AthLinks/ElementLink.icc

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/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/
/**
 * @file AthLinks/ElementLink.h
 * @author scott snyder <snyder@bnl.gov>
 * @date Apr, 2014
 * @brief a persistable pointer to an element of a STORABLE (data object)
 */
 
 
#include "AthLinks/exceptions.h"
#include "AthenaKernel/proxyDictFromEventContext.h"
#include "AthenaKernel/IProxyDict.h"
 
 
/**
 * @brief Return the CLID for the class that we reference.
 */
template <class STORABLE>
inline
const CLID& ElementLink<STORABLE>::classID()
{
  return ClassID_traits<value_type>::ID(); 
}
 
 
/**
 * @brief Default constructor.  Makes a null link.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink()
{
}
 
 
/**
 * @brief Construct a link from a string storable key and an index.  O(1)
 * @param dataID Key of the object.
 * @param elemID The index of the element within the container.
 * @param sg Associated store.
 *
 * If @c sg is 0, we take the global default.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink(const ID_type& dataID, index_type elemID, 
                                   IProxyDict* sg /*= 0*/)
  : Base (dataID, classID(), elemID, sg)
{
}
 
 
/**
 * @brief Construct a link from a string storable key and an index.  O(1)
 * @param dataID Key of the object.
 * @param elemID The index of the element within the container.
 * @param ctx Event context for this link.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink(const ID_type& dataID, index_type elemID, 
                                   const EventContext& ctx)
  : Base (dataID, classID(), elemID, Atlas::proxyDictFromEventContext(ctx))
{
}
 
 
/**
 * @brief Construct a link from a hashed storable key and an index.  O(1)
 * @param key Hashed key of the object.
 * @param elemID The index of the element within the container.
 * @param sg Associated store.
 *
 * If @c sg is 0, we take the global default.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink(sgkey_t key, index_type elemID, 
                                   IProxyDict* sg /*= 0*/)
  : Base (key, classID(), elemID, sg)
{
}
 
 
/**
 * @brief Construct a link from a hashed storable key and an index.  O(1)
 * @param key Hashed key of the object.
 * @param elemID The index of the element within the container.
 * @param ctx Event context for this link.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink(sgkey_t key, index_type elemID, 
                                   const EventContext& ctx)
  : Base (key, classID(), elemID, Atlas::proxyDictFromEventContext(ctx))
{
}
 
 
/**
 * @brief Construct from a string storable key, index, AND pointer to element.  O(1)
 * @param dataID Key of the object.
 * @param elemID The index of the element within the container.
 * @param pEl Pointer to the element.
 * @param sg Associated store.
 * 
 * USE CAREFULLY: no coherency checks, we just trust you!
 *
 * If @c sg is 0, we take the global default.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink(const ID_type& dataID,
                                   index_type elemID,
                                   ElementType pEl,
                                   IProxyDict* sg /*= 0*/)
  : Base (dataID, classID(), elemID, pEl, sg)
{
}
 
 
/**
 * @brief Construct from a string storable key, index, AND pointer to element.  O(1)
 * @param dataID Key of the object.
 * @param elemID The index of the element within the container.
 * @param pEl Pointer to the element.
 * @param ctx Event context for this link.
 * 
 * USE CAREFULLY: no coherency checks, we just trust you!
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink(const ID_type& dataID,
                                   index_type elemID,
                                   ElementType pEl,
                                   const EventContext& ctx)
  : Base (dataID, classID(), elemID, pEl, Atlas::proxyDictFromEventContext(ctx))
{
}
 
 
/**
 * @brief Construct from a hashed storable key, index, AND pointer to element.  O(1)
 * @param key Hashed key of the object.
 * @param elemID The index of the element within the container.
 * @param pEl Pointer to the element.
 * @param sg Associated store.
 * 
 * USE CAREFULLY: no coherency checks, we just trust you!
 *
 * If @c sg is 0, we take the global default.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink (sgkey_t key,
                                    index_type elemID,
                                    ElementType pEl,
                                    IProxyDict* sg /*= 0*/)
  : Base (key, classID(), elemID, pEl, sg)
{
}
 
