Added boost header

test/external/boost/geometry/strategies/cartesian/area_surveyor.hpp

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+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands.
+// Copyright (c) 2008-2011 Bruno Lalande, Paris, France.
+// Copyright (c) 2009-2011 Mateusz Loskot, London, UK.
+
+// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
+// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
+
+// Use, modification and distribution is subject to the Boost Software License,
+// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_AREA_SURVEYOR_HPP
+#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_AREA_SURVEYOR_HPP
+
+
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits.hpp>
+
+#include <boost/geometry/geometries/point_xy.hpp>
+
+
+namespace boost { namespace geometry
+{
+
+namespace strategy { namespace area
+{
+
+/*!
+\brief Area calculation for cartesian points
+\ingroup strategies
+\details Calculates area using the Surveyor's formula, a well-known
+    triangulation algorithm
+\tparam PointOfSegment \tparam_segment_point
+\tparam CalculationType \tparam_calculation
+
+\qbk{
+[heading See also]
+[link geometry.reference.algorithms.area.area_2_with_strategy area (with strategy)]
+}
+
+*/
+template
+<
+    typename PointOfSegment,
+    typename CalculationType = void
+>
+class surveyor
+{
+public :
+    // If user specified a calculation type, use that type,
+    //   whatever it is and whatever the point-type is.
+    // Else, use the pointtype, but at least double
+    typedef typename
+        boost::mpl::if_c
+        <
+            boost::is_void<CalculationType>::type::value,
+            typename select_most_precise
+            <
+                typename coordinate_type<PointOfSegment>::type,
+                double
+            >::type,
+            CalculationType
+        >::type return_type;
+
+
+private :
+
+    class summation
+    {
+        friend class surveyor;
+
+        return_type sum;
+    public :
+
+        inline summation() : sum(return_type())
+        {
+            // Strategy supports only 2D areas
+            assert_dimension<PointOfSegment, 2>();
+        }
+        inline return_type area() const
+        {
+            return_type result = sum;
+            result /= 2;
+            return result;
+        }
+    };
+
+public :
+    typedef summation state_type;
+    typedef PointOfSegment segment_point_type;
+
+    static inline void apply(PointOfSegment const& p1,
+                PointOfSegment const& p2,
+                summation& state)
+    {
+        // SUM += x2 * y1 - x1 * y2;
+        state.sum += get<0>(p2) * get<1>(p1) - get<0>(p1) * get<1>(p2);
+    }
+
+    static inline return_type result(summation const& state)
+    {
+        return state.area();
+    }
+
+};
+
+#ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
+
+namespace services
+{
+    template <typename Point>
+    struct default_strategy<cartesian_tag, Point>
+    {
+        typedef strategy::area::surveyor<Point> type;
+    };
+
+} // namespace services
+
+#endif // DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
+
+
+}} // namespace strategy::area
+
+
+
+}} // namespace boost::geometry
+
+
+#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_AREA_SURVEYOR_HPP