<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Any Hooks: A single hook for any Intrusive container</title> <link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../intrusive.html" title="Chapter 10. Boost.Intrusive"> <link rel="prev" href="obtaining_iterators_from_values.html" title="Obtaining iterators from values"> <link rel="next" href="concepts.html" title="Concepts explained"> </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="obtaining_iterators_from_values.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../intrusive.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="concepts.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="intrusive.any_hooks"></a><a class="link" href="any_hooks.html" title="Any Hooks: A single hook for any Intrusive container"> Any Hooks: A single hook for any Intrusive container</a> </h2></div></div></div> <p> Sometimes, a class programmer wants to place a class in several intrusive containers but no at the same time. In this case, the programmer might decide to insert two hooks in the same class. </p> <p> </p> <pre class="programlisting"><span class="keyword">class</span> <span class="identifier">MyClass</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">list_base_hook</span><span class="special"><>,</span> <span class="keyword">public</span> <span class="identifier">slist_base_hook</span><span class="special"><></span> <span class="comment">//... </span><span class="special">{};</span> </pre> <p> However, there is a more size-efficient alternative in <span class="bold"><strong>Boost.Intrusive</strong></span>: "any" hooks (<code class="computeroutput"><a class="link" href="../boost/intrusive/any_base_hook.html" title="Class template any_base_hook">any_base_hook</a></code> and <code class="computeroutput"><a class="link" href="../boost/intrusive/any_member_hook.html" title="Class template any_member_hook">any_member_hook</a></code>). These hooks can be used to store a type in several containers offered by <span class="bold"><strong>Boost.Intrusive</strong></span> minimizing the size of the class. </p> <p> These hooks support these options: </p> <div class="itemizedlist"><ul class="itemizedlist" type="disc"> <li class="listitem"> <span class="bold"><strong><code class="computeroutput"><span class="identifier">tag</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">Tag</span><span class="special">></span></code></strong></span> (for base hooks only): This argument serves as a tag, so you can derive from more than one slist hook. Default: <code class="computeroutput"><span class="identifier">tag</span><span class="special"><</span><span class="identifier">default_tag</span><span class="special">></span></code>. </li> <li class="listitem"> <span class="bold"><strong><code class="computeroutput"><span class="identifier">link_mode</span><span class="special"><</span><span class="identifier">link_mode_type</span> <span class="identifier">LinkMode</span><span class="special">></span></code></strong></span>: The linking policy. <code class="computeroutput"><span class="identifier">link_mode</span><span class="special"><</span><span class="identifier">auto_unlink</span><span class="special">></span></code> is <span class="bold"><strong>not</strong></span> supported and <code class="computeroutput"><span class="identifier">link_mode</span><span class="special"><</span><span class="identifier">safe_mode</span><span class="special">></span></code> might offer weaker error detection in any hooks than in other hooks. Default: <code class="computeroutput"><span class="identifier">link_mode</span><span class="special"><</span><span class="identifier">safe_link</span><span class="special">></span></code>. </li> <li class="listitem"> <span class="bold"><strong><code class="computeroutput"><span class="identifier">void_pointer</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">VoidPointer</span><span class="special">></span></code></strong></span>: The pointer type to be used internally in the hook and propagated to the container. Default: <code class="computeroutput"><span class="identifier">void_pointer</span><span class="special"><</span><span class="keyword">void</span><span class="special">*></span></code>. </li> </ul></div> <p> <code class="computeroutput"><span class="identifier">auto_unlink</span></code> can't be supported because the hook does not know in which type of container might be currently inserted. Additionally, these hooks don't support <code class="computeroutput"><span class="identifier">unlink</span><span class="special">()</span></code> and <code class="computeroutput"><span class="identifier">swap_nodes</span><span class="special">()</span></code> operations for the same reason. </p> <p> Here is an example that creates a class with two any hooks, and uses one to insert the class in a <code class="computeroutput">slist</code> and the other one in a <code class="computeroutput">list</code>. </p> <p> </p> <p> </p> <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">intrusive</span><span class="special">/</span><span class="identifier">any_hook</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">intrusive</span><span class="special">/</span><span class="identifier">slist</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">intrusive</span><span class="special">/</span><span class="identifier">list</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">intrusive</span><span class="special">;</span> <span class="keyword">class</span> <span class="identifier">MyClass</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">any_base_hook</span><span class="special"><></span> <span class="comment">//Base hook </span><span class="special">{</span> <span class="keyword">int</span> <span class="identifier">int_</span><span class="special">;</span> <span class="keyword">public</span><span class="special">:</span> <span class="identifier">any_member_hook</span><span class="special"><></span> <span class="identifier">member_hook_</span><span class="special">;</span> <span class="comment">//Member hook </span> <span class="identifier">MyClass</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">)</span> <span class="special">:</span> <span class="identifier">int_</span><span class="special">(</span><span class="identifier">i</span><span class="special">)</span> <span class="special">{}</span> <span class="special">};</span> <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> <span class="special">{</span> <span class="comment">//Define a base hook option that converts any_base_hook to a slist hook </span> <span class="keyword">typedef</span> <span class="identifier">any_to_slist_hook</span> <span class="special"><</span> <span class="identifier">base_hook</span><span class="special"><</span> <span class="identifier">any_base_hook</span><span class="special"><></span> <span class="special">></span> <span