 
/**
 * @brief Construct from a hashed storable key, index, AND pointer to element.  O(1)
 * @param key Hashed key of the object.
 * @param elemID The index of the element within the container.
 * @param pEl Pointer to the element.
 * @param ctx Event context for this link.
 * 
 * USE CAREFULLY: no coherency checks, we just trust you!
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink (sgkey_t key,
                                    index_type elemID,
                                    ElementType pEl,
                                    const EventContext& ctx)
  : Base (key, classID(), elemID, pEl, Atlas::proxyDictFromEventContext(ctx))
{
}
 
 
/**
 * @brief Construct a link from an index and reference to the container. O(1)
 * @param data Reference to the container (storable).
 * @param elemID The index of the element within the container.
 * @param sg Associated store.
 * 
 * If @c sg is 0, we take the global default.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink (BaseConstReference data,
                                    index_type elemID, 
                                    IProxyDict* sg /* = 0*/)
  : Base (&data, classID(), elemID, sg)
{
}
 
 
/**
 * @brief Construct a link from an index and reference to the container. O(1)
 * @param data Reference to the container (storable).
 * @param elemID The index of the element within the container.
 * @param ctx Event context for this link.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink (BaseConstReference data,
                                    index_type elemID, 
                                    const EventContext& ctx)
  : Base (&data, classID(), elemID, Atlas::proxyDictFromEventContext(ctx))
{
}
 
 
/**
 * @brief Construct from an element and reference to the container. O(N)
 * @param element The element to reference.
 * @param data Reference to the container (storable).
 * @param sg Associated store.
 *
 * Does the same thing as the default ctor followed by @c toContainedElement.
 * Note the reversed parameter order compared to the previous
 * constructor.  This is to prevent ambiguities in the case that
 * the contained type is convertable to an int.
 *
 * Will throw @c SG::ExcElementNotFound if the element is not
 * in the container.
 * 
 * If @c sg is 0, we take the global default.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink (const ElementType& element, 
                                    BaseConstReference data,
                                    IProxyDict* sg /*= 0*/)
{
  toContainedElement (data, element, sg);
}
 
 
/**
 * @brief Construct from an element and reference to the container. O(N)
 * @param element The element to reference.
 * @param data Reference to the container (storable).
 * @param ctx Event context for this link.
 *
 * Does the same thing as the default ctor followed by @c toContainedElement.
 * Note the reversed parameter order compared to the previous
 * constructor.  This is to prevent ambiguities in the case that
 * the contained type is convertable to an int.
 *
 * Will throw @c SG::ExcElementNotFound if the element is not
 * in the container.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink (const ElementType& element, 
                                    BaseConstReference data,
                                    const EventContext& ctx)
{
  toContainedElement (data, element, ctx);
}
 
 
/**
 * @brief Construct a link from another link, changing the index.
 * @param other The source link.
 * @param elemID The index for the new link.
 *
 * The index being constructed will reference the same container
 * as @c other, but it will refer to element @c elemID.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink (const ElementLink& other,
                                    index_type elemID)
  : Base (other, elemID)
{
}
 
 
/**
 * @brief Construct a link from a DataLink and an index.
 * @param dlink Link to the container.
 * @param index The index of the element within the container.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::ElementLink (const DataLink<STORABLE>& dlink,
                                    index_type index)
  : Base (dlink, index)
{
}
 
 
/**
 * @brief Constructor allowing a derived -> base conversion.
 */
template <class STORABLE>
template <class U>
inline
ElementLink<STORABLE>::ElementLink (const ElementLink<U>& other)
  : Base (other,
          (SG::ElementLinkTraits<U>*)0,
          (Traits*)0)
{
}
 
 
/**
 * @brief Return a pointer to the currently-referenced container object.
 * @return A pointer to an object of the type given by @a clid,
 *         or null on a failure (or if the reference is null).
 */
template <class STORABLE>
inline
typename ElementLink<STORABLE>::const_pointer
ElementLink<STORABLE>::getDataPtr() const
{
  return reinterpret_cast<const_pointer> (this->storable());
}
 
 
/**
 * @brief Return a pointer to the currently-referenced container object.
 * @return A pointer to an object of the type given by @a clid,
 *         or null on a failure (or if the reference is null).
 */
template <class STORABLE>
inline
typename ElementLink<STORABLE>::pointer
ElementLink<STORABLE>::getDataNonConstPtr()
{
  return reinterpret_cast<pointer> (this->storableNonConst());
}
 
