ceph/src/boost/libs/spirit/example/x3/calc/calc4c/calc4c.cpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2014 Joel de Guzman
   3     Copyright (c) 2013-2014 Agustin Berge
   4
   5     Distributed under the Boost Software License, Version 1.0. (See accompanying
   6     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7 =============================================================================*/
   8 ///////////////////////////////////////////////////////////////////////////////
   9 //
  10 //  A Calculator example demonstrating generation of AST. The AST,
  11 //  once created, is traversed, 1) To print its contents and
  12 //  2) To evaluate the result.
  13 //
  14 //  [ JDG April 28, 2008 ]      For BoostCon 2008
  15 //  [ JDG February 18, 2011 ]   Pure attributes. No semantic actions.
  16 //  [ JDG January 9, 2013 ]     Spirit X3
  17 //
  18 ///////////////////////////////////////////////////////////////////////////////
  19
  20 #include "grammar.hpp"
  21
  22 #include <iostream>
  23 #include <string>
  24
  25 ///////////////////////////////////////////////////////////////////////////////
  26 //  Main program
  27 ///////////////////////////////////////////////////////////////////////////////
  28 int
  29 main()
  30 {
  31     std::cout << "/////////////////////////////////////////////////////////\n\n";
  32     std::cout << "Expression parser...\n\n";
  33     std::cout << "/////////////////////////////////////////////////////////\n\n";
  34     std::cout << "Type an expression...or [q or Q] to quit\n\n";
  35
  36     typedef std::string::const_iterator iterator_type;
  37     typedef client::ast::program ast_program;
  38     typedef client::ast::printer ast_print;
  39     typedef client::ast::eval ast_eval;
  40
  41     std::string str;
  42     while (std::getline(std::cin, str))
  43     {
  44         if (str.empty() || str[0] == 'q' || str[0] == 'Q')
  45             break;
  46
  47         auto& calc = client::calculator;    // Our grammar
  48         ast_program program;                // Our program (AST)
  49         ast_print print;                    // Prints the program
  50         ast_eval eval;                      // Evaluates the program
  51
  52         iterator_type iter = str.begin();
  53         iterator_type end = str.end();
  54         boost::spirit::x3::ascii::space_type space;
  55         bool r = phrase_parse(iter, end, calc, space, program);
  56
  57         if (r && iter == end)
  58         {
  59             std::cout << "-------------------------\n";
  60             std::cout << "Parsing succeeded\n";
  61             print(program);
  62             std::cout << "\nResult: " << eval(program) << std::endl;
  63             std::cout << "-------------------------\n";
  64         }
  65         else
  66         {
  67             std::string rest(iter, end);
  68             std::cout << "-------------------------\n";
  69             std::cout << "Parsing failed\n";
  70             std::cout << "stopped at: \"" << rest << "\"\n";
  71             std::cout << "-------------------------\n";
  72         }
  73     }
  74
  75     std::cout << "Bye... :-) \n\n";
  76     return 0;
  77 }