ceph/src/boost/boost/geometry/core/visit.hpp

   1 // Boost.Geometry
   2
   3 // Copyright (c) 2021, Oracle and/or its affiliates.
   4
   5 // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
   6
   7 // Licensed under the Boost Software License version 1.0.
   8 // http://www.boost.org/users/license.html
   9
  10 #ifndef BOOST_GEOMETRY_CORE_VISIT_HPP
  11 #define BOOST_GEOMETRY_CORE_VISIT_HPP
  12
  13 #include <utility>
  14
  15 #include <boost/range/value_type.hpp>
  16
  17 #include <boost/geometry/core/static_assert.hpp>
  18 #include <boost/geometry/util/type_traits_std.hpp>
  19
  20
  21 namespace boost { namespace geometry { namespace traits
  22 {
  23
  24 // TODO: Alternatives:
  25 // - free function
  26 //    template <typename Visitor, typename ...Variants>
  27 //    auto visit(Visitor &&, Variants && ...) {}
  28 //
  29 // - additional Enable tparam
  30 //    template <bool Enable, typename ...DynamicGeometries>
  31 //    struct visit {};
  32
  33 template <typename ...DynamicGeometries>
  34 struct visit
  35 {
  36     BOOST_GEOMETRY_STATIC_ASSERT_FALSE(
  37         "Not implemented for these DynamicGeometries types.",
  38         DynamicGeometries...);
  39 };
  40
  41 // By default call 1-parameter visit for each geometry
  42 template <typename DynamicGeometry1, typename DynamicGeometry2>
  43 struct visit<DynamicGeometry1, DynamicGeometry2>
  44 {
  45     template <typename Function, typename Variant1, typename Variant2>
  46     static void apply(Function && function, Variant1 && variant1, Variant2 && variant2)
  47     {
  48         visit<util::remove_cref_t<Variant1>>::apply([&](auto && g1)
  49         {
  50             using ref1_t = decltype(g1);
  51             visit<util::remove_cref_t<Variant2>>::apply([&](auto && g2)
  52             {
  53                 function(std::forward<ref1_t>(g1),
  54                          std::forward<decltype(g2)>(g2));
  55             }, std::forward<Variant2>(variant2));
  56         }, std::forward<Variant1>(variant1));
  57     }
  58 };
  59
  60 // By default treat GeometryCollection as a range of DynamicGeometries
  61 template <typename GeometryCollection>
  62 struct iter_visit
  63 {
  64     template <typename Function, typename Iterator>
  65     static void apply(Function && function, Iterator iterator)
  66     {
  67         using value_t = typename boost::range_value<GeometryCollection>::type;
  68         using reference_t = typename std::iterator_traits<Iterator>::reference;
  69         visit<value_t>::apply(std::forward<Function>(function),
  70                               std::forward<reference_t>(*iterator));
  71     }
  72 };
  73
  74 }}} // namespace boost::geometry::traits
  75
  76 #endif // BOOST_GEOMETRY_CORE_VISIT_HPP