boost/multi_index/detail/no_duplicate_tags.hpp
/* Copyright 2003-2013 Joaquin M Lopez Munoz.
* 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_NO_DUPLICATE_TAGS_HPP
#define BOOST_MULTI_INDEX_DETAIL_NO_DUPLICATE_TAGS_HPP
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
#include <boost/mpl/fold.hpp>
#include <boost/mpl/set/set0.hpp>
namespace boost{
namespace multi_index{
namespace detail{
/* no_duplicate_tags check at compile-time that a tag list
* has no duplicate tags.
* The algorithm deserves some explanation: tags
* are sequentially inserted into a mpl::set if they were
* not already present. Due to the magic of mpl::set
* (mpl::has_key is contant time), this operation takes linear
* time, and even MSVC++ 6.5 handles it gracefully (other obvious
* solutions are quadratic.)
*/
struct duplicate_tag_mark{};
struct duplicate_tag_marker
{
template <typename MplSet,typename Tag>
struct apply
{
typedef mpl::s_item<
typename mpl::if_<mpl::has_key<MplSet,Tag>,duplicate_tag_mark,Tag>::type,
MplSet
> type;
};
};
template<typename TagList>
struct no_duplicate_tags
{
typedef typename mpl::fold<
TagList,
mpl::set0<>,
duplicate_tag_marker
>::type aux;
BOOST_STATIC_CONSTANT(
bool,value=!(mpl::has_key<aux,duplicate_tag_mark>::value));
};
/* Variant for an index list: duplication is checked
* across all the indices.
*/
struct duplicate_tag_list_marker
{
template <typename MplSet,typename Index>
struct apply:mpl::fold<
BOOST_DEDUCED_TYPENAME Index::tag_list,
MplSet,
duplicate_tag_marker>
{
};
};
template<typename IndexList>
struct no_duplicate_tags_in_index_list
{
typedef typename mpl::fold<
IndexList,
mpl::set0<>,
duplicate_tag_list_marker
>::type aux;
BOOST_STATIC_CONSTANT(
bool,value=!(mpl::has_key<aux,duplicate_tag_mark>::value));
};
} /* namespace multi_index::detail */
} /* namespace multi_index */
} /* namespace boost */
#endif