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// TensorIndexOrder class definition file -*- C++ -*-
/* Copyright 2008 Mike Williams (mwill@jlab.org)
*
* This file is part of qft++.
*
* qft++ 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.
*
* qft++ 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 qft++. If not, see <http://www.gnu.org/licenses/>.
*/
// Author: Mike Williams
// Author: Matt Shepherd
#ifndef _TensorIndexOrder_h
#define _TensorIndexOrder_h
//_____________________________________________________________________________
#include <cassert>
#include <iostream>
using namespace std;
//_____________________________________________________________________________
/** @file TensorIndexOrder.h
* @brief TensorIndexOrder class definition file.
*/
//_____________________________________________________________________________
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#include <iostream>
class TensorIndexOrder {
private:
unsigned int _rank; ///< Tensor rank this deals with
int _index; ///< Index to Tensor vector of elements
public:
// create/copy/destroy
TensorIndexOrder() : _rank(0),_index(0){/** Default Constructor */}
/// Constructor (connect with rank @a rank tensor)
TensorIndexOrder(unsigned int __rank) : _index(0){
assert( __rank < 8 );
_rank = __rank;
}
virtual ~TensorIndexOrder() {/** Destructor */}
// operators:
/// Returns the tensor index value for @a level
inline int operator[](unsigned int __level) const {
return ((_index >> (__level << 2 ) ) & 0xF);
}
// permutation functions:
/** Obtains the next valid permuation of the current stored index.
*
* This function is NOT to be used when the TensorIndexOrder object is being
* used to get elements from a tensor (the normal use).
* This function is meant to be used on a TensorIndexOrder object declared for
* the sole purpose of performing permutations on the indicies of a Tensor.
*/
TensorIndexOrder& Permute();
/** Checks to see if the current index permutation is valid.
*
* Valid means all indicies are between 0 and Rank-1. The function doesn't
* actually check if any 2 indicies are equal, this is done in
* TensorIndexOrder::Permutation.
*/
bool PermIsValid() const {
for(int i = 0; i < this->Size(); i++){
if(((*this)[i] < 0)||((*this)[i] >= this->Size())) return false;
}
return true;
}
// functions:
/// Returns the number of entries (coresponds to tensor rank)
inline int Size() const {return _rank;}
/// Set the index value
inline void SetIndex(unsigned int __i,unsigned int __value){
// assert(__value < 16 && __i < _rank );
_index = (_index & ~(0xF << (__i << 2))) + (__value << (__i << 2));
}
};
//_____________________________________________________________________________
#endif /* _TensorIndexOrder_H */