GeoNodePath.cxx

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// LArSoft libraries
#include "larcorealg/Geometry/GeoNodePath.h"

// ROOT libraries
#include "TGeoNode.h"

// Boost includes
#include "boost/functional/hash.hpp"

// C++ STL libraries
#include <iostream>

namespace {
  std::size_t combine(std::size_t a, std::size_t const b)
  {
    boost::hash_combine(a, b);
    return a;
  }

  std::hash<TGeoNode const*> node_hash;
  geo::GeoNodePath::Entry entry_for(TGeoNode const* node)
  {
    return {node, node_hash(node)};
  }
  geo::GeoNodePath::Entry entry_for(geo::GeoNodePath::Entry const& parent, TGeoNode const* node)
  {
    return {node, combine(parent.hash_value, node_hash(node))};
  }
}

namespace geo {

  GeoNodePath::GeoNodePath(TGeoNode const* topNode) : fNodes{entry_for(topNode)} {}

  bool GeoNodePath::empty() const
  {
    return fNodes.empty();
  }

  GeoNodePath::Depth_t GeoNodePath::depth() const
  {
    return fNodes.size();
  }

  TGeoNode const* GeoNodePath::current() const
  {
    return current_entry().node;
  }

  auto GeoNodePath::current_entry() const -> Entry
  {
    return fNodes.back();
  }

  auto GeoNodePath::parent_entry() const -> Entry
  {
    if (auto const size = depth(); size > 1ull) { return fNodes[size - 2ull]; }
    return {};
  }

  void GeoNodePath::append(TGeoNode const* node)
  {
    auto entry = empty() ? entry_for(node) : entry_for(current_entry(), node);
    fNodes.push_back(std::move(entry));
  }

  void GeoNodePath::pop()
  {
    fNodes.pop_back();
  }

  GeoNodePath::operator std::string() const
  {
    std::string s = "[";
    auto it = fNodes.cbegin(), end = fNodes.cend();
    if (it != end) {
      s += it->node->GetName();
      while (++it != fNodes.cend()) {
        s += '/';
        s += it->node->GetName();
      }
    } // if
    return s + ']';
  }
}