| /*============================================================================= |
| 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) |
| =============================================================================*/ |
| /////////////////////////////////////////////////////////////////////////////// |
| // |
| // A calculator example demonstrating the grammar and semantic actions |
| // using phoenix to do the actual expression evaluation. The parser is |
| // essentially an "interpreter" that evaluates expressions on the fly. |
| // |
| // [ JDG June 29, 2002 ] spirit1 |
| // [ JDG March 5, 2007 ] spirit2 |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| // Spirit v2.5 allows you to suppress automatic generation |
| // of predefined terminals to speed up complation. With |
| // BOOST_SPIRIT_NO_PREDEFINED_TERMINALS defined, you are |
| // responsible in creating instances of the terminals that |
| // you need (e.g. see qi::uint_type uint_ below). |
| #define BOOST_SPIRIT_NO_PREDEFINED_TERMINALS |
| |
| #include <boost/config/warning_disable.hpp> |
| #include <boost/spirit/include/qi.hpp> |
| #include <boost/spirit/include/phoenix_operator.hpp> |
| |
| #include <iostream> |
| #include <string> |
| |
| namespace client |
| { |
| namespace qi = boost::spirit::qi; |
| namespace ascii = boost::spirit::ascii; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Our calculator grammar |
| /////////////////////////////////////////////////////////////////////////// |
| template <typename Iterator> |
| struct calculator : qi::grammar<Iterator, int(), ascii::space_type> |
| { |
| calculator() : calculator::base_type(expression) |
| { |
| qi::_val_type _val; |
| qi::_1_type _1; |
| qi::uint_type uint_; |
| |
| expression = |
| term [_val = _1] |
| >> *( ('+' >> term [_val += _1]) |
| | ('-' >> term [_val -= _1]) |
| ) |
| ; |
| |
| term = |
| factor [_val = _1] |
| >> *( ('*' >> factor [_val *= _1]) |
| | ('/' >> factor [_val /= _1]) |
| ) |
| ; |
| |
| factor = |
| uint_ [_val = _1] |
| | '(' >> expression [_val = _1] >> ')' |
| | ('-' >> factor [_val = -_1]) |
| | ('+' >> factor [_val = _1]) |
| ; |
| } |
| |
| qi::rule<Iterator, int(), ascii::space_type> 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"; |
| |
| typedef std::string::const_iterator iterator_type; |
| typedef client::calculator<iterator_type> calculator; |
| |
| boost::spirit::ascii::space_type space; // Our skipper |
| calculator calc; // Our grammar |
| |
| std::string str; |
| int result; |
| 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(); |
| bool r = phrase_parse(iter, end, calc, space, result); |
| |
| if (r && iter == end) |
| { |
| std::cout << "-------------------------\n"; |
| std::cout << "Parsing succeeded\n"; |
| std::cout << "result = " << result << std::endl; |
| 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; |
| } |
| |
| |