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  26 <a name="boost.unordered_map"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Class template unordered_map</span></h2>
  29 <p>boost::unordered_map &#8212;
  30             An unordered associative container that associates unique keys with another value.
  31           </p>
  32 </div>
  33 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  34 <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="../unordered/reference.html#header.boost.unordered_map_hpp" title="Header &lt;boost/unordered_map.hpp&gt;">boost/unordered_map.hpp</a>&gt;
  35
  36 </span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Key<span class="special">,</span> <span class="keyword">typename</span> Mapped<span class="special">,</span> <span class="keyword">typename</span> Hash <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">hash</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">&gt;</span><span class="special">,</span>
  37          <span class="keyword">typename</span> Pred <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">equal_to</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">&gt;</span><span class="special">,</span>
  38          <span class="keyword">typename</span> Alloc <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">Key</span> <span class="keyword">const</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">&gt;&gt;</span> <span class="special">&gt;</span>
  39 <span class="keyword">class</span> <a class="link" href="unordered_map.html" title="Class template unordered_map">unordered_map</a> <span class="special">{</span>
  40 <span class="keyword">public</span><span class="special">:</span>
  41   <span class="comment">// <a class="link" href="unordered_map.html#boost.unordered_maptypes">types</a></span>
  42   <span class="keyword">typedef</span> <span class="identifier">Key</span>                                    <a name="boost.unordered_map.key_type"></a><span class="identifier">key_type</span><span class="special">;</span>
  43   <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">Key</span> <span class="keyword">const</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">&gt;</span>           <a name="boost.unordered_map.value_type"></a><span class="identifier">value_type</span><span class="special">;</span>
  44   <span class="keyword">typedef</span> <span class="identifier">Mapped</span>                                 <a name="boost.unordered_map.mapped_type"></a><span class="identifier">mapped_type</span><span class="special">;</span>
  45   <span class="keyword">typedef</span> <span class="identifier">Hash</span>                                   <a name="boost.unordered_map.hasher"></a><span class="identifier">hasher</span><span class="special">;</span>
  46   <span class="keyword">typedef</span> <span class="identifier">Pred</span>                                   <a name="boost.unordered_map.key_equal"></a><span class="identifier">key_equal</span><span class="special">;</span>
  47   <span class="keyword">typedef</span> <span class="identifier">Alloc</span>                                  <a name="boost.unordered_map.allocator_type"></a><span class="identifier">allocator_type</span><span class="special">;</span>
  48   <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">allocator_type</span><span class="special">::</span><span class="identifier">pointer</span>       <a class="link" href="unordered_map.html#boost.unordered_map.pointer"><span class="identifier">pointer</span></a><span class="special">;</span>
  49   <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">allocator_type</span><span class="special">::</span><span class="identifier">const_pointer</span> <a class="link" href="unordered_map.html#boost.unordered_map.const_pointer"><span class="identifier">const_pointer</span></a><span class="special">;</span>
  50   <span class="keyword">typedef</span> <span class="identifier">value_type</span><span class="special">&amp;</span>                            <a name="boost.unordered_map.reference"></a><span class="identifier">reference</span><span class="special">;</span>             <span class="comment">// lvalue of value_type.</span>
  51   <span class="keyword">typedef</span> <span class="identifier">value_type</span> <span class="keyword">const</span><span class="special">&amp;</span>                      <a name="boost.unordered_map.const_reference"></a><span class="identifier">const_reference</span><span class="special">;</span>       <span class="comment">// const lvalue of value_type.</span>
  52   <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span>                 <a class="link" href="unordered_map.html#boost.unordered_map.size_type"><span class="identifier">size_type</span></a><span class="special">;</span>
  53   <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span>                 <a class="link" href="unordered_map.html#boost.unordered_map.difference_type"><span class="identifier">difference_type</span></a><span class="special">;</span>
  54   <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span>                 <a class="link" href="unordered_map.html#boost.unordered_map.iterator"><span class="identifier">iterator</span></a><span class="special">;</span>
  55   <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span>                 <a class="link" href="unordered_map.html#boost.unordered_map.const_iterator"><span class="identifier">const_iterator</span></a><span class="special">;</span>
  56   <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span>                 <a class="link" href="unordered_map.html#boost.unordered_map.local_iterator"><span class="identifier">local_iterator</span></a><span class="special">;</span>
  57   <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span>                 <a class="link" href="unordered_map.html#boost.unordered_map.const_local_iterator"><span class="identifier">const_local_iterator</span></a><span class="special">;</span>
  58
  59   <span class="comment">// <a class="link" href="unordered_map.html#boost.unordered_mapconstruct-copy-destruct">construct/copy/destruct</a></span>
  60   <span class="keyword">explicit</span> <a class="link" href="unordered_map.html#idp304975248-bb"><span class="identifier">unordered_map</span></a><span class="special">(</span><span class="identifier">size_type</span> <span class="special">=</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span><span class="special">,</span>
  61                          <span class="identifier">hasher</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="special">=</span> <span class="identifier">hasher</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
  62                          <span class="identifier">key_equal</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="special">=</span> <span class="identifier">key_equal</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
  63                          <span class="identifier">allocator_type</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="special">=</span> <span class="identifier">allocator_type</span><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span>
  64   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> InputIterator<span class="special">&gt;</span>
  65     <a class="link" href="unordered_map.html#idp222771392-bb"><span class="identifier">unordered_map</span></a><span class="special">(</span><span class="identifier">InputIterator</span><span class="special">,</span> <span class="identifier">InputIterator</span><span class="special">,</span>
  66                   <span class="identifier">size_type</span> <span class="special">=</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span><span class="special">,</span>
  67                   <span class="identifier">hasher</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="special">=</span> <span class="identifier">hasher</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">key_equal</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="special">=</span> <span class="identifier">key_equal</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
  68                   <span class="identifier">allocator_type</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="special">=</span> <span class="identifier">allocator_type</span><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span>
  69   <a class="link" href="unordered_map.html#idp222785744-bb"><span class="identifier">unordered_map</span></a><span class="special">(</span><span class="identifier">unordered_map</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  70   <a class="link" href="unordered_map.html#idp222790224-bb"><span class="identifier">unordered_map</span></a><span class="special">(</span><span class="identifier">unordered_map</span> <span class="special">&amp;&amp;</span><span class="special">)</span><span class="special">;</span>
  71   <span class="keyword">explicit</span> <a class="link" href="unordered_map.html#idp222796320-bb"><span class="identifier">unordered_map</span></a><span class="special">(</span><span class="identifier">Allocator</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  72   <a class="link" href="unordered_map.html#idp222799520-bb"><span class="identifier">unordered_map</span></a><span class="special">(</span><span class="identifier">unordered_map</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  73   <a class="link" href="unordered_map.html#idp222804192-bb"><span class="special">~</span><span class="identifier">unordered_map</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  74   <span class="identifier">unordered_map</span><span class="special">&amp;</span> <a class="link" href="unordered_map.html#idp222805600-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="identifier">unordered_map</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  75   <span class="identifier">unordered_map</span><span class="special">&amp;</span> <a class="link" href="unordered_map.html#idp222811280-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="identifier">unordered_map</span> <span class="special">&amp;&amp;</span><span class="special">)</span><span class="special">;</span>
  76   <span class="identifier">allocator_type</span> <a class="link" href="unordered_map.html#idp222818128-bb"><span class="identifier">get_allocator</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  77
  78   <span class="comment">// <a class="link" href="unordered_map.html#idp222819568-bb">size and capacity</a></span>
  79   <span class="keyword">bool</span> <a class="link" href="unordered_map.html#idp222820128-bb"><span class="identifier">empty</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  80   <span class="identifier">size_type</span> <a class="link" href="unordered_map.html#idp222822752-bb"><span class="identifier">size</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  81   <span class="identifier">size_type</span> <a class="link" href="unordered_map.html#idp222825984-bb"><span class="identifier">max_size</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  82
  83   <span class="comment">// <a class="link" href="unordered_map.html#idp222828576-bb">iterators</a></span>
  84   <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp222829696-bb"><span class="identifier">begin</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  85   <span class="identifier">const_iterator</span> <a class="link" href="unordered_map.html#idp222830272-bb"><span class="identifier">begin</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  86   <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp222832416-bb"><span class="identifier">end</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  87   <span class="identifier">const_iterator</span> <a class="link" href="unordered_map.html#idp222833312-bb"><span class="identifier">end</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  88   <span class="identifier">const_iterator</span> <a class="link" href="unordered_map.html#idp222835152-bb"><span class="identifier">cbegin</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  89   <span class="identifier">const_iterator</span> <a class="link" href="unordered_map.html#idp222837184-bb"><span class="identifier">cend</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  90
  91   <span class="comment">// <a class="link" href="unordered_map.html#idp222839312-bb">modifiers</a></span>
  92   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span><span class="special">...</span> Args<span class="special">&gt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <a class="link" href="unordered_map.html#idp222839872-bb"><span class="identifier">emplace</span></a><span class="special">(</span><span class="identifier">Args</span><span class="special">&amp;&amp;</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  93   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span><span class="special">...</span> Args<span class="special">&gt;</span> <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp314023856-bb"><span class="identifier">emplace_hint</span></a><span class="special">(</span><span class="identifier">const_iterator</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  94   <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <a class="link" href="unordered_map.html#idp314040416-bb"><span class="identifier">insert</span></a><span class="special">(</span><span class="identifier">value_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  95   <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <a class="link" href="unordered_map.html#idp314050016-bb"><span class="identifier">insert</span></a><span class="special">(</span><span class="identifier">value_type</span><span class="special">&amp;&amp;</span><span class="special">)</span><span class="special">;</span>
  96   <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp314059616-bb"><span class="identifier">insert</span></a><span class="special">(</span><span class="identifier">const_iterator</span><span class="special">,</span> <span class="identifier">value_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  97   <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp314070992-bb"><span class="identifier">insert</span></a><span class="special">(</span><span class="identifier">const_iterator</span><span class="special">,</span> <span class="identifier">value_type</span><span class="special">&amp;&amp;</span><span class="special">)</span><span class="special">;</span>
  98   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> InputIterator<span class="special">&gt;</span> <span class="keyword">void</span> <a class="link" href="unordered_map.html#idp314082528-bb"><span class="identifier">insert</span></a><span class="special">(</span><span class="identifier">InputIterator</span><span class="special">,</span> <span class="identifier">InputIterator</span><span class="special">)</span><span class="special">;</span>
  99   <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp219224656-bb"><span class="identifier">erase</span></a><span class="special">(</span><span class="identifier">const_iterator</span><span class="special">)</span><span class="special">;</span>
