#include "boost/spirit/core.hpp"
using namespace boost::spirit;

#include <iostream>
#include <string>
using namespace std;

struct expr_grammar : public grammar<expr_grammar>
{
    static const int escaped_expr_id = 1;

	template <typename ScannerT>
	struct definition
	{
		definition(expr_grammar const& self)
		{
			escaped_expr
				=	ch_p('{') >> ch_p('}')
				;
		}
		
        rule<ScannerT, parser_context, parser_tag<escaped_expr_id> >	escaped_expr;
		
		rule<ScannerT> const& start() const { return escaped_expr; }
	};
};

int main()
{
    cout << "Type an expression...or [q or Q] to quit\n\n";

	expr_grammar g;
		
    string str;
    while (getline(cin, str))
    {
        if (str[0] == 'q' || str[0] == 'Q')
            break;

        parse_info<> info = parse(str.c_str(), g, space_p);

        if (info.full)
            cout << "Parsing succeeded\n";
        else
            cout << "Parsing failed\n";
    }
    return 0;
}