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- /*=============================================================================
- Copyright (c) 2001-2014 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 lambda functions. The parser prints code suitable for a stack
- // based virtual machine.
- //
- // [ JDG May 10, 2002 ] spirit 1
- // [ JDG March 4, 2007 ] spirit 2
- // [ JDG February 21, 2011 ] spirit 2.5
- // [ JDG June 6, 2014 ] spirit x3 (from qi calc2, but using lambda functions)
- //
- ///////////////////////////////////////////////////////////////////////////////
- #include <boost/config/warning_disable.hpp>
- #include <boost/spirit/home/x3.hpp>
- #include <boost/spirit/home/x3/support/ast/variant.hpp>
- #include <boost/fusion/include/adapt_struct.hpp>
- #include <iostream>
- #include <string>
- #include <list>
- #include <numeric>
- namespace x3 = boost::spirit::x3;
- namespace client
- {
- ///////////////////////////////////////////////////////////////////////////////
- // Semantic actions
- ////////////////////////////////////////////////////////1///////////////////////
- namespace
- {
- using x3::_attr;
- auto do_int = [](auto& ctx) { std::cout << "push " << _attr(ctx) << std::endl; };
- auto do_add = []{ std::cout << "add\n"; };
- auto do_subt = []{ std::cout << "subtract\n"; };
- auto do_mult = []{ std::cout << "mult\n"; };
- auto do_div = []{ std::cout << "divide\n"; };
- auto do_neg = []{ std::cout << "negate\n"; };
- }
- ///////////////////////////////////////////////////////////////////////////////
- // The calculator grammar
- ///////////////////////////////////////////////////////////////////////////////
- namespace calculator_grammar
- {
- using x3::uint_;
- using x3::char_;
- x3::rule<class expression> const expression("expression");
- x3::rule<class term> const term("term");
- x3::rule<class factor> const factor("factor");
- auto const expression_def =
- term
- >> *( ('+' >> term [do_add])
- | ('-' >> term [do_subt])
- )
- ;
- auto const term_def =
- factor
- >> *( ('*' >> factor [do_mult])
- | ('/' >> factor [do_div])
- )
- ;
- auto const factor_def =
- uint_ [do_int]
- | '(' >> expression >> ')'
- | ('-' >> factor [do_neg])
- | ('+' >> factor)
- ;
- BOOST_SPIRIT_DEFINE(
- expression
- , term
- , factor
- );
- auto calculator = expression;
- }
- using calculator_grammar::calculator;
- }
- ///////////////////////////////////////////////////////////////////////////////
- // 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;
- std::string str;
- while (std::getline(std::cin, str))
- {
- if (str.empty() || str[0] == 'q' || str[0] == 'Q')
- break;
- auto& calc = client::calculator; // Our grammar
- iterator_type iter = str.begin();
- iterator_type end = str.end();
- boost::spirit::x3::ascii::space_type space;
- bool r = phrase_parse(iter, end, calc, space);
- if (r && iter == end)
- {
- std::cout << "-------------------------\n";
- std::cout << "Parsing succeeded\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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