DataLinkBase.icc

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/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/
/**
 * @file AthLinks/DataLinkBase.icc
 * @author scott snyder <snyder@bnl.gov>
 * @date Mar, 2014
 * @brief Type-independent part of @c DataLink; holds the persistent state.
 */
 
#include "AthenaKernel/proxyDictFromEventContext.h"
 
/**
 * @brief Test to see if we're in the default state.
 */
inline
bool DataLinkBase::isDefault() const
{
  return m_persKey == 0 && m_proxy.isDefault();
}
 
 
/**
 * @brief Return the SG key that we reference, as a string.
 *
 * Returns a null string on failure.
 */
inline
const DataLinkBase::ID_type& DataLinkBase::dataID() const
{
  return m_proxy.dataID();
}
 
 
/**
 * @brief Return the SG key that we reference, as a hash.
 *
 * Returns 0 on failure.
 */
inline
DataLinkBase::sgkey_t DataLinkBase::key() const
{
  return m_persKey;
}
 
 
/**
 * @brief Clear the link (make it null).
 */
inline
void DataLinkBase::clear()
{
  m_persKey = 0;
  m_proxy.clear();
}
 
 
/**
 * @brief Return the @c DataProxy for this link.
 * @param nothrow If true, return 0 on failure instead of throwing
 *                an exception.
 *
 * If this is a null link, we return 0.
 * If we're directly referencing an object that's not in StoreGate,
 * either return 0 or throw @c ExcPointerNotInSG, depending
 * on @c nothrow.  Otherwise, return the proxy for the object
 * we're referencing.
 */
inline
SG::DataProxy* DataLinkBase::proxy (bool nothrow /*= false*/) const
{
  return m_proxy.proxy (nothrow);
}
 
 
/**
 * @brief Return the data source for this reference.
 */
inline
IProxyDict* DataLinkBase::source() const
{
  return m_proxy.source();
}
 
 
/**
 * @brief Finish initialization after link has been read.
 * @param sg Associated store.
 *
 * This should be called after a link has been read by root
 * in order to set the proxy pointer.
 * Returns true on success.
 *
 * If @c sg is 0, then we use the global default store.
 */
inline
bool DataLinkBase::toTransient (IProxyDict* sg /*= 0*/)
{
  m_proxy.toTransient (m_persKey, sg);
  return true;
}
 
 
/**
 * @brief Finish initialization after link has been read.
 * @param ctx Event context for this link.
 *
 * This should be called after a link has been read by root
 * in order to set the proxy pointer.
 * Returns true on success.
 */
inline
bool DataLinkBase::toTransient (const EventContext& ctx)
{
  m_proxy.toTransient (m_persKey, Atlas::proxyDictFromEventContext(ctx));
  return true;
}
 
 
/**
 * @brief Finish initialization like the link as just been read from root,
 *        but with a specified key.
 * @param dataID Key of the object.
 * @param link_clid CLID of the link being set.
 * @param sg Associated store.
 *
 * The link should be clear before this is called.
 * Returns true.
 *
 * If @c sg is 0, then we use the global default store.
 */
inline
bool DataLinkBase::toTransient (const ID_type& dataID,
                                CLID link_clid,
                                IProxyDict* sg /*= 0*/)
{
  if (!isDefault()) SG::throwExcBadToTransient();
  m_persKey = m_proxy.toTransient (dataID, link_clid, sg);
  return true;
}
 
 
/**
 * @brief Finish initialization like the link as just been read from root,
 *        but with a specified key.
 * @param dataID Key of the object.
 * @param link_clid CLID of the link being set.
 * @param ctx Event context for this link.
 *
 * The link should be clear before this is called.
 * Returns true.
 */
inline
bool DataLinkBase::toTransient (const ID_type& dataID,
                                CLID link_clid,
                                const EventContext& ctx)
{
  if (!isDefault()) SG::throwExcBadToTransient();
  m_persKey = m_proxy.toTransient (dataID, link_clid, Atlas::proxyDictFromEventContext(ctx));
  return true;
}
 
 
/**
 * @brief Prepare this link for writing.
 *
 * One of the @c toPersistent methods should be called before
 * trying to write the link with root.
 *
 * Ensures the hashed SG key to be saved is correct.
 * If this link is referencing an object not in SG,
 * we throw @c ExcPointerNotInSG.
 *
 * Returns true.
 *
 * This version does not perform link remapping.
 */
inline
bool DataLinkBase::toPersistent()
{
  size_t dum = 0;
  m_proxy.toPersistent (m_persKey, dum);
  return true;
}
 
 
/**
 * @brief Prepare this link for writing.
 *
 * One of the @c toPersistent methods should be called before
 * trying to write the link with root.
 *
 * Ensures the hashed SG key to be saved is correct.
 * If this link is referencing an object not in SG,
 * we throw @c ExcPointerNotInSG.
 *
 * This version does not perform link remapping.
 *
 * Returns true.
 */
inline
bool DataLinkBase::toPersistentNoRemap()
{
  m_proxy.toPersistentNoRemap (m_persKey);
  return true;
}
 
