ConstDataVector.icc

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// Dear emacs, this is -*- c++ -*-
/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
/**
 * @file AthContainers/ConstDataVector.icc
 * @author scott snyder <snyder@bnl.gov>
 * @date Sep, 2011
 * @brief @c DataVector adapter that acts like it holds const pointers.
 */
 
 
#include "CxxUtils/checker_macros.h"
#include "CxxUtils/throw_out_of_range.h"
#include <functional>
#include <ranges>
 
 
namespace ConstDataVector_detail {
 
 
/// Functional to cast const away.
template <class T>
class remove_const
{
public:
  T* operator() (const T* p) const {
    T* pp ATLAS_THREAD_SAFE = const_cast<T*> (p);
    return pp;
  }
};
 
 
} // namespace ConstDataVector_detail
 
 
//=== Constructors, destructors, assignment.
 
 
/**
 * @brief Default constructor.
 * @param ownPolicy The ownership mode for the container.
 *
 * By default, a @c DataVector will own its elements.
 * To avoid this, pass @c SG::VIEW_ELEMENTS for @a ownPolicy.
 */
template <class DV>
inline
ConstDataVector<DV>::ConstDataVector
  (SG::OwnershipPolicy ownPolicy /*= SG::OWN_ELEMENTS*/)
    : DV (ownPolicy)
{
  base_data_vector::clear (ownPolicy, SG::NEVER_TRACK_INDICES);
}
 
 
/**
 * @brief Constructor with argument forwarding.
 * @param ownPolicy The ownership mode for the container.
 *
 * All arguments are forwarded to the base class constructor.
 */
template <class DV>
template <typename... ARGS>
inline
ConstDataVector<DV>::ConstDataVector (SG::OwnershipPolicy ownPolicy,
                                      ARGS&&... args)
  : DV (ownPolicy, std::forward<ARGS>(args)...)
{
  base_data_vector::clear (ownPolicy, SG::NEVER_TRACK_INDICES);
}
 
 
/**
 * @brief Sized constructor.
 * @param n The size of the container.
 * @param ownPolicy The ownership mode for the container.
 *
 * Note that unlike the standard vector constructor, you can't specify
 * an initial value here.  The container will be initialized with 0's.
 *
 * By default, a @c DataVector will own its elements.
 * To avoid this, pass @c SG::VIEW_ELEMENTS for @a ownPolicy.
 */
template <class DV>
inline
ConstDataVector<DV>::ConstDataVector
  (size_type n,
   SG::OwnershipPolicy ownPolicy /*= SG::OWN_ELEMENTS*/)
    : DV (n, ownPolicy)
{
  base_data_vector::clear (ownPolicy, SG::NEVER_TRACK_INDICES);
  DV::resize (n);
}
 
 
/**
 * @brief Constructor from iterators.
 * @param first The start of the range to put in the new container.
 * @param last The end of the range to put in the new container.
 * @param ownPolicy The ownership mode for the container.
 *
 * By default, a @c DataVector will own its elements (and take ownership
 * of the pointers passed to this constructor).
 * To avoid this, pass @c SG::VIEW_ELEMENTS for @a ownPolicy.
 */
template <class DV>
template <class InputIterator>
inline
ConstDataVector<DV>::ConstDataVector
  (InputIterator first,
   InputIterator last,
   SG::OwnershipPolicy ownPolicy /*= SG::VIEW_ELEMENTS*/)
    : DV (ownPolicy)
{
  base_data_vector::clear (ownPolicy, SG::NEVER_TRACK_INDICES);
  reserve (std::distance (first, last));
  while (first != last)
    push_back (*first++);
}
 
 
/**
 * @brief Move constructor.
 * @param rhs The container from which to move.
 *
 * Any auxiliary data will be moved along with the container contents.
 */
template <class DV>
inline
ConstDataVector<DV>::ConstDataVector (ConstDataVector&& rhs)
  : DV (std::move (rhs))
{
}
 
