boost/geometry/algorithms/detail/turns/filter_continue_turns.hpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2
   3 // Copyright (c) 2014, Oracle and/or its affiliates.
   4
   5 // Licensed under the Boost Software License version 1.0.
   6 // http://www.boost.org/users/license.html
   7
   8 // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
   9
  10
  11 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_FILTER_CONTINUE_TURNS_HPP
  12 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_FILTER_CONTINUE_TURNS_HPP
  13
  14 #include <algorithm>
  15 #include <boost/geometry/algorithms/detail/overlay/turn_info.hpp>
  16
  17 namespace boost { namespace geometry
  18 {
  19
  20 namespace detail { namespace turns
  21 {
  22
  23
  24 template <typename Turns, bool Enable>
  25 struct filter_continue_turns
  26 {
  27     static inline void apply(Turns&) {}
  28 };
  29
  30
  31 template <typename Turns>
  32 class filter_continue_turns<Turns, true>
  33 {
  34 private:
  35     class IsContinueTurn
  36     {
  37     private:
  38         template <typename Operation>
  39         inline bool is_continue_or_opposite(Operation const& operation) const
  40         {
  41             return operation == detail::overlay::operation_continue
  42                 || operation == detail::overlay::operation_opposite;
  43         }
  44
  45     public:
  46         template <typename Turn>
  47         bool operator()(Turn const& turn) const
  48         {
  49             if ( turn.method != detail::overlay::method_collinear
  50                  && turn.method != detail::overlay::method_equal )
  51             {
  52                 return false;
  53             }
  54
  55             return is_continue_or_opposite(turn.operations[0].operation)
  56                 && is_continue_or_opposite(turn.operations[1].operation);
  57         }
  58     };
  59
  60
  61 public:
  62     static inline void apply(Turns& turns)
  63     {
  64         turns.erase( std::remove_if(turns.begin(), turns.end(),
  65                                     IsContinueTurn()),
  66                      turns.end()
  67                      );
  68     }
  69 };
  70
  71
  72 }} // namespace detail::turns
  73
  74 }} // namespect boost::geometry
  75
  76
  77
  78 #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_FILTER_CONTINUE_TURNS_HPP