| /*============================================================================= |
| Copyright (c) 2001-2010 Joel de Guzman |
| Copyright (c) 2001-2010 Hartmut Kaiser |
| |
| 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 which gets dumped into |
| // a reverse polish notation afterwards. |
| // |
| // [ JDG April 28, 2008 ] |
| // [ HK April 28, 2008 ] |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| #include <boost/config/warning_disable.hpp> |
| |
| #include <iostream> |
| #include <vector> |
| #include <string> |
| |
| #include "calc2_ast.hpp" |
| |
| #include <boost/spirit/include/qi.hpp> |
| #include <boost/spirit/include/karma.hpp> |
| #include <boost/fusion/include/adapt_struct.hpp> |
| |
| using namespace boost::spirit; |
| using namespace boost::spirit::ascii; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Our calculator parser grammar |
| /////////////////////////////////////////////////////////////////////////////// |
| template <typename Iterator> |
| struct calculator |
| : qi::grammar<Iterator, expression_ast(), space_type> |
| { |
| calculator() : calculator::base_type(expression) |
| { |
| 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 = neg(_1)]) |
| | ('+' >> factor [_val = pos(_1)]) |
| ; |
| } |
| |
| qi::rule<Iterator, expression_ast(), space_type> expression, term, factor; |
| }; |
| |
| // We need to tell fusion about our binary_op and unary_op structs |
| // to make them a first-class fusion citizen |
| // |
| // Note: we register the members exactly in the same sequence as we need them |
| // in the grammar |
| BOOST_FUSION_ADAPT_STRUCT( |
| binary_op, |
| (expression_ast, left) |
| (expression_ast, right) |
| (char, op) |
| ) |
| |
| BOOST_FUSION_ADAPT_STRUCT( |
| unary_op, |
| (expression_ast, right) |
| (char, op) |
| ) |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Our AST grammar for the generator, this prints the AST in reverse polish |
| // notation |
| /////////////////////////////////////////////////////////////////////////////// |
| template <typename OuputIterator> |
| struct ast_rpn |
| : karma::grammar<OuputIterator, expression_ast(), space_type> |
| { |
| ast_rpn() : ast_rpn::base_type(ast_node) |
| { |
| ast_node %= int_ | binary_node | unary_node; |
| binary_node %= ast_node << ast_node << char_; |
| unary_node %= '(' << ast_node << char_ << ')'; |
| } |
| |
| karma::rule<OuputIterator, expression_ast(), space_type> ast_node; |
| karma::rule<OuputIterator, binary_op(), space_type> binary_node; |
| karma::rule<OuputIterator, unary_op(), space_type> unary_node; |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Main program |
| /////////////////////////////////////////////////////////////////////////////// |
| int |
| main() |
| { |
| std::cout << "/////////////////////////////////////////////////////////\n\n"; |
| std::cout << "RPN generator for simple expressions...\n\n"; |
| std::cout << "/////////////////////////////////////////////////////////\n\n"; |
| std::cout << "Type an expression...or [q or Q] to quit\n\n"; |
| |
| // Our parser grammar definitions |
| typedef std::string::const_iterator iterator_type; |
| typedef calculator<iterator_type> calculator; |
| |
| calculator calc; |
| |
| // Our generator grammar definitions |
| typedef std::back_insert_iterator<std::string> output_iterator_type; |
| typedef ast_rpn<output_iterator_type> ast_rpn; |
| |
| ast_rpn ast_grammar; |
| |
| std::string str; |
| while (std::getline(std::cin, str)) |
| { |
| if (str.empty() || str[0] == 'q' || str[0] == 'Q') |
| break; |
| |
| expression_ast ast; // this will hold the generated AST |
| |
| std::string::const_iterator iter = str.begin(); |
| std::string::const_iterator end = str.end(); |
| bool r = qi::phrase_parse(iter, end, calc, space, ast); |
| |
| if (r && iter == end) |
| { |
| std::string generated; |
| output_iterator_type outit(generated); |
| r = karma::generate_delimited(outit, ast_grammar, space, ast); |
| |
| if (r) |
| { |
| std::cout << "RPN for '" << str << "': \n" << generated |
| << std::endl; |
| std::cout << "-------------------------\n"; |
| } |
| else |
| { |
| std::cout << "-------------------------\n"; |
| std::cout << "Generating failed\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; |
| } |
| |
| |