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  25 <div class="refentry">
  26 <a name="boost.pool_allocator"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Class template pool_allocator</span></h2>
  29 <p>boost::pool_allocator &#8212; A C++ Standard Library conforming allocator, based on an underlying pool. </p>
  30 </div>
  31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../header/boost/pool/pool_alloc_hpp.html" title="Header &lt;boost/pool/pool_alloc.hpp&gt;">boost/pool/pool_alloc.hpp</a>&gt;
  33
  34 </span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">,</span> <span class="keyword">typename</span> UserAllocator<span class="special">,</span> <span class="keyword">typename</span> Mutex<span class="special">,</span>
  35          <span class="keyword">unsigned</span> NextSize<span class="special">,</span> <span class="keyword">unsigned</span> MaxSize<span class="special">&gt;</span>
  36 <span class="keyword">class</span> <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a> <span class="special">{</span>
  37 <span class="keyword">public</span><span class="special">:</span>
  38   <span class="comment">// types</span>
  39   <span class="keyword">typedef</span> <span class="identifier">T</span>                                      <a name="boost.pool_allocator.value_type"></a><span class="identifier">value_type</span><span class="special">;</span>       <span class="comment">// value_type of template parameter T. </span>
  40   <span class="keyword">typedef</span> <span class="identifier">UserAllocator</span>                          <a name="boost.pool_allocator.user_allocator"></a><span class="identifier">user_allocator</span><span class="special">;</span>   <span class="comment">// allocator that defines the method that the underlying Pool will use to allocate memory from the system. </span>
  41   <span class="keyword">typedef</span> <span class="identifier">Mutex</span>                                  <a name="boost.pool_allocator.mutex"></a><span class="identifier">mutex</span><span class="special">;</span>            <span class="comment">// typedef mutex publishes the value of the template parameter Mutex. </span>
  42   <span class="keyword">typedef</span> <span class="identifier">value_type</span> <span class="special">*</span>                           <a name="boost.pool_allocator.pointer"></a><span class="identifier">pointer</span><span class="special">;</span>
  43   <span class="keyword">typedef</span> <span class="keyword">const</span> <span class="identifier">value_type</span> <span class="special">*</span>                     <a name="boost.pool_allocator.const_pointer"></a><span class="identifier">const_pointer</span><span class="special">;</span>
  44   <span class="keyword">typedef</span> <span class="identifier">value_type</span> <span class="special">&amp;</span>                           <a name="boost.pool_allocator.reference"></a><span class="identifier">reference</span><span class="special">;</span>
  45   <span class="keyword">typedef</span> <span class="keyword">const</span> <span class="identifier">value_type</span> <span class="special">&amp;</span>                     <a name="boost.pool_allocator.const_reference"></a><span class="identifier">const_reference</span><span class="special">;</span>
  46   <span class="keyword">typedef</span> <a class="link" href="pool.html" title="Class template pool">pool</a><span class="special">&lt;</span> <span class="identifier">UserAllocator</span> <span class="special">&gt;</span><span class="special">::</span><span class="identifier">size_type</span>       <a name="boost.pool_allocator.size_type"></a><span class="identifier">size_type</span><span class="special">;</span>
  47   <span class="keyword">typedef</span> <a class="link" href="pool.html" title="Class template pool">pool</a><span class="special">&lt;</span> <span class="identifier">UserAllocator</span> <span class="special">&gt;</span><span class="special">::</span><span class="identifier">difference_type</span> <a name="boost.pool_allocator.difference_type"></a><span class="identifier">difference_type</span><span class="special">;</span>
  48
  49   <span class="comment">// member classes/structs/unions</span>
  50
  51   <span class="comment">// Nested class rebind allows for transformation from pool_allocator&lt;T&gt; to
  52   // pool_allocator&lt;U&gt;.</span>
  53   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> U<span class="special">&gt;</span>
  54   <span class="keyword">struct</span> <a class="link" href="pool_allocator/rebind.html" title="Struct template rebind">rebind</a> <span class="special">{</span>
  55     <span class="comment">// types</span>
  56     <span class="keyword">typedef</span> <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a><span class="special">&lt;</span> <span class="identifier">U</span><span class="special">,</span> <span class="identifier">UserAllocator</span><span class="special">,</span> <span class="identifier">Mutex</span><span class="special">,</span> <span class="identifier">NextSize</span><span class="special">,</span> <span class="identifier">MaxSize</span> <span class="special">&gt;</span> <a class="link" href="pool_allocator/rebind.html#boost.pool_allocator.rebind.other"><span class="identifier">other</span></a><span class="special">;</span>