 
/**
 * @brief Constructor from an initializer list.
 * @param l An initializer list.
 * @param last The end of the range to put in the new container.
 * @param ownPolicy The ownership mode for the container.
 *
 * By default, a @c DataVector will own its elements (and take ownership
 * of the pointers passed to this constructor).
 * To avoid this, pass @c SG::VIEW_ELEMENTS for @a ownPolicy.
 */
template <class DV>
inline
ConstDataVector<DV>::ConstDataVector
  (std::initializer_list<value_type> l,
   SG::OwnershipPolicy ownPolicy /*= SG::VIEW_ELEMENTS*/)
    : ConstDataVector (l.begin(), l.end(), ownPolicy)
{
}
 
 
/**
 * @brief Constructor from a vector of ElementLinks.
 * @param v The vector from which to initialize.
 *
 * This will make a view container.
 */
template <class DV>
template <class CONTAINER>
ConstDataVector<DV>::ConstDataVector
  (const std::vector<ElementLink<CONTAINER> >& v)
  : DV (SG::VIEW_ELEMENTS)
{
  this->reserve (v.size());
  for (const ElementLink<CONTAINER>& el : v)
    this->push_back (*el);
}
 
 
/**
 * @brief Assignment operator.
 * @param rhs The DataVector from which to assign.
 * @return This object.
 *
 * This is a `shallow' copy; after the completion of this, the DataVector
 * will not own its elements.  Any elements it owned prior to this call
 * will be released.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 */
template <class DV>
inline
ConstDataVector<DV>&
ConstDataVector<DV>::operator= (const ConstDataVector& rhs) 
{
  *static_cast<DV*>(this) = rhs;
  return *this;
}
 
 
/**
 * @brief Move assignment.
 * @param rhs The container from which to move.
 *
 * Any auxiliary data will be moved along with the container contents.
 */
template <class DV>
inline
ConstDataVector<DV>&
ConstDataVector<DV>::operator= (ConstDataVector&& rhs)
{
  if (this != &rhs) {
    DV::operator= (std::move (rhs));
  }
  return *this;
}
 
 
/**
 * @brief Assignment operator, from an initializer list.
 * @param l An initializer list.
 * @return This object.
 *
 * This is equivalent to @c assign.
 * Any existing owned elements will be released.
 * The @c DataVector's ownership policy determines whether it will take
 * ownership of the new elements.
 */
template <class DV>
inline
ConstDataVector<DV>&
ConstDataVector<DV>::operator= (std::initializer_list<value_type> l)
{
  this->assign (l.begin(), l.end());
  return *this;
}
 
 
/**
 * @brief Assign from iterators.
 * @param first The start of the range to put in the container.
 * @param last The end of the range to put in the container.
 *
 * Any existing owned elements will be released.
 * The @c DataVector's ownership policy determines whether it will take
 * ownership of the new elements.
 */
template <class DV>
template <class InputIterator>
inline
void ConstDataVector<DV>::assign(InputIterator first, InputIterator last)
{
  clear();
  reserve (std::distance (first, last));
  while (first != last)
    push_back (*first++);
}
 
 
/**
 * @brief Assign from an initializer list.
 * @param l An initializer list.
 *
 * Any existing owned elements will be released.
 * The @c DataVector's ownership policy determines whether it will take
 * ownership of the new elements.
 */
template <class DV>
inline
void ConstDataVector<DV>::assign(std::initializer_list<value_type> l)
{
  this->assign (l.begin(), l.end());
}
 
 
/**
 * @brief Assign from a vector of ElementLinks.
 * @param v The vector from which to initialize.
 *
 * This will change the container to a view container.
 */
template <class DV>
template <class CONTAINER>
void ConstDataVector<DV>::assign (const std::vector<ElementLink<CONTAINER> >& v)
{
  this->clear(SG::VIEW_ELEMENTS);
  this->reserve (v.size());
  for (const ElementLink<CONTAINER>& el : v)
    this->push_back (*el);
}
 
 
//=== Element access.
 
