TruthParticleChildAssociationTool.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
 
#include "TruthParticleChildAssociationTool.h"
#include "xAODTruth/TruthVertex.h"
#include "AthenaKernel/errorcheck.h"
#include "TruthUtils/MagicNumbers.h"
 
namespace D3PD {
 

TruthParticleChildAssociationTool::TruthParticleChildAssociationTool
  (const std::string& type,
   const std::string& name,
   const IInterface* parent)
    : Base (type, name, parent),
      m_i (0)
{}
 

StatusCode TruthParticleChildAssociationTool::initialize()
{
  return Base::initialize();
}
 

StatusCode
TruthParticleChildAssociationTool::reset (const xAOD::TruthParticle& p)
{
  m_i = 0;
  m_xaod_children.clear();
 
  const xAOD::TruthVertex* vx = p.decayVtx();
  if (!vx) {
    return StatusCode::SUCCESS;
  }
 
  size_t sz = vx->nOutgoingParticles();
  m_xaod_children.reserve (sz);
  for (unsigned int i = 0; i < sz; i++) {
    const xAOD::TruthParticle* p2 = vx->outgoingParticle (i);
    if (p2)
      m_xaod_children.push_back(p2);
  }
  std::sort (m_xaod_children.begin(), m_xaod_children.end(), [](const auto & a, const auto & b) -> bool{ return HepMC::uniqueID(a) < HepMC::uniqueID(b); }); // FIXME barcode-based - NB ordering may change when this function switches to return id rather than barcode
  return StatusCode::SUCCESS;
}
 

const xAOD::TruthParticle* TruthParticleChildAssociationTool::next()
{
  if (m_i < m_xaod_children.size())
    return m_xaod_children[m_i++];
  return 0;
}
 
 
} // namespace D3PD