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- /*=============================================================================
- 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;
- }
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