/* Copyright 2003-2005 Joaquín M López Muñoz.

  * Distributed under the Boost Software License, Version 1.0.

  * (See accompanying file LICENSE_1_0.txt or copy at

  * http://www.boost.org/LICENSE_1_0.txt)

  *

  * See http://www.boost.org/libs/multi_index for library home page.

  */

 #ifndef BOOST_MULTI_INDEX_DETAIL_HASH_INDEX_ARGS_HPP

 #define BOOST_MULTI_INDEX_DETAIL_HASH_INDEX_ARGS_HPP

 #if defined(_MSC_VER)&&(_MSC_VER>=1200)

 #pragma once

 #endif

 #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */

 #include <boost/functional/hash/hash.hpp>

 #include <boost/mpl/aux_/na.hpp>

 #include <boost/mpl/eval_if.hpp>

 #include <boost/mpl/identity.hpp>

 #include <boost/mpl/if.hpp>

 #include <boost/multi_index/tag.hpp>

 #include <boost/static_assert.hpp>

 #include <boost/type_traits/is_same.hpp>

 #include <functional>

 namespace boost{

 template<class T> struct hash; /* fwd decl. */

 namespace multi_index{

 namespace detail{

 /* Hashed index specifiers can be instantiated in two forms:

  *

  *   (hashed_unique|hashed_non_unique)<

  *     KeyFromValue,

  *     Hash=boost::hash<KeyFromValue::result_type>,

  *     Pred=std::equal_to<KeyFromValue::result_type> >

  *   (hashed_unique|hashed_non_unique)<

  *     TagList,

  *     KeyFromValue,

  *     Hash=boost::hash<KeyFromValue::result_type>,

  *     Pred=std::equal_to<KeyFromValue::result_type> >

  *

  * hashed_index_args implements the machinery to accept this

  * argument-dependent polymorphism.

  */

 template<typename KeyFromValue>

 struct index_args_default_hash

 {

   typedef ::boost::hash<typename KeyFromValue::result_type> type;

 };

 template<typename KeyFromValue>

 struct index_args_default_pred

 {

   typedef std::equal_to<typename KeyFromValue::result_type> type;

 };

 template<typename Arg1,typename Arg2,typename Arg3,typename Arg4>

 struct hashed_index_args

 {

   typedef is_tag<Arg1> full_form;

   typedef typename mpl::if_<

     full_form,

     Arg1,

     tag< > >::type                                   tag_list_type;

   typedef typename mpl::if_<

     full_form,

     Arg2,

     Arg1>::type                                      key_from_value_type;

   typedef typename mpl::if_<

     full_form,

     Arg3,

     Arg2>::type                                      supplied_hash_type;

   typedef typename mpl::eval_if<

     mpl::is_na<supplied_hash_type>,

     index_args_default_hash<key_from_value_type>,

     mpl::identity<supplied_hash_type>

   >::type                                            hash_type;

   typedef typename mpl::if_<

     full_form,

     Arg4,

     Arg3>::type                                      supplied_pred_type;

   typedef typename mpl::eval_if<

     mpl::is_na<supplied_pred_type>,

     index_args_default_pred<key_from_value_type>,

     mpl::identity<supplied_pred_type>

   >::type                                            pred_type;

   BOOST_STATIC_ASSERT(is_tag<tag_list_type>::value);

   BOOST_STATIC_ASSERT(!mpl::is_na<key_from_value_type>::value);

   BOOST_STATIC_ASSERT(!mpl::is_na<hash_type>::value);

   BOOST_STATIC_ASSERT(!mpl::is_na<pred_type>::value);

 };

 } /* namespace multi_index::detail */

 } /* namespace multi_index */

 } /* namespace boost */

 #endif