/* Copyright (c) 1997-2010
   Ewgenij Gawrilow, Michael Joswig (Technische Universitaet Darmstadt, Germany)
   http://www.polymake.de

   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 2, or (at your option) any
   later version: http://www.gnu.org/licenses/gpl.txt.

   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.
--------------------------------------------------------------------------------
   $Project: polymake $$Id: link.cc 9831 2010-10-30 18:47:05Z gawrilow $
*/

#include <polymake.h>
#include <complex_tools.h>

namespace polymake { namespace topaz {
  
perl::Object link_complex(perl::Object p_in, const Set<int>& F, perl::OptionSet options)
{
   const Array< Set<int> > C = p_in.give("FACETS");
   const int n_vert=p_in.give("N_VERTICES");

   if (F.front()<0 || F.back()>n_vert-1)
      throw std::runtime_error("t_link: Specified vertex indices out of range");
   
   std::list< Set<int> > Link;
   copy(entire(link(C,F)), std::back_inserter(Link));
   
   if (Link.empty()) {
      std::ostringstream e;
      wrap(e) << "t_link: " << F << " does not specify a face.";
      throw std::runtime_error(e.str());
   }
   
   const Set<int> V = accumulate(Link, operations::add());
   adj_numbering(Link,V);
   
   perl::Object p_out("SimplicialComplex");
   p_out.set_description()<<"Link of "<<F<<" in " << p_in.name() << "."<<endl;
   p_out.take("FACETS") << as_array(Link);
   
   if (!options["no_labels"]) {
      const Array<std::string> L=p_in.give("VERTEX_LABELS");
      const Array<std::string> new_L(V.size(), select(L,V).begin());
      p_out.take("VERTEX_LABELS") << new_L;
   }
   return p_out;
}

   UserFunction4perl("# @category  Producing a new simplicial complex from others"
		     "#  Produce the __link__ of a //face// of the //complex//"
		     "# @param SimplicialComplex complex"
		     "# @param Set<int> face"
		     "# @option Bool no_labels  tells the client not to create any labels.",
		     &link_complex,"link_complex(SimplicialComplex, $ { no_labels => 0 })");


} }



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