| /*============================================================================= |
| 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 = expression_def |
| , term = term_def |
| , factor = factor_def |
| ); |
| |
| 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; |
| } |