title: Override std::equal
body: <p>In providing a specialization for the equal_to operator for std::unordered_map, I was wondering if it's possible to determine which of the lhs or rhs is the data currently stored in the hashmap? I'd like to do something like this:</p>
  
  <pre><code>template&lt;&gt;
  struct equal_to&lt;METADATA&gt;
  {
      bool operator() (METADATA const&amp; data1, METADATA const&amp; data2)
      {
          if (data1.Size == data2.Size)
          {
              // Need to look up the stored pointer in a global data structure
              SIZE_T Pointer = g_Pointer + data1.Offset;
  
              return memcmp(reinterpret_cast&lt;void*&gt;(Pointer), reinterpret_cast&lt;void*&gt;(data2.Pointer), data1.Size) == 0;
          }
  
          return false;            
      }
  };
  </code></pre>
  
  <p>Thanks.</p>