 100   <span class="identifier">size_type</span> <a class="link" href="unordered_map.html#idp219232688-bb"><span class="identifier">erase</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 101   <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp219239008-bb"><span class="identifier">erase</span></a><span class="special">(</span><span class="identifier">const_iterator</span><span class="special">,</span> <span class="identifier">const_iterator</span><span class="special">)</span><span class="special">;</span>
 102   <span class="keyword">void</span> <a class="link" href="unordered_map.html#idp219247984-bb"><span class="identifier">quick_erase</span></a><span class="special">(</span><span class="identifier">const_iterator</span><span class="special">)</span><span class="special">;</span>
 103   <span class="keyword">void</span> <a class="link" href="unordered_map.html#idp219255648-bb"><span class="identifier">erase_return_void</span></a><span class="special">(</span><span class="identifier">const_iterator</span><span class="special">)</span><span class="special">;</span>
 104   <span class="keyword">void</span> <a class="link" href="unordered_map.html#idp219263312-bb"><span class="identifier">clear</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
 105   <span class="keyword">void</span> <a class="link" href="unordered_map.html#idp219267616-bb"><span class="identifier">swap</span></a><span class="special">(</span><span class="identifier">unordered_map</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 106
 107   <span class="comment">// <a class="link" href="unordered_map.html#idp219275120-bb">observers</a></span>
 108   <span class="identifier">hasher</span> <a class="link" href="unordered_map.html#idp219275680-bb"><span class="identifier">hash_function</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 109   <span class="identifier">key_equal</span> <a class="link" href="unordered_map.html#idp219277536-bb"><span class="identifier">key_eq</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 110
 111   <span class="comment">// <a class="link" href="unordered_map.html#idp219279552-bb">lookup</a></span>
 112   <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp219280672-bb"><span class="identifier">find</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 113   <span class="identifier">const_iterator</span> <a class="link" href="unordered_map.html#idp219282736-bb"><span class="identifier">find</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 114   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> CompatibleKey<span class="special">,</span> <span class="keyword">typename</span> CompatibleHash<span class="special">,</span>
 115            <span class="keyword">typename</span> CompatiblePredicate<span class="special">&gt;</span>
 116     <span class="identifier">iterator</span> <a class="link" href="unordered_map.html#idp219285072-bb"><span class="identifier">find</span></a><span class="special">(</span><span class="identifier">CompatibleKey</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">,</span> <span class="identifier">CompatibleHash</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">,</span>
 117                   <span class="identifier">CompatiblePredicate</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 118   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> CompatibleKey<span class="special">,</span> <span class="keyword">typename</span> CompatibleHash<span class="special">,</span>
 119            <span class="keyword">typename</span> CompatiblePredicate<span class="special">&gt;</span>
 120     <span class="identifier">const_iterator</span>
 121     <a class="link" href="unordered_map.html#idp219291616-bb"><span class="identifier">find</span></a><span class="special">(</span><span class="identifier">CompatibleKey</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">,</span> <span class="identifier">CompatibleHash</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">,</span>
 122          <span class="identifier">CompatiblePredicate</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 123   <span class="identifier">size_type</span> <a class="link" href="unordered_map.html#idp213144768-bb"><span class="identifier">count</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 124   <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="identifier">iterator</span><span class="special">&gt;</span> <a class="link" href="unordered_map.html#idp213149248-bb"><span class="identifier">equal_range</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 125   <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">const_iterator</span><span class="special">,</span> <span class="identifier">const_iterator</span><span class="special">&gt;</span> <a class="link" href="unordered_map.html#idp213151328-bb"><span class="identifier">equal_range</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 126   <span class="identifier">mapped_type</span><span class="special">&amp;</span> <a class="link" href="unordered_map.html#idp213156816-bb"><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 127   <span class="identifier">Mapped</span><span class="special">&amp;</span> <a class="link" href="unordered_map.html#idp213166096-bb"><span class="identifier">at</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 128   <span class="identifier">Mapped</span> <span class="keyword">const</span><span class="special">&amp;</span> <a class="link" href="unordered_map.html#idp213167520-bb"><span class="identifier">at</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 129
 130   <span class="comment">// <a class="link" href="unordered_map.html#idp213173120-bb">bucket interface</a></span>
 131   <span class="identifier">size_type</span> <a class="link" href="unordered_map.html#idp213173680-bb"><span class="identifier">bucket_count</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 132   <span class="identifier">size_type</span> <a class="link" href="unordered_map.html#idp213176016-bb"><span class="identifier">max_bucket_count</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 133   <span class="identifier">size_type</span> <a class="link" href="unordered_map.html#idp213178320-bb"><span class="identifier">bucket_size</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 134   <span class="identifier">size_type</span> <a class="link" href="unordered_map.html#idp213183760-bb"><span class="identifier">bucket</span></a><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 135   <span class="identifier">local_iterator</span> <a class="link" href="unordered_map.html#idp213189520-bb"><span class="identifier">begin</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span><span class="special">;</span>
 136   <span class="identifier">const_local_iterator</span> <a class="link" href="unordered_map.html#idp213191584-bb"><span class="identifier">begin</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 137   <span class="identifier">local_iterator</span> <a class="link" href="unordered_map.html#idp213197664-bb"><span class="identifier">end</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span><span class="special">;</span>
 138   <span class="identifier">const_local_iterator</span> <a class="link" href="unordered_map.html#idp213199728-bb"><span class="identifier">end</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 139   <span class="identifier">const_local_iterator</span> <a class="link" href="unordered_map.html#idp213205264-bb"><span class="identifier">cbegin</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 140   <span class="identifier">const_local_iterator</span> <a class="link" href="unordered_map.html#idp213210912-bb"><span class="identifier">cend</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span><span class="special">;</span>
 141
 142   <span class="comment">// <a class="link" href="unordered_map.html#idp213216464-bb">hash policy</a></span>
 143   <span class="keyword">float</span> <a class="link" href="unordered_map.html#idp213217024-bb"><span class="identifier">load_factor</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 144   <span class="keyword">float</span> <a class="link" href="unordered_map.html#idp300598064-bb"><span class="identifier">max_load_factor</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
 145   <span class="keyword">void</span> <a class="link" href="unordered_map.html#idp300600256-bb"><span class="identifier">max_load_factor</span></a><span class="special">(</span><span class="keyword">float</span><span class="special">)</span><span class="special">;</span>
 146   <span class="keyword">void</span> <a class="link" href="unordered_map.html#idp300603904-bb"><span class="identifier">rehash</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span><span class="special">;</span>
 147   <span class="keyword">void</span> <a class="link" href="unordered_map.html#idp300609168-bb"><span class="identifier">reserve</span></a><span class="special">(</span><span class="identifier">size_type</span><span class="special">)</span><span class="special">;</span>
 148 <span class="special">}</span><span class="special">;</span>
 149
 150 <span class="comment">// <a class="link" href="unordered_map.html#idp300613664-bb">Equality Comparisons</a></span>
 151 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Key<span class="special">,</span> <span class="keyword">typename</span> Mapped<span class="special">,</span> <span class="keyword">typename</span> Hash<span class="special">,</span> <span class="keyword">typename</span> Pred<span class="special">,</span>
 152          <span class="keyword">typename</span> Alloc<span class="special">&gt;</span>
 153   <span class="keyword">bool</span> <a class="link" href="unordered_map.html#boost.unordered_map.operator==_idp300614224"><span class="keyword">operator</span><span class="special">==</span></a><span class="special">(</span><span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">,</span>
 154                   <span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 155 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Key<span class="special">,</span> <span class="keyword">typename</span> Mapped<span class="special">,</span> <span class="keyword">typename</span> Hash<span class="special">,</span> <span class="keyword">typename</span> Pred<span class="special">,</span>
 156          <span class="keyword">typename</span> Alloc<span class="special">&gt;</span>
 157   <span class="keyword">bool</span> <a class="link" href="unordered_map.html#boost.unordered_map.operator!=_idp300626416"><span class="keyword">operator</span><span class="special">!=</span></a><span class="special">(</span><span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">,</span>
 158                   <span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
 159
 160 <span class="comment">// <a class="link" href="unordered_map.html#idp300638768-bb">swap</a></span>
 161 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Key<span class="special">,</span> <span class="keyword">typename</span> Mapped<span class="special">,</span> <span class="keyword">typename</span> Hash<span class="special">,</span> <span class="keyword">typename</span> Pred<span class="special">,</span>
 162          <span class="keyword">typename</span> Alloc<span class="special">&gt;</span>
 163   <span class="keyword">void</span> <a class="link" href="unordered_map.html#boost.unordered_map.swap_idp300639328"><span class="identifier">swap</span></a><span class="special">(</span><span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span><span class="special">&amp;</span><span class="special">,</span>
 164             <span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span></pre></div>
 165 <div class="refsect1">
 166 <a name="idp520351136"></a><h2>Description</h2>
 167 <p><span class="bold"><strong>Template Parameters</strong></span>
 168               </p>
 169 <div class="informaltable"><table class="table">
 170 <colgroup>
 171 <col>
 172 <col>
 173 </colgroup>
 174 <tbody>
 175 <tr>
 176 <td><span class="emphasis"><em>Key</em></span></td>
 177 <td>
 178 <code class="computeroutput">Key</code> must be <code class="computeroutput">Erasable</code> from the container
 179                         (i.e. <code class="computeroutput">allocator_traits</code> can <code class="computeroutput">destroy</code> it).
 180                       </td>
 181 </tr>
 182 <tr>
 183 <td><span class="emphasis"><em>Mapped</em></span></td>
 184 <td>
 185 <code class="computeroutput">Mapped</code> must be <code class="computeroutput">Erasable</code> from the container
 186                         (i.e. <code class="computeroutput">allocator_traits</code> can <code class="computeroutput">destroy</code> it).
 187                       </td>
 188 </tr>
 189 <tr>
 190 <td><span class="emphasis"><em>Hash</em></span></td>
 191 <td>A unary function object type that acts a hash function for a <code class="computeroutput">Key</code>. It takes a single argument of type <code class="computeroutput">Key</code> and returns a value of type std::size_t.</td>
 192 </tr>
 193 <tr>
 194 <td><span class="emphasis"><em>Pred</em></span></td>
 195 <td>A binary function object that implements an equivalence relation on values of type <code class="computeroutput">Key</code>.
 196                         A binary function object that induces an equivalence relation on values of type <code class="computeroutput">Key</code>.
 197                         It takes two arguments of type <code class="computeroutput">Key</code> and returns a value of type bool.</td>
 198 </tr>
 199 <tr>
 200 <td><span class="emphasis"><em>Alloc</em></span></td>
 201 <td>An allocator whose value type is the same as the container's value type.</td>
 202 </tr>
 203 </tbody>
 204 </table></div>
 205 <p>The elements are organized into buckets. Keys with the same hash code are stored in the same bucket.</p>
 206 <p>The number of buckets can be automatically increased by a call to insert, or as the result of calling rehash.</p>
 207 <div class="refsect2">
 208 <a name="idp520369840"></a><h3>
 209 <a name="boost.unordered_maptypes"></a><code class="computeroutput">unordered_map</code>
 210         public
 211        types</h3>
 212 <div class="orderedlist"><ol class="orderedlist" type="1">
 213 <li class="listitem">
 214 <p>
 215 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">allocator_type</span><span class="special">::</span><span class="identifier">pointer</span> <a name="boost.unordered_map.pointer"></a><span class="identifier">pointer</span><span class="special">;</span></p>
 216 <p>
 217                 <code class="computeroutput">value_type*</code> if
 218                 <code class="computeroutput">allocator_type::pointer</code> is not defined.
 219               </p>
 220 </li>
 221 <li class="listitem">
 222 <p>
 223 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">allocator_type</span><span class="special">::</span><span class="identifier">const_pointer</span> <a name="boost.unordered_map.const_pointer"></a><span class="identifier">const_pointer</span><span class="special">;</span></p>
 224 <p>
 225                 <code class="computeroutput">boost::pointer_to_other&lt;pointer, value_type&gt;::type</code>
 226                 if <code class="computeroutput">allocator_type::const_pointer</code> is not defined.
