filtered_iterator.h

// ---------------------------------------------------------------------
//
// Copyright (C) 2002 - 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_filtered_iterator_h
#define dealii_filtered_iterator_h


#include <deal.II/base/std_cxx14/memory.h>
#include <deal.II/base/config.h>
#include <deal.II/base/exceptions.h>
#include <deal.II/base/iterator_range.h>
#include <deal.II/grid/tria_iterator_base.h>

#include <set>
#include <tuple>

DEAL_II_NAMESPACE_OPEN


namespace IteratorFilters
{
  class Active
  {
  public:
    template <class Iterator>
    bool operator () (const Iterator &i) const;
  };

  class UserFlagSet
  {
  public:
    template <class Iterator>
    bool operator () (const Iterator &i) const;
  };


  class UserFlagNotSet
  {
  public:
    template <class Iterator>
    bool operator () (const Iterator &i) const;
  };


  class LevelEqualTo
  {
  public:
    LevelEqualTo (const unsigned int level);

    template <class Iterator>
    bool operator () (const Iterator &i) const;

  protected:
    const unsigned int level;
  };



  class SubdomainEqualTo
  {
  public:
    SubdomainEqualTo (const types::subdomain_id subdomain_id);

    template <class Iterator>
    bool operator () (const Iterator &i) const;

  protected:
    const types::subdomain_id subdomain_id;
  };



  class LocallyOwnedCell
  {
  public:
    template <class Iterator>
    bool operator () (const Iterator &i) const;
  };



  class LocallyOwnedLevelCell
  {
  public:
    template <class Iterator>
    bool operator () (const Iterator &i) const;
  };


  class MaterialIdEqualTo
  {
  public:
    MaterialIdEqualTo (const types::material_id material_id,
                       const bool only_locally_owned = false);

    MaterialIdEqualTo (const std::set<types::material_id> &material_ids,
                       const bool only_locally_owned = false);

    template <class Iterator>
    bool operator () (const Iterator &i) const;

  protected:
    const std::set<types::material_id> material_ids;
    const bool only_locally_owned;
  };

  class ActiveFEIndexEqualTo
  {
  public:
    ActiveFEIndexEqualTo (const unsigned int active_fe_index,
                          const bool only_locally_owned = false);

    ActiveFEIndexEqualTo (const std::set<unsigned int> &active_fe_indices,
                          const bool only_locally_owned = false);

    template <class Iterator>
    bool operator () (const Iterator &i) const;

  protected:
    const std::set<unsigned int> active_fe_indices;
    const bool only_locally_owned;
  };

  class AtBoundary
  {
  public:
    template <class Iterator>
    bool operator () (const Iterator &i) const;
  };
}


template <typename BaseIterator>
class FilteredIterator : public BaseIterator
{
public:
  typedef typename BaseIterator::AccessorType AccessorType;

  template <typename Predicate>
  FilteredIterator (Predicate p);

  template <typename Predicate>
  FilteredIterator (Predicate           p,
                    const BaseIterator &bi);

  FilteredIterator (const FilteredIterator &fi);

  ~FilteredIterator ();

  FilteredIterator &operator = (const FilteredIterator &fi);

  FilteredIterator &operator = (const BaseIterator &fi);

  FilteredIterator &
  set_to_next_positive (const BaseIterator &bi);

  FilteredIterator &
  set_to_previous_positive (const BaseIterator &bi);

  bool operator == (const FilteredIterator &fi) const;

  bool operator == (const BaseIterator &fi) const;

  bool operator != (const FilteredIterator &fi) const;

  bool operator != (const BaseIterator &fi) const;

  bool operator <  (const FilteredIterator &fi) const;

  bool operator <  (const BaseIterator &fi) const;

  FilteredIterator &operator ++ ();

  FilteredIterator   operator ++ (int);

  FilteredIterator &operator -- ();

  FilteredIterator   operator -- (int);

  DeclException1 (ExcInvalidElement,
                  BaseIterator,
                  << "The element " << arg1
                  << " with which you want to compare or which you want to"
                  << " assign from is invalid since it does not satisfy the predicate.");

private:

  class PredicateBase
  {
  public:
    virtual ~PredicateBase () = default;

    virtual bool operator () (const BaseIterator &bi) const = 0;

    virtual std::unique_ptr<PredicateBase> clone () const = 0;
  };


  template <typename Predicate>
  class PredicateTemplate : public PredicateBase
  {
  public:
    PredicateTemplate (const Predicate &predicate);

    virtual bool operator () (const BaseIterator &bi) const override;

    virtual std::unique_ptr<PredicateBase> clone () const override;

  private:
    const Predicate predicate;
  };

  std::unique_ptr<const PredicateBase> predicate;

