IntermediateHitTriplets.h

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#ifndef RecoPixelVertexing_PixelTriplets_IntermediateHitTriplets_h
#define RecoPixelVertexing_PixelTriplets_IntermediateHitTriplets_h

#include "RecoTracker/TkHitPairs/interface/LayerHitMapCache.h"
#include "RecoTracker/TkHitPairs/interface/IntermediateHitDoublets.h"
#include "TrackingTools/TransientTrackingRecHit/interface/SeedingLayerSetsHits.h"
#include "RecoPixelVertexing/PixelTriplets/interface/OrderedHitTriplets.h"

class IntermediateHitTriplets {
public:
  using LayerPair = std::tuple<SeedingLayerSetsHits::LayerIndex,
                               SeedingLayerSetsHits::LayerIndex>;
  using LayerTriplet = std::tuple<SeedingLayerSetsHits::LayerIndex,
                                  SeedingLayerSetsHits::LayerIndex,
                                  SeedingLayerSetsHits::LayerIndex>;
  using RegionIndex = ihd::RegionIndex;


  class PLayerHitTriplets {
  public:
    PLayerHitTriplets(const LayerTriplet& layerTriplet, unsigned int tripletsBegin):
      layerTriplet_(layerTriplet),
      tripletsBegin_(tripletsBegin), tripletsEnd_(tripletsBegin)
    {}

    void setTripletsEnd(unsigned int end) { tripletsEnd_ = end; }

    const LayerTriplet& layerTriplet() const { return layerTriplet_; }

    unsigned int tripletsBegin() const { return tripletsBegin_; }
    unsigned int tripletsEnd() const { return tripletsEnd_; }

  private:
    LayerTriplet layerTriplet_;
    unsigned int tripletsBegin_;
    unsigned int tripletsEnd_;
  };


  class LayerHitTriplets {
  public:
    using const_iterator = std::vector<OrderedHitTriplet>::const_iterator;

    LayerHitTriplets(const IntermediateHitTriplets *hitSets,
                     const PLayerHitTriplets *layerTriplet):
      hitSets_(hitSets),
      layerTriplet_(layerTriplet)
    {}

    using TripletRange = std::pair<std::vector<OrderedHitTriplet>::const_iterator,
                                   std::vector<OrderedHitTriplet>::const_iterator>;

    SeedingLayerSetsHits::LayerIndex innerLayerIndex() const { return std::get<0>(layerTriplet_->layerTriplet()); }
    SeedingLayerSetsHits::LayerIndex middleLayerIndex() const { return std::get<1>(layerTriplet_->layerTriplet()); }
    SeedingLayerSetsHits::LayerIndex outerLayerIndex() const { return std::get<2>(layerTriplet_->layerTriplet()); }

    const_iterator begin() const { return hitSets_->tripletsBegin() + layerTriplet_->tripletsBegin(); }
    const_iterator cbegin() const { return begin(); }
    const_iterator end() const { return hitSets_->tripletsBegin() + layerTriplet_->tripletsEnd(); }
    const_iterator cend() const { return end(); }

  private:
    const IntermediateHitTriplets *hitSets_;
    const PLayerHitTriplets *layerTriplet_;
  };


  class RegionLayerSets {
  public:
    using PLayerHitTripletsConstIterator = std::vector<PLayerHitTriplets>::const_iterator;
    using TripletConstIterator = std::vector<OrderedHitTriplet>::const_iterator;

    class const_iterator {
    public:
      using internal_iterator_type = PLayerHitTripletsConstIterator;
      using value_type = LayerHitTriplets;
      using difference_type = internal_iterator_type::difference_type;

      struct end_tag {};

      const_iterator(const IntermediateHitTriplets *hitSets, const RegionLayerSets *regionLayerSets):
        hitSets_(hitSets),
        regionLayerSets_(regionLayerSets),
        iter_(regionLayerSets->layerSetsBegin())
      {
        assert(regionLayerSets->layerSetsBegin() != regionLayerSets->layerSetsEnd());
      }

      const_iterator(const IntermediateHitTriplets *hitSets, const RegionLayerSets *regionLayerSets, end_tag):
        iter_(regionLayerSets->layerSetsEnd())
      {}

      value_type operator*() const {
        return value_type(hitSets_, &(*iter_));
      }

      const_iterator& operator++() {
        ++iter_;
        return *this;
      }

      const_iterator operator++(int) {
        const_iterator clone(*this);
        operator++();
        return clone;
      }

      bool operator==(const const_iterator& other) const { return iter_ == other.iter_; }
      bool operator!=(const const_iterator& other) const { return !operator==(other); }

    private:
      const IntermediateHitTriplets *hitSets_;
      const RegionLayerSets *regionLayerSets_;
      internal_iterator_type iter_;
    };

    RegionLayerSets(const TrackingRegion* region,
                    const LayerHitMapCache *cache,
                    const IntermediateHitTriplets *hitSets,
                    PLayerHitTripletsConstIterator tripletBegin,
                    PLayerHitTripletsConstIterator tripletEnd):
      region_(region),
      cache_(cache),
      hitSets_(hitSets),
      layerSetsBegin_(tripletBegin), layerSetsEnd_(tripletEnd)
    {}

    const TrackingRegion& region() const { return *region_; }
    const LayerHitMapCache& layerHitMapCache() const { return *cache_; }
    size_t layerTripletsSize() const { return std::distance(layerSetsBegin_, layerSetsEnd_); }

    const_iterator begin() const {
      if(layerSetsBegin_ != layerSetsEnd_)
        return const_iterator(hitSets_, this);
      else
        return end();
    }
    const_iterator cbegin() const { return begin(); }
    const_iterator end() const { return const_iterator(hitSets_, this, const_iterator::end_tag()); }
    const_iterator cend() const { return end(); }

