An unspecified value, except that equal arguments shall yield the same
            result
          </para>
        </returns>
      </overloaded-function>

      <!--
        boost::hash_value - arrays
        -->

      <overloaded-function name="hash_value">
        <purpose>
            Implementation of a hash function for built in arrays.
        </purpose>

        <description><para>
          Generally shouldn't be called directly by users, instead they should use
          <classname>boost::hash</classname>, <functionname>boost::hash_range</functionname>
          or <functionname>boost::hash_combine</functionname> which
          call hash_value without namespace qualification so that overloads
          for custom types are found via ADL.
        </para></description>
        <notes>
          <para>Overloads for other types supplied in other headers.</para>
          <para>This is an extension to TR1</para>
        </notes>
        
        <signature>
          <template>
            <template-type-parameter name="T"/>
            <template-nontype-parameter name="N"><type>unsigned</type></template-nontype-parameter>
          </template>
          <type>std::size_t</type>
          <parameter><paramtype>T (&amp;val)[N]</paramtype></parameter>
        </signature>

        <signature>
          <template>
            <template-type-parameter name="T"/>
            <template-nontype-parameter name="N"><type>unsigned</type></template-nontype-parameter>
          </template>
          <type>std::size_t</type>
          <parameter><paramtype>const T (&amp;val)[N]</paramtype></parameter>
        </signature>

        <returns><code>hash_range(val, val+N)</code></returns>
      </overloaded-function>

      <!--
        boost::hash_value - string
        -->

      <overloaded-function name="hash_value">
        <purpose>
            Implementation of a hash function for <code>std::basic_string</code>.
        </purpose>

        <description><para>
          Generally shouldn't be called directly by users, instead they should use
          <classname>boost::hash</classname>, <functionname>boost::hash_range</functionname>
          or <functionname>boost::hash_combine</functionname> which
          call hash_value without namespace qualification so that overloads
          for custom types are found via ADL.
        </para></description>
        <notes>
          <para>Overloads for other types supplied in other headers.</para>
          <para>This is an extension to TR1</para>
        </notes>

        <signature>
          <template>
            <template-type-parameter name="Ch"/>
            <template-type-parameter name="A"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val">
              <paramtype>std::basic_string&lt;Ch, std::char_traits&lt;Ch&gt;, A&gt; const&amp;</paramtype>
          </parameter>
        </signature>

        <returns><code>hash_range(val.begin(), val.end())</code></returns>
      </overloaded-function>
    </namespace>
  </header>

  <header name="boost/functional/hash/pair.hpp">
    <para>
      Hash implementation for <code>std::pair</code>.
    </para>
    <namespace name="boost">
      <overloaded-function name="hash_value">
        <signature>
          <template>
            <template-type-parameter name="A"/>
            <template-type-parameter name="B"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val"><paramtype>std::pair&lt;A, B&gt; const &amp;</paramtype></parameter>
        </signature>
        <effects><programlisting>
size_t seed = 0;
<functionname>hash_combine</functionname>(seed, val.first);
<functionname>hash_combine</functionname>(seed, val.second);
return seed;
        </programlisting></effects>
        <throws>
          Only throws if <code><functionname>hash_value</functionname>(A)</code>
          or <code><functionname>hash_value</functionname>(B)</code> throws.
        </throws>
        <notes><para>This is an extension to TR1</para></notes>
      </overloaded-function>
    </namespace>
  </header>

  <header name="boost/functional/hash/vector.hpp">
    <para>
      Hash implementation for <code>std::vector</code>.
    </para>
    <namespace name="boost">
      <overloaded-function name="hash_value">
        <signature>
          <template>
            <template-type-parameter name="T"/>
            <template-type-parameter name="A"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val"><paramtype>std::vector&lt;T, A&gt; const &amp;</paramtype></parameter>
        </signature>
        <returns>
          <code><functionname>hash_range</functionname>(val.begin(), val.end());</code>
        </returns>
        <throws>
          Only throws if <code><functionname>hash_value</functionname>(T)</code> throws.
        </throws>
        <notes><para>This is an extension to TR1</para></notes>
      </overloaded-function>      
    </namespace>
  </header>

  <header name="boost/functional/hash/list.hpp">
    <para>
      Hash implementation for <code>std::list</code>.
    </para>
    <namespace name="boost">
      <overloaded-function name="hash_value">
        <signature>
          <template>
            <template-type-parameter name="T"/>
            <template-type-parameter name="A"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val"><paramtype>std::list&lt;T, A&gt; const &amp;</paramtype></parameter>
        </signature>
        <returns>
          <code><functionname>hash_range</functionname>(val.begin(), val.end());</code>
        </returns>
        <throws>
          Only throws if <code><functionname>hash_value</functionname>(T)</code> throws.
        </throws>
        <notes><para>This is an extension to TR1</para></notes>
      </overloaded-function>      
    </namespace>
  </header>

