dft_tools/triqs/utility/dressed_iterator.hpp

/*******************************************************************************
 *
 * TRIQS: a Toolbox for Research in Interacting Quantum Systems
 *
 * Copyright (C) 2013 by O. Parcollet
 *
 * TRIQS 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.
 *
 * TRIQS 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
 * TRIQS. If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/
#ifndef TRIQS_UTILITY_ITERATOR_DRESSING_H
#define TRIQS_UTILITY_ITERATOR_DRESSING_H
#include "./first_include.hpp"
#include<iterator>
#include <boost/iterator/iterator_facade.hpp>
#include "./macros.hpp"

namespace triqs { namespace utility {

 /**
  * Usage :
  *
  * Suppose we have :
  *  - an iterator of type IteratorType
  *  - a little struct that views the data pointed to by it using a set of references,
  * like e.g. :
  *
  * struct _dress  {double const & tau; int & a;  _dress ( it_type const & it); };
  *
  * then dressed_iterator<IteratorType, _dress> is :
  *
  *  - a bidirectional or forward iterator (depending whether IteratorType is), STL compliant (generated by boost::iterator_facade).
  *  - that is dereferenced to a _dress.
  *
  *  Example : See doc or test/utility/iterator_dressing.cpp ...
  *
  *
  * Variant : one can keep in the iterator a pointer to anything (typically the parent container)
  * which may be useful in some cases (e.g. writing cyclic iterators)
  * See iterator_dressing3 for an example
  */
 template< typename IteratorType, typename Dressing, typename DressingAuxiliaryArgumentPtrType = void> struct dressed_iterator;

 namespace details {
  template< typename IteratorType> struct is_bidir: std::is_same<typename IteratorType::iterator_category,std::bidirectional_iterator_tag>{};
 }

 // specialization when a aux data is present
 template< typename IteratorType, typename Dressing, typename DressingAuxiliaryArgumentPtrType>
  struct dressed_iterator : public boost::iterator_facade<dressed_iterator<IteratorType,Dressing,DressingAuxiliaryArgumentPtrType>, Dressing,
  typename std::conditional<details::is_bidir<IteratorType>::value, boost::bidirectional_traversal_tag,  boost::forward_traversal_tag>::type, Dressing > {
   public :
    dressed_iterator () {}
    template<typename T> dressed_iterator (T const & it, DressingAuxiliaryArgumentPtrType * aux): _it(it), _aux(aux) {}
    dressed_iterator (dressed_iterator const & it) = default;
    dressed_iterator (dressed_iterator && it) = default;
    dressed_iterator & operator = (dressed_iterator const & it) =default;
    dressed_iterator & operator = (dressed_iterator && it) noexcept { using std::swap; swap(it._it, this->_it); swap(this->_aux, it._aux); return *this;} 
    //dressed_iterator (IteratorType const & it, DressingAuxiliaryArgumentPtrType * aux): _it(it), _aux(aux) {}
    IteratorType const & get() const { return _it;}
    IteratorType       & get()       { return _it;}
    operator IteratorType() const { return _it;}
    DressingAuxiliaryArgumentPtrType * get_aux() { return _aux;}
    const DressingAuxiliaryArgumentPtrType * get_aux() const { return _aux;}
   private:
    friend class boost::iterator_core_access;
    void increment(){ ++_it;}
    template<bool BiDir = details::is_bidir<IteratorType>::value>
     ENABLE_IFC(BiDir) decrement(){ --_it;}
    bool equal(dressed_iterator const & other) const { return(other._it==_it);}
    Dressing dereference() const { return Dressing(_it,_aux); }
    IteratorType _it;
    DressingAuxiliaryArgumentPtrType * _aux;// keep a pointer to maintain assignment of iterator !
  };


 // specialisation when no auxiliary data is present
 template< typename IteratorType, typename Dressing>
  struct dressed_iterator<IteratorType, Dressing,void> : public boost::iterator_facade<dressed_iterator<IteratorType,Dressing>,
  Dressing, typename std::conditional<details::is_bidir<IteratorType>::value, boost::bidirectional_traversal_tag,  boost::forward_traversal_tag>::type, Dressing > {
   public :
    dressed_iterator () {}
    template<typename T> dressed_iterator (T const & it): _it(it) {}
    dressed_iterator (dressed_iterator const & it) = default;
    dressed_iterator (dressed_iterator && it) = default;
    dressed_iterator & operator = (dressed_iterator const & it) =default;
    dressed_iterator & operator = (dressed_iterator && it) noexcept { using std::swap; swap(it._it, this->_it); return *this;} 
    //dressed_iterator (IteratorType const & it): _it(it) {}
    IteratorType const & get() const { return _it;}
    IteratorType       & get()       { return _it;}
    operator IteratorType() const { return _it;}
   private:
    friend class boost::iterator_core_access;
    void increment(){ ++_it;}
    template<bool BiDir = details::is_bidir<IteratorType>::value>
     ENABLE_IFC(BiDir) decrement(){ --_it;}
    bool equal(dressed_iterator const & other) const { return(other._it==_it);}
    Dressing dereference() const { return Dressing(_it); }
    IteratorType _it;
  };

}}
#endif