 
/**
 * @brief Return a link to the currently-referenced container object.
 */
template <class STORABLE>
inline
DataLink<STORABLE> ElementLink<STORABLE>::getDataLink()
{
  return DataLink<STORABLE> (this->key(), this->proxyHolder());
}
 
 
/**
 * @brief Return a link to the currently-referenced container object.
 */
template <class STORABLE>
inline
const DataLink<STORABLE> ElementLink<STORABLE>::getDataLink() const
{
  return DataLink<STORABLE> (this->key(), this->proxyHolder());
}
 
 
/**
 * @brief Return a pointer to the currently-referenced container object.
 */
template <class STORABLE>
inline
typename ElementLink<STORABLE>::BaseConstPointer
ElementLink<STORABLE>::getStorableObjectPointer() const
{
  return getDataPtr();
}
 
 
/**
 * @brief Return a reference to the currently-referenced container object.
 */
template <class STORABLE>
inline
typename ElementLink<STORABLE>::BaseConstReference
ElementLink<STORABLE>::getStorableObjectRef() const
{
  return *getDataPtr();
}
 
 
/**
 * @brief Return a pointer to the referenced element.
 *
 * Be aware: if the element is a pointer, then this will yield
 * a pointer to a pointer.
 */
template <class STORABLE>
inline
typename ElementLink<STORABLE>::ElementConstPointer
ElementLink<STORABLE>::cptr() const
{
  ElementConstPointer ret = 0;
  if (this->getCachedElement (ret))
    return ret;
 
  const STORABLE* ptr = this->getDataPtr();
  if (ptr && IndexingPolicy::isValid(this->storedIndex())) {
    this->setCachedElement (IndexingPolicy::lookup(this->storedIndex(), *ptr));
    this->getCachedElement (ret);
  }
  return ret;
}
 
 
/**
 * @brief Return a reference to the referenced element.
 *
 * Will throw an exception if the link is not valid.
 */
template <class STORABLE>
inline
typename ElementLink<STORABLE>::ElementConstReference
ElementLink<STORABLE>::operator* () const
{
  ElementConstPointer ptr = cptr();
  if (!ptr)
    SG::throwExcInvalidLink (classID(), this->dataID(), this->key());
  return *ptr;
}
 
 
/**
 * @brief Return a pointer to the referenced element.
 */
template <class STORABLE>
inline
typename ElementLink<STORABLE>::ElementConstPointer
ElementLink<STORABLE>::operator->() const
{
  return cptr();
}
 
 
/**
 * @brief Convert to a pointer to the referenced element.
 */
template <class STORABLE>
inline
ElementLink<STORABLE>::operator ElementConstPointer () const
{
  return cptr();
}
 
 
/**
 * @brief Test to see if the link can be dereferenced.
 *
 * Will throw an exception if the container is not empty and the
 * referenced element cannot be retrieved.
 */
template <class STORABLE>
inline
bool ElementLink<STORABLE>::isValid() const
{
  // This used to just call cptr(), but that was leading to dangling-pointer
  // warnings with gcc12 when we were returning ElementLink's by value,
  // as in ElementLinkVector.  Doing it like this allows us to save
  // a little work, anyway.
  if (this->hasCachedElement()) return true;
 
  const STORABLE* ptr = this->getDataPtr();
  if (ptr && !ptr->empty() && IndexingPolicy::isValid(this->storedIndex())) {
    this->setCachedElement (IndexingPolicy::lookup(this->storedIndex(), *ptr));
    return true;
  }
  return false;
}
 
 
/**
 * @brief Test to see if the link can not be dereferenced.
 */
template <class STORABLE>
inline
bool ElementLink<STORABLE>::operator!() const
{
  return !isValid();
}
 
 
/**
 * @brief Return the cached element, if any.
 */
template <class STORABLE>
inline
typename ElementLink<STORABLE>::ElementType
ElementLink<STORABLE>::cachedElement() const
{ 
  ElementConstPointer ret = 0;
  if (this->getCachedElement (ret))
    return *ret;
  return ElementType();
}
 