 
/**
 * @brief Access an element, as an lvalue.
 * @param n Array index to access.
 * @return Proxy to the element at @a n.
 *
 * No bounds checking is done.
 * Note that we return a proxy object rather than a reference;
 * the proxy will handle deleting an owned element if it's assigned to.
 */
template <class DV>
inline
typename ConstDataVector<DV>::ElementProxy
ConstDataVector<DV>::operator[] (size_type n)
{
  return to_element_proxy (this->m_pCont.begin() + n);
}
 
 
/**
 * @brief Access an element, as an lvalue.
 * @param n Array index to access.
 * @return Proxy to the element at @a n.
 *
 * Will raise @c std::out_of_range if the index is out-of-bounds.
 * Note that we return a proxy object rather than a reference;
 * the proxy will handle deleting an owned element if it's assigned to.
 */
template <class DV>
inline
typename ConstDataVector<DV>::ElementProxy
ConstDataVector<DV>::at (size_type n)
{
  if (n >= this->size())
    CxxUtils::throw_out_of_range (__PRETTY_FUNCTION__, n, this->size(), this);
  return to_element_proxy (this->m_pCont.begin() + n);
}
 
 
/**
 * @brief Access the first element in the collection as an lvalue.
 * @return Proxy to the first element in the collection.
 *
 * No checking is done to ensure that the container is not empty.
 * Note that we return a proxy object rather than a reference;
 * the proxy will handle deleting an owned element if it's assigned to.
 */
template <class DV>
inline
typename ConstDataVector<DV>::ElementProxy
ConstDataVector<DV>::front ()
{
  return to_element_proxy (this->m_pCont.begin());
}
 
 
/**
 * @brief Access the last element in the collection as an lvalue.
 * @return Proxy to the last element in the collection.
 *
 * No checking is done to ensure that the container is not empty.
 * Note that we return a proxy object rather than a reference;
 * the proxy will handle deleting an owned element if it's assigned to.
 */
template <class DV>
inline
typename ConstDataVector<DV>::ElementProxy
ConstDataVector<DV>::back ()
{
  return to_element_proxy (this->m_pCont.end()-1);
}
 
 
//=== Iterator creation.
 
 
/**
 * @brief Return an @c iterator pointing at the beginning
 *        of the collection.
 * @return An @c iterator.
 *
 * Note that dereferencing the iterator will yield a proxy rather
 * than a reference; the proxy will handle deleting an owned element
 * if it's assigned to.
 */
template <class DV>
inline
typename ConstDataVector<DV>::iterator
ConstDataVector<DV>::begin() noexcept
{
  return to_my_iterator (DV::begin());
}
 
 
/**
 * @brief Return an @c iterator pointing past the end
 *        of the collection.
 * @return An @c iterator.
 *
 * Note that dereferencing the iterator will yield a proxy rather
 * than a reference; the proxy will handle deleting an owned element
 * if it's assigned to.
 */
template <class DV>
inline
typename ConstDataVector<DV>::iterator
ConstDataVector<DV>::end() noexcept
{
  return to_my_iterator (DV::end());
}
 
 
/**
 * @brief Return a @c reverse_iterator pointing past the end
 *        of the collection.
 * @return A @c reverse_iterator.
 *
 * Note that dereferencing the iterator will yield a proxy rather
 * than a reference; the proxy will handle deleting an owned element
 * if it's assigned to.
 */
template <class DV>
inline
typename ConstDataVector<DV>::reverse_iterator
ConstDataVector<DV>::rbegin() noexcept
{
  return reverse_iterator (to_my_iterator (DV::end()));
}
 
 
/**
 * @brief Return a @c reverse_iterator pointing at the beginning
 *        of the collection.
 * @return A @c reverse_iterator.
 *
 * Note that dereferencing the iterator will yield a proxy rather
 * than a reference; the proxy will handle deleting an owned element
 * if it's assigned to.
 */
template <class DV>
inline
typename ConstDataVector<DV>::reverse_iterator
ConstDataVector<DV>::rend() noexcept
{
  return reverse_iterator (to_my_iterator (DV::begin()));
}
 
 
//=== Insertion operations.
 
