Add an adapter so that one can sort arbitary things and access the point via a property map

Convex_hull_2/examples/Convex_hull_2/convex_hull_indices.cpp

@@ -0,0 +1,39 @@
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/convex_hull_2.h>
+#include <CGAL/Convex_hull_traits_adapter_2.h>
+#include <CGAL/property_map.h>
+#include <vector>
+
+typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
+typedef K::Point_2 Point_2;
+typedef CGAL::Convex_hull_traits_adapter_2<K,
+          CGAL::Pointer_property_map<Point_2>::type > Convex_hull_traits_2;
+
+int main()
+{
+  std::vector<Point_2> points;
+
+  points.push_back(Point_2(10,0));
+  points.push_back(Point_2(0,10));
+  points.push_back(Point_2(1,1));
+  points.push_back(Point_2(3,4));
+  points.push_back(Point_2(0,0));
+  points.push_back(Point_2(10,10));
+  points.push_back(Point_2(2,6));
+  
+  std::vector<std::size_t> indices(points.size()), out;
+
+  for(int i=0; i < indices.size();i++){
+    indices[i] = i;
+  }
+
+  
+  CGAL::convex_hull_2(indices.begin(), indices.end(), std::back_inserter(out),
+                      Convex_hull_traits_2(CGAL::make_property_map(points)));
+
+  for( std::size_t i : out){
+    std::cout << "points[" << i << "] = " << points[i] << std::endl;
+  }
+
+  return 0;
+}

