Hi, Could someone help me understand why my fairly simple spirit::qi parser does not work as I expect? I try to parse string "2 c" into the structure: struct Data { char val; }; std::map<int, Data> map; such that the map contains one element with an int 2 as key and char "c" wrapped into structure Data as the value. I am using Boost 1.42. The rules for the grammar w/o semantic actions are as follows. value = qi::char_; list = (qi::int_ >> value); // the start rule I know the grammar could be expressed more simply; my real life example is more complex and makes sense, but I tried to reduce it as much as possible. The full grammar definition reads: typedef std::string::const_iterator Iter; BOOST_FUSION_ADAPT_STRUCT(Data,(char, val)); struct TestGrammar : qi::grammar<Iter, std::map<int,Data>(), ascii::space_type> { qi::rule<Iter, std::map<int,Data>(), ascii::space_type> list; qi::rule<Iter, Data(), ascii::space_type> value; TestGrammar() : TestGrammar::base_type(list) { value = qi::char_[ at_c<0>(_val) = _1 ]; list = (qi::int_ >> value)[ _val[_1] = _2 ]; } }; The code that does the parsing reads int main( ) { std::string input = "2 c"; Iter iter = input.begin(), end = input.end(); TestGrammar grammar; std::map<int,Data> map; bool ans = phrase_parse( iter, end, grammar, space, map ); assert( ans ); assert( iter == end ); BOOST_AUTO( it, map.find(2) ); assert( it != map.end() ); assert( it->second.val == 'c' ); // FAILS! } I marked my expectations with assertions. The parsing does succeed, i.e. phrase_parse returns true and the entire input is consumed, the key of the map's element is right, but its value is somehow lost. Can anyone tell what I am missing? I enclose the entire program code in the attachment. Thanks in advance for help. Regards, &rzej