 
/**
 * @brief Set the link to an element given by index and pointer to container.
 * @param data Reference to the container (storable).
 * @param elemID The index of the element within the container.
 * @param sg Associated store.
 * @returns True if the link was changed.
 *
 * If the link is already set, this will return false and leave the
 * link unchanged.
 *
 * If @c sg is 0, then we take the store from whatever the link's currently
 * set to.  If the link has no current store, then we take the global
 * default.
 */
template <class STORABLE>
inline
bool
ElementLink<STORABLE>::toIndexedElement(BaseConstReference data,
                                        index_type elemID,
                                        IProxyDict* sg /*= 0*/)
{
  return Base::toIndexedElement (&data, classID(), elemID, sg);
}
 
 
/**
 * @brief Set the link to an element given by index and pointer to container.
 * @param data Reference to the container (storable).
 * @param elemID The index of the element within the container.
 * @param ctx The event context.
 * @returns True if the link was changed.
 *
 * If the link is already set, this will return false and leave the
 * link unchanged.
 */
template <class STORABLE>
inline
bool
ElementLink<STORABLE>::toIndexedElement(BaseConstReference data,
                                        index_type elemID,
                                        const EventContext& ctx)
{
  return Base::toIndexedElement (&data, classID(), elemID, Atlas::proxyDictFromEventContext(ctx));
}
 
 
/**
 * @brief Set from element pointer and a reference to the container (storable)
 * @param data Reference to the container (storable).
 * @param element The element.
 * @param sg Associated store.
 * @returns True if the link was changed.
 *
 * O(N) for sequences!
 *
 * If the link is already set, this will return false and leave the
 * link unchanged.
 *
 * If @c sg is 0, then we take the store from whatever the link's currently
 * set to.  If the link has no current store, then we take the global
 * default.
 */
template <class STORABLE>
inline
bool ElementLink<STORABLE>::toContainedElement(BaseConstReference data,
                                               ElementType element,
                                               IProxyDict* sg /*= 0*/)
{
  index_type index = this->index();
  IndexingPolicy::reverseLookup (data, element, index);
  bool ret = Base::toIndexedElement (&data, classID(), index, sg);
  if (ret)
    this->storeCachedElement (element);
  return ret;
}
 
 
/**
 * @brief Set from element pointer and a reference to the container (storable)
 * @param data Reference to the container (storable).
 * @param element The element.
 * @param ctx The event context.
 * @returns True if the link was changed.
 *
 * O(N) for sequences!
 *
 * If the link is already set, this will return false and leave the
 * link unchanged.
 */
template <class STORABLE>
inline
bool ElementLink<STORABLE>::toContainedElement(BaseConstReference data,
                                               ElementType element,
                                               const EventContext& ctx)
{
  index_type index = this->index();
  IndexingPolicy::reverseLookup (data, element, index);
  bool ret = Base::toIndexedElement (&data, classID(), index, Atlas::proxyDictFromEventContext(ctx));
  if (ret)
    this->storeCachedElement (element);
  return ret;
}
 
 
/**
 * @brief Set to point to an element.
 * @param element The element.
 * @returns True if the link was changed.
 *
 * The collection and the element can be specified independently
 * using @c setElement and @c setStorableObject.
 *
 * If the link is already set, this will return false and leave the
 * link unchanged.
 */
template <class STORABLE>
inline
bool ElementLink<STORABLE>::setElement(ElementType element)
{
  if (!this->isDefaultIndex() || this->hasCachedElement())
    return false;
  this->storeCachedElement (element);
  const STORABLE* ptr = this->getDataPtr();
  if (ptr) {
    index_type index = this->index();
    IndexingPolicy::reverseLookup (*ptr, element, index);
    this->setIndex (index);
  }
  return true;
}
 
 
/**
 * @brief Set link to point to a new container (storable).
 * @param data Reference to the container (storable).
 * @param replace True if we can change an existing link.
 * @param sg Associated store.
 * @returns True if the link was changed.
 *
 * If the link is already set, this will return false and leave the
 * link unchanged unless @c replace is set.  The @c replace argument
 * should be set if the element is now in a new storable container;
 * e.g. element ptr has been put in a new view container.
 *
 * If @c sg is 0, then we take the store from whatever the link's currently
 * set to.  If the link has no current store, then we take the global
 * default.
 */
template <class STORABLE>
inline
bool ElementLink<STORABLE>::setStorableObject(BaseConstReference data,
                                              bool replace /*= false*/,
                                              IProxyDict* sg /*= 0*/)
{
  bool ret = Base::setStorableObject (&data, classID(), replace, sg);
  if (ret) {
    ElementConstPointer elt = 0;
    if (this->isDefaultIndex() && this->getCachedElement (elt)) {
      index_type index = this->index();
      IndexingPolicy::reverseLookup (data, *elt, index);
      this->setIndex (index);
      return true;
    }
  }
  return ret;
}
 