  57   <span class="special">}</span><span class="special">;</span>
  58
  59   <span class="comment">// <a class="link" href="pool_allocator.html#boost.pool_allocatorconstruct-copy-destruct">construct/copy/destruct</a></span>
  60   <a class="link" href="pool_allocator.html#id377842-bb"><span class="identifier">pool_allocator</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  61   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> U<span class="special">&gt;</span>
  62     <a class="link" href="pool_allocator.html#id377861-bb"><span class="identifier">pool_allocator</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a><span class="special">&lt;</span> <span class="identifier">U</span><span class="special">,</span> <span class="identifier">UserAllocator</span><span class="special">,</span> <span class="identifier">Mutex</span><span class="special">,</span> <span class="identifier">NextSize</span><span class="special">,</span> <span class="identifier">MaxSize</span> <span class="special">&gt;</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  63
  64   <span class="comment">// <a class="link" href="pool_allocator.html#id377811-bb">public member functions</a></span>
  65   <span class="keyword">bool</span> <a class="link" href="pool_allocator.html#id377813-bb"><span class="keyword">operator</span><span class="special">==</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  66   <span class="keyword">bool</span> <a class="link" href="pool_allocator.html#id377828-bb"><span class="keyword">operator</span><span class="special">!=</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  67
  68   <span class="comment">// <a class="link" href="pool_allocator.html#id377895-bb">public static functions</a></span>
  69   <span class="keyword">static</span> <span class="identifier">pointer</span> <a class="link" href="pool_allocator.html#id377897-bb"><span class="identifier">address</span></a><span class="special">(</span><span class="identifier">reference</span><span class="special">)</span><span class="special">;</span>
  70   <span class="keyword">static</span> <span class="identifier">const_pointer</span> <a class="link" href="pool_allocator.html#id377908-bb"><span class="identifier">address</span></a><span class="special">(</span><span class="identifier">const_reference</span><span class="special">)</span><span class="special">;</span>
  71   <span class="keyword">static</span> <span class="identifier">size_type</span> <a class="link" href="pool_allocator.html#id377919-bb"><span class="identifier">max_size</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  72   <span class="keyword">static</span> <span class="keyword">void</span> <a class="link" href="pool_allocator.html#id377925-bb"><span class="identifier">construct</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">pointer</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">value_type</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  73   <span class="keyword">static</span> <span class="keyword">void</span> <a class="link" href="pool_allocator.html#id377940-bb"><span class="identifier">destroy</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">pointer</span><span class="special">)</span><span class="special">;</span>
  74   <span class="keyword">static</span> <span class="identifier">pointer</span> <a class="link" href="pool_allocator.html#id377951-bb"><span class="identifier">allocate</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">size_type</span><span class="special">)</span><span class="special">;</span>
  75   <span class="keyword">static</span> <span class="identifier">pointer</span> <a class="link" href="pool_allocator.html#id377962-bb"><span class="identifier">allocate</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">size_type</span><span class="special">,</span> <span class="keyword">const</span> <span class="keyword">void</span> <span class="special">*</span><span class="special">)</span><span class="special">;</span>
  76   <span class="keyword">static</span> <span class="keyword">void</span> <a class="link" href="pool_allocator.html#id377987-bb"><span class="identifier">deallocate</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">pointer</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">size_type</span><span class="special">)</span><span class="special">;</span>
  77
  78   <span class="comment">// public data members</span>
  79   <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">unsigned</span> <span class="identifier">next_size</span><span class="special">;</span>  <span class="comment">// next_size publishes the values of the template parameter NextSize. </span>
  80 <span class="special">}</span><span class="special">;</span></pre></div>
  81 <div class="refsect1">
  82 <a name="id933084"></a><h2>Description</h2>
  83 <p>Template parameters for <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a> are defined as follows:</p>
  84 <p><span class="bold"><strong>T</strong></span> Type of object to allocate/deallocate.</p>
