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