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| <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> |
| <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> |
| <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> |
| </div> |
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| <td align="right"><div class="copyright-footer">Copyright © 2005 Olaf Krzikalla, 2006-2010 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>) |
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