 
/**
 * @brief Set link to point to a new container (storable).
 * @param data Reference to the container (storable).
 * @param replace True if we can change an existing link.
 * @param ctx The event context.
 * @returns True if the link was changed.
 *
 * If the link is already set, this will return false and leave the
 * link unchanged unless @c replace is set.  The @c replace argument
 * should be set if the element is now in a new storable container;
 * e.g. element ptr has been put in a new view container.
 */
template <class STORABLE>
inline
bool ElementLink<STORABLE>::setStorableObject(BaseConstReference data,
                                              bool replace,
                                              const EventContext& ctx)
{
  bool ret = Base::setStorableObject (&data, classID(), replace, Atlas::proxyDictFromEventContext(ctx));
  if (ret) {
    ElementConstPointer elt = 0;
    if (this->isDefaultIndex() && this->getCachedElement (elt)) {
      index_type index = this->index();
      IndexingPolicy::reverseLookup (data, *elt, index);
      this->setIndex (index);
      return true;
    }
  }
  return ret;
}
 
 
/**
 * @brief Set the link to an element given by string key and index.
 * @param dataID Key of the object.
 * @param elemID The index of the element within the container.
 * @param sg Associated store.
 *
 * If @c sg is 0, then we take the store from whatever the link's currently
 * set to.  If the link has no current store, then we take the global
 * default.
 */
template <class STORABLE>
inline
void ElementLink<STORABLE>::resetWithKeyAndIndex(const ID_type& dataID,
                                                 index_type elemID, 
                                                 IProxyDict* sg /*= 0*/)
{
  Base::resetWithKeyAndIndex (dataID, classID(), elemID, sg);
}
 
 
/**
 * @brief Set the link to an element given by string key and index.
 * @param dataID Key of the object.
 * @param elemID The index of the element within the container.
 * @param ctx The event context.
 */
template <class STORABLE>
inline
void ElementLink<STORABLE>::resetWithKeyAndIndex(const ID_type& dataID,
                                                 index_type elemID,
                                                 const EventContext& ctx)
{
  Base::resetWithKeyAndIndex (dataID, classID(), elemID, Atlas::proxyDictFromEventContext(ctx));
}
 
 
/**
 * @brief Set the link to an element given by string key and index.
 * @param key Hashed key of the object.
 * @param elemID The index of the element within the container.
 * @param sg Associated store.
 *
 * If @c sg is 0, then we take the store from whatever the link's currently
 * set to.  If the link has no current store, then we take the global
 * default.
 */
template <class STORABLE>
inline
void ElementLink<STORABLE>::resetWithKeyAndIndex(sgkey_t key,
                                                 index_type elemID, 
                                                 IProxyDict* sg /*= 0*/)
{
  Base::resetWithKeyAndIndex (key, classID(), elemID, sg);
}
 
 
/**
 * @brief Set the link to an element given by string key and index.
 * @param key Hashed key of the object.
 * @param elemID The index of the element within the container.
 * @param ctx The event context.
 */
template <class STORABLE>
inline
void ElementLink<STORABLE>::resetWithKeyAndIndex(sgkey_t key,
                                                 index_type elemID, 
                                                 const EventContext& ctx)
{
  Base::resetWithKeyAndIndex (key, classID(), elemID, Atlas::proxyDictFromEventContext(ctx));
}
 
 
/**
 * @brief Return a (void) pointer to the currently-referenced
 *        container object.
 * @return A pointer to an object of the type given by @a clid,
 *         or null on a failure (or if the reference is null).
 */
template <class STORABLE>
inline
const void* ElementLink<STORABLE>::storable() const
{
  typedef STORABLE* fn_t (SG::DataProxy*);
  fn_t* fn = &SG::DataProxy_cast<STORABLE>;
  return this->storableBase (reinterpret_cast<castfn_t*> (fn), classID(), true);
}
 
