79 lines
2.2 KiB
C++
79 lines
2.2 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2014 Samuel Debionne, Grenoble, France.
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// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
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// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
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// Use, modification and distribution is subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_GEOMETRY_UTIL_COMBINE_IF_HPP
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#define BOOST_GEOMETRY_UTIL_COMBINE_IF_HPP
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#include <boost/mpl/fold.hpp>
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#include <boost/mpl/if.hpp>
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#include <boost/mpl/bind.hpp>
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#include <boost/mpl/set.hpp>
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#include <boost/mpl/insert.hpp>
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#include <boost/mpl/placeholders.hpp>
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#include <boost/type_traits.hpp>
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namespace boost { namespace geometry
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{
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namespace util
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{
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/*!
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\brief Meta-function to generate all the combination of pairs of types
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from a given sequence Sequence except those that does not satisfy the
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predicate Pred
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\ingroup utility
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\par Example
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\code
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typedef mpl::vector<mpl::int_<0>, mpl::int_<1> > types;
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typedef combine_if<types, types, always<true_> >::type combinations;
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typedef mpl::vector<
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pair<mpl::int_<1>, mpl::int_<1> >,
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pair<mpl::int_<1>, mpl::int_<0> >,
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pair<mpl::int_<0>, mpl::int_<1> >,
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pair<mpl::int_<0>, mpl::int_<0> >
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> result_types;
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BOOST_MPL_ASSERT(( mpl::equal<combinations, result_types> ));
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\endcode
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*/
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template <typename Sequence1, typename Sequence2, typename Pred>
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struct combine_if
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{
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struct combine
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{
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template <typename Result, typename T>
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struct apply
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{
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typedef typename mpl::fold<Sequence2, Result,
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mpl::if_
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<
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mpl::bind<typename mpl::lambda<Pred>::type, T, mpl::_2>,
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mpl::insert<mpl::_1, mpl::pair<T, mpl::_2> >,
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mpl::_1
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>
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>::type type;
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};
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};
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typedef typename mpl::fold<Sequence1, mpl::set0<>, combine>::type type;
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};
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} // namespace util
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_UTIL_COMBINE_IF_HPP
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