MapIndexingPolicy.icc

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
// $Id$
/**
 * @file AthLinks/tools/MapIndexingPolicy.icc
 * @author scott snyder <snyder@bnl.gov>
 * @date Apr, 2014
 * @brief Indexing policy for a set-like container.
 */
 
 
namespace SG {
 
 
/**
 * @brief Test to see if an index is valid.
 * @param index The index to test.
 */
template <CxxUtils::detail::PairAssociativeContainer MAP>
inline
bool MapIndexingPolicy<MAP>::isValid (const stored_index_type& index) 
{
  return index.isValid();
}
 
 
/**
 * @brief Convert from stored to external index types.
 * @param index The stored index.
 */
template <CxxUtils::detail::PairAssociativeContainer MAP>
inline
typename MapIndexingPolicy<MAP>::index_type
MapIndexingPolicy<MAP>::storedToExternal (stored_index_type index)
{
  return index;
}
 
 
/**
 * @brief Make an index invalid.
 * @param index[out] The index to reset.
 */
template <CxxUtils::detail::PairAssociativeContainer MAP>
inline
void MapIndexingPolicy<MAP>::reset (stored_index_type& index)
{
  index.reset();
}
  
 
/**
 * @brief Retrieve from a container the element corresponding to an index.
 * @param index The index to fetch.
 * @param data The container.
 *
 * Will throw SG::ExcInvalidIndex if the index is invalid and
 * SG::ExcIndexNotFound if the index is not in the container.
 */
template <CxxUtils::detail::PairAssociativeContainer MAP>
typename MapIndexingPolicy<MAP>::ElementType
MapIndexingPolicy<MAP>::lookup(const stored_index_type& index,
                               const MAP& data)
{
  if (!isValid(index))
    SG::throwExcInvalidIndex ("MapIndexingPolicy");
  const_iterator iter = data.find(index);
  if (iter == data.end()) 
    SG::throwExcIndexNotFound ("MapIndexingPolicy");
  return iter->second;
}
 
 
/**
 * @brief Find the index of the (first) instance of ELEMENT in DATA.
 * @param data The container to search.
 * @param element The element to find.
 * @param index[out] The index in the container of @c element.
 *
 * Throws SG::ExcElementNotFound if the element is not in the container.
 */
template <CxxUtils::detail::PairAssociativeContainer MAP>
void
MapIndexingPolicy<MAP>::reverseLookup(const MAP& data,
                                      ElementConstReference element,
                                      index_type& index) 
{
  //compiler checks we can compare elements
  static_assert(std::equality_comparable<ElementType>, "ElementType must support == and !=");
 
  // Note that reverseLookup will recalculate index even if m_valid is true.
  // Must ensure that index is write before persistency
  const_iterator it = data.begin();
  const_iterator iend = data.end();
  while (it != iend) {
    if (it->second == element) break;
    ++it;
  }
 
  if (it != iend) 
  {
    index = it->first ;
  }
  else {
    SG::throwExcElementNotFound ("reverseLookup");
  }
}
 
 
} // namespace SG