Exchange.hh

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/*
 
Cadabra: a field-theory motivated computer algebra system.
Copyright (C) 2001-2014  Kasper Peeters <kasper.peeters@phi-sci.com>
 
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/>.
 
*/

 
#pragma once
 
#include <vector>
 
#include "Storage.hh"
 
#include "properties/GammaMatrix.hh"
#include "properties/Spinor.hh"
#include "properties/Traceless.hh"
#include "properties/GammaTraceless.hh"
#include "properties/SelfCommutingBehaviour.hh"
#include "properties/CommutingBehaviour.hh"
 
namespace cadabra {
 
    class exchange {
        public:
            struct identical_tensors_t {
                unsigned int                           number_of_indices;
                std::vector<Ex::sibling_iterator> tensors;
                std::vector<int>                       seq_numbers_of_first_indices;
 
                const SelfCommutingBehaviour *comm;
                const Spinor                 *spino;
                const TableauBase            *tab;
                const Traceless              *traceless;
                const GammaTraceless         *gammatraceless;
                int                           extra_sign;
                };
 
            // Obtain index exchange symmetries under tensor permutation. Returns 'false' if
            // an identically zero expression is encountered.
            static int          collect_identical_tensors(const Properties& pr, Ex& tr, Ex::iterator it,
                  std::vector<identical_tensors_t>& idts);
            static unsigned int possible_singlets(Ex&, Ex::iterator);
            static bool         get_node_gs(const Properties&, Ex&, Ex::iterator, std::vector<std::vector<int> >& );
 
            //      static void get_index_gs(Ex::iterator, std::vector<std::vector<int> >& );
 
            struct tensor_type_t {
                nset_t::iterator name;
                unsigned int     number_of_indices;
                };
 
        };
 
    bool operator<(const exchange::tensor_type_t& one, const exchange::tensor_type_t& two);
 
 
    }