};



template <typename BaseIterator, typename Predicate>
FilteredIterator<BaseIterator>
make_filtered_iterator (const BaseIterator &i,
                        const Predicate    &p)
{
  FilteredIterator<BaseIterator> fi(p);
  fi.set_to_next_positive (i);
  return fi;
}



namespace internal
{
  namespace FilteredIteratorImplementation
  {
    // The following classes create a nested sequence of
    // FilteredIterator<FilteredIterator<...<BaseIterator>...>> with as many
    // levels of FilteredIterator classes as there are elements in the TypeList
    // if the latter is given as a std::tuple<Args...>.
    template <typename BaseIterator, typename TypeList>
    struct NestFilteredIterators;

    template <typename BaseIterator, typename Predicate>
    struct NestFilteredIterators<BaseIterator, std::tuple<Predicate> >
    {
      typedef ::FilteredIterator<BaseIterator> type;
    };

    template <typename BaseIterator, typename Predicate, typename... Targs>
    struct NestFilteredIterators<BaseIterator, std::tuple<Predicate, Targs...> >
    {
      typedef ::FilteredIterator<typename NestFilteredIterators<BaseIterator,
              std::tuple<Targs...> >::type> type;
    };
  }
}



template <typename BaseIterator, typename Predicate>
IteratorRange<FilteredIterator<BaseIterator> >
filter_iterators (IteratorRange<BaseIterator> i,
                  const Predicate &p)
{
  FilteredIterator<BaseIterator> fi(p, *(i.begin()));
  FilteredIterator<BaseIterator> fi_end(p, *(i.end()));

  return IteratorRange<FilteredIterator<BaseIterator> > (fi, fi_end);
}



template <typename BaseIterator, typename Predicate, typename... Targs>
IteratorRange<typename internal::FilteredIteratorImplementation::
NestFilteredIterators<BaseIterator,std::tuple<Predicate, Targs...> >::type>
filter_iterators (IteratorRange<BaseIterator> i,
                  const Predicate &p,
                  const Targs... args)
{
  // Recursively create filtered iterators, one predicate at a time
  auto fi = filter_iterators(i,p);
  return filter_iterators(fi, args...);
}


/* ------------------ Inline functions and templates ------------ */


template <typename BaseIterator>
template <typename Predicate>
inline
FilteredIterator<BaseIterator>::
FilteredIterator (Predicate p)
  :
  predicate (new PredicateTemplate<Predicate>(p))
{}



template <typename BaseIterator>
template <typename Predicate>
inline
FilteredIterator<BaseIterator>::
FilteredIterator (Predicate          p,
                  const BaseIterator &bi)
  :
  BaseIterator (bi),
  predicate (new PredicateTemplate<Predicate>(p))
{
  if ((this->state() == IteratorState::valid) &&
      ! (*predicate) (*this))
    set_to_next_positive (bi);
}



template <typename BaseIterator>
inline
FilteredIterator<BaseIterator>::
FilteredIterator (const FilteredIterator &fi)
  :
// this construction looks strange, but without going through the
// address of fi, GCC would not cast fi to the base class of type
// BaseIterator but tries to go through constructing a new
// BaseIterator with an Accessor.
  BaseIterator (*(BaseIterator *)(&fi)),
  predicate (fi.predicate->clone ())
{}



template <typename BaseIterator>
inline
FilteredIterator<BaseIterator>::
~FilteredIterator ()
{
  predicate.reset();
}



template <typename BaseIterator>
inline
FilteredIterator<BaseIterator> &
FilteredIterator<BaseIterator>::
operator = (const FilteredIterator &fi)
{
  // Using equivalent code to the one for 'operator=(const BaseIterator &bi)'
  // below, some compiler would not cast fi to the base class of type
  // BaseIterator but try to go through constructing a new Accessor from fi
  // which fails. Hence, we just use an explicit upcast and call the above-
  // mentioned method.
  const BaseIterator &bi = fi;
  return operator = (bi);
}