    // used internally by the LayerHitTriplets helper class
    PLayerHitTripletsConstIterator layerSetsBegin() const { return layerSetsBegin_; }
    PLayerHitTripletsConstIterator layerSetsEnd() const { return layerSetsEnd_; }

  private:
    const TrackingRegion *region_ = nullptr;
    const LayerHitMapCache *cache_ = nullptr;
    const IntermediateHitTriplets *hitSets_ = nullptr;
    const PLayerHitTripletsConstIterator layerSetsBegin_;
    const PLayerHitTripletsConstIterator layerSetsEnd_;
  };


  using const_iterator = ihd::const_iterator<RegionLayerSets, IntermediateHitTriplets>;


  class RegionFiller {
  public:
    RegionFiller(): obj_(nullptr) {}
    explicit RegionFiller(IntermediateHitTriplets *obj): obj_(obj) {}

    ~RegionFiller() = default;

    bool valid() const { return obj_ != nullptr; }

    LayerHitMapCache& layerHitMapCache() { return obj_->regions_.back().layerHitMapCache(); }

    void addTriplets(const LayerPair& layerPair,
                     const std::vector<SeedingLayerSetsHits::SeedingLayer>& thirdLayers,
                     const OrderedHitTriplets& triplets,
                     const std::vector<int>& thirdLayerIndex,
                     const std::vector<size_t>& permutations) {
      assert(triplets.size() == thirdLayerIndex.size());
      assert(triplets.size() == permutations.size());

      if(triplets.empty()) {
        return;
      }

      int prevLayer = -1;
      for(size_t i=0, size=permutations.size(); i<size; ++i) {
        // We go through the 'triplets' in the order defined by
        // 'permutations', which is sorted such that we first go through
        // triplets from (3rd) layer 0, then layer 1 and so on.
        const size_t realIndex = permutations[i];

        const int layer = thirdLayerIndex[realIndex];
        if(layer != prevLayer) {
          prevLayer = layer;
          obj_->layerTriplets_.emplace_back(LayerTriplet(std::get<0>(layerPair), std::get<1>(layerPair), thirdLayers[layer].index()), obj_->hitTriplets_.size());
        }

        obj_->hitTriplets_.emplace_back(triplets[realIndex]);
        obj_->layerTriplets_.back().setTripletsEnd(obj_->hitTriplets_.size());
      }

      obj_->regions_.back().setLayerSetsEnd(obj_->layerTriplets_.size());
    }
  private:
    IntermediateHitTriplets *obj_;
  };

  // allows declaring local variables with auto
  static RegionFiller dummyFiller() { return RegionFiller(); }


  IntermediateHitTriplets(): seedingLayers_(nullptr) {}
  explicit IntermediateHitTriplets(const SeedingLayerSetsHits *seedingLayers): seedingLayers_(seedingLayers) {}
  IntermediateHitTriplets(const IntermediateHitTriplets& rh); // only to make ROOT dictionary generation happy
  IntermediateHitTriplets(IntermediateHitTriplets&&) = default;
  IntermediateHitTriplets& operator=(IntermediateHitTriplets&&) = default;
  ~IntermediateHitTriplets() = default;

  void reserve(size_t nregions, size_t nlayersets, size_t ntriplets) {
    regions_.reserve(nregions);
    layerTriplets_.reserve(nregions*nlayersets);
    hitTriplets_.reserve(ntriplets);
  }

  void shrink_to_fit() {
    regions_.shrink_to_fit();
    layerTriplets_.shrink_to_fit();
    hitTriplets_.shrink_to_fit();
  }

  RegionFiller beginRegion(const TrackingRegion *region) {
    regions_.emplace_back(region, layerTriplets_.size());
    return RegionFiller(this);
  }

  const SeedingLayerSetsHits& seedingLayerHits() const { return *seedingLayers_; }
  bool empty() const { return regions_.empty(); }
  size_t regionSize() const { return regions_.size(); }
  size_t tripletsSize() const { return hitTriplets_.size(); }

  const_iterator begin() const { return const_iterator(this, regions_.begin()); }
  const_iterator cbegin() const { return begin(); }
  const_iterator end() const { return const_iterator(this, regions_.end()); }
  const_iterator cend() const { return end(); }

  // used internally by all the helper classes
  std::vector<RegionIndex>::const_iterator regionsBegin() const { return regions_.begin(); }
  std::vector<RegionIndex>::const_iterator regionsEnd() const { return regions_.end(); }
  std::vector<PLayerHitTriplets>::const_iterator layerSetsBegin() const { return layerTriplets_.begin(); }
  std::vector<PLayerHitTriplets>::const_iterator layerSetsEnd() const { return layerTriplets_.end(); }
  std::vector<OrderedHitTriplet>::const_iterator tripletsBegin() const { return hitTriplets_.begin(); }
  std::vector<OrderedHitTriplet>::const_iterator tripletsEnd() const { return hitTriplets_.end(); }

private:
  const SeedingLayerSetsHits *seedingLayers_;    

  std::vector<RegionIndex> regions_;             
  std::vector<PLayerHitTriplets> layerTriplets_; 
  std::vector<OrderedHitTriplet> hitTriplets_;   
};

#endif