 227               </p>
 228 </li>
 229 <li class="listitem">
 230 <p>
 231 <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span> <a name="boost.unordered_map.size_type"></a><span class="identifier">size_type</span><span class="special">;</span></p>
 232 <p>An unsigned integral type.</p>
 233 <p>size_type can represent any non-negative value of difference_type.</p>
 234 </li>
 235 <li class="listitem">
 236 <p>
 237 <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span> <a name="boost.unordered_map.difference_type"></a><span class="identifier">difference_type</span><span class="special">;</span></p>
 238 <p>A signed integral type.</p>
 239 <p>Is identical to the difference type of iterator and const_iterator.</p>
 240 </li>
 241 <li class="listitem">
 242 <p>
 243 <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span> <a name="boost.unordered_map.iterator"></a><span class="identifier">iterator</span><span class="special">;</span></p>
 244 <p>An iterator whose value type is value_type. </p>
 245 <p>The iterator category is at least a forward iterator.</p>
 246 <p>Convertible to const_iterator.</p>
 247 </li>
 248 <li class="listitem">
 249 <p>
 250 <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span> <a name="boost.unordered_map.const_iterator"></a><span class="identifier">const_iterator</span><span class="special">;</span></p>
 251 <p>A constant iterator whose value type is value_type. </p>
 252 <p>The iterator category is at least a forward iterator.</p>
 253 </li>
 254 <li class="listitem">
 255 <p>
 256 <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span> <a name="boost.unordered_map.local_iterator"></a><span class="identifier">local_iterator</span><span class="special">;</span></p>
 257 <p>An iterator with the same value type, difference type and pointer and reference type as iterator.</p>
 258 <p>A local_iterator object can be used to iterate through a single bucket.</p>
 259 </li>
 260 <li class="listitem">
 261 <p>
 262 <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span> <a name="boost.unordered_map.const_local_iterator"></a><span class="identifier">const_local_iterator</span><span class="special">;</span></p>
 263 <p>A constant iterator with the same value type, difference type and pointer and reference type as const_iterator.</p>
 264 <p>A const_local_iterator object can be used to iterate through a single bucket.</p>
 265 </li>
 266 </ol></div>
 267 </div>
 268 <div class="refsect2">
 269 <a name="idp520421264"></a><h3>
 270 <a name="boost.unordered_mapconstruct-copy-destruct"></a><code class="computeroutput">unordered_map</code>
 271         public
 272        construct/copy/destruct</h3>
 273 <div class="orderedlist"><ol class="orderedlist" type="1">
 274 <li class="listitem">
 275 <pre class="literallayout"><span class="keyword">explicit</span> <a name="idp304975248-bb"></a><span class="identifier">unordered_map</span><span class="special">(</span><span class="identifier">size_type</span> n <span class="special">=</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span><span class="special">,</span>
 276                        <span class="identifier">hasher</span> <span class="keyword">const</span><span class="special">&amp;</span> hf <span class="special">=</span> <span class="identifier">hasher</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
 277                        <span class="identifier">key_equal</span> <span class="keyword">const</span><span class="special">&amp;</span> eq <span class="special">=</span> <span class="identifier">key_equal</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
 278                        <span class="identifier">allocator_type</span> <span class="keyword">const</span><span class="special">&amp;</span> a <span class="special">=</span> <span class="identifier">allocator_type</span><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span></pre>
 279 <p>Constructs an empty container with at least n buckets, using hf as the hash function, eq as the key equality predicate, a as the allocator and a maximum load factor of 1.0.</p>
 280 <div class="variablelist"><table border="0" class="variablelist compact">
 281 <colgroup>
 282 <col align="left" valign="top">
 283 <col>
 284 </colgroup>
 285 <tbody>
 286 <tr>
 287 <td><p><span class="term">Postconditions:</span></p></td>
 288 <td><code class="computeroutput"><a class="link" href="unordered_map.html#idp222822752-bb">size</a>() == 0</code></td>
 289 </tr>
 290 <tr>
 291 <td><p><span class="term">Requires:</span></p></td>
 292 <td><p>If the defaults are used, <code class="computeroutput">hasher</code>, <code class="computeroutput">key_equal</code> and
 293                 <code class="computeroutput">allocator_type</code> need to be <code class="computeroutput">DefaultConstructible</code>.
 294               </p></td>
 295 </tr>
 296 </tbody>
 297 </table></div>
 298 </li>
 299 <li class="listitem">
 300 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> InputIterator<span class="special">&gt;</span>
 301   <a name="idp222771392-bb"></a><span class="identifier">unordered_map</span><span class="special">(</span><span class="identifier">InputIterator</span> f<span class="special">,</span> <span class="identifier">InputIterator</span> l<span class="special">,</span>
 302                 <span class="identifier">size_type</span> n <span class="special">=</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">defined</span></em></span><span class="special">,</span>
 303                 <span class="identifier">hasher</span> <span class="keyword">const</span><span class="special">&amp;</span> hf <span class="special">=</span> <span class="identifier">hasher</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
 304                 <span class="identifier">key_equal</span> <span class="keyword">const</span><span class="special">&amp;</span> eq <span class="special">=</span> <span class="identifier">key_equal</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
 305                 <span class="identifier">allocator_type</span> <span class="keyword">const</span><span class="special">&amp;</span> a <span class="special">=</span> <span class="identifier">allocator_type</span><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span></pre>
 306 <p>Constructs an empty container with at least n buckets, using hf as the hash function, eq as the key equality predicate, a as the allocator and a maximum load factor of 1.0 and inserts the elements from [f, l) into it.</p>
 307 <div class="variablelist"><table border="0" class="variablelist compact">
 308 <colgroup>
 309 <col align="left" valign="top">
 310 <col>
 311 </colgroup>
 312 <tbody><tr>
 313 <td><p><span class="term">Requires:</span></p></td>
 314 <td><p>If the defaults are used, <code class="computeroutput">hasher</code>, <code class="computeroutput">key_equal</code> and
 315                 <code class="computeroutput">allocator_type</code> need to be <code class="computeroutput">DefaultConstructible</code>.
 316               </p></td>
 317 </tr></tbody>
 318 </table></div>
 319 </li>
 320 <li class="listitem">
 321 <pre class="literallayout"><a name="idp222785744-bb"></a><span class="identifier">unordered_map</span><span class="special">(</span><span class="identifier">unordered_map</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span></pre>
 322 <p>The copy constructor. Copies the contained elements, hash function, predicate, maximum load factor and allocator.</p>
 323 <p>If <code class="computeroutput">Allocator::select_on_container_copy_construction</code>
 324               exists and has the right signature, the allocator will be
 325               constructed from its result.</p>
 326 <div class="variablelist"><table border="0" class="variablelist compact">
 327 <colgroup>
 328 <col align="left" valign="top">
 329 <col>
 330 </colgroup>
 331 <tbody><tr>
 332 <td><p><span class="term">Requires:</span></p></td>
 333 <td><p><code class="computeroutput">value_type</code> is copy constructible</p></td>
 334 </tr></tbody>
 335 </table></div>
 336 </li>
 337 <li class="listitem">
 338 <pre class="literallayout"><a name="idp222790224-bb"></a><span class="identifier">unordered_map</span><span class="special">(</span><span class="identifier">unordered_map</span> <span class="special">&amp;&amp;</span><span class="special">)</span><span class="special">;</span></pre>
 339 <p>The move constructor.</p>
 340 <div class="variablelist"><table border="0" class="variablelist compact">
 341 <colgroup>
 342 <col align="left" valign="top">
 343 <col>
 344 </colgroup>
 345 <tbody>
 346 <tr>
 347 <td><p><span class="term">Notes:</span></p></td>
 348 <td><p>This is implemented using Boost.Move.</p></td>
 349 </tr>
 350 <tr>
 351 <td><p><span class="term">Requires:</span></p></td>
 352 <td>
 353 <p>
 354                 <code class="computeroutput">value_type</code> is move constructible.
 355               </p>
 356 <p>
 357                 On compilers without rvalue reference support the
 358                 emulation does not support moving without calling
 359                 <code class="computeroutput">boost::move</code> if <code class="computeroutput">value_type</code> is
 360                 not copyable. So, for example, you can't return the
 361                 container from a function.
 362               </p>
 363 </td>
 364 </tr>
 365 </tbody>
 366 </table></div>
 367 </li>
 368 <li class="listitem">
 369 <pre class="literallayout"><span class="keyword">explicit</span> <a name="idp222796320-bb"></a><span class="identifier">unordered_map</span><span class="special">(</span><span class="identifier">Allocator</span> <span class="keyword">const</span><span class="special">&amp;</span> a<span class="special">)</span><span class="special">;</span></pre>
 370 <p>Constructs an empty container, using allocator <code class="computeroutput">a</code>.</p>
 371 </li>
 372 <li class="listitem">
 373 <pre class="literallayout"><a name="idp222799520-bb"></a><span class="identifier">unordered_map</span><span class="special">(</span><span class="identifier">unordered_map</span> <span class="keyword">const</span><span class="special">&amp;</span> x<span class="special">,</span> <span class="identifier">Allocator</span> <span class="keyword">const</span><span class="special">&amp;</span> a<span class="special">)</span><span class="special">;</span></pre>
 374 <p>Constructs an container, copying <code class="computeroutput">x</code>'s contained elements, hash function, predicate, maximum load factor, but using allocator <code class="computeroutput">a</code>.</p>
 375 </li>
 376 <li class="listitem">
 377 <pre class="literallayout"><a name="idp222804192-bb"></a><span class="special">~</span><span class="identifier">unordered_map</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
 378 <div class="variablelist"><table border="0" class="variablelist compact">
 379 <colgroup>
 380 <col align="left" valign="top">
 381 <col>
 382 </colgroup>
 383 <tbody><tr>
 384 <td><p><span class="term">Notes:</span></p></td>
 385 <td><p>The destructor is applied to every element, and all memory is deallocated</p></td>
 386 </tr></tbody>
 387 </table></div>
 388 </li>
 389 </ol></div>
 390 </div>
 391 <pre class="literallayout"><span class="identifier">unordered_map</span><span class="special">&amp;</span> <a name="idp222805600-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="identifier">unordered_map</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span></pre>
 392 <p>The assignment operator. Copies the contained elements, hash function, predicate and maximum load factor but not the allocator.</p>
 393 <p>If <code class="computeroutput">Alloc::propagate_on_container_copy_assignment</code>
 394               exists and <code class="computeroutput">Alloc::propagate_on_container_copy_assignment::value
 395               </code> is true, the allocator is overwritten, if not the
 396               copied elements are created using the existing
 397               allocator.</p>
 398 <div class="variablelist"><table border="0" class="variablelist compact">
 399 <colgroup>
 400 <col align="left" valign="top">
 401 <col>
 402 </colgroup>
 403 <tbody><tr>
 404 <td><p><span class="term">Requires:</span></p></td>
 405 <td><p><code class="computeroutput">value_type</code> is copy constructible</p></td>
 406 </tr></tbody>
 407 </table></div>
 408 <pre class="literallayout"><span class="identifier">unordered_map</span><span class="special">&amp;</span> <a name="idp222811280-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="identifier">unordered_map</span> <span class="special">&amp;&amp;</span><span class="special">)</span><span class="special">;</span></pre>
 409 <p>The move assignment operator.</p>
 410 <p>If <code class="computeroutput">Alloc::propagate_on_container_move_assignment</code>
 411               exists and <code class="computeroutput">Alloc::propagate_on_container_move_assignment::value
 412               </code> is true, the allocator is overwritten, if not the
 413               moved elements are created using the existing
 414               allocator.</p>
 415 <div class="variablelist"><table border="0" class="variablelist compact">
 416 <colgroup>
 417 <col align="left" valign="top">
 418 <col>
 419 </colgroup>
 420 <tbody>
 421 <tr>
 422 <td><p><span class="term">Notes:</span></p></td>
 423 <td><p>
 424                 On compilers without rvalue references, this is emulated using
 425                 Boost.Move. Note that on some compilers the copy assignment
 426                 operator may be used in some circumstances.