 
/**
 * @brief Return a (void) pointer to the currently-referenced
 *        container object.
 * @return A pointer to an object of the type given by @a clid,
 *         or null on a failure (or if the reference is null).
 */
template <class STORABLE>
inline
void* ElementLink<STORABLE>::storableNonConst()
{
  typedef STORABLE* fn_t (SG::DataProxy*);
  fn_t* fn = &SG::DataProxy_cast<STORABLE>;
  return this->storableBase (reinterpret_cast<castfn_t*> (fn), classID(), false);
}
 
 
/**
 * @brief Ordering relation for @c ElementLink (less-than)
 * @param lhs Left-hand-side EL.
 * @param rhs Right-hand-side EL.
 */
template <typename STORABLE>
bool operator < (const ElementLink<STORABLE>& lhs,
         const ElementLink<STORABLE>& rhs)
{
  bool lhsDefault = lhs.isDefault();
  bool rhsDefault = rhs.isDefault();
  if (lhsDefault && rhsDefault) return false;
  if (lhsDefault) return true;
  if (rhsDefault) return false;
  if (lhs.key() == 0 || rhs.key() == 0 || lhs.isDefaultIndex() || rhs.isDefaultIndex())
    SG::throwExcIncomparableEL();
  if (SG::sgkeyLess (lhs.key(), rhs.key())) return true;
  if (SG::sgkeyLess (rhs.key(), lhs.key())) return false;
  if (lhs.index() < rhs.index()) return true;
  return false;
} 
 
 
/**
 * @brief Ordering relation for @c ElementLink (greater-than)
 * @param lhs Left-hand-side EL.
 * @param rhs Right-hand-side EL.
 */
template <typename STORABLE>
inline
bool operator > (const ElementLink<STORABLE>& lhs,
         const ElementLink<STORABLE>& rhs)
{
  return (rhs < lhs);
}
 
 
/**
 * @brief Equality relation for @c ElementLink.
 * @param lhs Left-hand-side EL.
 * @param rhs Right-hand-side EL.
 */
template <typename STORABLE>
inline
bool operator == (const ElementLink<STORABLE>& lhs,
          const ElementLink<STORABLE>& rhs)
{
  return !((lhs < rhs) || (rhs < lhs));
}
 
 
/**
 * @brief Inequality relation for @c ElementLink.
 * @param lhs Left-hand-side EL.
 * @param rhs Right-hand-side EL.
 */
template <typename STORABLE>
inline
bool operator != (const ElementLink<STORABLE>& lhs,
          const ElementLink<STORABLE>& rhs)
{
  return !(lhs == rhs);
}
 
 
namespace SG_detail {
 
 
/**
 * @brief See if an EL is being remapped.
 * @param sgkey_in Original hashed key of the EL.
 * @param index_in Original index of the EL.
 * @param sgkey_out[out] New hashed key for the EL.
 * @param index_out[out] New index for the EL.
 * @return True if there is a remapping; false otherwise.
 *
 * This version is for the case where the EL index is a @c size_t.
 * For other index types, the the templated version below is used
 * (which doesn't allow remapping indices).
 */
inline
bool checkForRemap (IProxyDict* sg,
                    SG::sgkey_t sgkey_in,
                    size_t index_in,
                    SG::sgkey_t& sgkey_out,
                    size_t& index_out)
{
  return sg->tryELRemap (sgkey_in, index_in, sgkey_out, index_out);
}
 
 
/**
 * @brief See if an EL is being remapped.
 * @param sgkey_in Original hashed key of the EL.
 * @param dum_in Ignored.
 * @param sgkey_out[out] New hashed key for the EL.
 * @param dum_out[out] Ignored.
 * @return True if there is a remapping; false otherwise.
 *
 * This version catches the cases where the container index type
 * isn't a @c size_t.  We don't support changing the index in this case.
 */
template <class T>
inline
bool checkForRemap (IProxyDict* sg,
                    SG::sgkey_t sgkey_in,
                    const T& /*dum_in*/,
                    SG::sgkey_t& sgkey_out,
                    T& /*dum_out*/)
{
  size_t index_in = 0;
  size_t index_out;
  return sg->tryELRemap (sgkey_in, index_in, sgkey_out, index_out);
}
 
 
} // namespace SG_detail