 
/**
 * @brief Add an element to the end of the collection.
 * @param pElem The element to add to the collection.
 *
 * The container's ownership policy will determine if it takes ownership
 * of the new element.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 *
 * Returns the pushed pointer.
 */
template <class DV>
inline
typename ConstDataVector<DV>::value_type
ConstDataVector<DV>::push_back(value_type pElem)
{
  typename DV::value_type p ATLAS_THREAD_SAFE = const_cast<typename DV::value_type> (pElem);
  DV::push_back (p);
  return p;
}
 
 
/**
 * @brief Add an element to the end of the collection.
 * @param pElem The element to add to the collection.
 *
 * The container's ownership policy will determine if it takes ownership
 * of the new element.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 *
 * For @c DataVector, this is like the same as @c push_back, and
 * it returns the pushed element.
 * It's included just for interface compatibility with `std::vector`.
 */
template <class DV>
inline
typename ConstDataVector<DV>::value_type
ConstDataVector<DV>::emplace_back(value_type pElem)
{
  this->push_back (pElem);
  return pElem;
}
 
 
/**
 * @brief Add a new element to the collection.
 * @param position Iterator before which the element will be added.
 * @param pElem The element to add to the collection.
 * @return An iterator that points to the inserted data.
 *
 * The container's ownership policy will determine if it takes ownership
 * of the new element.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 */
template <class DV>
inline
typename ConstDataVector<DV>::iterator
ConstDataVector<DV>::insert(iterator position, value_type pElem)
{
  typename DV::value_type p ATLAS_THREAD_SAFE = const_cast<typename DV::value_type> (pElem);
  return to_my_iterator
    (DV::insert (to_base_iterator (position), p));
}
 
 
/**
 * @brief Add a new element to the collection.
 * @param position Iterator before which the element will be added.
 * @param pElem The element to add to the collection.
 * @return An iterator that points to the inserted data.
 *
 * The container's ownership policy will determine if it takes ownership
 * of the new element.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 *
 * For @c DataVector, this is just the same as @c insert.
 * It's included just for interface compatibility with `std::vector`.
 */
template <class DV>
inline
typename ConstDataVector<DV>::iterator
ConstDataVector<DV>::emplace(iterator position, value_type pElem)
{
  return this->insert (position, pElem);
}
 
 
/**
 * @brief Add a group of new elements to the collection.
 * @param position Iterator before which the element will be added.
 * @param first The start of the range to put in the container.
 * @param last The end of the range to put in the container.
 *
 * The container's ownership policy will determine if it takes ownership
 * of the new element.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 */
template <class DV>
template <class InputIterator>
inline
void ConstDataVector<DV>::insert (iterator position,
                                  InputIterator first,
                                  InputIterator last)
{
  ConstDataVector_detail::remove_const<typename DV::base_value_type> cast;
  auto view = std::ranges::subrange(first, last) | std::views::transform(cast);
  DV::insert(to_base_iterator(position), view.begin(), view.end());
}
 
 
/**
 * @brief Add an element to the end of the collection.
 * @param pElem The element to add to the collection.
 *
 * The container must be an owning container.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 *
 * Returns the pushed pointer.
 */
template <class DV>
inline
typename ConstDataVector<DV>::value_type
ConstDataVector<DV>::push_back(std::unique_ptr<const base_value_type> pElem)
{
  typename DV::value_type ptmp ATLAS_THREAD_SAFE =
    const_cast<typename DV::value_type> (pElem.release());
  std::unique_ptr<typename DV::base_value_type> ptr (ptmp);
  DV::push_back (std::move (ptr));
  return DV::back();
}
 
 
/**
 * @brief Add a new element to the collection.
 * @param position Iterator before which the element will be added.
 * @param pElem The element to add to the collection.
 * @return An iterator that points to the inserted data.
 *
 * The container must be an owning container.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 */
template <class DV>
inline
typename ConstDataVector<DV>::iterator
ConstDataVector<DV>::insert(iterator position,
                            std::unique_ptr<const base_value_type> pElem)
{
  typename DV::value_type ptmp ATLAS_THREAD_SAFE =
    const_cast<typename DV::value_type> (pElem.release());
  std::unique_ptr<typename DV::base_value_type> ptr (ptmp);
  return to_my_iterator
    (DV::insert (to_base_iterator (position), std::move (ptr)));
}
 
