| /*============================================================================= |
| 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 |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| // This rather naive example demonstrates that you can pass an instance of a |
| // utree as the attribute for almost any grammar. As the result the utree will |
| // be filled with the parse tree as generated during the parsing. This is most |
| // of the time not what's desired, but is usually a good first step in order to |
| // prepare your grammar to generate a customized AST. See the calc_utree_ast |
| // example for a modified version of this grammar filling the attribute with a |
| // AST (abstract syntax tree) representing the math expression as matched from |
| // the input. |
| |
| // #define BOOST_SPIRIT_DEBUG |
| |
| #include <boost/config/warning_disable.hpp> |
| #include <boost/spirit/include/qi.hpp> |
| #include <boost/spirit/include/support_utree.hpp> |
| |
| #include <iostream> |
| #include <string> |
| |
| 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::char_; |
| |
| expression = |
| term |
| >> *( (char_('+') >> term) |
| | (char_('-') >> term) |
| ) |
| ; |
| |
| term = |
| factor |
| >> *( (char_('*') >> factor) |
| | (char_('/') >> factor) |
| ) |
| ; |
| |
| factor = |
| uint_ |
| | '(' >> expression >> ')' |
| | (char_('-') >> factor) |
| | (char_('+') >> factor) |
| ; |
| |
| BOOST_SPIRIT_DEBUG_NODE(expression); |
| BOOST_SPIRIT_DEBUG_NODE(term); |
| BOOST_SPIRIT_DEBUG_NODE(factor); |
| } |
| |
| qi::rule<Iterator, ascii::space_type, spirit::utree()> expression; |
| qi::rule<Iterator, ascii::space_type, spirit::utree::list_type()> term; |
| qi::rule<Iterator, ascii::space_type, spirit::utree::list_type()> 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; |
| } |
| |
| |