refactor!: Hard-code vertex fitter, finder + density combinations (#2952

)

They're not actually exchangeable, there's a 1:1 correspondence that they can be used in. Therefore, we don't need to template the finders on the only respective valid density.

- `AdaptiveGridDensityVertexFinder` => `AdaptiveGridTrackDensity`
- `AdaptiveMultiVertexFinder` => `AdaptiveMultiVertexFitter`
- `TrackDensityVertexFinder` => `GaussianTrackDensity`
- `IterativeVertexFinder` => `FullBilloirVertexFitter`

The main reason for this is that the vertex fitters and the track densities do not actually have common interfaces. This is probably desirable, but out of scope for this refactor, and should probably be implemented with an interface like `IVertexFinder`.

Part of:
- #2842 

Blocked by:
- #2951

Core/include/Acts/Vertexing/AdaptiveGridDensityVertexFinder.hpp

@@ -31,18 +31,16 @@ namespace Acts {
 /// Unlike the GridDensityVertexFinder, this seeder implements an adaptive
 /// version where the density grid grows bigger with added tracks.
 class AdaptiveGridDensityVertexFinder final : public IVertexFinder {
-  using GridDensity = AdaptiveGridTrackDensity;
-
  public:
-  using DensityMap = typename GridDensity::DensityMap;
+  using DensityMap = AdaptiveGridTrackDensity::DensityMap;
 
   /// @brief The Config struct
   struct Config {
     ///@param gDensity The grid density
-    Config(const GridDensity& gDensity) : gridDensity(gDensity) {}
+    Config(const AdaptiveGridTrackDensity& gDensity) : gridDensity(gDensity) {}
 
     // The grid density object
-    GridDensity gridDensity;
+    AdaptiveGridTrackDensity gridDensity;
 
     // Cache the main grid and the density contributions (trackGrid and z-bin)
     // for every single track.

Core/include/Acts/Vertexing/AdaptiveMultiVertexFinder.hpp

@@ -15,6 +15,7 @@
 #include "Acts/Utilities/Logger.hpp"
 #include "Acts/Utilities/Result.hpp"
 #include "Acts/Vertexing/AMVFInfo.hpp"
+#include "Acts/Vertexing/AdaptiveMultiVertexFitter.hpp"
 #include "Acts/Vertexing/IVertexFinder.hpp"
 #include "Acts/Vertexing/ImpactPointEstimator.hpp"
 #include "Acts/Vertexing/TrackLinearizer.hpp"
@@ -25,19 +26,9 @@
 
 namespace Acts {
 /// @brief Implements an iterative vertex finder
-///
-////////////////////////////////////////////////////////////
-///
-/// Brief description of the algorithm implemented:
-/// TODO
-///
-////////////////////////////////////////////////////////////
-///
-/// @tparam vfitter_t Vertex fitter type
-/// @tparam sfinder_t Seed finder type
-template <typename vfitter_t>
 class AdaptiveMultiVertexFinder final : public IVertexFinder {
-  using FitterState_t = typename vfitter_t::State;
+  using VertexFitter = AdaptiveMultiVertexFitter;
+  using VertexFitterState = VertexFitter::State;
 
  public:
   /// Configuration struct
@@ -48,7 +39,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
     /// @param sfinder The seed finder
     /// @param ipEst ImpactPointEstimator
     /// @param bIn Input magnetic field
-    Config(vfitter_t fitter, std::shared_ptr<const IVertexFinder> sfinder,
+    Config(VertexFitter fitter, std::shared_ptr<const IVertexFinder> sfinder,
            ImpactPointEstimator ipEst,
            std::shared_ptr<const MagneticFieldProvider> bIn)
         : vertexFitter(std::move(fitter)),
@@ -57,7 +48,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
           bField{std::move(bIn)} {}
 
     // Vertex fitter
-    vfitter_t vertexFitter;
+    VertexFitter vertexFitter;
 
     // Vertex seed finder
     std::shared_ptr<const IVertexFinder> seedFinder;
@@ -264,7 +255,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   /// @param vertexingOptions Vertexing options
   Result<void> addCompatibleTracksToVertex(
       const std::vector<InputTrack>& tracks, Vertex& vtx,
-      FitterState_t& fitterState,
+      VertexFitterState& fitterState,
       const VertexingOptions& vertexingOptions) const;
 