 
/**
 * @brief Add a group of new elements to the collection.
 * @param position Iterator before which the element will be added.
 * @param l An initializer list.
 *
 * The container's ownership policy will determine if it takes ownership
 * of the new element.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 */
template <class DV>
inline
void ConstDataVector<DV>::insert (iterator position,
                                  std::initializer_list<value_type> l)
{
  this->insert (position, l.begin(), l.end());
}
 
 
//=== Erasure operations.
 
 
/**
 * @brief Remove element at a given position.
 * @param position Iterator pointing to the element to be removed.
 * @return An iterator pointing to the next element (or @c end()).
 *
 * If the container owns its elements, then the pointed-to element
 * will be deleted.
 */
template <class DV>
inline
typename ConstDataVector<DV>::iterator
ConstDataVector<DV>::erase(iterator position)
{
  return to_my_iterator (DV::erase (to_base_iterator (position)));
}
 
 
/**
 * @brief Remove a range of elements.
 * @param first Iterator pointing to the first element to be removed.
 * @param last Iterator pointing one past the last element to be removed.
 * @return An iterator pointing to the element pointed to by @a last
 *         prior to erasing (or @c end()).
 *
 * If the container owns its elements, then the removed elements
 * will be deleted.  Any duplicates will be removed in this process,
 * but don't rely on this.
 */
template <class DV>
inline
typename ConstDataVector<DV>::iterator
ConstDataVector<DV>::erase(iterator first, iterator last)
{
  return to_my_iterator
    (DV::erase (to_base_iterator (first),
                to_base_iterator (last)));
}
 
 
/**
 * @brief clear()
 * @brief Erase all the elements in the collection.
 *
 * If the container owns its elements, then the removed elements
 * will be deleted.  Any duplicates will be removed in this process,
 * but don't rely on this.
 */
template <class DV>
inline
void ConstDataVector<DV>::clear()
{
  DV::clear();
}
 
 
/**
 * @brief Swap this collection with another.
 * @param rhs The collection with which to swap.
 *
 * Ownership is swapped along with the collection content.
 *
 * Note: this method may only be called using the most-derived
 * @c DataVector in the hierarchy.  The @a rhs must also be
 * referenced using the most-derived @c DataVector.
 */
template <class DV>
inline
void ConstDataVector<DV>::swap (ConstDataVector& rhs)
{
  DV::swap (rhs);
}
 
 
/**
 * @brief Swap the referents of two @c DataVector iterators.
 * @param a The first iterator for the swap.
 * @param b The second iterator for the swap.
 */
template <class DV>
inline
void ConstDataVector<DV>::iter_swap (iterator a, iterator b)
{
  DV::iter_swap (to_base_iterator (a),
                 to_base_iterator (b));
}
 
 
//=== Non-standard operations.
 
 
/**
 * @brief Swap one element out of the container.
 * @param index Index of the element in the container to swap.
 * @param newElem New element to put in the container.
 *                May be 0.
 * @param oldElem Reference to receive the element removed from the
 *                container.
 *
 * Reference @a oldElem is initialized with element @a index of the
 * collection (no bounds checking).  Then element @a index is set
 * to @c newElem.  If the collection owns its elements, then it will
 * take ownership of @a newElem and release (without deleting)
 * the element returned through @a oldElem.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 */
template <class DV>
inline
void
ConstDataVector<DV>::swapElement (size_type index,
                                  value_type newElem,
                                  reference oldElem)
{
  typename DV::value_type pnew ATLAS_THREAD_SAFE = const_cast<typename DV::value_type>(newElem);
  typename DV::reference rold ATLAS_THREAD_SAFE = const_cast<typename DV::reference>(oldElem);
  DV::swapElement (index, pnew, rold);
}
 
