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// Boost.Geometry (aka GGL, Generic Geometry Library)
// Copyright (c) 2014-2015 Samuel Debionne, Grenoble, France.
// This file was modified by Oracle on 2015.
// Modifications copyright (c) 2015, Oracle and/or its affiliates.
// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
// Use, modification and distribution is subject to 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)
#ifndef BOOST_GEOMETRY_UTIL_COMBINE_IF_HPP
#define BOOST_GEOMETRY_UTIL_COMBINE_IF_HPP
#include <boost/mpl/fold.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/bind.hpp>
#include <boost/mpl/set.hpp>
#include <boost/mpl/insert.hpp>
#include <boost/mpl/placeholders.hpp>
#include <boost/type_traits.hpp>
namespace boost { namespace geometry
{
namespace util
{
/*!
\brief Meta-function to generate all the combination of pairs of types
from a given sequence Sequence except those that does not satisfy the
predicate Pred
\ingroup utility
\par Example
\code
typedef boost::mpl::vector<boost::mpl::int_<0>, boost::mpl::int_<1> > types;
typedef combine_if<types, types, always<true_> >::type combinations;
typedef boost::mpl::vector<
pair<boost::mpl::int_<1>, boost::mpl::int_<1> >,
pair<boost::mpl::int_<1>, boost::mpl::int_<0> >,
pair<boost::mpl::int_<0>, boost::mpl::int_<1> >,
pair<boost::mpl::int_<0>, boost::mpl::int_<0> >
> result_types;
BOOST_MPL_ASSERT(( boost::mpl::equal<combinations, result_types> ));
\endcode
*/
template <typename Sequence1, typename Sequence2, typename Pred>
struct combine_if
{
struct combine
{
template <typename Result, typename T>
struct apply
{
typedef typename boost::mpl::fold<Sequence2, Result,
boost::mpl::if_
<
boost::mpl::bind
<
typename boost::mpl::lambda<Pred>::type,
T,
boost::mpl::_2
>,
boost::mpl::insert
<
boost::mpl::_1, boost::mpl::pair<T, boost::mpl::_2>
>,
boost::mpl::_1
>
>::type type;
};
};
typedef typename boost::mpl::fold
<
Sequence1, boost::mpl::set0<>, combine
>::type type;
};
} // namespace util
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_UTIL_COMBINE_IF_HPP
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