Re: [Boost-users] [spirit/qi] Error handler not called

2013/1/27 Szymon Gatner

Hi,

I am trying to develop a JSON parser using spirit/qi so far it is not going bad but I am having serious problem with on_error and error handler. This is my code:

namespace qi = boost::spirit::qi; namespace ascii = boost::spirit::ascii; namespace phoenix = boost::phoenix;

template <typename Iterator> struct error_handler { template struct result { typedef void type; };

void operator()(Iterator first, Iterator last, Iterator err_pos, const boost::spirit::info& info) const { std::cout << "never called"; } };

template <class Iterator> struct JsonGrammar : public qi::grammar { JsonGrammar() : JsonGrammar::base_type(json, "json"), error(error_handler<Iterator>()) { using qi::double_; using qi::lexeme; using qi::char_; using qi::int_; using qi::on_error; using qi::fail; using phoenix::construct; using phoenix::val; using namespace qi::labels;

qi::on_errorqi::fail(json, error(_1, _2, _3, _4));

string %= lexeme['"' >> +(char_ - '"') >> '"']; number = int_; member = string >> ':' >> value; array = '[' >> value % ',' >> ']'; object = '{' >> member >> *(',' >> member) >> '}'; value = array | object | number | string | qi::bool_ | "null"; json = array | object;

json.name("json");

}

phoenix::function const error; qi::rule string; qi::rule number; qi::rule json; qi::rule array; qi::rule value; qi::rule object; qi::rule(), ascii::space_type> member; };

now when i try to parse

std::string json = "[1, 2, 3, 4, t]";

parising result is false. but error handelr is never called. What am I doing wrong?

You're not using expectation point (i.e. ">"), so no error would be triggered.