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

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Simple Bimap

This is the example from the one minute tutorial section.

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#include <string>
#include <iostream>

#include <boost/bimap.hpp>

template< class MapType >
void print_map(const MapType & map,
               const std::string & separator,
               std::ostream & os )
{
    typedef typename MapType::const_iterator const_iterator;

    for( const_iterator i = map.begin(), iend = map.end(); i != iend; ++i )
    {
        os << i->first << separator << i->second << std::endl;
    }
}

int main()
{
    // Soccer World cup

    typedef boost::bimap< std::string, int > results_bimap;
    typedef results_bimap::value_type position;

    results_bimap results;
    results.insert( position("Argentina"    ,1) );
    results.insert( position("Spain"        ,2) );
    results.insert( position("Germany"      ,3) );
    results.insert( position("France"       ,4) );

    std::cout << "The number of countries is " << results.size()
              << std::endl;

    std::cout << "The winner is " << results.right.at(1)
              << std::endl
              << std::endl;

    std::cout << "Countries names ordered by their final position:"
              << std::endl;

    // results.right works like a std::map< int, std::string >

    print_map( results.right, ") ", std::cout );

    std::cout << std::endl
              << "Countries names ordered alphabetically along with"
                    "their final position:"
              << std::endl;

    // results.left works like a std::map< std::string, int >

    print_map( results.left, " ends in position ", std::cout );

    return 0;
}

You can rewrite it using tags to gain readability.

Go to source code

#include <iostream>

#include <boost/bimap.hpp>

struct country  {};
struct place    {};

int main()
{
    using namespace boost::bimaps;

    // Soccer World cup.

    typedef bimap
    <
        tagged< std::string, country >,
        tagged< int        , place   >

    > results_bimap;

    typedef results_bimap::value_type position;

    results_bimap results;
    results.insert( position("Argentina"    ,1) );
    results.insert( position("Spain"        ,2) );
    results.insert( position("Germany"      ,3) );
    results.insert( position("France"       ,4) );

    std::cout << "Countries names ordered by their final position:"
                << std::endl;

    1for( results_bimap::map_by<place>::const_iterator
            i    = results.by<place>().begin(),
            iend = results.by<place>().end() ;
            i != iend; ++i )
    {
        2std::cout << i->get<place  >() << ") "
                  << i->get<country>() << std::endl;
    }

    std::cout << std::endl
              << "Countries names ordered alfabetically along with"
                 "their final position:"
              << std::endl;

    3for( results_bimap::map_by<country>::const_iterator
            i    = results.by<country>().begin(),
            iend = results.by<country>().end() ;
            i != iend; ++i )
    {
        std::cout << i->get<country>() << " ends "
                  << i->get<place  >() << "º"
                  << std::endl;
    }

    return 0;
}

1

results.by<place>() is equivalent to results.right

2

get<Tag> works for each view of the bimap

3

results.by<country>() is equivalent to results.left


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