/*============================================================================= Copyright (c) 2001-2014 Joel de Guzman Copyright (c) 2013-2014 Agustin Berge 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 generation of AST. The AST, // once created, is traversed, 1) To print its contents and // 2) To evaluate the result. // // [ JDG April 28, 2008 ] For BoostCon 2008 // [ JDG February 18, 2011 ] Pure attributes. No semantic actions. // [ JDG January 9, 2013 ] Spirit X3 // /////////////////////////////////////////////////////////////////////////////// #include "grammar.hpp" #include #include /////////////////////////////////////////////////////////////////////////////// // 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::ast::program ast_program; typedef client::ast::printer ast_print; typedef client::ast::eval ast_eval; 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 ast_program program; // Our program (AST) ast_print print; // Prints the program ast_eval eval; // Evaluates the program 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, program); if (r && iter == end) { std::cout << "-------------------------\n"; std::cout << "Parsing succeeded\n"; print(program); std::cout << "\nResult: " << eval(program) << 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; }