 427               </p></td>
 428 </tr>
 429 <tr>
 430 <td><p><span class="term">Requires:</span></p></td>
 431 <td><p>
 432                 <code class="computeroutput">value_type</code> is move constructible.
 433               </p></td>
 434 </tr>
 435 </tbody>
 436 </table></div>
 437 <pre class="literallayout"><span class="identifier">allocator_type</span> <a name="idp222818128-bb"></a><span class="identifier">get_allocator</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 438 <div class="refsect2">
 439 <a name="idp520553072"></a><h3>
 440 <a name="idp222819568-bb"></a><code class="computeroutput">unordered_map</code> size and capacity</h3>
 441 <div class="orderedlist"><ol class="orderedlist" type="1">
 442 <li class="listitem">
 443 <pre class="literallayout"><span class="keyword">bool</span> <a name="idp222820128-bb"></a><span class="identifier">empty</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 444 <div class="variablelist"><table border="0" class="variablelist compact">
 445 <colgroup>
 446 <col align="left" valign="top">
 447 <col>
 448 </colgroup>
 449 <tbody><tr>
 450 <td><p><span class="term">Returns:</span></p></td>
 451 <td><code class="computeroutput"><a class="link" href="unordered_map.html#idp222822752-bb">size</a>() == 0</code></td>
 452 </tr></tbody>
 453 </table></div>
 454 </li>
 455 <li class="listitem">
 456 <pre class="literallayout"><span class="identifier">size_type</span> <a name="idp222822752-bb"></a><span class="identifier">size</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 457 <div class="variablelist"><table border="0" class="variablelist compact">
 458 <colgroup>
 459 <col align="left" valign="top">
 460 <col>
 461 </colgroup>
 462 <tbody><tr>
 463 <td><p><span class="term">Returns:</span></p></td>
 464 <td><code class="computeroutput">std::distance(<a class="link" href="unordered_map.html#idp222829136-bb">begin</a>(), <a class="link" href="unordered_map.html#idp222831856-bb">end</a>())</code></td>
 465 </tr></tbody>
 466 </table></div>
 467 </li>
 468 <li class="listitem">
 469 <pre class="literallayout"><span class="identifier">size_type</span> <a name="idp222825984-bb"></a><span class="identifier">max_size</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 470 <div class="variablelist"><table border="0" class="variablelist compact">
 471 <colgroup>
 472 <col align="left" valign="top">
 473 <col>
 474 </colgroup>
 475 <tbody><tr>
 476 <td><p><span class="term">Returns:</span></p></td>
 477 <td>
 478 <code class="computeroutput"><a class="link" href="unordered_map.html#idp222822752-bb">size</a>()</code> of the largest possible container.
 479               </td>
 480 </tr></tbody>
 481 </table></div>
 482 </li>
 483 </ol></div>
 484 </div>
 485 <div class="refsect2">
 486 <a name="idp520578736"></a><h3>
 487 <a name="idp222828576-bb"></a><code class="computeroutput">unordered_map</code> iterators</h3>
 488 <div class="orderedlist"><ol class="orderedlist" type="1">
 489 <li class="listitem">
 490 <pre class="literallayout"><a name="idp222829136-bb"></a><span class="identifier">iterator</span> <a name="idp222829696-bb"></a><span class="identifier">begin</span><span class="special">(</span><span class="special">)</span><span class="special">;</span>
 491 <span class="identifier">const_iterator</span> <a name="idp222830272-bb"></a><span class="identifier">begin</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 492 <div class="variablelist"><table border="0" class="variablelist compact">
 493 <colgroup>
 494 <col align="left" valign="top">
 495 <col>
 496 </colgroup>
 497 <tbody><tr>
 498 <td><p><span class="term">Returns:</span></p></td>
 499 <td>An iterator referring to the first element of the container, or if the container is empty the past-the-end value for the container.
 500               </td>
 501 </tr></tbody>
 502 </table></div>
 503 </li>
 504 <li class="listitem">
 505 <pre class="literallayout"><a name="idp222831856-bb"></a><span class="identifier">iterator</span> <a name="idp222832416-bb"></a><span class="identifier">end</span><span class="special">(</span><span class="special">)</span><span class="special">;</span>
 506 <span class="identifier">const_iterator</span> <a name="idp222833312-bb"></a><span class="identifier">end</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 507 <div class="variablelist"><table border="0" class="variablelist compact">
 508 <colgroup>
 509 <col align="left" valign="top">
 510 <col>
 511 </colgroup>
 512 <tbody><tr>
 513 <td><p><span class="term">Returns:</span></p></td>
 514 <td>An iterator which refers to the past-the-end value for the container.
 515               </td>
 516 </tr></tbody>
 517 </table></div>
 518 </li>
 519 <li class="listitem">
 520 <pre class="literallayout"><span class="identifier">const_iterator</span> <a name="idp222835152-bb"></a><span class="identifier">cbegin</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 521 <div class="variablelist"><table border="0" class="variablelist compact">
 522 <colgroup>
 523 <col align="left" valign="top">
 524 <col>
 525 </colgroup>
 526 <tbody><tr>
 527 <td><p><span class="term">Returns:</span></p></td>
 528 <td>A constant iterator referring to the first element of the container, or if the container is empty the past-the-end value for the container.
 529               </td>
 530 </tr></tbody>
 531 </table></div>
 532 </li>
 533 <li class="listitem">
 534 <pre class="literallayout"><span class="identifier">const_iterator</span> <a name="idp222837184-bb"></a><span class="identifier">cend</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 535 <div class="variablelist"><table border="0" class="variablelist compact">
 536 <colgroup>
 537 <col align="left" valign="top">
 538 <col>
 539 </colgroup>
 540 <tbody><tr>
 541 <td><p><span class="term">Returns:</span></p></td>
 542 <td>A constant iterator which refers to the past-the-end value for the container.
 543               </td>
 544 </tr></tbody>
 545 </table></div>
 546 </li>
 547 </ol></div>
 548 </div>
 549 <div class="refsect2">
 550 <a name="idp520614416"></a><h3>
 551 <a name="idp222839312-bb"></a><code class="computeroutput">unordered_map</code> modifiers</h3>
 552 <div class="orderedlist"><ol class="orderedlist" type="1">
 553 <li class="listitem">
 554 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span><span class="special">...</span> Args<span class="special">&gt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <a name="idp222839872-bb"></a><span class="identifier">emplace</span><span class="special">(</span><span class="identifier">Args</span><span class="special">&amp;&amp;</span><span class="special">...</span> args<span class="special">)</span><span class="special">;</span></pre>
 555 <p>Inserts an object, constructed with the arguments <code class="computeroutput">args</code>, in the container if and only if there is no element in the container with an equivalent key.</p>
 556 <div class="variablelist"><table border="0" class="variablelist compact">
 557 <colgroup>
 558 <col align="left" valign="top">
 559 <col>
 560 </colgroup>
 561 <tbody>
 562 <tr>
 563 <td><p><span class="term">Requires:</span></p></td>
 564 <td><p><code class="computeroutput">value_type</code> is <code class="computeroutput">EmplaceConstructible</code> into
 565                   <code class="computeroutput">X</code> from <code class="computeroutput">args</code>.
 566                 </p></td>
 567 </tr>
 568 <tr>
 569 <td><p><span class="term">Returns:</span></p></td>
 570 <td>
 571 <p>The bool component of the return type is true if an insert took place.</p>
 572 <p>If an insert took place, then the iterator points to the newly inserted element. Otherwise, it points to the element with equivalent key.</p>
 573 </td>
 574 </tr>
 575 <tr>
 576 <td><p><span class="term">Throws:</span></p></td>
 577 <td><p>If an exception is thrown by an operation other than a call to <code class="computeroutput">hasher</code> the function has no effect.</p></td>
 578 </tr>
 579 <tr>
 580 <td><p><span class="term">Notes:</span></p></td>
 581 <td>
 582 <p>Can invalidate iterators, but only if the insert causes the load factor to be greater to or equal to the maximum load factor.</p>
 583 <p>Pointers and references to elements are never invalidated.</p>
 584 <p>If the compiler doesn't support variadic template arguments or rvalue
 585                       references, this is emulated for up to 10 arguments, with no support
 586                       for rvalue references or move semantics.</p>
 587 <p>Since existing <code class="computeroutput">std::pair</code> implementations don't support
 588                       <code class="computeroutput">std::piecewise_construct</code> this emulates it,
 589                       but using <code class="computeroutput">boost::unordered::piecewise_construct</code>.</p>
 590 </td>
 591 </tr>
 592 </tbody>
 593 </table></div>
 594 </li>
 595 <li class="listitem">
 596 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span><span class="special">...</span> Args<span class="special">&gt;</span>
 597   <span class="identifier">iterator</span> <a name="idp314023856-bb"></a><span class="identifier">emplace_hint</span><span class="special">(</span><span class="identifier">const_iterator</span> hint<span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;</span><span class="special">...</span> args<span class="special">)</span><span class="special">;</span></pre>
 598 <p>Inserts an object, constructed with the arguments <code class="computeroutput">args</code>, in the container if and only if there is no element in the container with an equivalent key.</p>
 599 <p><code class="computeroutput">hint</code> is a suggestion to where the element should be inserted.</p>
 600 <div class="variablelist"><table border="0" class="variablelist compact">
 601 <colgroup>
 602 <col align="left" valign="top">
 603 <col>
 604 </colgroup>
 605 <tbody>
 606 <tr>
 607 <td><p><span class="term">Requires:</span></p></td>
 608 <td><p><code class="computeroutput">value_type</code> is <code class="computeroutput">EmplaceConstructible</code> into
 609                   <code class="computeroutput">X</code> from <code class="computeroutput">args</code>.