class="special">></span> <span class="identifier">BaseSlistOption</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="identifier">slist</span><span class="special"><</span><span class="identifier">MyClass</span><span class="special">,</span> <span class="identifier">BaseSlistOption</span><span class="special">></span> <span class="identifier">BaseSList</span><span class="special">;</span> <span class="comment">//Define a member hook option that converts any_member_hook to a list hook </span> <span class="keyword">typedef</span> <span class="identifier">any_to_list_hook</span><span class="special"><</span> <span class="identifier">member_hook</span> <span class="special"><</span> <span class="identifier">MyClass</span><span class="special">,</span> <span class="identifier">any_member_hook</span><span class="special"><>,</span> <span class="special">&</span><span class="identifier">MyClass</span><span class="special">::</span><span class="identifier">member_hook_</span><span class="special">></span> <span class="special">></span> <span class="identifier">MemberListOption</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="identifier">list</span><span class="special"><</span><span class="identifier">MyClass</span><span class="special">,</span> <span class="identifier">MemberListOption</span><span class="special">></span> <span class="identifier">MemberList</span><span class="special">;</span> <span class="comment">//Create several MyClass objects, each one with a different value </span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">MyClass</span><span class="special">></span> <span class="identifier">values</span><span class="special">;</span> <span class="keyword">for</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special"><</span> <span class="number">100</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">){</span> <span class="identifier">values</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">MyClass</span><span class="special">(</span><span class="identifier">i</span><span class="special">));</span> <span class="special">}</span> <span class="identifier">BaseSList</span> <span class="identifier">base_slist</span><span class="special">;</span> <span class="identifier">MemberList</span> <span class="identifier">member_list</span><span class="special">;</span> <span class="comment">//Now insert them in reverse order in the slist and in order in the list </span> <span class="keyword">for</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">MyClass</span><span class="special">>::</span><span class="identifier">iterator</span> <span class="identifier">it</span><span class="special">(</span><span class="identifier">values</span><span class="special">.</span><span class="identifier">begin</span><span class="special">()),</span> <span class="identifier">itend</span><span class="special">(</span><span class="identifier">values</span><span class="special">.</span><span class="identifier">end</span><span class="special">());</span> <span class="identifier">it</span> <span class="special">!=</span> <span class="identifier">itend</span><span class="special">;</span> <span class="special">++</span><span class="identifier">it</span><span class="special">)</span> <span class="identifier">base_slist</span><span class="special">.</span><span class="identifier">push_front</span><span class="special">(*</span><span class="identifier">it</span><span class="special">),</span> <span class="identifier">member_list</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(*</span><span class="identifier">it</span><span class="special">);</span> <span class="comment">//Now test lists </span> <span class="identifier">BaseSList</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">bit</span><span class="special">(</span><span class="identifier">base_slist</span><span class="special">.</span><span class="identifier">begin</span><span class="special">()),</span> <span class="identifier">bitend</span><span class="special">(</span><span class="identifier">base_slist</span><span class="special">.</span><span class="identifier">end</span><span class="special">());</span> <span class="identifier">MemberList</span><span class="special">::</span><span class="identifier">reverse_iterator</span> <span class="identifier">mrit</span><span class="special">(</span><span class="identifier">member_list</span><span class="special">.</span><span class="identifier">rbegin</span><span class="special">()),</span> <span class="identifier">mritend</span><span class="special">(</span><span class="identifier">member_list</span><span class="special">.</span><span class="identifier">rend</span><span class="special">());</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">MyClass</span><span class="special">>::</span><span class="identifier">reverse_iterator</span> <span class="identifier">rit</span><span class="special">(</span><span class="identifier">values</span><span class="special">.</span><span class="identifier">rbegin</span><span class="special">()),</span> <span class="identifier">ritend</span><span class="special">(</span><span class="identifier">values</span><span class="special">.</span><span class="identifier">rend</span><span class="special">());</span> <span class="comment">//Test the objects inserted in the base hook list </span> <span class="keyword">for</span><span class="special">(;</span> <span class="identifier">rit</span> <span class="special">!=</span> <span class="identifier">ritend</span><span class="special">;</span> <span class="special">++</span><span class="identifier">rit</span><span class="special">,</span> <span class="special">++</span><span class="identifier">bit</span><span class="special">,</span> <span class="special">++</span><span class="identifier">mrit</span><span class="special">)</span> <span class="keyword">if</span><span class="special">(&*</span><span class="identifier">bit</span> <span class="special">!=</span> <span class="special">&*</span><span class="identifier">rit</span> <span class="special">||</span> <span class="special">&*</span><span class="identifier">mrit</span> <span class="special">!=</span> <span class="special">&*</span><span class="identifier">rit</span><span class="special">)</span> <span class="keyword">return</span> <span class="number">1</span><span class="special">;</span> <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> <span class="special">}</span> </pre> <p> </p> <p> </p> </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 © 2005 Olaf Krzikalla, 2006-2009 Ion Gaztanaga<p> 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>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="obtaining_iterators_from_values.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../intrusive.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="concepts.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>