Chris@16: // Boost.Geometry (aka GGL, Generic Geometry Library)
Chris@16: 
Chris@16: // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
Chris@16: // Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
Chris@16: // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
Chris@16: 
Chris@16: // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
Chris@16: // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
Chris@16: 
Chris@16: // Use, modification and distribution is subject to the Boost Software License,
Chris@16: // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: 
Chris@16: #ifndef BOOST_GEOMETRY_STRATEGIES_COMPARE_HPP
Chris@16: #define BOOST_GEOMETRY_STRATEGIES_COMPARE_HPP
Chris@16: 
Chris@16: #include <cstddef>
Chris@16: #include <functional>
Chris@16: 
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: 
Chris@16: #include <boost/geometry/core/cs.hpp>
Chris@16: #include <boost/geometry/core/coordinate_type.hpp>
Chris@16: 
Chris@16: #include <boost/geometry/strategies/tags.hpp>
Chris@16: 
Chris@16: 
Chris@16: namespace boost { namespace geometry
Chris@16: {
Chris@16: 
Chris@16: 
Chris@16: /*!
Chris@16:     \brief Traits class binding a comparing strategy to a coordinate system
Chris@16:     \ingroup util
Chris@16:     \tparam Tag tag of coordinate system of point-type
Chris@16:     \tparam Direction direction to compare on: 1 for less (-> ascending order)
Chris@16:         and -1 for greater (-> descending order)
Chris@16:     \tparam Point point-type
Chris@16:     \tparam CoordinateSystem coordinate sytem of point
Chris@16:     \tparam Dimension: the dimension to compare on
Chris@16: */
Chris@16: template
Chris@16: <
Chris@16:     typename Tag,
Chris@16:     int Direction,
Chris@16:     typename Point,
Chris@16:     typename CoordinateSystem,
Chris@16:     std::size_t Dimension
Chris@16: >
Chris@16: struct strategy_compare
Chris@16: {
Chris@16:     typedef strategy::not_implemented type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: #ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
Chris@16: 
Chris@16: // For compare we add defaults specializations,
Chris@16: // because they defaultly redirect to std::less / greater / equal_to
Chris@16: template
Chris@16: <
Chris@16:     typename Tag,
Chris@16:     typename Point,
Chris@16:     typename CoordinateSystem,
Chris@16:     std::size_t Dimension
Chris@16: >
Chris@16: struct strategy_compare<Tag, 1, Point, CoordinateSystem, Dimension>
Chris@16: {
Chris@16:     typedef std::less<typename coordinate_type<Point>::type> type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: template
Chris@16: <
Chris@16:     typename Tag,
Chris@16:     typename Point,
Chris@16:     typename CoordinateSystem,
Chris@16:     std::size_t Dimension
Chris@16: >
Chris@16: struct strategy_compare<Tag, -1, Point, CoordinateSystem, Dimension>
Chris@16: {
Chris@16:     typedef std::greater<typename coordinate_type<Point>::type> type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: template
Chris@16: <
Chris@16:     typename Tag,
Chris@16:     typename Point,
Chris@16:     typename CoordinateSystem,
Chris@16:     std::size_t Dimension
Chris@16: >
Chris@16: struct strategy_compare<Tag, 0, Point, CoordinateSystem, Dimension>
Chris@16: {
Chris@16:     typedef std::equal_to<typename coordinate_type<Point>::type> type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: 
Chris@16: namespace strategy { namespace compare
Chris@16: {
Chris@16: 
Chris@16: 
Chris@16: /*!
Chris@16:     \brief Default strategy, indicates the default strategy for comparisons
Chris@16:     \details The default strategy for comparisons defer in most cases
Chris@16:         to std::less (for ascending) and std::greater (for descending).
Chris@16:         However, if a spherical coordinate system is used, and comparison
Chris@16:         is done on longitude, it will take another strategy handling circular
Chris@16: */
Chris@16: struct default_strategy {};
Chris@16: 
Chris@16: 
Chris@16: #ifndef DOXYGEN_NO_DETAIL
Chris@16: namespace detail
Chris@16: {
Chris@16: 
Chris@16: template <typename Type>
Chris@16: struct is_default : boost::false_type
Chris@16: {};
Chris@16: 
Chris@16: 
Chris@16: template <>
Chris@16: struct is_default<default_strategy> : boost::true_type
Chris@16: {};
Chris@16: 
Chris@16: 
Chris@16: /*!
Chris@16:     \brief Meta-function to select strategy
Chris@16:     \details If "default_strategy" is specified, it will take the
Chris@16:         traits-registered class for the specified coordinate system.
Chris@16:         If another strategy is explicitly specified, it takes that one.
Chris@16: */
Chris@16: template
Chris@16: <
Chris@16:     typename Strategy,
Chris@16:     int Direction,
Chris@16:     typename Point,
Chris@16:     std::size_t Dimension
Chris@16: >
Chris@16: struct select_strategy
Chris@16: {
Chris@16:     typedef typename
Chris@16:         boost::mpl::if_
Chris@16:         <
Chris@16:             is_default<Strategy>,
Chris@16:             typename strategy_compare
Chris@16:             <
Chris@16:                 typename cs_tag<Point>::type,
Chris@16:                 Direction,
Chris@16:                 Point,
Chris@16:                 typename coordinate_system<Point>::type,
Chris@16:                 Dimension
Chris@16:             >::type,
Chris@16:             Strategy
Chris@16:         >::type type;
Chris@16: };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: #endif // DOXYGEN_NO_DETAIL
Chris@16: 
Chris@16: 
Chris@16: }} // namespace strategy::compare
Chris@16: 
Chris@16: 
Chris@16: }} // namespace boost::geometry
Chris@16: 
Chris@16: 
Chris@16: #endif // BOOST_GEOMETRY_STRATEGIES_COMPARE_HPP