 610                 </p></td>
 611 </tr>
 612 <tr>
 613 <td><p><span class="term">Returns:</span></p></td>
 614 <td><p>If an insert took place, then the iterator points to the newly inserted element. Otherwise, it points to the element with equivalent key.</p></td>
 615 </tr>
 616 <tr>
 617 <td><p><span class="term">Throws:</span></p></td>
 618 <td><p>If an exception is thrown by an operation other than a call to <code class="computeroutput">hasher</code> the function has no effect.</p></td>
 619 </tr>
 620 <tr>
 621 <td><p><span class="term">Notes:</span></p></td>
 622 <td>
 623 <p>The standard is fairly vague on the meaning of the hint. But the only practical way to use it, and the only way that Boost.Unordered supports is to point to an existing element with the same key. </p>
 624 <p>Can invalidate iterators, but only if the insert causes the load factor to be greater to or equal to the maximum load factor.</p>
 625 <p>Pointers and references to elements are never invalidated.</p>
 626 <p>If the compiler doesn't support variadic template arguments or rvalue
 627                       references, this is emulated for up to 10 arguments, with no support
 628                       for rvalue references or move semantics.</p>
 629 <p>Since existing <code class="computeroutput">std::pair</code> implementations don't support
 630                       <code class="computeroutput">std::piecewise_construct</code> this emulates it,
 631                       but using <code class="computeroutput">boost::unordered::piecewise_construct</code>.</p>
 632 </td>
 633 </tr>
 634 </tbody>
 635 </table></div>
 636 </li>
 637 <li class="listitem">
 638 <pre class="literallayout"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <a name="idp314040416-bb"></a><span class="identifier">insert</span><span class="special">(</span><span class="identifier">value_type</span> <span class="keyword">const</span><span class="special">&amp;</span> obj<span class="special">)</span><span class="special">;</span></pre>
 639 <p>Inserts <code class="computeroutput">obj</code> in the container if and only if there is no element in the container with an equivalent key.</p>
 640 <div class="variablelist"><table border="0" class="variablelist compact">
 641 <colgroup>
 642 <col align="left" valign="top">
 643 <col>
 644 </colgroup>
 645 <tbody>
 646 <tr>
 647 <td><p><span class="term">Requires:</span></p></td>
 648 <td><p><code class="computeroutput">value_type</code> is <code class="computeroutput">CopyInsertable</code>.</p></td>
 649 </tr>
 650 <tr>
 651 <td><p><span class="term">Returns:</span></p></td>
 652 <td>
 653 <p>The bool component of the return type is true if an insert took place.</p>
 654 <p>If an insert took place, then the iterator points to the newly inserted element. Otherwise, it points to the element with equivalent key.</p>
 655 </td>
 656 </tr>
 657 <tr>
 658 <td><p><span class="term">Throws:</span></p></td>
 659 <td><p>If an exception is thrown by an operation other than a call to <code class="computeroutput">hasher</code> the function has no effect.</p></td>
 660 </tr>
 661 <tr>
 662 <td><p><span class="term">Notes:</span></p></td>
 663 <td>
 664 <p>Can invalidate iterators, but only if the insert causes the load factor to be greater to or equal to the maximum load factor.</p>
 665 <p>Pointers and references to elements are never invalidated.</p>
 666 </td>
 667 </tr>
 668 </tbody>
 669 </table></div>
 670 </li>
 671 <li class="listitem">
 672 <pre class="literallayout"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <a name="idp314050016-bb"></a><span class="identifier">insert</span><span class="special">(</span><span class="identifier">value_type</span><span class="special">&amp;&amp;</span> obj<span class="special">)</span><span class="special">;</span></pre>
 673 <p>Inserts <code class="computeroutput">obj</code> in the container if and only if there is no element in the container with an equivalent key.</p>
 674 <div class="variablelist"><table border="0" class="variablelist compact">
 675 <colgroup>
 676 <col align="left" valign="top">
 677 <col>
 678 </colgroup>
 679 <tbody>
 680 <tr>
 681 <td><p><span class="term">Requires:</span></p></td>
 682 <td><p><code class="computeroutput">value_type</code> is <code class="computeroutput">MoveInsertable</code>.</p></td>
 683 </tr>
 684 <tr>
 685 <td><p><span class="term">Returns:</span></p></td>
 686 <td>
 687 <p>The bool component of the return type is true if an insert took place.</p>
 688 <p>If an insert took place, then the iterator points to the newly inserted element. Otherwise, it points to the element with equivalent key.</p>
 689 </td>
 690 </tr>
 691 <tr>
 692 <td><p><span class="term">Throws:</span></p></td>
 693 <td><p>If an exception is thrown by an operation other than a call to <code class="computeroutput">hasher</code> the function has no effect.</p></td>
 694 </tr>
 695 <tr>
 696 <td><p><span class="term">Notes:</span></p></td>
 697 <td>
 698 <p>Can invalidate iterators, but only if the insert causes the load factor to be greater to or equal to the maximum load factor.</p>
 699 <p>Pointers and references to elements are never invalidated.</p>
 700 </td>
 701 </tr>
 702 </tbody>
 703 </table></div>
 704 </li>
 705 <li class="listitem">
 706 <pre class="literallayout"><span class="identifier">iterator</span> <a name="idp314059616-bb"></a><span class="identifier">insert</span><span class="special">(</span><span class="identifier">const_iterator</span> hint<span class="special">,</span> <span class="identifier">value_type</span> <span class="keyword">const</span><span class="special">&amp;</span> obj<span class="special">)</span><span class="special">;</span></pre>
 707 <p>Inserts <code class="computeroutput">obj</code> in the container if and only if there is no element in the container with an equivalent key.</p>
 708 <p>hint is a suggestion to where the element should be inserted.</p>
 709 <div class="variablelist"><table border="0" class="variablelist compact">
 710 <colgroup>
 711 <col align="left" valign="top">
 712 <col>
 713 </colgroup>
 714 <tbody>
 715 <tr>
 716 <td><p><span class="term">Requires:</span></p></td>
 717 <td><p><code class="computeroutput">value_type</code> is <code class="computeroutput">CopyInsertable</code>.</p></td>
 718 </tr>
 719 <tr>
 720 <td><p><span class="term">Returns:</span></p></td>
 721 <td><p>If an insert took place, then the iterator points to the newly inserted element. Otherwise, it points to the element with equivalent key.</p></td>
 722 </tr>
 723 <tr>
 724 <td><p><span class="term">Throws:</span></p></td>
 725 <td><p>If an exception is thrown by an operation other than a call to <code class="computeroutput">hasher</code> the function has no effect.</p></td>
 726 </tr>
 727 <tr>
 728 <td><p><span class="term">Notes:</span></p></td>
 729 <td>
 730 <p>The standard is fairly vague on the meaning of the hint. But the only practical way to use it, and the only way that Boost.Unordered supports is to point to an existing element with the same key. </p>
 731 <p>Can invalidate iterators, but only if the insert causes the load factor to be greater to or equal to the maximum load factor.</p>
 732 <p>Pointers and references to elements are never invalidated.</p>
 733 </td>
 734 </tr>
 735 </tbody>
 736 </table></div>
 737 </li>
 738 <li class="listitem">
 739 <pre class="literallayout"><span class="identifier">iterator</span> <a name="idp314070992-bb"></a><span class="identifier">insert</span><span class="special">(</span><span class="identifier">const_iterator</span> hint<span class="special">,</span> <span class="identifier">value_type</span><span class="special">&amp;&amp;</span> obj<span class="special">)</span><span class="special">;</span></pre>
 740 <p>Inserts <code class="computeroutput">obj</code> in the container if and only if there is no element in the container with an equivalent key.</p>
 741 <p>hint is a suggestion to where the element should be inserted.</p>
 742 <div class="variablelist"><table border="0" class="variablelist compact">
 743 <colgroup>
 744 <col align="left" valign="top">
 745 <col>
 746 </colgroup>
 747 <tbody>
 748 <tr>
 749 <td><p><span class="term">Requires:</span></p></td>
 750 <td><p><code class="computeroutput">value_type</code> is <code class="computeroutput">MoveInsertable</code>.</p></td>
 751 </tr>
 752 <tr>
 753 <td><p><span class="term">Returns:</span></p></td>
 754 <td><p>If an insert took place, then the iterator points to the newly inserted element. Otherwise, it points to the element with equivalent key.</p></td>
 755 </tr>
 756 <tr>
 757 <td><p><span class="term">Throws:</span></p></td>
 758 <td><p>If an exception is thrown by an operation other than a call to <code class="computeroutput">hasher</code> the function has no effect.</p></td>
 759 </tr>
 760 <tr>
 761 <td><p><span class="term">Notes:</span></p></td>
 762 <td>
 763 <p>The standard is fairly vague on the meaning of the hint. But the only practical way to use it, and the only way that Boost.Unordered supports is to point to an existing element with the same key. </p>
 764 <p>Can invalidate iterators, but only if the insert causes the load factor to be greater to or equal to the maximum load factor.</p>
 765 <p>Pointers and references to elements are never invalidated.</p>
 766 </td>
 767 </tr>
 768 </tbody>
 769 </table></div>
 770 </li>
 771 <li class="listitem">
 772 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> InputIterator<span class="special">&gt;</span>
 773   <span class="keyword">void</span> <a name="idp314082528-bb"></a><span class="identifier">insert</span><span class="special">(</span><span class="identifier">InputIterator</span> first<span class="special">,</span> <span class="identifier">InputIterator</span> last<span class="special">)</span><span class="special">;</span></pre>
 774 <p>Inserts a range of elements into the container. Elements are inserted if and only if there is no element in the container with an equivalent key.</p>
 775 <div class="variablelist"><table border="0" class="variablelist compact">
 776 <colgroup>
 777 <col align="left" valign="top">
 778 <col>
 779 </colgroup>
 780 <tbody>
 781 <tr>
 782 <td><p><span class="term">Requires:</span></p></td>
 783 <td><p><code class="computeroutput">value_type</code> is <code class="computeroutput">EmplaceConstructible</code> into
 784                   <code class="computeroutput">X</code> from <code class="computeroutput">*first</code>.</p></td>
 785 </tr>
 786 <tr>
 787 <td><p><span class="term">Throws:</span></p></td>
 788 <td><p>When inserting a single element, if an exception is thrown by an operation other than a call to <code class="computeroutput">hasher</code> the function has no effect.</p></td>
 789 </tr>
 790 <tr>
 791 <td><p><span class="term">Notes:</span></p></td>
 792 <td>
 793 <p>Can invalidate iterators, but only if the insert causes the load factor to be greater to or equal to the maximum load factor.</p>
 794 <p>Pointers and references to elements are never invalidated.</p>
 795 </td>
 796 </tr>
 797 </tbody>
 798 </table></div>
 799 </li>
 800 <li class="listitem">
 801 <pre class="literallayout"><span class="identifier">iterator</span> <a name="idp219224656-bb"></a><span class="identifier">erase</span><span class="special">(</span><span class="identifier">const_iterator</span> position<span class="special">)</span><span class="special">;</span></pre>
 802 <p>Erase the element pointed to by <code class="computeroutput">position</code>.</p>
 803 <div class="variablelist"><table border="0" class="variablelist compact">
 804 <colgroup>
 805 <col align="left" valign="top">
 806 <col>
 807 </colgroup>
 808 <tbody>
 809 <tr>
 810 <td><p><span class="term">Returns:</span></p></td>
 811 <td><p>The iterator following <code class="computeroutput">position</code> before the erasure.</p></td>
 812 </tr>
 813 <tr>
 814 <td><p><span class="term">Throws:</span></p></td>
 815 <td><p>Only throws an exception if it is thrown by <code class="computeroutput">hasher</code> or <code class="computeroutput">key_equal</code>.</p></td>
 816 </tr>
 817 <tr>
 818 <td><p><span class="term">Notes:</span></p></td>
 819 <td><p>
 820                   In older versions this could be inefficient because it had to search
 821                   through several buckets to find the position of the returned iterator.
 822                   The data structure has been changed so that this is no longer the case,
 823                   and the alternative erase methods have been deprecated.