template <typename BaseIterator>
inline
FilteredIterator<BaseIterator> &
FilteredIterator<BaseIterator>::
operator = (const BaseIterator &bi)
{
  Assert ((bi.state() != IteratorState::valid) || (*predicate)(bi),
          ExcInvalidElement(bi));
  BaseIterator::operator = (bi);
  return *this;
}



template <typename BaseIterator>
inline
FilteredIterator<BaseIterator> &
FilteredIterator<BaseIterator>::
set_to_next_positive (const BaseIterator &bi)
{
  BaseIterator::operator = (bi);
  while ((this->state() == IteratorState::valid) &&
         ( ! (*predicate)(*this)))
    BaseIterator::operator++ ();

  return *this;
}



template <typename BaseIterator>
inline
FilteredIterator<BaseIterator> &
FilteredIterator<BaseIterator>::
set_to_previous_positive (const BaseIterator &bi)
{
  BaseIterator::operator = (bi);
  while ((this->state() == IteratorState::valid) &&
         ( ! (*predicate)(*this)))
    BaseIterator::operator-- ();

  return *this;
}



template <typename BaseIterator>
inline
bool
FilteredIterator<BaseIterator>::
operator == (const FilteredIterator &fi) const
{
  return (static_cast<const BaseIterator &>(*this)
          ==
          static_cast<const BaseIterator &>(fi));
}



template <typename BaseIterator>
inline
bool
FilteredIterator<BaseIterator>::
operator != (const FilteredIterator &fi) const
{
  return (static_cast<const BaseIterator &>(*this)
          !=
          static_cast<const BaseIterator &>(fi));
}



template <typename BaseIterator>
inline
bool
FilteredIterator<BaseIterator>::
operator < (const FilteredIterator &fi) const
{
  return (static_cast<const BaseIterator &>(*this)
          <
          static_cast<const BaseIterator &>(fi));
}




template <typename BaseIterator>
inline
bool
FilteredIterator<BaseIterator>::
operator == (const BaseIterator &bi) const
{
  return (static_cast<const BaseIterator &>(*this) == bi);
}



template <typename BaseIterator>
inline
bool
FilteredIterator<BaseIterator>::
operator != (const BaseIterator &bi) const
{
  return (static_cast<const BaseIterator &>(*this) != bi);
}



template <typename BaseIterator>
inline
bool
FilteredIterator<BaseIterator>::
operator < (const BaseIterator &bi) const
{
  return (static_cast<const BaseIterator &>(*this) < bi);
}


template <typename BaseIterator>
inline
FilteredIterator<BaseIterator> &
FilteredIterator<BaseIterator>::
operator ++ ()
{
  if (this->state() == IteratorState::valid)
    do
      BaseIterator::operator++ ();
    while ((this->state() == IteratorState::valid) &&
           !(*predicate) (*this));
  return *this;
}



template <typename BaseIterator>
inline
FilteredIterator<BaseIterator>
FilteredIterator<BaseIterator>::
operator ++ (int)
{
  const FilteredIterator old_state = *this;

  if (this->state() == IteratorState::valid)
    do
      BaseIterator::operator++ ();
    while ((this->state() == IteratorState::valid) &&
           !(*predicate) (*this));
  return old_state;
}




template <typename BaseIterator>
inline
FilteredIterator<BaseIterator> &
FilteredIterator<BaseIterator>::
operator -- ()
{
  if (this->state() == IteratorState::valid)
    do
      BaseIterator::operator-- ();
    while ((this->state() == IteratorState::valid) &&
           !(*predicate) (*this));
  return *this;
}



template <typename BaseIterator>
inline
FilteredIterator<BaseIterator>
FilteredIterator<BaseIterator>::
operator -- (int)
{
  const FilteredIterator old_state = *this;

  if (this->state() == IteratorState::valid)
    do
      BaseIterator::operator-- ();
    while ((this->state() == IteratorState::valid) &&
           !(*predicate) (*this));
  return old_state;
}



template <typename BaseIterator>
template <typename Predicate>
inline
FilteredIterator<BaseIterator>::PredicateTemplate<Predicate>::
PredicateTemplate (const Predicate &predicate)
  :
  predicate (predicate)
{}



template <typename BaseIterator>
template <typename Predicate>
bool
FilteredIterator<BaseIterator>::PredicateTemplate<Predicate>::
operator () (const BaseIterator &bi) const
{
  return predicate(bi);
}



template <typename BaseIterator>
template <typename Predicate>
std::unique_ptr<typename FilteredIterator<BaseIterator>::PredicateBase>
FilteredIterator<BaseIterator>::PredicateTemplate<Predicate>::
clone () const
{
  return std_cxx14::make_unique<PredicateTemplate> (predicate);
}



namespace IteratorFilters
{

// ---------------- IteratorFilters::Active ---------

  template <class Iterator>
  inline
  bool
  Active::operator () (const Iterator &i) const
  {
    return (i->active());
  }


