/*============================================================================= Copyright (c) 2001-2011 Hartmut Kaiser Copyright (c) 2001-2011 Joel de Guzman Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) =============================================================================*/ /////////////////////////////////////////////////////////////////////////////// // // Plain calculator example demonstrating the grammar. The parser is a // syntax checker only and does not do any semantic evaluation. // // [ JDG May 10, 2002 ] spirit1 // [ JDG March 4, 2007 ] spirit2 // [ HK November 30, 2010 ] spirit2/utree // /////////////////////////////////////////////////////////////////////////////// // #define BOOST_SPIRIT_DEBUG #include <boost/config/warning_disable.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/spirit/include/support_utree.hpp> #include <boost/spirit/include/phoenix_operator.hpp> #include <boost/spirit/include/phoenix_function.hpp> #include <iostream> #include <string> #if BOOST_PHOENIX_VERSION == 0x2000 namespace boost { namespace phoenix { // There's a bug in the Phoenix V2 type deduction mechanism that prevents // correct return type deduction for the math operations below. Newer // versions of Phoenix will be switching to BOOST_TYPEOF. In the meantime, // we will use the specializations helping with return type deduction // below: template <> struct result_of_plus<spirit::utree&, spirit::utree&> { typedef spirit::utree type; }; template <> struct result_of_minus<spirit::utree&, spirit::utree&> { typedef spirit::utree type; }; template <> struct result_of_multiplies<spirit::utree&, spirit::utree&> { typedef spirit::utree type; }; template <> struct result_of_divides<spirit::utree&, spirit::utree&> { typedef spirit::utree type; }; template <> struct result_of_negate<spirit::utree&> { typedef spirit::utree type; }; }} #endif namespace client { namespace qi = boost::spirit::qi; namespace ascii = boost::spirit::ascii; namespace spirit = boost::spirit; /////////////////////////////////////////////////////////////////////////////// // Our calculator grammar /////////////////////////////////////////////////////////////////////////////// template <typename Iterator> struct calculator : qi::grammar<Iterator, ascii::space_type, spirit::utree()> { calculator() : calculator::base_type(expression) { using qi::uint_; using qi::_val; using qi::_1; expression = term [_val = _1] >> *( ('+' >> term [_val = _val + _1]) | ('-' >> term [_val = _val - _1]) ) ; term = factor [_val = _1] >> *( ('*' >> factor [_val = _val * _1]) | ('/' >> factor [_val = _val / _1]) ) ; factor = uint_ [_val = _1] | '(' >> expression [_val = _1] >> ')' | ('-' >> factor [_val = -_1]) | ('+' >> factor [_val = _1]) ; BOOST_SPIRIT_DEBUG_NODE(expression); BOOST_SPIRIT_DEBUG_NODE(term); BOOST_SPIRIT_DEBUG_NODE(factor); } qi::rule<Iterator, ascii::space_type, spirit::utree()> expression, term, factor; }; } /////////////////////////////////////////////////////////////////////////////// // Main program /////////////////////////////////////////////////////////////////////////////// int main() { std::cout << "/////////////////////////////////////////////////////////\n\n"; std::cout << "Expression parser...\n\n"; std::cout << "/////////////////////////////////////////////////////////\n\n"; std::cout << "Type an expression...or [q or Q] to quit\n\n"; using boost::spirit::ascii::space; using boost::spirit::utree; typedef std::string::const_iterator iterator_type; typedef client::calculator<iterator_type> calculator; calculator calc; // Our grammar std::string str; while (std::getline(std::cin, str)) { if (str.empty() || str[0] == 'q' || str[0] == 'Q') break; std::string::const_iterator iter = str.begin(); std::string::const_iterator end = str.end(); utree ut; bool r = phrase_parse(iter, end, calc, space, ut); if (r && iter == end) { std::cout << "-------------------------\n"; std::cout << "Parsing succeeded: " << ut << "\n"; std::cout << "-------------------------\n"; } else { std::string rest(iter, end); std::cout << "-------------------------\n"; std::cout << "Parsing failed\n"; std::cout << "stopped at: \": " << rest << "\"\n"; std::cout << "-------------------------\n"; } } std::cout << "Bye... :-) \n\n"; return 0; }