Changeset 1399 for trunk/yat/utility


Ignore:
Timestamp:
Aug 7, 2008, 12:52:39 AM (13 years ago)
Author:
Peter
Message:

refs #369 added a function to create a boost::transform_iterator that was mentioned in ticket:369 - should probably add the corresponding for pair::second too.

File:
1 edited

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  • trunk/yat/utility/stl_utility.h

    r1387 r1399  
    3535/// extensions to STL functionality.
    3636///
     37
     38#include <boost/iterator/transform_iterator.hpp>
     39#include <boost/mpl/if.hpp>
     40#include <boost/type_traits/is_const.hpp>
     41#include <boost/type_traits/add_const.hpp>
    3742
    3843#include <algorithm>
     
    266271  };
    267272
     273  /**
     274     \brief Functor that return std::pair.first
     275
     276     \see pair_first_iterator
     277
     278     \since New in yat 0.5
     279   */
     280  template <class Pair>
     281  struct PairFirst
     282  {
     283    /**
     284       The type returned is Pair::first_type& with the exception when
     285       Pair is const and Pair::first_type is non-const, in which case
     286       const Pair::first_type& is return type.
     287     */
     288    typedef typename boost::mpl::if_<
     289                  typename boost::is_const<Pair>::type,
     290                  typename boost::add_const<typename Pair::first_type>::type&,
     291                  typename Pair::first_type&>::type result_type;
     292   
     293    /**
     294       The argument type is Pair&.
     295     */
     296    typedef Pair& argument_type;
     297
     298    /**
     299       \return p.first
     300     */
     301    inline result_type operator()(argument_type p) const
     302    { return p.first; }
     303
     304  };
     305
     306
     307  /**
     308     Creates a transform_iterator that transforms an iterator with
     309     value type std::pair to an iterator with value type
     310     std::pair::first_type. This can be used, for example, to
     311     communicate between a std::map and std::vector
     312
     313     \code
     314     std::map<std::string, int> map;
     315     ...
     316     std::vector<std::string> vec;
     317     vec.resize(map.size());
     318     std::copy(pair_first_iterator(map.begin()), pair_first_iterator(map.end()),
     319               vec.begin());
     320     \endcode
     321
     322     \since New in yat 0.5
     323   */
     324  template<class Iter>
     325  boost::transform_iterator<
     326    PairFirst<typename std::iterator_traits<Iter>::value_type>,
     327    Iter> pair_first_iterator(Iter i)
     328  {
     329    typedef PairFirst<typename std::iterator_traits<Iter>::value_type> PF;
     330    return boost::transform_iterator<PF, Iter>(i, PF());
     331  }
     332
     333
     334
     335
    268336  ///
    269337  /// @brief Function converting a string to lower case
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