diff options
Diffstat (limited to 'boost/geometry/algorithms/detail/visit.hpp')
| -rw-r--r-- | boost/geometry/algorithms/detail/visit.hpp | 70 |
1 files changed, 51 insertions, 19 deletions
diff --git a/boost/geometry/algorithms/detail/visit.hpp b/boost/geometry/algorithms/detail/visit.hpp index 60958f4b40..7cbf9e2318 100644 --- a/boost/geometry/algorithms/detail/visit.hpp +++ b/boost/geometry/algorithms/detail/visit.hpp @@ -181,20 +181,16 @@ struct visit_breadth_first<Geometry, dynamic_geometry_tag> } }; -// NOTE: This specialization works partially like std::visit and partially like -// std::ranges::for_each. If the argument is rvalue reference then the elements -// are passed into the function as rvalue references as well. This is consistent -// with std::visit but different than std::ranges::for_each. It's done this way -// because visit_breadth_first is also specialized for static and dynamic geometries -// which and references for them has to be propagated like that. If this is not -// desireable then the support for other kinds of geometries should be dropped and -// this algorithm should work only for geometry collection. -// This is not a problem right now because only non-rvalue references are passed -// but in the future there might be some issues. Consider e.g. passing a temporary -// mutable proxy range as geometry collection. In such case the elements would be -// passed as rvalue references which would be incorrect. -template <typename Geometry> -struct visit_breadth_first<Geometry, geometry_collection_tag> +} // namespace dispatch +#endif // DOXYGEN_NO_DISPATCH + + +#ifndef DOXYGEN_NO_DETAIL +namespace detail +{ + +template <bool PassIterator = false> +struct visit_breadth_first_impl { template <typename F, typename Geom> static bool apply(F function, Geom && geom) @@ -217,7 +213,8 @@ struct visit_breadth_first<Geometry, geometry_collection_tag> bool result = true; traits::iter_visit<util::remove_cref_t<Geom>>::apply([&](auto && g) { - result = visit_or_enqueue(function, std::forward<decltype(g)>(g), queue, it); + result = visit_breadth_first_impl::visit_or_enqueue<PassIterator>( + function, std::forward<decltype(g)>(g), queue, it); }, it); if (! result) @@ -235,7 +232,7 @@ struct visit_breadth_first<Geometry, geometry_collection_tag> // so this call can be avoided. traits::iter_visit<util::remove_cref_t<Geom>>::apply([&](auto && g) { - set_iterators(std::forward<decltype(g)>(g), it, end); + visit_breadth_first_impl::set_iterators(std::forward<decltype(g)>(g), it, end); }, queue.front()); queue.pop_front(); } @@ -246,7 +243,7 @@ struct visit_breadth_first<Geometry, geometry_collection_tag> private: template < - typename F, typename Geom, typename Iterator, + bool PassIter, typename F, typename Geom, typename Iterator, std::enable_if_t<util::is_geometry_collection<Geom>::value, int> = 0 > static bool visit_or_enqueue(F &, Geom &&, std::deque<Iterator> & queue, Iterator iter) @@ -256,13 +253,22 @@ private: } template < - typename F, typename Geom, typename Iterator, - std::enable_if_t<! util::is_geometry_collection<Geom>::value, int> = 0 + bool PassIter, typename F, typename Geom, typename Iterator, + std::enable_if_t<! util::is_geometry_collection<Geom>::value && ! PassIter, int> = 0 > static bool visit_or_enqueue(F & f, Geom && g, std::deque<Iterator> & , Iterator) { return f(std::forward<Geom>(g)); } + template + < + bool PassIter, typename F, typename Geom, typename Iterator, + std::enable_if_t<! util::is_geometry_collection<Geom>::value && PassIter, int> = 0 + > + static bool visit_or_enqueue(F & f, Geom && g, std::deque<Iterator> & , Iterator iter) + { + return f(std::forward<Geom>(g), iter); + } template < @@ -283,6 +289,32 @@ private: {} }; +} // namespace detail +#endif // DOXYGEN_NO_DETAIL + + +#ifndef DOXYGEN_NO_DISPATCH +namespace dispatch +{ + +// NOTE: This specialization works partially like std::visit and partially like +// std::ranges::for_each. If the argument is rvalue reference then the elements +// are passed into the function as rvalue references as well. This is consistent +// with std::visit but different than std::ranges::for_each. It's done this way +// because visit_breadth_first is also specialized for static and dynamic geometries +// and references for them has to be propagated like that. If this is not +// desireable then the support for other kinds of geometries should be dropped and +// this algorithm should work only for geometry collection. Or forwarding of rvalue +// references should simply be dropped entirely. +// This is not a problem right now because only non-rvalue references are passed +// but in the future there might be some issues. Consider e.g. passing a temporary +// mutable proxy range as geometry collection. In such case the elements would be +// passed as rvalue references which would be incorrect. +template <typename Geometry> +struct visit_breadth_first<Geometry, geometry_collection_tag> + : detail::visit_breadth_first_impl<> +{}; + } // namespace dispatch #endif // DOXYGEN_NO_DISPATCH |