 
/**
 * @brief Swap one element out of the container.
 * @param pos The element in the container to swap.
 * @param newElem New element to put in the container.
 *                May be 0.
 * @param oldElem Reference to receive the element removed from the
 *                container.
 *
 * Reference @a oldElem is initialized with element @a pos of the
 * collection (no bounds checking).  Then element @a index is set
 * to @c newElem.  If the collection owns its elements, then it will
 * take ownership of @a newElem and release (without deleting)
 * the element returned through @a oldElem.
 *
 * Note: this method may only be called using the most derived
 * @c DataList in the hierarchy.
 */
template <class DV>
inline
void
ConstDataVector<DV>::swapElement (iterator pos,
                                  value_type newElem,
                                  reference oldElem)
{
  typename DV::value_type pnew ATLAS_THREAD_SAFE = const_cast<typename DV::value_type>(newElem);
  typename DV::reference rold ATLAS_THREAD_SAFE = const_cast<typename DV::reference>(oldElem);
  DV::swapElement (to_base_iterator(pos), pnew, rold);
}
 
 
/**
 * @brief Swap one element out of the container.
 * @param index Index of the element in the container to swap.
 * @param newElem New element to put in the container.
 *                May be 0.
 * @param oldElem Reference to receive the element removed from the
 *                container.
 *
 * Reference @a oldElem is initialized with element @a index of the
 * collection (no bounds checking).  Then element @a index is set
 * to @c newElem.
 *
 * The collection must own its elements to use its interface.
 * The collection will take ownership of @c newElem and will return
 * ownership of @c oldElem.
 *
 * Note: this method may only be called using the most derived
 * @c DataVector in the hierarchy.
 */
template <class DV>
inline
void
ConstDataVector<DV>::swapElement (size_type index,
                                  std::unique_ptr<const base_value_type> newElem,
                                  std::unique_ptr<const base_value_type>& oldElem)
{
  typename DV::value_type pelem ATLAS_THREAD_SAFE =
    const_cast<typename DV::value_type> (newElem.release());
  std::unique_ptr<typename DV::base_value_type> new_u (pelem);
  std::unique_ptr<typename DV::base_value_type> old_u;
  DV::swapElement (index, std::move(new_u), old_u);
  oldElem = std::move (old_u);
}
 
 
/**
 * @brief Swap one element out of the container.
 * @param pos The element in the container to swap.
 * @param newElem New element to put in the container.
 *                May be 0.
 * @param oldElem Reference to receive the element removed from the
 *                container.
 *
 * Reference @a oldElem is initialized with element @a pos of the
 * collection (no bounds checking).  Then element @a index is set
 * to @c newElem.
 *
 * The collection must own its elements to use its interface.
 * The collection will take ownership of @c newElem and will return
 * ownership of @c oldElem.
 *
 * Note: this method may only be called using the most derived
 * @c DataList in the hierarchy.
 */
template <class DV>
inline
void
ConstDataVector<DV>::swapElement (iterator pos,
                                  std::unique_ptr<const base_value_type> newElem,
                                  std::unique_ptr<const base_value_type>& oldElem)
{
  typename DV::value_type pelem ATLAS_THREAD_SAFE =
    const_cast<typename DV::value_type> (newElem.release());
  std::unique_ptr<typename DV::base_value_type> new_u (pelem);
  std::unique_ptr<typename DV::base_value_type> old_u;
  DV::swapElement (to_base_iterator(pos), std::move(new_u), old_u);
  oldElem = std::move (old_u);
}
 
 
/**
 * @brief Return a pointer to this object, as a const @c DataVector.
 */
template <class DV>
inline
const DV*
ConstDataVector<DV>::asDataVector() const
{
  return static_cast<const DV*>(this);
}
 
 
/**
 * @brief Cast from a @c DataVector to a @c ConstDataVector.
 * @param dv Pointer to object to cast.
 *
 * Return @c DV cast to a @c ConstDataVector.
 */
template <class DV>
const ConstDataVector<DV>* ConstDataVector<DV>::fromDataVector (const DV* dv)
{
  if (typeid (*dv) == typeid (ConstDataVector))
    return static_cast<const ConstDataVector*> (dv);
  return nullptr;
}
 
