collection.h

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 2021 - 2025 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Detailed license information governing the source code and contributions
// can be found in LICENSE.md and CONTRIBUTING.md at the top level directory.
//
// -----------------------------------------------------------------------------
 
#ifndef dealii_hp_collection_h
#define dealii_hp_collection_h
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/enable_observer_pointer.h>
#include <deal.II/base/exceptions.h>
#include <deal.II/base/memory_consumption.h>
 
#include <iterator>
#include <memory>
#include <vector>
 
DEAL_II_NAMESPACE_OPEN
 
namespace hp
{
  DeclExceptionMsg(ExcDifferentCollection,
                   "You are trying to compare iterators into different "
                   "hp::Collection objects.");
 
  template <typename T>
  class CollectionIterator
  {
  public:
    CollectionIterator(const std::vector<std::shared_ptr<const T>> &data,
                       const std::size_t                            index)
      : data(&data)
      , index(index)
    {}
 
    CollectionIterator(const CollectionIterator<T> &other) = default;
 
    CollectionIterator<T> &
    operator=(const CollectionIterator<T> &other) = default;
 
    bool
    operator==(const CollectionIterator<T> &other) const
    {
      Assert(this->data == other.data, ExcDifferentCollection());
      return this->index == other.index;
    }
 
    bool
    operator!=(const CollectionIterator<T> &other) const
    {
      Assert(this->data == other.data, ExcDifferentCollection());
      return this->index != other.index;
    }
 
    bool
    operator<(const CollectionIterator<T> &other) const
    {
      Assert(this->data == other.data, ExcDifferentCollection());
      return this->index < other.index;
    }
 
    bool
    operator<=(const CollectionIterator<T> &other) const
    {
      Assert(this->data == other.data, ExcDifferentCollection());
      return this->index <= other.index;
    }
 
    bool
    operator>(const CollectionIterator<T> &other) const
    {
      Assert(this->data == other.data, ExcDifferentCollection());
      return this->index > other.index;
    }
 
    bool
    operator>=(const CollectionIterator<T> &other) const
    {
      Assert(this->data == other.data, ExcDifferentCollection());
      return this->index >= other.index;
    }
 
    const T &
    operator*() const
    {
      AssertIndexRange(index, data->size());
      return *(*data)[index];
    }
 
    CollectionIterator<T> &
    operator++()
    {
      AssertIndexRange(index + 1, data->size() + 1);
      ++index;
      return *this;
    }
 
    CollectionIterator<T> &
    operator+=(const std::size_t offset)
    {
      AssertIndexRange(index + offset, data->size() + 1);
      index += offset;
      return *this;
    }
 
    CollectionIterator<T> &
    operator--()
    {
      Assert(
        index > 0,
        ExcMessage(
          "You can't decrement an iterator that is already at the beginning of the range."));
      --index;
      return *this;
    }
 
    CollectionIterator<T>
    operator+(const std::size_t &offset) const
    {
      AssertIndexRange(index + offset, T::size() + 1);
      return CollectionIterator<T>(*data, index + offset);
    }
 
    std::ptrdiff_t
    operator-(const CollectionIterator<T> &other) const
    {
      return static_cast<std::ptrdiff_t>(index) -
             static_cast<std::ptrdiff_t>(other.index);
    }
 
  private:
    const std::vector<std::shared_ptr<const T>> *data;
 
    std::size_t index;
  };
 
  template <typename T>
  class Collection : public EnableObserverPointer
  {
  public:
    Collection() = default;
 
    void
    push_back(const std::shared_ptr<const T> &new_entry);
 
    const T &
    operator[](const unsigned int index) const;
 
    unsigned int
    size() const;
 
    bool
    empty() const;
 
    std::size_t
    memory_consumption() const;
 
    CollectionIterator<T>
    begin() const;
 
    CollectionIterator<T>
    end() const;
 
  private:
    std::vector<std::shared_ptr<const T>> entries;
  };
 
 
  /* --------------- inline functions ------------------- */
 
 
 
  template <typename T>
  std::size_t
  Collection<T>::memory_consumption() const
  {
    return (sizeof(*this) + MemoryConsumption::memory_consumption(entries));
  }
 
 
 
  template <typename T>
  void
  Collection<T>::push_back(const std::shared_ptr<const T> &new_entry)
  {
    entries.push_back(new_entry);
  }
 
 
 
  template <typename T>
  inline unsigned int
  Collection<T>::size() const
  {
    return entries.size();
  }
 
 
 
  template <typename T>
  inline bool
  Collection<T>::empty() const
  {
    return this->size() == 0;
  }
 
 
 
  template <typename T>
  inline const T &
  Collection<T>::operator[](const unsigned int index) const
  {
    AssertIndexRange(index, entries.size());
    return *entries[index];
  }
 
 
 
  template <typename T>
  CollectionIterator<T>
  Collection<T>::begin() const
  {
    return CollectionIterator<T>(entries, 0);
  }
 
 
 
  template <typename T>
  CollectionIterator<T>
  Collection<T>::end() const
  {
    return CollectionIterator<T>(entries, entries.size());
  }
 
} // namespace hp
 
 
DEAL_II_NAMESPACE_CLOSE
 
namespace std
{
  template <class T>
  struct iterator_traits<::hp::CollectionIterator<T>>
    : public iterator_traits<
        typename std::vector<std::shared_ptr<const T>>::iterator>
  {};
} // namespace std
 
#endif