iterator_range.h

// ---------------------------------------------------------------------
//
// Copyright (C) 2014 - 2018 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, redistribute
// it, and/or modify it under the terms of the GNU Lesser General
// Public License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// The full text of the license can be found in the file LICENSE at
// the top level of the deal.II distribution.
//
// ---------------------------------------------------------------------

#ifndef dealii_iterator_range_h
#define dealii_iterator_range_h


#include <deal.II/base/config.h>

#include <iterator>


DEAL_II_NAMESPACE_OPEN


template <typename Iterator>
class IteratorRange
{
public:
  class IteratorOverIterators
  {
  public:
    typedef Iterator BaseIterator;

    IteratorOverIterators (const BaseIterator &iterator);

    BaseIterator operator* () const;

    const BaseIterator *operator-> () const;

    IteratorOverIterators &operator ++ ();

    IteratorOverIterators operator ++ (int);

    bool operator != (const IteratorOverIterators &i_o_i);

    typedef std::forward_iterator_tag          iterator_category;
    typedef Iterator                           value_type;
    typedef typename Iterator::difference_type difference_type;
    typedef Iterator                          *pointer;
    typedef Iterator                          &reference;

  private:
    BaseIterator element_of_iterator_collection;
  };


  typedef Iterator iterator;

  IteratorRange();

  IteratorRange (const iterator begin,
                 const iterator end);

  IteratorOverIterators begin();

  IteratorOverIterators end();

private:
  const iterator it_begin;
  const iterator it_end;
};


// ------------------- template member functions


template <typename Iterator>
inline
IteratorRange<Iterator>::IteratorOverIterators::
IteratorOverIterators (const BaseIterator &iterator)
  :
  element_of_iterator_collection (iterator)
{}



template <typename Iterator>
inline
typename IteratorRange<Iterator>::IteratorOverIterators::BaseIterator
IteratorRange<Iterator>::IteratorOverIterators::operator* () const
{
  return element_of_iterator_collection;
}



template <typename Iterator>
inline
const typename IteratorRange<Iterator>::IteratorOverIterators::BaseIterator *
IteratorRange<Iterator>::IteratorOverIterators::operator-> () const
{
  return &element_of_iterator_collection;
}



template <typename Iterator>
inline
typename IteratorRange<Iterator>::IteratorOverIterators &
IteratorRange<Iterator>::IteratorOverIterators::operator ++ ()
{
  ++element_of_iterator_collection;
  return *this;
}



template <typename Iterator>
inline
typename IteratorRange<Iterator>::IteratorOverIterators
IteratorRange<Iterator>::IteratorOverIterators::operator ++ (int)
{
  const IteratorOverIterators old_value = *this;
  ++element_of_iterator_collection;
  return *old_value;
}



template <typename Iterator>
inline
bool
IteratorRange<Iterator>::IteratorOverIterators::operator != (const IteratorOverIterators &i_o_i)
{
  return element_of_iterator_collection != i_o_i.element_of_iterator_collection;
}


template <typename Iterator>
inline
IteratorRange<Iterator>::IteratorRange ()
  :
  it_begin(),
  it_end()
{}



template <typename Iterator>
inline
IteratorRange<Iterator>::IteratorRange (const iterator b,
                                        const iterator e)
  :
  it_begin(b),
  it_end(e)
{}


template <typename Iterator>
inline
typename IteratorRange<Iterator>::IteratorOverIterators
IteratorRange<Iterator>::begin()
{
  return IteratorOverIterators(it_begin);
}


template <typename Iterator>
inline
typename IteratorRange<Iterator>::IteratorOverIterators
IteratorRange<Iterator>::end()
{
  return IteratorOverIterators(it_end);
}


DEAL_II_NAMESPACE_CLOSE

#endif