  85 <p><span class="bold"><strong>UserAllocator</strong></span>. Defines the method that the underlying Pool will use to allocate memory from the system. See <a href="../boost_pool/pool/pooling.html#boost_pool.pool.pooling.user_allocator" target="_top">User Allocators</a> for details.</p>
  86 <p><span class="bold"><strong>Mutex</strong></span> Allows the user to determine the type of synchronization to be used on the underlying <a class="link" href="singleton_pool.html" title="Class template singleton_pool">singleton_pool</a>.</p>
  87 <p><span class="bold"><strong>NextSize</strong></span> The value of this parameter is passed to the underlying <a class="link" href="singleton_pool.html" title="Class template singleton_pool">singleton_pool</a> when it is created.</p>
  88 <p><span class="bold"><strong>MaxSize</strong></span> Limit on the maximum size used.</p>
  89 <div class="note"><table border="0" summary="Note">
  90 <tr>
  91 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td>
  92 <th align="left">Note</th>
  93 </tr>
  94 <tr><td align="left" valign="top"><p>The underlying <a class="link" href="singleton_pool.html" title="Class template singleton_pool">singleton_pool</a> used by the this allocator constructs a pool instance that <span class="bold"><strong>is never freed</strong></span>. This means that memory allocated by the allocator can be still used after main() has completed, but may mean that some memory checking programs will complain about leaks. </p></td></tr>
  95 </table></div>
  96 <p>
  97 </p>
  98 <div class="refsect2">
  99 <a name="id933157"></a><h3>
 100 <a name="boost.pool_allocatorconstruct-copy-destruct"></a><code class="computeroutput">pool_allocator</code>
 101         public
 102        construct/copy/destruct</h3>
 103 <div class="orderedlist"><ol class="orderedlist" type="1">
 104 <li class="listitem">
 105 <pre class="literallayout"><a name="id377842-bb"></a><span class="identifier">pool_allocator</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
 106 <p>Results in default construction of the underlying <code class="computeroutput"><a class="link" href="singleton_pool.html" title="Class template singleton_pool">singleton_pool</a></code> IFF an instance of this allocator is constructed during global initialization ( required to ensure construction of <code class="computeroutput"><a class="link" href="singleton_pool.html" title="Class template singleton_pool">singleton_pool</a></code> IFF an instance of this allocator is constructed during global initialization. See ticket #2359 for a complete explanation at <a href="http://svn.boost.org/trac/boost/ticket/2359" target="_top">http://svn.boost.org/trac/boost/ticket/2359</a>) .</p>
 107 </li>
 108 <li class="listitem">
 109 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> U<span class="special">&gt;</span>
 110   <a name="id377861-bb"></a><span class="identifier">pool_allocator</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a><span class="special">&lt;</span> <span class="identifier">U</span><span class="special">,</span> <span class="identifier">UserAllocator</span><span class="special">,</span> <span class="identifier">Mutex</span><span class="special">,</span> <span class="identifier">NextSize</span><span class="special">,</span> <span class="identifier">MaxSize</span> <span class="special">&gt;</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span></pre>
 111 <p>Results in the default construction of the underlying <code class="computeroutput"><a class="link" href="singleton_pool.html" title="Class template singleton_pool">singleton_pool</a></code>, this is required to ensure construction of <code class="computeroutput"><a class="link" href="singleton_pool.html" title="Class template singleton_pool">singleton_pool</a></code> IFF an instance of this allocator is constructed during global initialization. See ticket #2359 for a complete explanation at <a href="http://svn.boost.org/trac/boost/ticket/2359" target="_top">http://svn.boost.org/trac/boost/ticket/2359</a> .</p>
 112 </li>
 113 </ol></div>
 114 </div>
 115 <div class="refsect2">
 116 <a name="id934733"></a><h3>
 117 <a name="id377811-bb"></a><code class="computeroutput">pool_allocator</code> public member functions</h3>
 118 <div class="orderedlist"><ol class="orderedlist" type="1">
 119 <li class="listitem"><pre class="literallayout"><span class="keyword">bool</span> <a name="id377813-bb"></a><span class="keyword">operator</span><span class="special">==</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre></li>
 120 <li class="listitem"><pre class="literallayout"><span class="keyword">bool</span> <a name="id377828-bb"></a><span class="keyword">operator</span><span class="special">!=</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="pool_allocator.html" title="Class template pool_allocator">pool_allocator</a> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre></li>
 121 </ol></div>
 122 </div>
 123 <div class="refsect2">
 124 <a name="id934845"></a><h3>
 125 <a name="id377895-bb"></a><code class="computeroutput">pool_allocator</code> public static functions</h3>
 126 <div class="orderedlist"><ol class="orderedlist" type="1">
 127 <li class="listitem"><pre class="literallayout"><span class="keyword">static</span> <span class="identifier">pointer</span> <a name="id377897-bb"></a><span class="identifier">address</span><span class="special">(</span><span class="identifier">reference</span> r<span class="special">)</span><span class="special">;</span></pre></li>