Convex_hull_2/include/CGAL/Convex_hull_traits_adapter_2.h

@@ -0,0 +1,128 @@
+// Copyright (c) 2019  GeometryFactory (France).
+// All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public License as
+// published by the Free Software Foundation; either version 3 of the License,
+// or (at your option) any later version.
+//
+// Licensees holding a valid commercial license may use this file in
+// accordance with the commercial license agreement provided with the software.
+//
+// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+//
+// $URL$
+// $Id$
+// SPDX-License-Identifier: LGPL-3.0+
+//
+// Author(s)     : Sebastien Loriot
+
+
+#ifndef CGAL_CONVEX_HULL_TRAITS_ADAPTER_2_H
+#define CGAL_CONVEX_HULL_TRAITS_ADAPTER_2_H
+
+#include <CGAL/disable_warnings.h>
+
+#include <boost/call_traits.hpp>
+
+#include <CGAL/property_map.h>
+
+
+namespace CGAL{
+  
+using ::get;
+
+template<class Base_traits,class PointPropertyMap>
+class Convex_hull_traits_adapter_2:public Base_traits{
+  PointPropertyMap ppmap_;
+public:
+  Convex_hull_traits_adapter_2(Base_traits base=Base_traits()):Base_traits(base){}
+
+  Convex_hull_traits_adapter_2(const PointPropertyMap& ppmap,Base_traits base=Base_traits())
+  :Base_traits(base),ppmap_(ppmap){}
+
+  typedef Base_traits Gt;
+  typedef typename boost::property_traits<PointPropertyMap>::key_type Point_2;
+  typedef typename boost::call_traits<Point_2>::param_type Arg_type;
+
+  struct Less_xy_2 : public Base_traits::Less_xy_2{
+    Less_xy_2(const PointPropertyMap& ppmap,const typename Base_traits::Less_xy_2& base):
+      Base_traits::Less_xy_2(base),ppmap_(ppmap){}
+    const PointPropertyMap& ppmap_;
+    bool operator()(Arg_type p,Arg_type q) const {
+      return static_cast<const typename Base_traits::Less_xy_2*>(this)->operator()(get(ppmap_,p),get(ppmap_,q));
+    }
+  };
+  
+  struct Equal_2 : public Base_traits::Equal_2{
+    Equal_2(const PointPropertyMap& ppmap,const typename Base_traits::Equal_2& base):
+      Base_traits::Equal_2(base),ppmap_(ppmap){}
+    const PointPropertyMap& ppmap_;
+    bool operator()(Arg_type p,Arg_type q) const {
+      return static_cast<const typename Base_traits::Equal_2*>(this)->operator()(get(ppmap_,p),get(ppmap_,q));
+    }
+  };
+  
+  struct Less_yx_2 : public Base_traits::Less_yx_2{
+    Less_yx_2(const PointPropertyMap& ppmap,const typename Base_traits::Less_yx_2& base):
+      Base_traits::Less_yx_2(base),ppmap_(ppmap){}
+    const PointPropertyMap& ppmap_;
+    bool operator()(Arg_type p,Arg_type q) const {
+      return static_cast<const typename Base_traits::Less_yx_2*>(this)->operator()(get(ppmap_,p),get(ppmap_,q));
+    }
+  };
+
+  struct Left_turn_2 : public Base_traits::Left_turn_2{
+    Left_turn_2(const PointPropertyMap& ppmap,const typename Base_traits::Left_turn_2& base):
+      Base_traits::Left_turn_2(base),ppmap_(ppmap){}
+    const PointPropertyMap& ppmap_;
+    bool operator()(Arg_type p,Arg_type q, Arg_type r) const {
+      return static_cast<const typename Base_traits::Left_turn_2*>(this)->operator()(get(ppmap_,p),get(ppmap_,q),get(ppmap_,r));
+    }
+  };
+  
+  struct Orientation_2 : public Base_traits::Orientation_2{
+    Orientation_2(const PointPropertyMap& ppmap,const typename Base_traits::Orientation_2& base):
+      Base_traits::Orientation_2(base),ppmap_(ppmap){}
+    const PointPropertyMap& ppmap_;
+    CGAL::Orientation operator()(Arg_type p,Arg_type q, Arg_type r) const {
+      return static_cast<const typename Base_traits::Orientation_2*>(this)->operator()(get(ppmap_,p),get(ppmap_,q),get(ppmap_,r));
+    }
+  };
+  
+  struct Less_rotate_ccw_2 : public Base_traits::Less_rotate_ccw_2{
+    Less_rotate_ccw_2(const PointPropertyMap& ppmap,const typename Base_traits::Less_rotate_ccw_2& base):
+      Base_traits::Less_rotate_ccw_2(base),ppmap_(ppmap){}
+    const PointPropertyMap& ppmap_;
+    bool operator()(Arg_type p,Arg_type q, Arg_type r) const {
+      return static_cast<const typename Base_traits::Less_rotate_ccw_2*>(this)->operator()(get(ppmap_,p),get(ppmap_,q),get(ppmap_,r));
+    }
+  };
+  
+  struct Less_signed_distance_to_line_2 : public Base_traits::Less_signed_distance_to_line_2{
+    Less_signed_distance_to_line_2(const PointPropertyMap& ppmap,const typename Base_traits::Less_signed_distance_to_line_2& base):
+      Base_traits::Less_signed_distance_to_line_2(base),ppmap_(ppmap){}
+    const PointPropertyMap& ppmap_;
+    bool operator()(Arg_type p,Arg_type q, Arg_type r, Arg_type s) const {
+      return static_cast<const typename Base_traits::Less_signed_distance_to_line_2 _2*>(this)->operator()(get(ppmap_,p),get(ppmap_,q),get(ppmap_,r),get(ppmap_,s));
+    }
+  };
+  
+  Equal_2 equal_2_object () const {return Equal_2(ppmap_,static_cast<const Gt*>(this)->equal_2_object() );}
+  Left_turn_2 left_turn_2_object () const {return Left_turn_2(ppmap_,static_cast<const Gt*>(this)->left_turn_2_object() );}
+  Orientation_2 orientation_2_object () const {return Orientation_2(ppmap_,static_cast<const Gt*>(this)->orientation_2_object() );}
+  Less_rotate_ccw_2   less_rotate_ccw_2_object () const {return Less_rotate_ccw_2(ppmap_,static_cast<const Gt*>(this)->less_rotate_ccw_2_object() );}
+  Less_signed_distance_to_line_2   less_signed_distance_to_line_2_object () const {return Less_signed_distance_to_line_2(ppmap_,static_cast<const Gt*>(this)->less_signed_distance_to_line_2_object() );}
+  Less_xy_2 less_xy_2_object () const {return Less_xy_2(ppmap_,static_cast<const Gt*>(this)->less_xy_2_object() );}
+  Less_yx_2 less_yx_2_object () const {return Less_yx_2(ppmap_,static_cast<const Gt*>(this)->less_yx_2_object() );}
+  
+  const PointPropertyMap& point_property_map() const {return ppmap_;}
+
+};
+
+} //namespace CGAL
+
+#include <CGAL/enable_warnings.h>
+
+#endif //CGAL_CONVEX_HULL_TRAITS_ADAPTER_2_H