 
/**
 * @brief Compare for equality.
 */
inline
bool DataLinkBase::operator== (const DataLinkBase& other) const
{
  if (m_persKey != 0 && other.m_persKey != 0)
    return SG::sgkeyEqual (m_persKey, other.m_persKey);
  return (m_proxy == other.m_proxy);
}
 
 
/**
 * @brief Compare for inequality.
 */
inline
bool DataLinkBase::operator!= (const DataLinkBase& other) const
{
  return !(*this == other);
}
 
 
//****************************************************************************
 
 
 
/**
 * @brief Default constructor.
 */
inline
DataLinkBase::DataLinkBase()
  : m_persKey(0)
{
}
 
 
/**
 * @brief Constructor from pointer to object.
 * @param obj Pointer to the object.
 * @param link_clid CLID of the link being set.
 * @param sg Associated store.
 *
 * If @c sg is 0, we take the global default.
 *
 * May throw @c ExcCLIDMismatch.
 */
inline
DataLinkBase::DataLinkBase (const_pointer_t obj,
                            CLID link_clid,
                            IProxyDict* sg)
{
  toStorableObject (obj, link_clid, sg);
}
 
 
/**
 * @brief Constructor from a string key.
 * @param dataID Key of the object.
 * @param link_clid CLID of the link being set.
 * @param sg Associated store.
 *
 * If @c sg is 0, we take the global default.
 *
 * May throw @c ExcCLIDMismatch.
 */
inline
DataLinkBase::DataLinkBase (const ID_type& dataID,
                            CLID link_clid,
                            IProxyDict* sg)
{
  toIdentifiedObject (dataID, link_clid, sg);
}
 
 
/**
 * @brief Constructor from a hashed key.
 * @param key Hashed key of the object.
 * @param link_clid CLID of the link being set.
 * @param sg Associated store.
 *
 * If @c sg is 0, we take the global default.
 *
 * May throw @c ExcCLIDMismatch.
 */
inline
DataLinkBase::DataLinkBase (sgkey_t key, CLID link_clid, IProxyDict* sg)
{
  toIdentifiedObject (key, link_clid, sg);
}
 
 
/**
 * @brief Constructor from a hashed key and a proxy holder object.
 *        Used internally for EL -> DL conversion.
 * @param key Hashed key of the object.
 * @param holder Internal holder object for the proxy.
 */
inline
DataLinkBase::DataLinkBase (sgkey_t key, const SG::DataProxyHolder& holder)
  : m_persKey (key),
    m_proxy (holder)
{
}
 
 
/**
 * @brief Set the link to an object given by a pointer.
 * @param obj Pointer to the object.
 * @param link_clid CLID of the link being set.
 * @param sg Associated store.
 * @returns The SG key for this object.
 *
 * 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.
 *
 * May throw @c ExcCLIDMismatch.
 */
inline
void DataLinkBase::toStorableObject (const_pointer_t obj,
                                     CLID link_clid,
                                     IProxyDict* sg)
{
  m_persKey = m_proxy.toStorableObject (obj, link_clid, sg);
}
 
 
/**
 * @brief Set the link to an object given by a string key.
 * @param dataID Key of the object.
 * @param link_clid CLID of the link being set.
 * @param sg Associated store.
 * @returns The SG key for this object.
 *
 * 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.
 */
inline
void DataLinkBase::toIdentifiedObject (const ID_type& dataID,
                                       CLID link_clid,
                                       IProxyDict* sg)
{
  m_persKey = m_proxy.toIdentifiedObject (dataID, link_clid, sg);
}
 
 
/**
 * @brief Set the link to an object given by a hashed key.
 * @param key Hashed key of the object.
 * @param link_clid CLID of the link being set.
 * @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.
 *
 * May throw @c ExcCLIDMismatch.
 */
inline
void DataLinkBase::toIdentifiedObject (sgkey_t key,
                                       CLID link_clid,
                                       IProxyDict* sg)
{
  m_persKey = key;
  m_proxy.toIdentifiedObject (key, link_clid, sg);
}
 
 
/**
 * @brief Return a pointer to the currently-referenced object.
 * @param castfn Function to do the cast from data proxy to object.
 *               If 0, use a dynamic cast.
 * @param clid The CLID of the desired object.
 *             This is used to determine how the returned pointer
 *             is to be converted.
 * @param isConst True if the returned object will be treated as const.
 * @return A pointer to an object of the type given by @a clid,
 *         or null on a failure (or if the reference is null).
 */
inline
void* DataLinkBase::storableBase (castfn_t* castfn,
                                  const CLID& clid,
                                  bool isConst) const
{
  return m_proxy.storableBase (castfn, clid, isConst);
}
 
 
/**
 * @brief Throw a @c ExcInvalidLink exception for this link.
 * @param sgkey The hashed key for this link.
 *
 * This will fill in parameters for the exception message from the proxy.
 */
inline
void DataLinkBase::throwInvalidLink() const
{
  m_proxy.throwInvalidLink(m_persKey);
}