ceph/src/boost/libs/context/doc/html/context/abstract_context/stack.html

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  25 <div class="section">
  26 <div class="titlepage"><div><div><h3 class="title">
  27 <a name="context.abstract_context.stack"></a><a class="link" href="stack.html" title="Stack allocation">Stack allocation</a>
  28 </h3></div></div></div>
  29 <div class="toc"><dl>
  30 <dt><span class="section"><a href="stack/protected_fixedsize.html">Class
  31         <span class="emphasis"><em>protected_fixedsize</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 <span class="emphasis"><em>segmented_stack</em></span></a></span></dt>
  34 <dt><span class="section"><a href="stack/stack_traits.html">Class
  35         <span class="emphasis"><em>stack_traits</em></span></a></span></dt>
  36 <dt><span class="section"><a href="stack/stack_context.html">Class
  37         <span class="emphasis"><em>stack_context</em></span></a></span></dt>
  38 <dt><span class="section"><a href="stack/valgrind.html">Support for
  39         valgrind</a></span></dt>
  40 </dl></div>
  41 <p>
  42         The memory used by the stack is allocated/deallocated via a <span class="emphasis"><em>StackAllocator</em></span>
  43         which is required to model a <span class="emphasis"><em>stack-allocator concept</em></span>.
  44       </p>
  45 <h5>
  46 <a name="context.abstract_context.stack.h0"></a>
  47         <span><a name="context.abstract_context.stack._emphasis_stack_allocator_concept__emphasis_"></a></span><a class="link" href="stack.html#context.abstract_context.stack._emphasis_stack_allocator_concept__emphasis_"><span class="emphasis"><em>stack-allocator
  48         concept</em></span></a>
  49       </h5>
  50 <p>
  51         A <span class="emphasis"><em>StackAllocator</em></span> must satisfy the <span class="emphasis"><em>stack-allocator
  52         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>
  53         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>
  54         is a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span></code>:
  55       </p>
  56 <div class="informaltable"><table class="table">
  57 <colgroup>
  58 <col>
  59 <col>
  60 <col>
  61 </colgroup>
  62 <thead><tr>
  63 <th>
  64                 <p>
  65                   expression
  66                 </p>
  67               </th>
  68 <th>
  69                 <p>
  70                   return type
  71                 </p>
  72               </th>
  73 <th>
  74                 <p>
  75                   notes
  76                 </p>
  77               </th>
  78 </tr></thead>
  79 <tbody>
  80 <tr>
  81 <td>
  82                 <p>
  83                   <code class="computeroutput"><span class="identifier">a</span><span class="special">(</span><span class="identifier">size</span><span class="special">)</span></code>
  84                 </p>
  85               </td>
  86 <td>
  87               </td>
  88 <td>
  89                 <p>
  90                   creates a stack allocator
  91                 </p>
  92               </td>
  93 </tr>
  94 <tr>
  95 <td>
  96                 <p>
  97                   <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">allocate</span><span class="special">()</span></code>
  98                 </p>
  99               </td>
 100 <td>
 101                 <p>
 102                   <code class="computeroutput"><span class="identifier">stack_context</span></code>
 103                 </p>
 104               </td>
 105 <td>
 106                 <p>
 107                   creates a stack
 108                 </p>
 109               </td>
 110 </tr>
 111 <tr>
 112 <td>
 113                 <p>
 114                   <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">deallocate</span><span class="special">(</span>
 115                   <span class="identifier">sctx</span><span class="special">)</span></code>
 116                 </p>
 117               </td>
 118 <td>
 119                 <p>
 120                   <code class="computeroutput"><span class="keyword">void</span></code>
 121                 </p>
 122               </td>
 123 <td>
 124                 <p>
 125                   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>
 126                 </p>
 127               </td>
 128 </tr>
 129 </tbody>
 130 </table></div>
 131 <div class="important"><table border="0" summary="Important">
 132 <tr>
 133 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../../doc/src/images/important.png"></td>
 134 <th align="left">Important</th>
 135 </tr>
 136 <tr><td align="left" valign="top"><p>
 137           The implementation of <code class="computeroutput"><span class="identifier">allocate</span><span class="special">()</span></code> might include logic to protect against
 138           exceeding the context's available stack size rather than leaving it as
 139           undefined behaviour.
 140         </p></td></tr>
 141 </table></div>
 142 <div class="important"><table border="0" summary="Important">
 143 <tr>
 144 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../../doc/src/images/important.png"></td>
 145 <th align="left">Important</th>
 146 </tr>
 147 <tr><td align="left" valign="top"><p>
 148           Calling <code class="computeroutput"><span class="identifier">deallocate</span><span class="special">()</span></code>
 149           with a <code class="computeroutput"><span class="identifier">stack_context</span></code> not
 150           set by <code class="computeroutput"><span class="identifier">allocate</span><span class="special">()</span></code>
 151           results in undefined behaviour.
 152         </p></td></tr>
 153 </table></div>
 154 <div class="note"><table border="0" summary="Note">
 155 <tr>
 156 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td>
 157 <th align="left">Note</th>
 158 </tr>
 159 <tr><td align="left" valign="top"><p>
 160           The stack is not required to be aligned; alignment takes place inside
 161           <span class="emphasis"><em>execution_context</em></span>.
 162         </p></td></tr>
 163 </table></div>
 164 <div class="note"><table border="0" summary="Note">
 165 <tr>
 166 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td>
 167 <th align="left">Note</th>
 168 </tr>
 169 <tr><td align="left" valign="top"><p>
 170           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
 171           stack (growing downwards) or the bottom of the stack (growing upwards).
 172         </p></td></tr>
 173 </table></div>
 174 </div>
 175 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 176 <td align="left"></td>
 177 <td align="right"><div class="copyright-footer">Copyright &#169; 2014 Oliver Kowalke<p>
 178         Distributed under the Boost Software License, Version 1.0. (See accompanying
 179         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>)
 180       </p>
 181 </div></td>
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