 824                 </p></td>
 825 </tr>
 826 </tbody>
 827 </table></div>
 828 </li>
 829 <li class="listitem">
 830 <pre class="literallayout"><span class="identifier">size_type</span> <a name="idp219232688-bb"></a><span class="identifier">erase</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span><span class="special">;</span></pre>
 831 <p>Erase all elements with key equivalent to <code class="computeroutput">k</code>.</p>
 832 <div class="variablelist"><table border="0" class="variablelist compact">
 833 <colgroup>
 834 <col align="left" valign="top">
 835 <col>
 836 </colgroup>
 837 <tbody>
 838 <tr>
 839 <td><p><span class="term">Returns:</span></p></td>
 840 <td><p>The number of elements erased.</p></td>
 841 </tr>
 842 <tr>
 843 <td><p><span class="term">Throws:</span></p></td>
 844 <td><p>Only throws an exception if it is thrown by <code class="computeroutput">hasher</code> or <code class="computeroutput">key_equal</code>.</p></td>
 845 </tr>
 846 </tbody>
 847 </table></div>
 848 </li>
 849 <li class="listitem">
 850 <pre class="literallayout"><span class="identifier">iterator</span> <a name="idp219239008-bb"></a><span class="identifier">erase</span><span class="special">(</span><span class="identifier">const_iterator</span> first<span class="special">,</span> <span class="identifier">const_iterator</span> last<span class="special">)</span><span class="special">;</span></pre>
 851 <p>Erases the elements in the range from <code class="computeroutput">first</code> to <code class="computeroutput">last</code>.</p>
 852 <div class="variablelist"><table border="0" class="variablelist compact">
 853 <colgroup>
 854 <col align="left" valign="top">
 855 <col>
 856 </colgroup>
 857 <tbody>
 858 <tr>
 859 <td><p><span class="term">Returns:</span></p></td>
 860 <td><p>The iterator following the erased elements - i.e. <code class="computeroutput">last</code>.</p></td>
 861 </tr>
 862 <tr>
 863 <td><p><span class="term">Throws:</span></p></td>
 864 <td>
 865 <p>Only throws an exception if it is thrown by <code class="computeroutput">hasher</code> or <code class="computeroutput">key_equal</code>.</p>
 866 <p>In this implementation, this overload doesn't call either function object's methods so it is no throw, but this might not be true in other implementations.</p>
 867 </td>
 868 </tr>
 869 </tbody>
 870 </table></div>
 871 </li>
 872 <li class="listitem">
 873 <pre class="literallayout"><span class="keyword">void</span> <a name="idp219247984-bb"></a><span class="identifier">quick_erase</span><span class="special">(</span><span class="identifier">const_iterator</span> position<span class="special">)</span><span class="special">;</span></pre>
 874 <p>Erase the element pointed to by <code class="computeroutput">position</code>.</p>
 875 <div class="variablelist"><table border="0" class="variablelist compact">
 876 <colgroup>
 877 <col align="left" valign="top">
 878 <col>
 879 </colgroup>
 880 <tbody>
 881 <tr>
 882 <td><p><span class="term">Throws:</span></p></td>
 883 <td>
 884 <p>Only throws an exception if it is thrown by <code class="computeroutput">hasher</code> or <code class="computeroutput">key_equal</code>.</p>
 885 <p>In this implementation, this overload doesn't call either function object's methods so it is no throw, but this might not be true in other implementations.</p>
 886 </td>
 887 </tr>
 888 <tr>
 889 <td><p><span class="term">Notes:</span></p></td>
 890 <td><p>
 891                   This method was implemented because returning an iterator to
 892                   the next element from <code class="computeroutput">erase</code> was expensive, but
 893                   the container has been redesigned so that is no longer the
 894                   case. So this method is now deprecated.
 895                 </p></td>
 896 </tr>
 897 </tbody>
 898 </table></div>
 899 </li>
 900 <li class="listitem">
 901 <pre class="literallayout"><span class="keyword">void</span> <a name="idp219255648-bb"></a><span class="identifier">erase_return_void</span><span class="special">(</span><span class="identifier">const_iterator</span> position<span class="special">)</span><span class="special">;</span></pre>
 902 <p>Erase the element pointed to by <code class="computeroutput">position</code>.</p>
 903 <div class="variablelist"><table border="0" class="variablelist compact">
 904 <colgroup>
 905 <col align="left" valign="top">
 906 <col>
 907 </colgroup>
 908 <tbody>
 909 <tr>
 910 <td><p><span class="term">Throws:</span></p></td>
 911 <td>
 912 <p>Only throws an exception if it is thrown by <code class="computeroutput">hasher</code> or <code class="computeroutput">key_equal</code>.</p>
 913 <p>In this implementation, this overload doesn't call either function object's methods so it is no throw, but this might not be true in other implementations.</p>
 914 </td>
 915 </tr>
 916 <tr>
 917 <td><p><span class="term">Notes:</span></p></td>
 918 <td><p>
 919                   This method was implemented because returning an iterator to
 920                   the next element from <code class="computeroutput">erase</code> was expensive, but
 921                   the container has been redesigned so that is no longer the
 922                   case. So this method is now deprecated.
 923                 </p></td>
 924 </tr>
 925 </tbody>
 926 </table></div>
 927 </li>
 928 <li class="listitem">
 929 <pre class="literallayout"><span class="keyword">void</span> <a name="idp219263312-bb"></a><span class="identifier">clear</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
 930 <p>Erases all elements in the container.</p>
 931 <div class="variablelist"><table border="0" class="variablelist compact">
 932 <colgroup>
 933 <col align="left" valign="top">
 934 <col>
 935 </colgroup>
 936 <tbody>
 937 <tr>
 938 <td><p><span class="term">Postconditions:</span></p></td>
 939 <td><p><code class="computeroutput"><a class="link" href="unordered_map.html#idp222822752-bb">size</a>() == 0</code></p></td>
 940 </tr>
 941 <tr>
 942 <td><p><span class="term">Throws:</span></p></td>
 943 <td><p>Never throws an exception.</p></td>
 944 </tr>
 945 </tbody>
 946 </table></div>
 947 </li>
 948 <li class="listitem">
 949 <pre class="literallayout"><span class="keyword">void</span> <a name="idp219267616-bb"></a><span class="identifier">swap</span><span class="special">(</span><span class="identifier">unordered_map</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span></pre>
 950 <p>Swaps the contents of the container with the parameter.</p>
 951 <p>If <code class="computeroutput">Allocator::propagate_on_container_swap</code> is declared and
 952                   <code class="computeroutput">Allocator::propagate_on_container_swap::value</code> is true then the
 953                   containers' allocators are swapped. Otherwise, swapping with unequal allocators
 954                   results in undefined behavior.</p>
 955 <div class="variablelist"><table border="0" class="variablelist compact">
 956 <colgroup>
 957 <col align="left" valign="top">
 958 <col>
 959 </colgroup>
 960 <tbody>
 961 <tr>
 962 <td><p><span class="term">Throws:</span></p></td>
 963 <td><p>Doesn't throw an exception unless it is thrown by the copy constructor or copy assignment operator of <code class="computeroutput">key_equal</code> or <code class="computeroutput">hasher</code>.</p></td>
 964 </tr>
 965 <tr>
 966 <td><p><span class="term">Notes:</span></p></td>
 967 <td><p>The exception specifications aren't quite the same as the C++11 standard, as
 968                   the equality predieate and hash function are swapped using their copy constructors.</p></td>
 969 </tr>
 970 </tbody>
 971 </table></div>
 972 </li>
 973 </ol></div>
 974 </div>
 975 <div class="refsect2">
 976 <a name="idp520826560"></a><h3>
 977 <a name="idp219275120-bb"></a><code class="computeroutput">unordered_map</code> observers</h3>
 978 <div class="orderedlist"><ol class="orderedlist" type="1">
 979 <li class="listitem">
 980 <pre class="literallayout"><span class="identifier">hasher</span> <a name="idp219275680-bb"></a><span class="identifier">hash_function</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 981 <div class="variablelist"><table border="0" class="variablelist compact">
 982 <colgroup>
 983 <col align="left" valign="top">
 984 <col>
 985 </colgroup>
 986 <tbody><tr>
 987 <td><p><span class="term">Returns:</span></p></td>
 988 <td>The container's hash function.
 989               </td>
 990 </tr></tbody>
 991 </table></div>
 992 </li>
 993 <li class="listitem">
 994 <pre class="literallayout"><span class="identifier">key_equal</span> <a name="idp219277536-bb"></a><span class="identifier">key_eq</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 995 <div class="variablelist"><table border="0" class="variablelist compact">
 996 <colgroup>
 997 <col align="left" valign="top">
 998 <col>
 999 </colgroup>
1000 <tbody><tr>
1001 <td><p><span class="term">Returns:</span></p></td>
1002 <td>The container's key equality predicate.
1003               </td>
1004 </tr></tbody>
1005 </table></div>
1006 </li>
1007 </ol></div>
1008 </div>
1009 <div class="refsect2">
1010 <a name="idp520841456"></a><h3>
1011 <a name="idp219279552-bb"></a><code class="computeroutput">unordered_map</code> lookup</h3>
1012 <div class="orderedlist"><ol class="orderedlist" type="1">
1013 <li class="listitem">
1014 <pre class="literallayout"><a name="idp219280112-bb"></a><span class="identifier">iterator</span> <a name="idp219280672-bb"></a><span class="identifier">find</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span><span class="special">;</span>
1015 <span class="identifier">const_iterator</span> <a name="idp219282736-bb"></a><span class="identifier">find</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
1016 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> CompatibleKey<span class="special">,</span> <span class="keyword">typename</span> CompatibleHash<span class="special">,</span>
1017          <span class="keyword">typename</span> CompatiblePredicate<span class="special">&gt;</span>
1018   <span class="identifier">iterator</span> <a name="idp219285072-bb"></a><span class="identifier">find</span><span class="special">(</span><span class="identifier">CompatibleKey</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">,</span> <span class="identifier">CompatibleHash</span> <span class="keyword">const</span><span class="special">&amp;</span> hash<span class="special">,</span>
1019                 <span class="identifier">CompatiblePredicate</span> <span class="keyword">const</span><span class="special">&amp;</span> eq<span class="special">)</span><span class="special">;</span>
1020 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> CompatibleKey<span class="special">,</span> <span class="keyword">typename</span> CompatibleHash<span class="special">,</span>
1021          <span class="keyword">typename</span> CompatiblePredicate<span class="special">&gt;</span>
1022   <span class="identifier">const_iterator</span>
1023   <a name="idp219291616-bb"></a><span class="identifier">find</span><span class="special">(</span><span class="identifier">CompatibleKey</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">,</span> <span class="identifier">CompatibleHash</span> <span class="keyword">const</span><span class="special">&amp;</span> hash<span class="special">,</span>
1024        <span class="identifier">CompatiblePredicate</span> <span class="keyword">const</span><span class="special">&amp;</span> eq<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1025 <div class="variablelist"><table border="0" class="variablelist compact">
1026 <colgroup>
1027 <col align="left" valign="top">
1028 <col>
1029 </colgroup>
1030 <tbody>
1031 <tr>
1032 <td><p><span class="term">Returns:</span></p></td>
1033 <td><p>An iterator pointing to an element with key equivalent to <code class="computeroutput">k</code>, or <code class="computeroutput">b.end()</code> if no such element exists.</p></td>
1034 </tr>
1035 <tr>
1036 <td><p><span class="term">Notes:</span></p></td>
1037 <td><p>
1038                 The templated overloads are a non-standard extensions which
1039                 allows you to use a compatible hash function and equality
1040                 predicate for a key of a different type in order to avoid
1041                 an expensive type cast. In general, its use is not encouraged.
