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