boost/libs/spirit/example/x3/calc4c/calc4c.cpp

/*=============================================================================
    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 <iostream>
#include <string>

///////////////////////////////////////////////////////////////////////////////
//  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;
}