1042               </p></td>
1043 </tr>
1044 </tbody>
1045 </table></div>
1046 </li>
1047 <li class="listitem">
1048 <pre class="literallayout"><span class="identifier">size_type</span> <a name="idp213144768-bb"></a><span class="identifier">count</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1049 <div class="variablelist"><table border="0" class="variablelist compact">
1050 <colgroup>
1051 <col align="left" valign="top">
1052 <col>
1053 </colgroup>
1054 <tbody><tr>
1055 <td><p><span class="term">Returns:</span></p></td>
1056 <td><p>The number of elements with key equivalent to <code class="computeroutput">k</code>.</p></td>
1057 </tr></tbody>
1058 </table></div>
1059 </li>
1060 <li class="listitem">
1061 <pre class="literallayout"><a name="idp213148688-bb"></a><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="identifier">iterator</span><span class="special">&gt;</span> <a name="idp213149248-bb"></a><span class="identifier">equal_range</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span><span class="special">;</span>
1062 <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">const_iterator</span><span class="special">,</span> <span class="identifier">const_iterator</span><span class="special">&gt;</span> <a name="idp213151328-bb"></a><span class="identifier">equal_range</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1063 <div class="variablelist"><table border="0" class="variablelist compact">
1064 <colgroup>
1065 <col align="left" valign="top">
1066 <col>
1067 </colgroup>
1068 <tbody><tr>
1069 <td><p><span class="term">Returns:</span></p></td>
1070 <td><p>A range containing all elements with key equivalent to <code class="computeroutput">k</code>.
1071                   If the container doesn't container any such elements, returns
1072                   <code class="computeroutput">std::make_pair(b.end(),b.end())</code>.
1073                   </p></td>
1074 </tr></tbody>
1075 </table></div>
1076 </li>
1077 <li class="listitem">
1078 <pre class="literallayout"><span class="identifier">mapped_type</span><span class="special">&amp;</span> <a name="idp213156816-bb"></a><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span><span class="special">;</span></pre>
1079 <div class="variablelist"><table border="0" class="variablelist compact">
1080 <colgroup>
1081 <col align="left" valign="top">
1082 <col>
1083 </colgroup>
1084 <tbody>
1085 <tr>
1086 <td><p><span class="term">Effects:</span></p></td>
1087 <td><p>If the container does not already contain an elements with a key equivalent to <code class="computeroutput">k</code>, inserts the value <code class="computeroutput">std::pair&lt;key_type const, mapped_type&gt;(k, mapped_type())</code></p></td>
1088 </tr>
1089 <tr>
1090 <td><p><span class="term">Returns:</span></p></td>
1091 <td><p>A reference to <code class="computeroutput">x.second</code> where x is the element already in the container, or the newly inserted element with a key equivalent to <code class="computeroutput">k</code></p></td>
1092 </tr>
1093 <tr>
1094 <td><p><span class="term">Throws:</span></p></td>
1095 <td><p>If an exception is thrown by an operation other than a call to <code class="computeroutput">hasher</code> the function has no effect.</p></td>
1096 </tr>
1097 <tr>
1098 <td><p><span class="term">Notes:</span></p></td>
1099 <td>
1100 <p>Can invalidate iterators, but only if the insert causes the load factor to be greater to or equal to the maximum load factor.</p>
1101 <p>Pointers and references to elements are never invalidated.</p>
1102 </td>
1103 </tr>
1104 </tbody>
1105 </table></div>
1106 </li>
1107 <li class="listitem">
1108 <pre class="literallayout"><a name="idp213165536-bb"></a><span class="identifier">Mapped</span><span class="special">&amp;</span> <a name="idp213166096-bb"></a><span class="identifier">at</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span><span class="special">;</span>
1109 <span class="identifier">Mapped</span> <span class="keyword">const</span><span class="special">&amp;</span> <a name="idp213167520-bb"></a><span class="identifier">at</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1110 <div class="variablelist"><table border="0" class="variablelist compact">
1111 <colgroup>
1112 <col align="left" valign="top">
1113 <col>
1114 </colgroup>
1115 <tbody>
1116 <tr>
1117 <td><p><span class="term">Returns:</span></p></td>
1118 <td><p>A reference to <code class="computeroutput">x.second</code> where <code class="computeroutput">x</code> is the (unique) element whose key is equivalent to <code class="computeroutput">k</code>.</p></td>
1119 </tr>
1120 <tr>
1121 <td><p><span class="term">Throws:</span></p></td>
1122 <td><p>An exception object of type <code class="computeroutput">std::out_of_range</code> if no such element is present.</p></td>
1123 </tr>
1124 </tbody>
1125 </table></div>
1126 </li>
1127 </ol></div>
1128 </div>
1129 <div class="refsect2">
1130 <a name="idp520961328"></a><h3>
1131 <a name="idp213173120-bb"></a><code class="computeroutput">unordered_map</code> bucket interface</h3>
1132 <div class="orderedlist"><ol class="orderedlist" type="1">
1133 <li class="listitem">
1134 <pre class="literallayout"><span class="identifier">size_type</span> <a name="idp213173680-bb"></a><span class="identifier">bucket_count</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1135 <div class="variablelist"><table border="0" class="variablelist compact">
1136 <colgroup>
1137 <col align="left" valign="top">
1138 <col>
1139 </colgroup>
1140 <tbody><tr>
1141 <td><p><span class="term">Returns:</span></p></td>
1142 <td><p>The number of buckets.</p></td>
1143 </tr></tbody>
1144 </table></div>
1145 </li>
1146 <li class="listitem">
1147 <pre class="literallayout"><span class="identifier">size_type</span> <a name="idp213176016-bb"></a><span class="identifier">max_bucket_count</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1148 <div class="variablelist"><table border="0" class="variablelist compact">
1149 <colgroup>
1150 <col align="left" valign="top">
1151 <col>
1152 </colgroup>
1153 <tbody><tr>
1154 <td><p><span class="term">Returns:</span></p></td>
1155 <td><p>An upper bound on the number of buckets.</p></td>
1156 </tr></tbody>
1157 </table></div>
1158 </li>
1159 <li class="listitem">
1160 <pre class="literallayout"><span class="identifier">size_type</span> <a name="idp213178320-bb"></a><span class="identifier">bucket_size</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1161 <div class="variablelist"><table border="0" class="variablelist compact">
1162 <colgroup>
1163 <col align="left" valign="top">
1164 <col>
1165 </colgroup>
1166 <tbody>
1167 <tr>
1168 <td><p><span class="term">Requires:</span></p></td>
1169 <td><p><code class="computeroutput">n &lt; <a class="link" href="unordered_map.html#idp213173680-bb">bucket_count</a>()</code></p></td>
1170 </tr>
1171 <tr>
1172 <td><p><span class="term">Returns:</span></p></td>
1173 <td><p>The number of elements in bucket <code class="computeroutput">n</code>.</p></td>
1174 </tr>
1175 </tbody>
1176 </table></div>
1177 </li>
1178 <li class="listitem">
1179 <pre class="literallayout"><span class="identifier">size_type</span> <a name="idp213183760-bb"></a><span class="identifier">bucket</span><span class="special">(</span><span class="identifier">key_type</span> <span class="keyword">const</span><span class="special">&amp;</span> k<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1180 <div class="variablelist"><table border="0" class="variablelist compact">
1181 <colgroup>
1182 <col align="left" valign="top">
1183 <col>
1184 </colgroup>
1185 <tbody>
1186 <tr>
1187 <td><p><span class="term">Returns:</span></p></td>
1188 <td><p>The index of the bucket which would contain an element with key <code class="computeroutput">k</code>.</p></td>
1189 </tr>
1190 <tr>
1191 <td><p><span class="term">Postconditions:</span></p></td>
1192 <td><p>The return value is less than <code class="computeroutput">bucket_count()</code></p></td>
1193 </tr>
1194 </tbody>
1195 </table></div>
1196 </li>
1197 <li class="listitem">
1198 <pre class="literallayout"><a name="idp213188960-bb"></a><span class="identifier">local_iterator</span> <a name="idp213189520-bb"></a><span class="identifier">begin</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span><span class="special">;</span>
1199 <span class="identifier">const_local_iterator</span> <a name="idp213191584-bb"></a><span class="identifier">begin</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1200 <div class="variablelist"><table border="0" class="variablelist compact">
1201 <colgroup>
1202 <col align="left" valign="top">
1203 <col>
1204 </colgroup>
1205 <tbody>
1206 <tr>
1207 <td><p><span class="term">Requires:</span></p></td>
1208 <td><p><code class="computeroutput">n</code> shall be in the range <code class="computeroutput">[0, bucket_count())</code>.</p></td>
1209 </tr>
1210 <tr>
1211 <td><p><span class="term">Returns:</span></p></td>
1212 <td><p>A local iterator pointing the first element in the bucket with index <code class="computeroutput">n</code>.</p></td>
1213 </tr>
1214 </tbody>
1215 </table></div>
1216 </li>
1217 <li class="listitem">
1218 <pre class="literallayout"><a name="idp213197104-bb"></a><span class="identifier">local_iterator</span> <a name="idp213197664-bb"></a><span class="identifier">end</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span><span class="special">;</span>
1219 <span class="identifier">const_local_iterator</span> <a name="idp213199728-bb"></a><span class="identifier">end</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1220 <div class="variablelist"><table border="0" class="variablelist compact">
1221 <colgroup>
1222 <col align="left" valign="top">
1223 <col>
1224 </colgroup>
1225 <tbody>
1226 <tr>
1227 <td><p><span class="term">Requires:</span></p></td>
1228 <td><p><code class="computeroutput">n</code> shall be in the range <code class="computeroutput">[0, bucket_count())</code>.</p></td>
1229 </tr>
1230 <tr>
1231 <td><p><span class="term">Returns:</span></p></td>
1232 <td><p>A local iterator pointing the 'one past the end' element in the bucket with index <code class="computeroutput">n</code>.</p></td>
1233 </tr>
1234 </tbody>
1235 </table></div>
1236 </li>
1237 <li class="listitem">
1238 <pre class="literallayout"><span class="identifier">const_local_iterator</span> <a name="idp213205264-bb"></a><span class="identifier">cbegin</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1239 <div class="variablelist"><table border="0" class="variablelist compact">
1240 <colgroup>
1241 <col align="left" valign="top">
1242 <col>
1243 </colgroup>
1244 <tbody>
1245 <tr>
1246 <td><p><span class="term">Requires:</span></p></td>
1247 <td><p><code class="computeroutput">n</code> shall be in the range <code class="computeroutput">[0, bucket_count())</code>.</p></td>
1248 </tr>
1249 <tr>
1250 <td><p><span class="term">Returns:</span></p></td>
1251 <td><p>A constant local iterator pointing the first element in the bucket with index <code class="computeroutput">n</code>.</p></td>
1252 </tr>
1253 </tbody>
1254 </table></div>
1255 </li>
1256 <li class="listitem">
1257 <pre class="literallayout"><span class="identifier">const_local_iterator</span> <a name="idp213210912-bb"></a><span class="identifier">cend</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span><span class="special">;</span></pre>
1258 <div class="variablelist"><table border="0" class="variablelist compact">
1259 <colgroup>
1260 <col align="left" valign="top">
1261 <col>
1262 </colgroup>
1263 <tbody>
1264 <tr>
1265 <td><p><span class="term">Requires:</span></p></td>
1266 <td><p><code class="computeroutput">n</code> shall be in the range <code class="computeroutput">[0, bucket_count())</code>.</p></td>
