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

This is the documentation for a snapshot of the develop branch, built from commit 8c076c3913.

Move iterators

template<class Iterator>
class move_iterator;

template<class It>
move_iterator<It> make_move_iterator(const It &it);

move_iterator is an iterator adaptor with the same behavior as the underlying iterator except that its dereference operator implicitly converts the value returned by the underlying iterator's dereference operator to a rvalue reference: boost::move(*underlying_iterator) It is a read-once iterator, but can have up to random access traversal characteristics.

move_iterator is very useful because some generic algorithms and container insertion functions can be called with move iterators to replace copying with moving. For example:

//header file "movable.hpp"
#include <boost/move/core.hpp>
#include <boost/move/traits.hpp>

//A movable class
class movable
   int value_;

   movable() : value_(1){}

   //Move constructor and assignment
   movable(BOOST_RV_REF(movable) m)
   {  value_ = m.value_;   m.value_ = 0;  }

   movable & operator=(BOOST_RV_REF(movable) m)
   {  value_ = m.value_;   m.value_ = 0;  return *this;  }

   bool moved() const //Observer
   {  return !value_; }

   int value() const //Observer
   {  return value_; }

namespace boost{

struct has_nothrow_move<movable>
   static const bool value = true;

}  //namespace boost{

movable objects can be moved from one container to another using move iterators and insertion and assignment operations.w

#include <boost/container/vector.hpp>
#include "movable.hpp"
#include <cassert>

int main()
   using namespace ::boost::container;

   //Create a vector with 10 default constructed objects
   vector<movable> v(10);

   //Move construct all elements in v into v2
   vector<movable> v2( boost::make_move_iterator(v.begin())
                     , boost::make_move_iterator(v.end()));

   //Now move assign all elements from in v2 back into v
   v.assign( boost::make_move_iterator(v2.begin())
           , boost::make_move_iterator(v2.end()));

   return 0;