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  25 </div>
  26 <div class="refentry">
  27 <a name="boost.container.pmr.memory_resource"></a><div class="titlepage"></div>
  28 <div class="refnamediv">
  29 <h2><span class="refentrytitle">Class memory_resource</span></h2>
  30 <p>boost::container::pmr::memory_resource</p>
  31 </div>
  32 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  33 <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="../../../boost_container_header_reference.html#header.boost.container.pmr.memory_resource_hpp" title="Header &lt;boost/container/pmr/memory_resource.hpp&gt;">boost/container/pmr/memory_resource.hpp</a>&gt;
  34
  35 </span>
  36 <span class="keyword">class</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">{</span>
  37 <span class="keyword">public</span><span class="special">:</span>
  38   <span class="comment">// <a class="link" href="memory_resource.html#boost.container.pmr.memory_resourceconstruct-copy-destruct">construct/copy/destruct</a></span>
  39   <a class="link" href="memory_resource.html#idm45666070084928-bb"><span class="special">~</span><span class="identifier">memory_resource</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  40
  41   <span class="comment">// <a class="link" href="memory_resource.html#idm45666070097936-bb">public member functions</a></span>
  42   <span class="keyword">void</span> <span class="special">*</span> <a class="link" href="memory_resource.html#idm45666070097376-bb"><span class="identifier">allocate</span></a><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="special">=</span> <span class="identifier">max_align</span><span class="special">)</span><span class="special">;</span>
  43   <span class="keyword">void</span> <a class="link" href="memory_resource.html#idm45666070093424-bb"><span class="identifier">deallocate</span></a><span class="special">(</span><span class="keyword">void</span> <span class="special">*</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="special">=</span> <span class="identifier">max_align</span><span class="special">)</span><span class="special">;</span>
  44   <span class="keyword">bool</span> <a class="link" href="memory_resource.html#idm45666070088784-bb"><span class="identifier">is_equal</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
  45
  46   <span class="comment">// <a class="link" href="memory_resource.html#idm45666070082928-bb">friend functions</a></span>
  47   <span class="keyword">friend</span> <span class="keyword">bool</span> <a class="link" href="memory_resource.html#idm45666070082368-bb"><span class="keyword">operator</span><span class="special">==</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span><span class="special">,</span> <span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  48   <span class="keyword">friend</span> <span class="keyword">bool</span> <a class="link" href="memory_resource.html#idm45666070077536-bb"><span class="keyword">operator</span><span class="special">!=</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span><span class="special">,</span> <span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  49
  50   <span class="comment">// <a class="link" href="memory_resource.html#idm45666070073008-bb">protected member functions</a></span>
  51   <span class="keyword">virtual</span> <span class="keyword">void</span> <span class="special">*</span> <a class="link" href="memory_resource.html#idm45666070072432-bb"><span class="identifier">do_allocate</span></a><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">)</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
  52   <span class="keyword">virtual</span> <span class="keyword">void</span> <a class="link" href="memory_resource.html#idm45666070066608-bb"><span class="identifier">do_deallocate</span></a><span class="special">(</span><span class="keyword">void</span> <span class="special">*</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">)</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
  53   <span class="keyword">virtual</span> <span class="keyword">bool</span> <a class="link" href="memory_resource.html#idm45666070059840-bb"><span class="identifier">do_is_equal</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
  54
  55   <span class="comment">// public data members</span>
  56   <span class="keyword">static</span> <span class="keyword">constexpr</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_align</span><span class="special">;</span>
  57 <span class="special">}</span><span class="special">;</span></pre></div>
  58 <div class="refsect1">
  59 <a name="id-1.3.10.14.21.3.4"></a><h2>Description</h2>
  60 <p>The <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> class is an abstract interface to an unbounded set of classes encapsulating memory resources. </p>
  61 <div class="refsect2">
  62 <a name="id-1.3.10.14.21.3.4.3"></a><h3>
  63 <a name="boost.container.pmr.memory_resourceconstruct-copy-destruct"></a><code class="computeroutput">memory_resource</code>
  64         public
  65        construct/copy/destruct</h3>
  66 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
  67 <pre class="literallayout"><a name="idm45666070084928-bb"></a><span class="special">~</span><span class="identifier">memory_resource</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
  68 <p><span class="bold"><strong>Effects</strong></span>: Destroys this <code class="computeroutput"><a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a></code>. </p>
  69 </li></ol></div>
  70 </div>
  71 <div class="refsect2">
  72 <a name="id-1.3.10.14.21.3.4.4"></a><h3>
  73 <a name="idm45666070097936-bb"></a><code class="computeroutput">memory_resource</code> public member functions</h3>
  74 <div class="orderedlist"><ol class="orderedlist" type="1">
  75 <li class="listitem">
  76 <pre class="literallayout"><span class="keyword">void</span> <span class="special">*</span> <a name="idm45666070097376-bb"></a><span class="identifier">allocate</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> bytes<span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> alignment <span class="special">=</span> <span class="identifier">max_align</span><span class="special">)</span><span class="special">;</span></pre>
  77 <p><span class="bold"><strong>Effects</strong></span>: Equivalent to <code class="computeroutput">return do_allocate(bytes, alignment);</code> </p>
  78 </li>
  79 <li class="listitem">
