Top_faces.h

 /*    This file is part of the Gudhi Library. The Gudhi library
  *    (Geometric Understanding in Higher Dimensions) is a generic C++
  *    library for computational topology.
  *
  *    Author(s):       David Salinas
  *
  *    Copyright (C) 2014  INRIA Sophia Antipolis-Mediterranee (France)
  *
  *    This program is free software: you can redistribute it and/or modify
  *    it under the terms of the GNU General Public License as published by
  *    the Free Software Foundation, either version 3 of the License, or
  *    (at your option) any later version.
  *
  *    This program is distributed in the hope that it will be useful,
  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *    GNU General Public License for more details.
  *
  *    You should have received a copy of the GNU General Public License
  *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
#ifndef TOP_FACES_H_
#define TOP_FACES_H_

#include <list>
#include <vector>
#include <set>

template<typename SimplexHandle>
std::list<SimplexHandle> subfaces(SimplexHandle top_face){
    std::list<SimplexHandle> res;
    if(top_face.dimension()==-1) return res;
    if(top_face.dimension()==0) {
        res.push_back(top_face);
        return res;
    }
    else{
        auto first_vertex = top_face.first_vertex();
        top_face.remove_vertex(first_vertex);
        res = subfaces(top_face);
        std::list<SimplexHandle> copy = res;
        for(auto& simplex : copy){
            simplex.add_vertex(first_vertex);
        }
        res.push_back(SimplexHandle(first_vertex));
        res.splice(res.end(),copy);
        return res;
    }
}

template<typename SimplexHandle>
void register_faces(
        std::vector< std::set<SimplexHandle> >& simplices_per_dimension,
        const SimplexHandle& top_face){
    std::list<SimplexHandle> subfaces_list = subfaces(top_face);
    for(auto& simplex : subfaces_list ){
        simplices_per_dimension[simplex.dimension()].insert(simplex);
    }
}




#endif /* TOP_FACES_H_ */