/* 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