  <header name="boost/functional/hash/deque.hpp">
    <para>
      Hash implementation for <code>std::deque</code>.
    </para>
    <namespace name="boost">
      <overloaded-function name="hash_value">
        <signature>
          <template>
            <template-type-parameter name="T"/>
            <template-type-parameter name="A"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val"><paramtype>std::deque&lt;T, A&gt; const &amp;</paramtype></parameter>
        </signature>
        <returns>
          <code><functionname>hash_range</functionname>(val.begin(), val.end());</code>
        </returns>
        <throws>
          Only throws if <code><functionname>hash_value</functionname>(T)</code> throws.
        </throws>
        <notes><para>This is an extension to TR1</para></notes>
      </overloaded-function>      
    </namespace>
  </header>

  <header name="boost/functional/hash/set.hpp">
    <para>
      Hash implementation for <code>std::set</code> and <code>std::multiset</code>.
    </para>
    <namespace name="boost">
      <overloaded-function name="hash_value">
        <signature>
          <template>
            <template-type-parameter name="K"/>
            <template-type-parameter name="C"/>
            <template-type-parameter name="A"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val"><paramtype>std::set&lt;K, C, A&gt; const &amp;</paramtype></parameter>
        </signature>

        <signature>
          <template>
            <template-type-parameter name="K"/>
            <template-type-parameter name="C"/>
            <template-type-parameter name="A"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val"><paramtype>std::multiset&lt;K, C, A&gt; const &amp;</paramtype></parameter>
        </signature>
        <returns>
          <code><functionname>hash_range</functionname>(val.begin(), val.end());</code>
        </returns>
        <throws>
          Only throws if <code><functionname>hash_value</functionname>(T)</code> throws.
        </throws>
        <notes><para>This is an extension to TR1</para></notes>
      </overloaded-function>      
    </namespace>
  </header>

  <header name="boost/functional/hash/map.hpp">
    <para>
      Hash implementation for <code>std::map</code> and <code>std::multimap</code>.
    </para>
    <namespace name="boost">
      <overloaded-function name="hash_value">
        <signature>
          <template>
            <template-type-parameter name="K"/>
            <template-type-parameter name="T"/>
            <template-type-parameter name="C"/>
            <template-type-parameter name="A"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val"><paramtype>std::map&lt;K, T, C, A&gt; const &amp;</paramtype></parameter>
        </signature>

        <signature>
          <template>
            <template-type-parameter name="K"/>
            <template-type-parameter name="T"/>
            <template-type-parameter name="C"/>
            <template-type-parameter name="A"/>
          </template>
          <type>std::size_t</type>
          <parameter name="val"><paramtype>std::multimap&lt;K, T, C, A&gt; const &amp;</paramtype></parameter>
        </signature>
        <returns>
          <code><functionname>hash_range</functionname>(val.begin(), val.end());</code>
        </returns>
        <throws>
          Only throws if
          <code><functionname>hash_value</functionname>(std::pair&lt;K const, T&gt;)</code>
          throws.
        </throws>
        <notes><para>This is an extension to TR1</para></notes>
      </overloaded-function>      
    </namespace>
  </header>
</library-reference>
'''
[/ Remove this comment and everything goes wrong! ;) ]
[endsect]

[section:links Links]

[*A Proposal to Add Hash Tables to the Standard Library]\n
[@http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1456.html]\n
The hash table proposal explains much of the design. The hash function object
is discussed in Section D.

[*The C++ Standard Library Technical Report.]\n
[@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1745.pdf]\n
Contains the hash function specification in section 6.3.2.

[*Library Extension Technical Report Issues List.]\n
[@http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf]\n
The library implements the extension described in Issue 6.18.

[*Methods for Identifying Versioned and Plagiarised Documents]\n
Timothy C. Hoad, Justin Zobel\n
[@http://www.cs.rmit.edu.au/~jz/fulltext/jasist-tch.pdf]\n
Contains the hash function that __hash_combine is based on.

[endsect]

[section:acknowledgements Acknowledgements]

This library is based on the design by Peter Dimov. During the inital development
Joaquín M López Mu?oz made many useful suggestions and contributed fixes.

The review was managed by Thorsten Ottosen, and the library reviewed by:
David Abrahams, Alberto Barbati, Topher Cooper, Caleb Epstein, Dave Harris,
Chris Jefferson, Bronek Kozicki, John Maddock, Tobias Swinger,Jaap Suter
and Rob Stewart.

The implementation of the hash function for pointers is based on suggestions
made by Alberto Barbati and Dave Harris. Dave Harris also suggested an
important improvement to __hash_combine that was taken up.

The original implementation came from Jeremy B. Maitin-Shepard's hash table
library, although this is a complete rewrite.

[endsect]