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  26 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
  27 <a name="context.stack"></a><a name="stack"></a><a class="link" href="stack.html" title="Stack allocation">Stack allocation</a>
  28 </h2></div></div></div>
  29 <div class="toc"><dl class="toc">
  30 <dt><span class="section"><a href="stack/protected_fixedsize.html">Class <span class="emphasis"><em>protected_fixedsize</em></span></a></span></dt>
  31 <dt><span class="section"><a href="stack/pooled_fixedsize.html">Class <span class="emphasis"><em>pooled_fixedsize_stack</em></span></a></span></dt>
  32 <dt><span class="section"><a href="stack/fixedsize.html">Class <span class="emphasis"><em>fixedsize_stack</em></span></a></span></dt>
  33 <dt><span class="section"><a href="stack/segmented.html">Class
  34       <span class="emphasis"><em>segmented_stack</em></span></a></span></dt>
  35 <dt><span class="section"><a href="stack/stack_traits.html">Class <span class="emphasis"><em>stack_traits</em></span></a></span></dt>
  36 <dt><span class="section"><a href="stack/stack_context.html">Class <span class="emphasis"><em>stack_context</em></span></a></span></dt>
  37 <dt><span class="section"><a href="stack/valgrind.html">Support for valgrind</a></span></dt>
  38 <dt><span class="section"><a href="stack/sanitizers.html">Support for sanitizers</a></span></dt>
  39 </dl></div>
  40 <p>
  41       The memory used by the stack is allocated/deallocated via a <span class="emphasis"><em>StackAllocator</em></span>
  42       which is required to model a <span class="emphasis"><em>stack-allocator concept</em></span>.
  43     </p>
  44 <h4>
  45 <a name="context.stack.h0"></a>
  46       <span class="phrase"><a name="context.stack._emphasis_stack_allocator_concept__emphasis_"></a></span><a class="link" href="stack.html#context.stack._emphasis_stack_allocator_concept__emphasis_"><span class="emphasis"><em>stack-allocator
  47       concept</em></span></a>
  48     </h4>
  49 <p>
  50       A <span class="emphasis"><em>StackAllocator</em></span> must satisfy the <span class="emphasis"><em>stack-allocator
  51       concept</em></span> requirements shown in the following table, in which <code class="computeroutput"><span class="identifier">a</span></code> is an object of a <span class="emphasis"><em>StackAllocator</em></span>
  52       type, <code class="computeroutput"><span class="identifier">sctx</span></code> is a <code class="computeroutput"><span class="identifier">stack_context</span></code>, and <code class="computeroutput"><span class="identifier">size</span></code>
  53       is a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span></code>:
  54     </p>
  55 <div class="informaltable"><table class="table">
  56 <colgroup>
  57 <col>
  58 <col>
  59 <col>
  60 </colgroup>
  61 <thead><tr>
  62 <th>
  63               <p>
  64                 expression
  65               </p>
  66             </th>
  67 <th>
  68               <p>
  69                 return type
  70               </p>
  71             </th>
  72 <th>
  73               <p>
  74                 notes
  75               </p>
  76             </th>
  77 </tr></thead>
  78 <tbody>
  79 <tr>
  80 <td>
  81               <p>
  82                 <code class="computeroutput"><span class="identifier">a</span><span class="special">(</span><span class="identifier">size</span><span class="special">)</span></code>
  83               </p>
  84             </td>
  85 <td>
  86             </td>
  87 <td>
  88               <p>
  89                 creates a stack allocator
  90               </p>
  91             </td>
  92 </tr>
  93 <tr>
  94 <td>
  95               <p>
  96                 <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">allocate</span><span class="special">()</span></code>
  97               </p>
  98             </td>
  99 <td>
 100               <p>
 101                 <code class="computeroutput"><span class="identifier">stack_context</span></code>
 102               </p>
 103             </td>
 104 <td>
 105               <p>
 106                 creates a stack
 107               </p>
 108             </td>
 109 </tr>
 110 <tr>
 111 <td>
 112               <p>
 113                 <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">deallocate</span><span class="special">(</span>
 114                 <span class="identifier">sctx</span><span class="special">)</span></code>
 115               </p>
 116             </td>
 117 <td>
 118               <p>
 119                 <code class="computeroutput"><span class="keyword">void</span></code>
 120               </p>
 121             </td>
 122 <td>
 123               <p>
 124                 deallocates the stack created by <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">allocate</span><span class="special">()</span></code>
 125               </p>
 126             </td>
 127 </tr>
 128 </tbody>
 129 </table></div>
 130 <div class="important"><table border="0" summary="Important">
 131 <tr>
 132 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../doc/src/images/important.png"></td>
 133 <th align="left">Important</th>
 134 </tr>
 135 <tr><td align="left" valign="top"><p>
 136         The implementation of <code class="computeroutput"><span class="identifier">allocate</span><span class="special">()</span></code> might include logic to protect against
 137         exceeding the context's available stack size rather than leaving it as undefined
 138         behaviour.
 139       </p></td></tr>
 140 </table></div>
 141 <div class="important"><table border="0" summary="Important">
 142 <tr>
 143 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../doc/src/images/important.png"></td>
 144 <th align="left">Important</th>
 145 </tr>
 146 <tr><td align="left" valign="top"><p>
 147         Calling <code class="computeroutput"><span class="identifier">deallocate</span><span class="special">()</span></code>
 148         with a <code class="computeroutput"><span class="identifier">stack_context</span></code> not
 149         set by <code class="computeroutput"><span class="identifier">allocate</span><span class="special">()</span></code>
 150         results in undefined behaviour.
 151       </p></td></tr>
 152 </table></div>
 153 <div class="note"><table border="0" summary="Note">
 154 <tr>
 155 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td>
 156 <th align="left">Note</th>
 157 </tr>
 158 <tr><td align="left" valign="top"><p>
 159         Depending on the architecture <code class="computeroutput"><span class="identifier">allocate</span><span class="special">()</span></code> stores an address from the top of the stack
 160         (growing downwards) or the bottom of the stack (growing upwards).
 161       </p></td></tr>
 162 </table></div>
 163 </div>
 164 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 165 <td align="left"></td>
 166 <td align="right"><div class="copyright-footer">Copyright &#169; 2014 Oliver Kowalke<p>
 167         Distributed under the Boost Software License, Version 1.0. (See accompanying
 168         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>)
 169       </p>
 170 </div></td>
 171 </tr></table>
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