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-rw-r--r--boost/geometry/util/select_sequence_element.hpp78
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diff --git a/boost/geometry/util/select_sequence_element.hpp b/boost/geometry/util/select_sequence_element.hpp
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+// Boost.Geometry
+
+// Copyright (c) 2017 Adam Wulkiewicz, Lodz, Poland.
+
+// 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_SELECT_SEQUENCE_ELEMENT
+#define BOOST_GEOMETRY_UTIL_SELECT_SEQUENCE_ELEMENT
+
+
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/int.hpp>
+#include <boost/mpl/at.hpp>
+#include <boost/mpl/size.hpp>
+
+#include <boost/type_traits/is_same.hpp>
+
+#include <boost/geometry/core/coordinate_type.hpp>
+#include <boost/geometry/util/select_most_precise.hpp>
+
+
+namespace boost { namespace geometry
+{
+
+namespace util
+{
+
+template <typename Curr, typename Next>
+struct pred_more_precise_coordinate_type
+{
+ typedef typename geometry::coordinate_type<Curr>::type curr_coord_t;
+ typedef typename geometry::coordinate_type<Next>::type next_coord_t;
+
+ typedef typename boost::mpl::if_c
+ <
+ boost::is_same
+ <
+ curr_coord_t,
+ typename select_most_precise
+ <
+ curr_coord_t,
+ next_coord_t
+ >::type
+ >::value,
+ Curr,
+ Next
+ >::type type;
+};
+
+template
+<
+ typename Seq,
+ template<typename, typename> class Pred = pred_more_precise_coordinate_type,
+ int I = 0,
+ int N = boost::mpl::size<Seq>::value
+>
+struct select_sequence_element
+{
+ typedef typename boost::mpl::at<Seq, boost::mpl::int_<I> >::type curr_t;
+ typedef typename select_sequence_element<Seq, Pred, I+1, N>::type next_t;
+
+ typedef typename Pred<curr_t, next_t>::type type;
+};
+
+template <typename Seq, template<typename, typename> class Pred, int N>
+struct select_sequence_element<Seq, Pred, N, N>
+{
+ typedef typename boost::mpl::at<Seq, boost::mpl::int_<N-1> >::type type;
+};
+
+} // namespace util
+
+}} // namespace boost::geometry
+
+
+#endif // BOOST_GEOMETRY_UTIL_SELECT_SEQUENCE_ELEMENT