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<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Move inserters</title> <link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../move.html" title="Chapter 19. Boost.Move"> <link rel="prev" href="move_iterator.html" title="Move iterators"> <link rel="next" href="move_algorithms.html" title="Move algorithms"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> <td align="center"><a href="../../../index.html">Home</a></td> <td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="move_iterator.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../move.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="move_algorithms.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="section"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="move.move_inserters"></a><a class="link" href="move_inserters.html" title="Move inserters">Move inserters</a> </h2></div></div></div> Similar to standard insert iterators, it's possible to deal with move insertion in the same way as writing into an array. A special kind of iterator adaptors, called move insert iterators, are provided with this library. With regular iterator classes, <pre class="programlisting">while (first != last) *result++ = *first++; </pre> causes a range [first,last) to be copied into a range starting with result. The same code with result being a move insert iterator will move insert corresponding elements into the container. This device allows all of the copying algorithms in the library to work in the move insert mode instead of the regular overwrite mode. This library offers 3 move insert iterators and their helper functions: <pre class="programlisting">// Note: C models Container template <typename C> class back_move_insert_iterator; template <typename C> back_move_insert_iterator<C> back_move_inserter(C& x); template <typename C> class front_move_insert_iterator; template <typename C> front_move_insert_iterator<C> front_move_inserter(C& x); template <typename C> class move_insert_iterator; template <typename C> move_insert_iterator<C> move_inserter(C& x, typename C::iterator it); </pre> A move insert iterator is constructed from a container and possibly one of its iterators pointing to where insertion takes place if it is neither at the beginning nor at the end of the container. Insert iterators satisfy the requirements of output iterators. <code class="computeroutput">operator*</code> returns the move insert iterator itself. The assignment <code class="computeroutput">operator=(T& x)</code> is defined on insert iterators to allow writing into them, it inserts x right before where the insert iterator is pointing. In other words, an <code class="computeroutput">insert iterator</code> is like a cursor pointing into the container where the insertion takes place. <code class="computeroutput">back_move_iterator</code> move inserts elements at the end of a container, <code class="computeroutput">front_insert_iterator</code> move inserts elements at the beginning of a container, and <code class="computeroutput">move_insert_iterator</code> move inserts elements where the iterator points to in a container. <code class="computeroutput">back_move_inserter</code>, <code class="computeroutput">front_move_inserter</code>, and <code class="computeroutput">move_inserter</code> are three functions making the insert iterators out of a container. Here's an example of how to use them: <pre class="programlisting">#include <boost/container/list.hpp> #include "movable.hpp" #include <cassert> #include <algorithm> using namespace ::boost::container; typedef list<movable> list_t; typedef list_t::iterator l_iterator; template<class MoveInsertIterator> void test_move_inserter(list_t &l2, MoveInsertIterator mit) { //Create a list with 10 default constructed objects list<movable> l(10); assert(!l.begin()->moved()); l2.clear(); //Move insert into l2 containers std::copy(l.begin(), l.end(), mit); //Check size and status assert(l2.size() == l.size()); assert(l.begin()->moved()); assert(!l2.begin()->moved()); } int main() { list_t l2; test_move_inserter(l2, boost::back_move_inserter(l2)); test_move_inserter(l2, boost::front_move_inserter(l2)); test_move_inserter(l2, boost::move_inserter(l2, l2.end())); return 0; } </pre> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2008-2014 Ion Gaztanaga Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="move_iterator.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../move.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="move_algorithms.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>