parse_bool.cpp

#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>

using namespace boost::spirit;
using namespace boost;
template<class It> 
struct bool_grammar : qi::grammar<It,bool(),ascii::space_type> {
	qi::rule<It,bool(),ascii::space_type> constant,formula;
	bool_grammar() : bool_grammar::base_type(formula) {
		using qi::lit;
		constant = (lit('T')[_val = true] | lit('F')[_val = false]);
		formula = (constant				 [_val = _1]	   |
			('(' >> formula >> 'v' >> formula >> ')')[_val = _1 || _2] |
			('(' >> formula >> '^' >> formula >> ')')[_val = _1 && _2]);
	}
};

#include <iostream>
#include <string>
using namespace std;
int main(){
	string buf;
	bool result;
	bool_grammar<string::const_iterator> grammar;
	while (getline(cin,buf)) {
		string::const_iterator first = buf.begin(), last = buf.end();
		bool success = qi::phrase_parse(
				first,last,
				grammar,
				ascii::space,
				result
				);
		if(success && first == last)
			cout << " => " << (result ? 'T' : 'F') << endl;
		else
			cout << " => parse failed" << endl;
	}
	return 0;
}