detail/turns/compare_turns.hpp

0001 // Boost.Geometry (aka GGL, Generic Geometry Library)
0002
0003 // Copyright (c) 2014-2015, Oracle and/or its affiliates.
0004
0005 // Licensed under the Boost Software License version 1.0.
0006 // http://www.boost.org/users/license.html
0007
0008 // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
0009
0010
0011 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_COMPARE_TURNS_HPP
0012 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_COMPARE_TURNS_HPP
0013
0014 #include <cstddef>
0015 #include <functional>
0016
0017 #include <boost/geometry/util/math.hpp>
0018 #include <boost/geometry/algorithms/detail/overlay/turn_info.hpp>
0019
0020
0021 namespace boost { namespace geometry
0022 {
0023
0024 namespace detail { namespace turns
0025 {
0026
0027 // TURNS SORTING AND SEARCHING
0028
0029 // sort turns by G1 - source_index == 0 by:
0030 // seg_id -> fraction -> other_id -> operation
0031 template
0032 <
0033     typename IdLess = std::less<signed_size_type>,
0034     int N = 0, int U = 1, int I = 2, int B = 3, int C = 4, int O = 0,
0035     std::size_t OpId = 0
0036 >
0037 struct less_seg_fraction_other_op
0038 {
0039     BOOST_STATIC_ASSERT(OpId < 2);
0040     static const std::size_t other_op_id = (OpId + 1) % 2;
0041
0042     template <typename Op>
0043     static inline int order_op(Op const& op)
0044     {
0045         switch (op.operation)
0046         {
0047         case detail::overlay::operation_none : return N;
0048         case detail::overlay::operation_union : return U;
0049         case detail::overlay::operation_intersection : return I;
0050         case detail::overlay::operation_blocked : return B;
0051         case detail::overlay::operation_continue : return C;
0052         case detail::overlay::operation_opposite : return O;
0053         }
0054         return -1;
0055     }
0056
0057     template <typename Op>
0058     static inline bool use_operation(Op const& left, Op const& right)
0059     {
0060         return order_op(left) < order_op(right);
0061     }
0062
0063     template <typename Turn>
0064     static inline bool use_other_id(Turn const& left, Turn const& right)
0065     {
0066         segment_identifier const& left_other_seg_id = left.operations[other_op_id].seg_id;
0067         segment_identifier const& right_other_seg_id = right.operations[other_op_id].seg_id;
0068
0069         if ( left_other_seg_id.multi_index != right_other_seg_id.multi_index )
0070         {
0071             return left_other_seg_id.multi_index < right_other_seg_id.multi_index;
0072         }
0073         if ( left_other_seg_id.ring_index != right_other_seg_id.ring_index )
0074         {
0075             return left_other_seg_id.ring_index != right_other_seg_id.ring_index;
0076         }
0077         if ( left_other_seg_id.segment_index != right_other_seg_id.segment_index )
0078         {
0079             return IdLess()(left_other_seg_id.segment_index,
0080                             right_other_seg_id.segment_index);
0081         }
0082         return use_operation(left.operations[OpId], right.operations[OpId]);
0083     }
0084
0085     template <typename Turn>
0086     static inline bool use_fraction(Turn const& left, Turn const& right)
0087     {
0088         return
0089             geometry::math::equals(left.operations[OpId].fraction,
0090                                    right.operations[OpId].fraction)
0091             ?
0092             use_other_id(left, right)
0093             :
0094             (left.operations[OpId].fraction < right.operations[OpId].fraction)
0095             ;
0096     }
0097
0098     template <typename Turn>
0099     inline bool operator()(Turn const& left, Turn const& right) const
0100     {
0101         segment_identifier const& sl = left.operations[OpId].seg_id;
0102         segment_identifier const& sr = right.operations[OpId].seg_id;
0103
0104         return sl < sr || ( sl == sr && use_fraction(left, right) );
0105     }
0106 };
0107
0108
0109
0110
0111
0112 }} // namespace detail::turns
0113
0114 }} // namespace boost::geometry
0115
0116
0117 #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_COMPARE_TURNS_HPP