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_matrix.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 formatting and printing a matrix 
//  of integers taken from a simple vector of vectors. The size and the 
//  contents of the printed matrix is generated randomly.
//
///////////////////////////////////////////////////////////////////////////////

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

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <ctime>

namespace karma = boost::spirit::karma;

namespace client
{
    ///////////////////////////////////////////////////////////////////////////
    //  Our matrix generator
    ///////////////////////////////////////////////////////////////////////////
    //[tutorial_karma_nummatrix_grammar
    template <typename OutputIterator>
    struct matrix_grammar 
      : karma::grammar<OutputIterator, std::vector<std::vector<int> >()>
    {
        matrix_grammar()
          : matrix_grammar::base_type(matrix)
        {
            using karma::int_;
            using karma::right_align;
            using karma::eol;

            element = right_align(10)[int_];
            row = '|' << *element << '|';
            matrix = row % eol;
        }

        karma::rule<OutputIterator, std::vector<std::vector<int> >()> matrix;
        karma::rule<OutputIterator, std::vector<int>()> row;
        karma::rule<OutputIterator, int()> element;
    };
    //]

    //[tutorial_karma_nummatrix
    template <typename OutputIterator>
    bool generate_matrix(OutputIterator& sink
      , std::vector<std::vector<int> > const& v)
    {
        matrix_grammar<OutputIterator> matrix;
        return karma::generate(
            sink,                           // destination: output iterator
            matrix,                         // the generator
            v                               // the data to output 
        );
    }
    //]
}

////////////////////////////////////////////////////////////////////////////
//  Main program
////////////////////////////////////////////////////////////////////////////
int
main()
{
    std::cout << "/////////////////////////////////////////////////////////\n\n";
    std::cout << "\tPrinting integers in a matrix using Spirit...\n\n";
    std::cout << "/////////////////////////////////////////////////////////\n\n";

    // here we put the data to generate
    std::vector<std::vector<int> > v;

    // now, generate the size and the contents for the matrix
    std::srand((unsigned int)std::time(NULL));
    std::size_t rows = std::rand() / (RAND_MAX / 10);
    std::size_t columns = std::rand() / (RAND_MAX / 10);

    v.resize(rows);
    for (std::size_t row = 0; row < rows; ++row)
    {
        v[row].resize(columns);
        std::generate(v[row].begin(), v[row].end(), std::rand);
    }

    // ok, we got the matrix, now print it out
    std::string generated;
    std::back_insert_iterator<std::string> sink(generated);
    if (!client::generate_matrix(sink, v))
    {
        std::cout << "-------------------------\n";
        std::cout << "Generating failed\n";
        std::cout << "-------------------------\n";
    }
    else
    {
        std::cout << "-------------------------\n";
        std::cout << "Generated:\n" << generated << "\n";
        std::cout << "-------------------------\n";
    }

    return 0;
}