Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Click here to view the latest version of this page.

libs/spirit/example/karma/num_list3.cpp

/*=============================================================================
    Copyright (c) 2002-2010 Hartmut Kaiser
    Copyright (c) 2002-2010 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)
=============================================================================*/
///////////////////////////////////////////////////////////////////////////////
//
//  This sample demonstrates a generator for a comma separated list of numbers.
//  No actions. It is based on the example qi/num_lists.cpp for reading in
//  some numbers to generate.
//
///////////////////////////////////////////////////////////////////////////////

#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/karma.hpp>

#include <iostream>
#include <string>
#include <vector>

namespace client
{
    ///////////////////////////////////////////////////////////////////////////
    //  Our number list parser, please see the example qi/numlist1.cpp for
    //  more information
    ///////////////////////////////////////////////////////////////////////////
    template <typename Iterator>
    bool parse_numbers(Iterator first, Iterator last, std::vector<double>& v)
    {
        using boost::spirit::qi::double_;
        using boost::spirit::qi::phrase_parse;
        using boost::spirit::ascii::space;

        bool r = phrase_parse(first, last, double_ % ',', space, v);
        if (first != last)
            return false;
        return r;
    }

    //[tutorial_karma_numlist3_complex
    // a simple complex number representation z = a + bi
    struct complex
    {
        complex (double a, double b = 0.0) : a(a), b(b) {}

        double a;
        double b;
    };

    // the streaming operator for the type complex
    std::ostream& 
    operator<< (std::ostream& os, complex const& z)
    {
        os << "{" << z.a << "," << z.b << "}";
        return os;
    }
    //]

    ///////////////////////////////////////////////////////////////////////////
    //  Our number list generator
    ///////////////////////////////////////////////////////////////////////////
    //[tutorial_karma_numlist3
    template <typename OutputIterator, typename Container>
    bool generate_numbers(OutputIterator& sink, Container const& v)
    {
        using boost::spirit::karma::stream;
        using boost::spirit::karma::generate;
        using boost::spirit::karma::eol;

        bool r = generate(
            sink,                           // destination: output iterator
            stream % eol,                   // the generator
            v                               // the data to output 
        );
        return r;
    }
    //]
}

////////////////////////////////////////////////////////////////////////////
//  Main program
////////////////////////////////////////////////////////////////////////////
int
main()
{
    std::cout << "/////////////////////////////////////////////////////////\n\n";
    std::cout << "\tA comma separated list generator for Spirit...\n\n";
    std::cout << "/////////////////////////////////////////////////////////\n\n";

    std::cout << "Give me a comma separated list of numbers.\n";
    std::cout << "Type [q or Q] to quit\n\n";

    std::string str;
    while (getline(std::cin, str))
    {
        if (str.empty() || str[0] == 'q' || str[0] == 'Q')
            break;

        std::vector<double> v;      // here we put the data gotten from input
        if (client::parse_numbers(str.begin(), str.end(), v))
        {
            // ok, we got some numbers, fill a vector of client::complex 
            // instances and print them back out
            std::vector<client::complex> vc;
            std::vector<double>::const_iterator end = v.end();
            for (std::vector<double>::const_iterator it = v.begin(); 
                 it != end; ++it)
            {
                double real(*it);
                if (++it != end)
                    vc.push_back(client::complex(real, *it));
                else
                    vc.push_back(client::complex(real));
            }

            std::cout << "-------------------------\n";

            std::string generated;
            std::back_insert_iterator<std::string> sink(generated);
            if (!client::generate_numbers(sink, vc))
            {
                std::cout << "-------------------------\n";
                std::cout << "Generating failed\n";
                std::cout << "-------------------------\n";
            }
            else
            {
                std::cout << "-------------------------\n";
                std::cout << "Generated:\n" << generated << "\n";
                std::cout << "-------------------------\n";
            }
        }
        else
        {
            std::cout << "-------------------------\n";
            std::cout << "Parsing failed\n";
            std::cout << "-------------------------\n";
        }
    }

    std::cout << "Bye... :-) \n\n";
    return 0;
}