1267 </tr>
1268 <tr>
1269 <td><p><span class="term">Returns:</span></p></td>
1270 <td><p>A constant local iterator pointing the 'one past the end' element in the bucket with index <code class="computeroutput">n</code>.</p></td>
1271 </tr>
1272 </tbody>
1273 </table></div>
1274 </li>
1275 </ol></div>
1276 </div>
1277 <div class="refsect2">
1278 <a name="idp521044784"></a><h3>
1279 <a name="idp213216464-bb"></a><code class="computeroutput">unordered_map</code> hash policy</h3>
1280 <div class="orderedlist"><ol class="orderedlist" type="1">
1281 <li class="listitem">
1282 <pre class="literallayout"><span class="keyword">float</span> <a name="idp213217024-bb"></a><span class="identifier">load_factor</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1283 <div class="variablelist"><table border="0" class="variablelist compact">
1284 <colgroup>
1285 <col align="left" valign="top">
1286 <col>
1287 </colgroup>
1288 <tbody><tr>
1289 <td><p><span class="term">Returns:</span></p></td>
1290 <td><p>The average number of elements per bucket.</p></td>
1291 </tr></tbody>
1292 </table></div>
1293 </li>
1294 <li class="listitem">
1295 <pre class="literallayout"><span class="keyword">float</span> <a name="idp300598064-bb"></a><span class="identifier">max_load_factor</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
1296 <div class="variablelist"><table border="0" class="variablelist compact">
1297 <colgroup>
1298 <col align="left" valign="top">
1299 <col>
1300 </colgroup>
1301 <tbody><tr>
1302 <td><p><span class="term">Returns:</span></p></td>
1303 <td><p>Returns the current maximum load factor.</p></td>
1304 </tr></tbody>
1305 </table></div>
1306 </li>
1307 <li class="listitem">
1308 <pre class="literallayout"><span class="keyword">void</span> <a name="idp300600256-bb"></a><span class="identifier">max_load_factor</span><span class="special">(</span><span class="keyword">float</span> z<span class="special">)</span><span class="special">;</span></pre>
1309 <div class="variablelist"><table border="0" class="variablelist compact">
1310 <colgroup>
1311 <col align="left" valign="top">
1312 <col>
1313 </colgroup>
1314 <tbody><tr>
1315 <td><p><span class="term">Effects:</span></p></td>
1316 <td><p>Changes the container's maximum load factor, using <code class="computeroutput">z</code> as a hint.</p></td>
1317 </tr></tbody>
1318 </table></div>
1319 </li>
1320 <li class="listitem">
1321 <pre class="literallayout"><span class="keyword">void</span> <a name="idp300603904-bb"></a><span class="identifier">rehash</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span><span class="special">;</span></pre>
1322 <p>Changes the number of buckets so that there at least <code class="computeroutput">n</code> buckets, and so that the load factor is less than the maximum load factor.</p>
1323 <p>Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.</p>
1324 <div class="variablelist"><table border="0" class="variablelist compact">
1325 <colgroup>
1326 <col align="left" valign="top">
1327 <col>
1328 </colgroup>
1329 <tbody><tr>
1330 <td><p><span class="term">Throws:</span></p></td>
1331 <td><p>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</p></td>
1332 </tr></tbody>
1333 </table></div>
1334 </li>
1335 <li class="listitem">
1336 <pre class="literallayout"><span class="keyword">void</span> <a name="idp300609168-bb"></a><span class="identifier">reserve</span><span class="special">(</span><span class="identifier">size_type</span> n<span class="special">)</span><span class="special">;</span></pre>
1337 <p>Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.</p>
1338 <div class="variablelist"><table border="0" class="variablelist compact">
1339 <colgroup>
1340 <col align="left" valign="top">
1341 <col>
1342 </colgroup>
1343 <tbody><tr>
1344 <td><p><span class="term">Throws:</span></p></td>
1345 <td><p>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</p></td>
1346 </tr></tbody>
1347 </table></div>
1348 </li>
1349 </ol></div>
1350 </div>
1351 <div class="refsect2">
1352 <a name="idp521081776"></a><h3>
1353 <a name="idp300613664-bb"></a><code class="computeroutput">unordered_map</code> Equality Comparisons</h3>
1354 <div class="orderedlist"><ol class="orderedlist" type="1">
1355 <li class="listitem">
1356 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Key<span class="special">,</span> <span class="keyword">typename</span> Mapped<span class="special">,</span> <span class="keyword">typename</span> Hash<span class="special">,</span> <span class="keyword">typename</span> Pred<span class="special">,</span>
1357          <span class="keyword">typename</span> Alloc<span class="special">&gt;</span>
1358   <span class="keyword">bool</span> <a name="boost.unordered_map.operator==_idp300614224"></a><span class="keyword">operator</span><span class="special">==</span><span class="special">(</span><span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> x<span class="special">,</span>
1359                   <span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> y<span class="special">)</span><span class="special">;</span></pre>
1360 <p>Return <code class="computeroutput">true</code> if <code class="computeroutput">x.size() ==
1361                 y.size</code> and for every element in <code class="computeroutput">x</code>,
1362                 there is an element in <code class="computeroutput">y</code> with the same
1363                 for the same key, with an equal value (using
1364                 <code class="computeroutput">operator==</code> to compare the value types).
1365                 </p>
1366 <div class="variablelist"><table border="0" class="variablelist compact">
1367 <colgroup>
1368 <col align="left" valign="top">
1369 <col>
1370 </colgroup>
1371 <tbody><tr>
1372 <td><p><span class="term">Notes:</span></p></td>
1373 <td>
1374 <p>The behavior of this function was changed to match
1375                   the C++11 standard in Boost 1.48.</p>
1376 <p>Behavior is undefined if the two containers don't have
1377                     equivalent equality predicates.</p>
1378 </td>
1379 </tr></tbody>
1380 </table></div>
1381 </li>
1382 <li class="listitem">
1383 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Key<span class="special">,</span> <span class="keyword">typename</span> Mapped<span class="special">,</span> <span class="keyword">typename</span> Hash<span class="special">,</span> <span class="keyword">typename</span> Pred<span class="special">,</span>
1384          <span class="keyword">typename</span> Alloc<span class="special">&gt;</span>
1385   <span class="keyword">bool</span> <a name="boost.unordered_map.operator!=_idp300626416"></a><span class="keyword">operator</span><span class="special">!=</span><span class="special">(</span><span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> x<span class="special">,</span>
1386                   <span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> y<span class="special">)</span><span class="special">;</span></pre>
1387 <p>Return <code class="computeroutput">false</code> if <code class="computeroutput">x.size() ==
1388                 y.size</code> and for every element in <code class="computeroutput">x</code>,
1389                 there is an element in <code class="computeroutput">y</code> with the same
1390                 for the same key, with an equal value (using
1391                 <code class="computeroutput">operator==</code> to compare the value types).
1392                 </p>
1393 <div class="variablelist"><table border="0" class="variablelist compact">
1394 <colgroup>
1395 <col align="left" valign="top">
1396 <col>
1397 </colgroup>
1398 <tbody><tr>
1399 <td><p><span class="term">Notes:</span></p></td>
1400 <td>
1401 <p>The behavior of this function was changed to match
1402                   the C++11 standard in Boost 1.48.</p>
1403 <p>Behavior is undefined if the two containers don't have
1404                     equivalent equality predicates.</p>
1405 </td>
1406 </tr></tbody>
1407 </table></div>
1408 </li>
1409 </ol></div>
1410 </div>
1411 <div class="refsect2">
1412 <a name="idp521156608"></a><h3>
1413 <a name="idp300638768-bb"></a><code class="computeroutput">unordered_map</code> swap</h3>
1414 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
1415 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Key<span class="special">,</span> <span class="keyword">typename</span> Mapped<span class="special">,</span> <span class="keyword">typename</span> Hash<span class="special">,</span> <span class="keyword">typename</span> Pred<span class="special">,</span>
1416          <span class="keyword">typename</span> Alloc<span class="special">&gt;</span>
1417   <span class="keyword">void</span> <a name="boost.unordered_map.swap_idp300639328"></a><span class="identifier">swap</span><span class="special">(</span><span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span><span class="special">&amp;</span> x<span class="special">,</span>
1418             <span class="identifier">unordered_map</span><span class="special">&lt;</span><span class="identifier">Key</span><span class="special">,</span> <span class="identifier">Mapped</span><span class="special">,</span> <span class="identifier">Hash</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">,</span> <span class="identifier">Alloc</span><span class="special">&gt;</span><span class="special">&amp;</span> y<span class="special">)</span><span class="special">;</span></pre>
1419 <p>Swaps the contents of <code class="computeroutput">x</code> and <code class="computeroutput">y</code>.</p>
1420 <p>If <code class="computeroutput">Allocator::propagate_on_container_swap</code> is declared and
1421                   <code class="computeroutput">Allocator::propagate_on_container_swap::value</code> is true then the
1422                   containers' allocators are swapped. Otherwise, swapping with unequal allocators
1423                   results in undefined behavior.</p>
1424 <div class="variablelist"><table border="0" class="variablelist compact">
1425 <colgroup>
1426 <col align="left" valign="top">
1427 <col>
1428 </colgroup>
1429 <tbody>
1430 <tr>
1431 <td><p><span class="term">Effects:</span></p></td>
1432 <td><p><code class="computeroutput">x.swap(y)</code></p></td>
1433 </tr>
1434 <tr>
1435 <td><p><span class="term">Throws:</span></p></td>
1436 <td><p>Doesn't throw an exception unless it is thrown by the copy constructor or copy assignment operator of <code class="computeroutput">key_equal</code> or <code class="computeroutput">hasher</code>.</p></td>
1437 </tr>
1438 <tr>
1439 <td><p><span class="term">Notes:</span></p></td>
1440 <td><p>The exception specifications aren't quite the same as the C++11 standard, as
1441                   the equality predieate and hash function are swapped using their copy constructors.</p></td>
1442 </tr>
1443 </tbody>
1444 </table></div>
1445 </li></ol></div>
1446 </div>
1447 </div>
1448 </div>
1449 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
1450 <td align="left"></td>
1451 <td align="right"><div class="copyright-footer">Copyright &#169; 2003, 2004 Jeremy B. Maitin-Shepard<br>Copyright &#169; 2005-2008 Daniel
1452       James<p>
1453         Distributed under the Boost Software License, Version 1.0. (See accompanying
1454         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>)
1455       </p>
1456 </div></td>
1457 </tr></table>
1458 <hr>
1459 <div class="spirit-nav">
1460 <a accesskey="p" href="unordered_multiset.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../unordered/reference.html#header.boost.unordered_map_hpp"><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="unordered_multimap.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
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