Hi together, I have to parse the following row: "a_token": true|false, the last comma is optional. Testing the following: bool value; test_parser(" \"orig_bool\": true,", qi::lit('"') >> *(ascii::alnum | qi::char_('_')) >> qi::lit('"') >> qi::lit(':') >> boost::spirit::qi::bool_[phx::ref(value)=_1] >> -(qi::lit(','))); it works, but with the following instead the program compile but hangs ... bool value; test_parser(" \"orig_bool\": true,", qi::lit('"') >> *(!qi::lit('"')) >> qi::lit('"') >> qi::lit(':') >> boost::spirit::qi::bool_[phx::ref(value)=_1] >> -(qi::lit(','))); the only difference is the way by means I get the content of the quoted string, actually instead of using *(ascii::alnum | qi::char_('_')) I'd like to use *(!qi::lit('"')) that - imho - should be better but it actually hangs. What/where am I actually missing/wrong? Many thanks in advance Giampiero