| /*============================================================================= |
| Copyright (c) 2001-2010 Hartmut Kaiser |
| Copyright (c) 2001-2010 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) |
| =============================================================================*/ |
| |
| // This example is not meant to be a sophisticated date parser. It's sole |
| // purpose is to demonstrate the intrinsic attribute transformation |
| // capabilities of a rule. |
| // |
| // Note how the rule exposes a fusion sequence, but gets passed an instance of |
| // a boost::gregorian::date as the attribute. In order to make these types |
| // compatible for the rule we define a specialization of the customization |
| // point called 'transform_attribute'. |
| |
| #include <boost/config/warning_disable.hpp> |
| #include <boost/spirit/include/qi.hpp> |
| #include <boost/fusion/include/vector.hpp> |
| #include <boost/date_time.hpp> |
| |
| // define custom transformation |
| namespace boost { namespace spirit { namespace traits |
| { |
| // This specialization of the customization point transform_attribute |
| // allows to pass a boost::gregorian::date to a rule which is expecting |
| // a fusion sequence consisting out of three integers as its attribute. |
| template<> |
| struct transform_attribute< |
| boost::gregorian::date, fusion::vector<int, int, int>, qi::domain> |
| { |
| typedef fusion::vector<int, int, int> date_parts; |
| |
| // The embedded typedef 'type' exposes the attribute as it will be |
| // passed to the right hand side of the rule. |
| typedef date_parts type; |
| |
| // The function pre() is called for down-stream conversion of the |
| // attribute supplied to the rule to the attribute expected by the |
| // right hand side. |
| // The supplied attribute might have been pre-initialized by parsers |
| // (i.e. semantic actions) higher up the parser hierarchy (in the |
| // grammar), in which case we would need to properly initialize the |
| // returned value from the argument. In this example this is not |
| // required, so we just create a new instance of a date_parts. |
| static date_parts pre(boost::gregorian::date) |
| { |
| return date_parts(); |
| } |
| |
| // The function post() is called for up-stream conversion of the |
| // results returned from parsing the right hand side of the rule. |
| // We need to initialize the attribute supplied to the rule (referenced |
| // by the first argument) with the values taken from the parsing |
| // results (referenced by the second argument). |
| static void post(boost::gregorian::date& d, date_parts const& v) |
| { |
| d = boost::gregorian::date(fusion::at_c<0>(v), fusion::at_c<1>(v) |
| , fusion::at_c<2>(v)); |
| } |
| |
| // The function fail() is called whenever the parsing of the right hand |
| // side of the rule fails. We don't need to do anything here. |
| static void fail(boost::gregorian::date&) {} |
| }; |
| }}} |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| namespace client |
| { |
| namespace qi = boost::spirit::qi; |
| |
| template <typename Iterator> |
| bool parse_date(Iterator& first, Iterator last, boost::gregorian::date& d) |
| { |
| typedef boost::fusion::vector<int, int, int> date_parts; |
| qi::rule<Iterator, date_parts(), qi::space_type> date = |
| qi::int_ >> '-' >> qi::int_ >> '-' >> qi::int_; |
| |
| return phrase_parse(first, last, date, qi::space, d); |
| } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| int main() |
| { |
| std::cout << "/////////////////////////////////////////////////////////\n\n"; |
| std::cout << "\t\tA date parser for Spirit...\n\n"; |
| std::cout << "/////////////////////////////////////////////////////////\n\n"; |
| |
| std::cout << "Give me a date of the form : year-month-day\n"; |
| std::cout << "Type [q or Q] to quit\n\n"; |
| |
| std::string str; |
| while (getline(std::cin, str)) |
| { |
| if (str.empty() || str[0] == 'q' || str[0] == 'Q') |
| break; |
| |
| boost::gregorian::date d; |
| std::string::const_iterator iter = str.begin(); |
| std::string::const_iterator end = str.end(); |
| bool r = client::parse_date(iter, end, d); |
| |
| if (r && iter == end) |
| { |
| std::cout << "-------------------------\n"; |
| std::cout << "Parsing succeeded\n"; |
| std::cout << "got: " << d << std::endl; |
| std::cout << "\n-------------------------\n"; |
| } |
| else |
| { |
| std::cout << "-------------------------\n"; |
| std::cout << "Parsing failed\n"; |
| std::cout << "-------------------------\n"; |
| } |
| } |
| |
| std::cout << "Bye... :-) \n\n"; |
| return 0; |
| return 0; |
| } |
| |
| |