 128 <li class="listitem"><pre class="literallayout"><span class="keyword">static</span> <span class="identifier">const_pointer</span> <a name="id377908-bb"></a><span class="identifier">address</span><span class="special">(</span><span class="identifier">const_reference</span> s<span class="special">)</span><span class="special">;</span></pre></li>
 129 <li class="listitem"><pre class="literallayout"><span class="keyword">static</span> <span class="identifier">size_type</span> <a name="id377919-bb"></a><span class="identifier">max_size</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre></li>
 130 <li class="listitem"><pre class="literallayout"><span class="keyword">static</span> <span class="keyword">void</span> <a name="id377925-bb"></a><span class="identifier">construct</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">pointer</span> ptr<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">value_type</span> <span class="special">&amp;</span> t<span class="special">)</span><span class="special">;</span></pre></li>
 131 <li class="listitem"><pre class="literallayout"><span class="keyword">static</span> <span class="keyword">void</span> <a name="id377940-bb"></a><span class="identifier">destroy</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">pointer</span> ptr<span class="special">)</span><span class="special">;</span></pre></li>
 132 <li class="listitem"><pre class="literallayout"><span class="keyword">static</span> <span class="identifier">pointer</span> <a name="id377951-bb"></a><span class="identifier">allocate</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">size_type</span> n<span class="special">)</span><span class="special">;</span></pre></li>
 133 <li class="listitem">
 134 <pre class="literallayout"><span class="keyword">static</span> <span class="identifier">pointer</span> <a name="id377962-bb"></a><span class="identifier">allocate</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">size_type</span> n<span class="special">,</span> <span class="keyword">const</span> <span class="keyword">void</span> <span class="special">*</span> const<span class="special">)</span><span class="special">;</span></pre>
 135 <p>allocate n bytes</p>
 136 <p>
 137 </p>
 138 <div class="variablelist"><table border="0">
 139 <col align="left" valign="top">
 140 <tbody><tr>
 141 <td><p><span class="term">Parameters:</span></p></td>
 142 <td><div class="variablelist"><table border="0">
 143 <col align="left" valign="top">
 144 <tbody><tr>
 145 <td><p><span class="term"><code class="computeroutput">n</code></span></p></td>
 146 <td><p>bytes to allocate. </p></td>
 147 </tr></tbody>
 148 </table></div></td>
 149 </tr></tbody>
 150 </table></div>
 151 </li>
 152 <li class="listitem">
 153 <pre class="literallayout"><span class="keyword">static</span> <span class="keyword">void</span> <a name="id377987-bb"></a><span class="identifier">deallocate</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">pointer</span> ptr<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">size_type</span> n<span class="special">)</span><span class="special">;</span></pre>
 154 <p>Deallocate n bytes from ptr
 155 </p>
 156 <div class="variablelist"><table border="0">
 157 <col align="left" valign="top">
 158 <tbody><tr>
 159 <td><p><span class="term">Parameters:</span></p></td>
 160 <td><div class="variablelist"><table border="0">
 161 <col align="left" valign="top">
 162 <tbody>
 163 <tr>
 164 <td><p><span class="term"><code class="computeroutput">n</code></span></p></td>
 165 <td><p>number of bytes to deallocate. </p></td>
 166 </tr>
 167 <tr>
 168 <td><p><span class="term"><code class="computeroutput">ptr</code></span></p></td>
 169 <td><p>location to deallocate from. </p></td>
 170 </tr>
 171 </tbody>
 172 </table></div></td>
 173 </tr></tbody>
 174 </table></div>
 175 </li>
 176 </ol></div>
 177 </div>
 178 <div class="refsect2">
 179 <a name="id935438"></a><h3>Specializations</h3>
 180 <div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><a class="link" href="pool_allocator_void__UserAllocator__M_id378014.html" title="Class template pool_allocator&lt;void, UserAllocator, Mutex, NextSize, MaxSize&gt;">Class template pool_allocator&lt;void, UserAllocator, Mutex, NextSize, MaxSize&gt;</a></p></li></ul></div>
 181 </div>
 182 </div>
 183 </div>
 184 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 185 <td align="left"></td>
 186 <td align="right"><div class="copyright-footer">Copyright &#169; 2000-2006 Stephen Cleary<br>Copyright &#169; 2011 Paul A. Bristow<p>
 187         Distributed under the Boost Software License, Version 1.0. (See accompanying
 188         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>)
 189       </p>
 190 </div></td>
 191 </tr></table>
 192 <hr>
 193 <div class="spirit-nav">
 194 <a accesskey="p" href="pool_allocator_tag.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../header/boost/pool/pool_alloc_hpp.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="pool_allocator/rebind.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
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