Teuchos_FilteredIterator.hpp

// @HEADER
// *****************************************************************************
//                    Teuchos: Common Tools Package
//
// Copyright 2004 NTESS and the Teuchos contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef TEUCHOS_FILTERED_ITERATOR_HPP
#define TEUCHOS_FILTERED_ITERATOR_HPP


#include "Teuchos_Assert.hpp"
#include "Teuchos_TypeNameTraits.hpp"
#include "Teuchos_Exceptions.hpp"


namespace Teuchos {


template<class IteratorType, class Predicate>
class FilteredIterator {
public:


  typedef std::bidirectional_iterator_tag iterator_category;
  typedef typename std::iterator_traits<IteratorType>::value_type value_type;
  typedef typename std::iterator_traits<IteratorType>::reference reference;
  typedef typename std::iterator_traits<IteratorType>::pointer pointer;
  typedef typename std::iterator_traits<IteratorType>::difference_type difference_type;



  FilteredIterator()
    {}
  FilteredIterator(IteratorType current_in, IteratorType begin_in, IteratorType end_in,
    Predicate pred_in = Predicate()
    )
    :current_(current_in), begin_(begin_in), end_(end_in), pred_(pred_in)
    { advanceForwardToValid(); }  
  template<class IteratorType2, class Predicate2>
  FilteredIterator(const FilteredIterator<IteratorType2,Predicate2>& rhs)
    :current_(rhs.current()), begin_(rhs.begin()), end_(rhs.end()), pred_(rhs.pred())
    {}
  template<class IteratorType2, class Predicate2>
  FilteredIterator & operator=(const FilteredIterator<IteratorType2,Predicate2>& rhs)
    {
      current_ = rhs.current();
      begin_ = rhs.begin();
      end_ = rhs.end();
      pred_ = rhs.pred();
      return *this;
    }



  reference operator*() const
    { return *current_; }
  pointer operator->() const
    { return current_.operator->(); }



  FilteredIterator& operator++()
    {
      assertNotIterateForwardPastEnd();
      ++current_;
      advanceForwardToValid();
      return *this;
    }
  const FilteredIterator operator++(int)
    {
      FilteredIterator tmp = *this;
      ++*this;
      return tmp;
    }
  FilteredIterator& operator--()
    {
      assertNotIterateBackwardPastBegin();
      --current_;
      advanceBackwardToValid();
      return *this;
    }
  const FilteredIterator operator--(int)
    {
      FilteredIterator tmp = *this;
      --*this;
      return tmp;
    }



  IteratorType  current() const { return current_; }
  IteratorType  begin() const { return begin_; }
  IteratorType  end() const { return end_; }
  Predicate pred() const{ return pred_; }


private: // Data members

  IteratorType current_;
  IteratorType begin_;
  IteratorType end_;
  Predicate pred_;

private: // Functions

  void advanceForwardToValid();
  void advanceBackwardToValid();
  void assertNotIterateForwardPastEnd()
#ifndef HAVE_TEUCHOS_ARRAY_BOUNDSCHECK
    {}
#else
  ;
#endif

  void assertNotIterateBackwardPastBegin()
#ifndef HAVE_TEUCHOS_ARRAY_BOUNDSCHECK
    {}
#else
  ;
#endif

};


template<class IteratorType, class Predicate>
inline bool operator==(const FilteredIterator<IteratorType,Predicate>& itr1,
  const FilteredIterator<IteratorType,Predicate>& itr2)
{
  return itr1.current() == itr2.current();
}


template<class IteratorType, class Predicate>
inline bool operator!=(const FilteredIterator<IteratorType,Predicate>& itr1,
  const FilteredIterator<IteratorType,Predicate>& itr2)
{
  return itr1.current() != itr2.current();
}


template<class IteratorType, class Predicate>
std::ostream& operator<<(std::ostream &out, const FilteredIterator<IteratorType,Predicate>& itr)
{
  out << "FilteredIterator{current=???, end=???, pred="<<TypeNameTraits<Predicate>::name()<<"}";
  return out;
}

//
// Template definitions
//


template<class IteratorType, class Predicate>
void FilteredIterator<IteratorType,Predicate>::advanceForwardToValid()
{
  while (current_ != end_ && !pred_(*current_)) {
    ++current_;
  }
}


template<class IteratorType, class Predicate>
void FilteredIterator<IteratorType,Predicate>::advanceBackwardToValid()
{
  while (current_ != begin_ && !pred_(*current_)) {
    --current_;
  }
}


#ifdef HAVE_TEUCHOS_ARRAY_BOUNDSCHECK


template<class IteratorType, class Predicate>
void FilteredIterator<IteratorType,Predicate>::assertNotIterateForwardPastEnd()
{
  const bool current_is_at_end = (current_ == end_);
  TEUCHOS_TEST_FOR_EXCEPTION( current_is_at_end, RangeError,
    "Error, trying to iterate " << *this << " forward ++ past end!");
}


template<class IteratorType, class Predicate>
void FilteredIterator<IteratorType,Predicate>::assertNotIterateBackwardPastBegin()
{
  const bool current_is_at_begin = (current_ == begin_);
  TEUCHOS_TEST_FOR_EXCEPTION( current_is_at_begin, RangeError,
    "Error, trying to iterate " << *this << " backward -- past begin!");
}


#endif // HAVE_TEUCHOS_ARRAY_BOUNDSCHECK


} // end namespace Teuchos


#endif // TEUCHOS_FILTERED_ITERATOR_HPP