 
/**
 * @brief Reset indices / reorder aux data after elements have been permuted.
 * @param beg Start of the range of elements to process.
 * @param end End of the range of elements to process.
 *
 * This is a no-op for @c ConstDataVector.
 */
template <class DV>
inline
void ConstDataVector<DV>::resortAux (iterator /*beg*/, iterator /*end*/)
{
}
 
 
/**
 * @brief Erase all the elements in the collection, and reset
 *        the ownership mode.
 * @param ownPolicy The new ownership policy of the container.
 *
 * If the container owns its elements, then the removed elements
 * will be deleted.  Any duplicates will be removed in this process,
 * but don't rely on this.
 */
template <class DV>
inline
void ConstDataVector<DV>::clear (SG::OwnershipPolicy ownPolicy)
{
  DV::clear (ownPolicy, SG::NEVER_TRACK_INDICES);
}
 
 
/**
 * @fn void clear
 * @brief Erase all the elements in the collection, and reset
 *        the ownership mode.
 * @param ownPolicy The new ownership policy of the container.
 * @param trackIndices The index tracking policy.
 *
 * If the container owns its elements, then the removed elements
 * will be deleted.  Any duplicates will be removed in this process,
 * but don't rely on this.
 */
template <class DV>
inline
void ConstDataVector<DV>::clear (SG::OwnershipPolicy ownPolicy,
                                 SG::IndexTrackingPolicy trackIndices)
{
  DV::clear (ownPolicy, trackIndices);
  if (DV::trackIndices()) std::abort();
}
 
 
/**
 * @brief Convert to @c AuxVectorBase.
 *
 * Needed to get @x AuxVectorBase from a @c ConstDataVector.
 * Present in @c DataVector as well for consistency.
 */
template <class DV>
inline
const SG::AuxVectorBase& ConstDataVector<DV>::auxbase() const
{
  return *this;
}
 
 
//=== Relational operators.
 
 
/**
 * @brief  Vector ordering relation.
 * @param  b  A @c ConstDataVector of the same type as @a *this.
 * @return  True iff @a *this is lexicographically less than @a b.
 *
 * This is a total ordering relation.  It is linear in the size of the
 * vectors.  Comparisons are done on the pointer values of the elements.
 *
 * See @c std::lexicographical_compare() for how the determination is made.
 */
template <class DV>
inline
bool ConstDataVector<DV>::operator< (const ConstDataVector& b) const
{
  return static_cast<const DV&>(*this) < static_cast<const DV&>(b);
}
 
 
/// Based on operator<
template <class DV>
inline
bool ConstDataVector<DV>::operator> (const ConstDataVector& b) const
{
  return static_cast<const DV&>(*this) > static_cast<const DV&>(b);
}
 
 
/// Based on operator<
template <class DV>
inline
bool ConstDataVector<DV>::operator<= (const ConstDataVector& b) const
{
  return static_cast<const DV&>(*this) <= static_cast<const DV&>(b);
}
 
 
/// Based on operator<
template <class DV>
inline
bool ConstDataVector<DV>::operator>= (const ConstDataVector& b) const
{
  return static_cast<const DV&>(*this) >= static_cast<const DV&>(b);
}
 
 
/**
 * @brief  Vector equality comparison.
 * @param  b  A @c ConstDataVector of the same type as @a *this.
 * @return  True iff the size and elements of the vectors are equal.
 *
 * This is an equivalence relation.  It is linear in the size of the
 * vectors.  Vectors are considered equivalent if their sizes are equal,
 * and if corresponding elements compare equal.
 */
template <class DV>
inline
bool ConstDataVector<DV>::operator== (const ConstDataVector& b) const
{
  return static_cast<const DV&>(*this) == static_cast<const DV&>(b);
}
 
 
/// Based on operator==
template <class DV>
inline
bool ConstDataVector<DV>::operator!= (const ConstDataVector& b) const
{
  return static_cast<const DV&>(*this) != static_cast<const DV&>(b);
}
 
 
//=== Private helpers.
 