// ---------------- IteratorFilters::UserFlagSet ---------

  template <class Iterator>
  inline
  bool
  UserFlagSet::operator () (const Iterator &i) const
  {
    return (i->user_flag_set());
  }


// ---------------- IteratorFilters::UserFlagNotSet ---------

  template <class Iterator>
  inline
  bool
  UserFlagNotSet::operator () (const Iterator &i) const
  {
    return (! i->user_flag_set());
  }


// ---------------- IteratorFilters::LevelEqualTo ---------
  inline
  LevelEqualTo::LevelEqualTo (const unsigned int level)
    :
    level (level)
  {}



  template <class Iterator>
  inline
  bool
  LevelEqualTo::operator () (const Iterator &i) const
  {
    return (static_cast<unsigned int>(i->level()) == level);
  }



// ---------------- IteratorFilters::SubdomainEqualTo ---------
  inline
  SubdomainEqualTo::SubdomainEqualTo (const types::subdomain_id subdomain_id)
    :
    subdomain_id (subdomain_id)
  {}



  template <class Iterator>
  inline
  bool
  SubdomainEqualTo::operator () (const Iterator &i) const
  {
    return (i->subdomain_id() == subdomain_id);
  }



// ---------------- IteratorFilters::LocallyOwnedCell ---------

  template <class Iterator>
  inline
  bool
  LocallyOwnedCell::operator () (const Iterator &i) const
  {
    return (i->is_locally_owned());
  }


// ---------------- IteratorFilters::LocallyOwnedLevelCell ---------

  template <class Iterator>
  inline
  bool
  LocallyOwnedLevelCell::operator () (const Iterator &i) const
  {
    return (i->is_locally_owned_on_level());
  }



// ---------------- IteratorFilters::MaterialIdEqualTo ---------
  inline
  MaterialIdEqualTo::MaterialIdEqualTo (const types::material_id material_id,
                                        const bool only_locally_owned)
    :
    material_ids {material_id},
               only_locally_owned (only_locally_owned)
  {}



  inline
  MaterialIdEqualTo::MaterialIdEqualTo (const std::set<types::material_id> &material_ids,
                                        const bool only_locally_owned)
    :
    material_ids (material_ids),
    only_locally_owned (only_locally_owned)
  {}



  template <class Iterator>
  inline
  bool
  MaterialIdEqualTo::operator () (const Iterator &i) const
  {
    return only_locally_owned == true ?
           (material_ids.find(i->material_id()) != material_ids.end() && i->is_locally_owned()):
           material_ids.find(i->material_id()) != material_ids.end();
  }



// ---------------- IteratorFilters::ActiveFEIndexEqualTo ---------
  inline
  ActiveFEIndexEqualTo::ActiveFEIndexEqualTo (const unsigned int active_fe_index,
                                              const bool only_locally_owned)
    :
    active_fe_indices {active_fe_index},
                    only_locally_owned (only_locally_owned)
  {}



  inline
  ActiveFEIndexEqualTo::ActiveFEIndexEqualTo (const std::set<unsigned int> &active_fe_indices,
                                              const bool only_locally_owned)
    :
    active_fe_indices (active_fe_indices),
    only_locally_owned (only_locally_owned)
  {}



  template <class Iterator>
  inline
  bool
  ActiveFEIndexEqualTo::operator () (const Iterator &i) const
  {
    return only_locally_owned == true ?
           (active_fe_indices.find(i->active_fe_index()) != active_fe_indices.end() && i->is_locally_owned()):
           active_fe_indices.find(i->active_fe_index()) != active_fe_indices.end();
  }



// ---------------- IteratorFilters::AtBoundary ---------

  template <class Iterator>
  inline
  bool
  AtBoundary::operator () (const Iterator &i) const
  {
    return (i->at_boundary());
  }
}


DEAL_II_NAMESPACE_CLOSE

/*------------------------- filtered_iterator.h ------------------------*/
#endif
/*------------------------- filtered_iterator.h ------------------------*/