AtomicConstAccessor.icc

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// This file's extension implies that it's C, but it's really -*- C++ -*-.
/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
/**
 * @file AthContainers/tools/AtomicConstAccessor.icc
 * @author scott snyder <snyder@bnl.gov>
 * @date Apr, 2018
 * @brief Access an auxiliary variable atomically.
 */
 
 
namespace SG {
 
 
/**
 * @brief Constructor.
 * @param name Name of this aux variable.
 *
 * The name -> auxid lookup is done here.
 */
template <class T, class ALLOC>
inline
AtomicConstAccessor<T, ALLOC>::AtomicConstAccessor (const std::string& name)
  : Base (name, "", SG::AuxVarFlags::Atomic)
{
}
 
 
/**
 * @brief Constructor.
 * @param name Name of this aux variable.
 * @param clsname The name of its associated class.  May be blank.
 *
 * The name -> auxid lookup is done here.
 */
template <class T, class ALLOC>
inline
AtomicConstAccessor<T, ALLOC>::AtomicConstAccessor (const std::string& name,
                                                    const std::string& clsname)
  : Base (name, clsname, SG::AuxVarFlags::Atomic)
{
}
 
 
/**
 * @brief Constructor taking an auxid directly.
 * @param auxid ID for this auxiliary variable.
 *
 * Will throw @c SG::ExcAuxTypeMismatch if the types don't match.
 */
template <class T, class ALLOC>
inline
AtomicConstAccessor<T, ALLOC>::AtomicConstAccessor (const SG::auxid_t auxid)
  : Base (auxid, SG::AuxVarFlags::Atomic)
{
}
 
 
/**
 * @brief Fetch the variable for one element, as a const reference.
 * @param e The element for which to fetch the variable.
 *
 * As this class can be used only read-only for basic types, return
 * the result by value.  That makes it easier to call from python.
 */
template <class T, class ALLOC>
template <IsConstAuxElement ELT>
inline
T AtomicConstAccessor<T, ALLOC>::operator() (const ELT& e) const
{
  return reinterpret_cast<const_reference_type> (Base::operator() (e));
}
 
 
/**
 * @brief Fetch the variable for one element, as a const reference.
 * @param container The container from which to fetch the variable.
 * @param index The index of the desired element.
 *
 * This allows retrieving aux data by container / index.
 * Looping over the index via this method will be faster then
 * looping over the elements of the container.
 *
 * As this class can be used only read-only for basic types, return
 * the result by value.  That makes it easier to call from python.
 */
template <class T, class ALLOC>
inline
T AtomicConstAccessor<T, ALLOC>::operator() (const AuxVectorData& container,
                                             size_t index) const
{
  return reinterpret_cast<const_reference_type> (Base::operator() (container, index));
}
 
 
/**
 * @brief Get a pointer to the start of the auxiliary data array.
 * @param container The container from which to fetch the variable.
 */
template <class T, class ALLOC>
inline
auto
AtomicConstAccessor<T, ALLOC>::getDataArray (const AuxVectorData& container) const
  -> const_container_pointer_type
{
  return reinterpret_cast<const_container_pointer_type>
    (container.getDataArray (Base::auxid()));
}
 
 
} // namespace SG