  80 <pre class="literallayout"><span class="keyword">void</span> <a name="idm45666070093424-bb"></a><span class="identifier">deallocate</span><span class="special">(</span><span class="keyword">void</span> <span class="special">*</span> p<span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> bytes<span class="special">,</span>
  81                 <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> alignment <span class="special">=</span> <span class="identifier">max_align</span><span class="special">)</span><span class="special">;</span></pre>
  82 <p><span class="bold"><strong>Effects</strong></span>: Equivalent to <code class="computeroutput">return do_deallocate(bytes, alignment);</code> </p>
  83 </li>
  84 <li class="listitem">
  85 <pre class="literallayout"><span class="keyword">bool</span> <a name="idm45666070088784-bb"></a><span class="identifier">is_equal</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span> other<span class="special">)</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span></pre>
  86 <p><span class="bold"><strong>Effects</strong></span>: Equivalent to <code class="computeroutput">return return do_is_equal(other);</code> </p>
  87 </li>
  88 </ol></div>
  89 </div>
  90 <div class="refsect2">
  91 <a name="id-1.3.10.14.21.3.4.5"></a><h3>
  92 <a name="idm45666070082928-bb"></a><code class="computeroutput">memory_resource</code> friend functions</h3>
  93 <div class="orderedlist"><ol class="orderedlist" type="1">
  94 <li class="listitem">
  95 <pre class="literallayout"><span class="keyword">friend</span> <span class="keyword">bool</span> <a name="idm45666070082368-bb"></a><span class="keyword">operator</span><span class="special">==</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span> a<span class="special">,</span> <span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span> b<span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span></pre>
  96 <p><span class="bold"><strong>Returns</strong></span>: <code class="computeroutput">&amp;a == &amp;b || a.is_equal(b)</code>. </p>
  97 </li>
  98 <li class="listitem">
  99 <pre class="literallayout"><span class="keyword">friend</span> <span class="keyword">bool</span> <a name="idm45666070077536-bb"></a><span class="keyword">operator</span><span class="special">!=</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span> a<span class="special">,</span> <span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span> b<span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span></pre>
 100 <p><span class="bold"><strong>Returns</strong></span>: !(a == b). </p>
 101 </li>
 102 </ol></div>
 103 </div>
 104 <div class="refsect2">
 105 <a name="id-1.3.10.14.21.3.4.6"></a><h3>
 106 <a name="idm45666070073008-bb"></a><code class="computeroutput">memory_resource</code> protected member functions</h3>
 107 <div class="orderedlist"><ol class="orderedlist" type="1">
 108 <li class="listitem">
 109 <pre class="literallayout"><span class="keyword">virtual</span> <span class="keyword">void</span> <span class="special">*</span> <a name="idm45666070072432-bb"></a><span class="identifier">do_allocate</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> bytes<span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> alignment<span class="special">)</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span></pre>
 110 <p><span class="bold"><strong>Requires</strong></span>: Alignment shall be a power of two.</p>
 111 <p><span class="bold"><strong>Returns</strong></span>: A derived class shall implement this function to return a pointer to allocated storage with a size of at least bytes. The returned storage is aligned to the specified alignment, if such alignment is supported; otherwise it is aligned to max_align.</p>
 112 <p><span class="bold"><strong>Throws</strong></span>: A derived class implementation shall throw an appropriate exception if it is unable to allocate memory with the requested size and alignment. </p>
 113 </li>
 114 <li class="listitem">
 115 <pre class="literallayout"><span class="keyword">virtual</span> <span class="keyword">void</span>
 116 <a name="idm45666070066608-bb"></a><span class="identifier">do_deallocate</span><span class="special">(</span><span class="keyword">void</span> <span class="special">*</span> p<span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> bytes<span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> alignment<span class="special">)</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span></pre>
 117 <p><span class="bold"><strong>Requires</strong></span>: p shall have been returned from a prior call to <code class="computeroutput">allocate(bytes, alignment)</code> on a memory resource equal to *this, and the storage at p shall not yet have been deallocated.</p>
 118 <p><span class="bold"><strong>Effects</strong></span>: A derived class shall implement this function to dispose of allocated storage.</p>
 119 <p><span class="bold"><strong>Throws</strong></span>: Nothing. </p>
 120 </li>
 121 <li class="listitem">
 122 <pre class="literallayout"><span class="keyword">virtual</span> <span class="keyword">bool</span> <a name="idm45666070059840-bb"></a><span class="identifier">do_is_equal</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="memory_resource.html" title="Class memory_resource">memory_resource</a> <span class="special">&amp;</span> other<span class="special">)</span> <span class="keyword">const</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span></pre>
 123 <p><span class="bold"><strong>Returns</strong></span>: A derived class shall implement this function to return true if memory allocated from this can be deallocated from other and vice-versa; otherwise it shall return false. <span class="emphasis"><em>[Note: The most-derived type of other might not match the type of this. For a derived class, D, a typical implementation of this function will compute <code class="computeroutput">dynamic_cast&lt;const D*&gt;(&amp;other)</code> and go no further (i.e., return false) if it returns nullptr. - end note]</em></span>. </p>
 124 </li>
 125 </ol></div>
 126 </div>
 127 </div>
 128 </div>
 129 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 130 <td align="left"></td>
 131 <td align="right"><div class="copyright-footer">Copyright &#169; 2009-2018 Ion Gaztanaga<p>
 132         Distributed under the Boost Software License, Version 1.0. (See accompanying
 133         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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