117 lines
3.1 KiB
C++
117 lines
3.1 KiB
C++
// Boost.Geometry
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// Copyright (c) 2017 Adam Wulkiewicz, Lodz, Poland.
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// Use, modification and distribution is subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_GEOMETRY_STRATEGIES_AREA_RESULT_HPP
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#define BOOST_GEOMETRY_STRATEGIES_AREA_RESULT_HPP
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#include <boost/geometry/core/coordinate_type.hpp>
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#include <boost/geometry/core/cs.hpp>
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#include <boost/geometry/strategies/area.hpp>
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#include <boost/geometry/strategies/default_strategy.hpp>
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#include <boost/geometry/util/select_most_precise.hpp>
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#include <boost/geometry/util/select_sequence_element.hpp>
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#include <boost/mpl/if.hpp>
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#include <boost/type_traits/is_same.hpp>
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#include <boost/variant/variant_fwd.hpp>
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namespace boost { namespace geometry
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{
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/*!
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\brief Meta-function defining return type of area function
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\ingroup area
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\note The return-type is defined by Geometry and Strategy
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*/
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template
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<
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typename Geometry,
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typename Strategy = default_strategy
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>
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struct area_result
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: Strategy::template result_type<Geometry>
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{};
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template <BOOST_VARIANT_ENUM_PARAMS(typename T), typename Strategy>
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struct area_result<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Strategy>
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: geometry::area_result
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<
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typename geometry::util::select_sequence_element
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<
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typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::types
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>::type,
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Strategy
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>
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{};
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template <typename Geometry>
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struct area_result<Geometry, default_strategy>
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: geometry::area_result
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<
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Geometry,
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typename geometry::strategy::area::services::default_strategy
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<
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typename cs_tag<Geometry>::type
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>::type
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>
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{};
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#ifndef DOXYGEN_NO_DETAIL
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namespace detail { namespace area
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{
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template <typename Curr, typename Next>
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struct pred_more_precise_default_area_result
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{
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typedef typename geometry::area_result<Curr, default_strategy>::type curr_result_t;
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typedef typename geometry::area_result<Next, default_strategy>::type next_result_t;
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typedef typename boost::mpl::if_c
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<
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boost::is_same
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<
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curr_result_t,
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typename geometry::select_most_precise
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<
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curr_result_t,
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next_result_t
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>::type
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>::value,
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Curr,
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Next
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>::type type;
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};
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}} // namespace detail::area
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#endif //DOXYGEN_NO_DETAIL
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template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
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struct area_result<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, default_strategy>
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: geometry::area_result
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<
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typename geometry::util::select_sequence_element
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<
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typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::types,
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geometry::detail::area::pred_more_precise_default_area_result
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>::type,
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default_strategy
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>
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{};
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_STRATEGIES_AREA_RESULT_HPP
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