 
/**
 * @brief Handle element assignment.
 * @param pos Position in the container to assign.
 * @param newElem The new element to assign.
 *
 * The old element is freed if this container owns elements.
 * Auxiliary data are copied if appropriate.
 */
template <class DV>
inline
void
ConstDataVector<DV>::assignElement (typename BaseContainer::iterator pos,
                                    value_type newElem)
{
  typename DV::value_type pelem ATLAS_THREAD_SAFE =
    const_cast<typename DV::value_type> (newElem);
  DV::assignElement (pos, pelem);
}
 
 
/**
 * @brief Handle element assignment.
 * @param pos Position in the container to assign.
 * @param newElem The new element to assign.
 *
 * The container must own its elements.
 * Auxiliary data are copied if appropriate.
 */
template <class DV>
inline
void
ConstDataVector<DV>::assignElement (typename BaseContainer::iterator pos,
                                    std::unique_ptr<const base_value_type> newElem)
{
  typename DV::value_type pelem ATLAS_THREAD_SAFE =
    const_cast<typename DV::value_type> (newElem.release());
  std::unique_ptr<typename DV::base_value_type> new_u (pelem);
  DV::assignElement (pos, std::move(new_u));
}
 
 
/**
 * @brief Handle element assignment from a base pointer.
 * @param pos Position in the container to assign.
 * @param newElem The new element to assign.
 *
 * The old element is freed if this container owns elements.
 * Auxiliary data are copied if appropriate.
 */
template <class DV>
inline
void
ConstDataVector<DV>::assignBaseElement (typename BaseContainer::iterator pos,
                                        typename BaseContainer::value_type newElem)
{
  DV::assignBaseElement (pos, newElem);
}
 
 
/**
 * @brief Convert a @c ConstDataVector::iterator to an iterator
 *        of the base @c DataVector.
 * @param it The @c ConstDataVector::iterator to convert.
 */
template <class DV>
inline
typename DV::iterator
ConstDataVector<DV>::to_base_iterator (iterator it)
{
  return typename DV::iterator (it.base(), it.container());
}
 
 
/**
 * @brief Convert an iterator of the base @c DataVector to
 *        a @c ConstDataVector::iterator.
 * @param it The base @c DataVector iterator to convert.
 */
template <class DV>
inline
typename ConstDataVector<DV>::iterator
ConstDataVector<DV>::to_my_iterator (typename DV::iterator it)
{
  return iterator (it.base(), this);
}
 
 
/**
 * @brief Convert an iterator of the base @c vector
 *        an @c ElementProxy for the @c ConstDataVector.
 * @param it The base @c vector iterator to convert.
 */
template <class DV>
inline
typename ConstDataVector<DV>::ElementProxy
ConstDataVector<DV>::to_element_proxy (typename BaseContainer::iterator i)
{
  return ElementProxy (i, this);
}
 
 
//=== Other helper classes.
 
 
#ifndef XAOD_STANDALONE
 
 
/**
 * @brief Constructor from a payload object.
 * @param data Object to hold in the bucket.
 */
namespace SG {
 
 
template <class DV>
DVLConstDataVectorBucket<DV>::DVLConstDataVectorBucket
  (ConstDataVector<DV>* data)
    : DVLDataBucket<DV>
      ([] (const DV* dv) { DV* dv_nc ATLAS_THREAD_SAFE = const_cast<DV*> (dv);
                           return dv_nc; }
        (data->asDataVector()))
{
}
 
 
/**
 * @brief Constructor from a payload object.
 * @param data Object to hold in the bucket.
 */
template <class DV>
DVLConstDataVectorBucket<DV>::DVLConstDataVectorBucket
  (std::unique_ptr<ConstDataVector<DV> > data)
    : DVLDataBucket<DV> (std::unique_ptr<DV>
                         ([] (const DV* dv) { DV* dv_nc ATLAS_THREAD_SAFE = const_cast<DV*> (dv);
                           return dv_nc; }
                           (data.release()->asDataVector())))
{
}
 
 
} // namespace SG
 
 
#endif // not XAOD_STANDALONE