::string senderRef;
std::string receiverRef;
unsigned int seqNoRef;
std::string id;
};
BOOST_FUSION_ADAPT_STRUCT(
message,
(std::string, title)
(std::string, sender)
(std::string, receiver)
(unsigned int, seqNo)
(std::string, senderRef)
(std::string, receiverRef)
(unsigned int, seqNoRef)
(std::string, id)
)
template<typename Iterator>
struct MyQiGrammar : qi::grammar<Iterator, message(), qi::space_type>
{
MyQiGrammar() : MyQiGrammar::base_type(start) {
qi::uint_parser<unsigned int, 10, 3, 3> uint_3p;
delim = qi::char_("-/"); // some values are delimited by '-' or '/'
title %= qi::repeat(3)[qi::upper]; // exactly 3 upper case letters
sender %= +qi::upper; // at least one upper case letter
receiver %= +qi::upper; // at least one upper case letter
seqNo %= uint_3p; // exactly 3 digits (e.g. 001)
id %= qi::repeat(1,7)[qi::alnum]; // at least 1 upper case letter and maximum 7
start %=
'('
>> title
>> sender >> delim >> receiver >> seqNo
>> -(sender >> delim >> receiver >> seqNo)
>> delim >> id
>>
')';
}
qi::rule<Iterator> delim;
qi::rule<Iterator, std::string(), qi::space_type> title;
qi::rule<Iterator, std::string(), qi::space_type> sender, receiver, id;
qi::rule<Iterator, unsigned int(), qi::space_type> seqNo;
qi::rule<Iterator, message(), qi::space_type> start;
};
int
main(int args, char** argv)
{
typedef std::istreambuf_iterator<char> base_iterator_type;
typedef boost::spirit::multi_pass<base_iterator_type> forward_iterator_type;
typedef boost::spirit::classic::position_iterator2<forward_iterator_type> pos_iterator_type;
typedef MyQiGrammar<pos_iterator_type> qi_parser;
std::string rawMsg = "(ABCZ/Y002-GWI4576)";
qi_parser myGrammarParser;
message msg;
std::istringstream iss(rawMsg);
base_iterator_type in_begin(iss);
forward_iterator_type fwd_begin = boost::spirit::make_default_multi_pass(in_begin);
forward_iterator_type fwd_end;
pos_iterator_type pos_begin(fwd_begin, fwd_end);
pos_iterator_type pos_end;
std::cout << rawMsg << std::endl;
try {
bool msgRes = qi::phrase_parse(pos_begin, pos_end,
myGrammarParser,
qi::space,
msg);
if(msgRes) {
std::cout << "Parsing succeeded!" << std::endl;
if(pos_begin == pos_end) {
std::cout << "Full match!" << std::endl;
std::cout << "Title : " << msg.title << std::endl;
std::cout << "Sender : " << msg.sender << std::endl;
std::cout << "Receiver : " << msg.receiver << std::endl;
std::cout << "Sequence number : " << msg.seqNo << std::endl;
std::cout << "Sender (ref.) : " << msg.senderRef << std::endl;
std::cout << "Receiver (ref.) : " << msg.receiverRef << std::endl;
std::cout << "Sequence number (ref.) : " << msg.seqNoRef << std::endl;
std::cout << "Message Identifier : " << msg.id << std::endl;
}
} else {
std::cout << "Parsing failed!" << std::endl;
std::cout << "Stopped at: " << pos_begin.get_position().line
<< ":" << pos_begin.get_position().column << std::endl;
}
} catch(qi::expectation_failure<pos_iterator_type>& e) {
const boost::spirit::classic::file_position_base<std::string>& pos = e.first.get_position();
std::stringstream ss;
ss << "Parse error at line " << pos.line << " column " << pos.column
<< "\n\t" << e.first.get_currentline()
<< "\n\t" << std::string(pos.column, ' ') << "^--here";
std::cerr << ss.str() << std::endl;
}
return 0;
}
In general, the message format looks like this:
'('<TITLE><SENDER>'/'<RECEIVER><SEQNO>[<SENDERREF>'/'<RECEIVERREF><SEQNOREF>]'-'<MID>')'
The output obviously shows that I'm doing something wrong with the optional message reference part:
Parsing succeeded!
Full match!
Title : ABC
Sender : Z
Receiver : Y
Sequence number : 2
Sender (ref.) :
Receiver (ref.) : GWI4576 <--- Message identifier
Sequence number (ref.) : 3072563792 <--- uninitialized, can be neglected
Message Identifier :
There are more wrong member assignments if rawMsg includes a message reference, for example "(ABCZ/Y002Y/Z001-GWI4576)":
Parsing succeeded!
Full match!
Title : ABC
Sender : Z
Receiver : Y
Sequence number : 2
Sender (ref.) : YZ <--- Sender and receiver!?
Receiver (ref.) : GWI4576 <--- Message identifier
Sequence number (ref.) : 3214704440 <--- uninitialized, but should be 1
Message Identifier :
What did I wrong in my rule(s)?
In addition, I observed that if an incorrect message format is parsed, then the line and column of the iterator is always set to 1 independent of the error position:
Parsing failed!
Stopped at: 1:1
Why is that?