title: Decoupled version of hash_map/unordered_map
body: <p>I'm writing an embedded application, and the environment I use does not, unfortunately, have C++11 support at present.</p>
  
  <p>I need to implement a hash/unordered map (a regular <code>std::map</code> won't do for performance reasons), but can't seem to find a way to do it cleanly.</p>
  
  <p>Boost doesn't want to work without bringing in practically the whole library. Even the original STL <code>hash_map</code> from SGI wants several headers, and duplicates standard library functionality, causing ambiguous function calls. It's a real mess.</p>
  
  <p>For ease of implementation, versioning, quality control, V&amp;V, etc. I really need something that leverages the existing standard library and exists in only a few header files that I can put right in the same folder as all the other source/header files. Does such a thing exist, or am I without hope? I've searched for a long while, but have come up empty-handed.</p>
  
  <p>Thanks very much for any help. I can certainly clarify further if necessary.</p>