   /// @brief Method that tries to recover from cases where no tracks
@@ -282,7 +273,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   Result<bool> canRecoverFromNoCompatibleTracks(
       const std::vector<InputTrack>& allTracks,
       const std::vector<InputTrack>& seedTracks, Vertex& vtx,
-      const Vertex& currentConstraint, FitterState_t& fitterState,
+      const Vertex& currentConstraint, VertexFitterState& fitterState,
       const VertexingOptions& vertexingOptions) const;
 
   /// @brief Method that tries to prepare the vertex for the fit
@@ -299,7 +290,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   Result<bool> canPrepareVertexForFit(
       const std::vector<InputTrack>& allTracks,
       const std::vector<InputTrack>& seedTracks, Vertex& vtx,
-      const Vertex& currentConstraint, FitterState_t& fitterState,
+      const Vertex& currentConstraint, VertexFitterState& fitterState,
       const VertexingOptions& vertexingOptions) const;
 
   /// @brief Method that checks if vertex is a good vertex and if
@@ -313,7 +304,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   /// @return pair(nCompatibleTracks, isGoodVertex)
   std::pair<int, bool> checkVertexAndCompatibleTracks(
       Vertex& vtx, const std::vector<InputTrack>& seedTracks,
-      FitterState_t& fitterState, bool useVertexConstraintInFit) const;
+      VertexFitterState& fitterState, bool useVertexConstraintInFit) const;
 
   /// @brief Method that removes all tracks that are compatible with
   /// current vertex from seedTracks
@@ -325,7 +316,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   /// removed
   void removeCompatibleTracksFromSeedTracks(
       Vertex& vtx, std::vector<InputTrack>& seedTracks,
-      FitterState_t& fitterState,
+      VertexFitterState& fitterState,
       std::vector<InputTrack>& removedSeedTracks) const;
 
   /// @brief Method that tries to remove an incompatible track
@@ -341,7 +332,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   /// @return Incompatible track was removed
   bool removeTrackIfIncompatible(Vertex& vtx,
                                  std::vector<InputTrack>& seedTracks,
-                                 FitterState_t& fitterState,
+                                 VertexFitterState& fitterState,
                                  std::vector<InputTrack>& removedSeedTracks,
                                  const GeometryContext& geoCtx) const;
 
@@ -354,7 +345,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   ///
   /// @return Keep new vertex
   bool keepNewVertex(Vertex& vtx, const std::vector<Vertex*>& allVertices,
-                     FitterState_t& fitterState) const;
+                     VertexFitterState& fitterState) const;
 
   /// @brief Method that evaluates if the new vertex candidate is
   /// merged with one of the previously found vertices
@@ -376,7 +367,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   /// @param vertexingOptions Vertexing options
   Result<void> deleteLastVertex(
       Vertex& vtx, std::vector<std::unique_ptr<Vertex>>& allVertices,
-      std::vector<Vertex*>& allVerticesPtr, FitterState_t& fitterState,
+      std::vector<Vertex*>& allVerticesPtr, VertexFitterState& fitterState,
       const VertexingOptions& vertexingOptions) const;
 
   /// @brief Prepares the output vector of vertices
@@ -387,7 +378,7 @@ class AdaptiveMultiVertexFinder final : public IVertexFinder {
   /// @return The output vertex collection
   Result<std::vector<Vertex>> getVertexOutputList(
       const std::vector<Vertex*>& allVerticesPtr,
-      FitterState_t& fitterState) const;
+      VertexFitterState& fitterState) const;
 };
 
 }  // namespace Acts

Core/include/Acts/Vertexing/AdaptiveMultiVertexFinder.ipp

@@ -9,8 +9,7 @@
 #include "Acts/Utilities/AlgebraHelpers.hpp"
 #include "Acts/Vertexing/VertexingError.hpp"
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::find(
+inline auto Acts::AdaptiveMultiVertexFinder::find(
     const std::vector<InputTrack>& allTracks,
     const VertexingOptions& vertexingOptions,
     IVertexFinder::State& anyState) const -> Result<std::vector<Vertex>> {
@@ -27,7 +26,8 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::find(
   // Seed tracks
   std::vector<InputTrack> seedTracks = allTracks;
 
-  FitterState_t fitterState(*m_cfg.bField, vertexingOptions.magFieldContext);
+  VertexFitterState fitterState(*m_cfg.bField,
+                                vertexingOptions.magFieldContext);
   auto seedFinderState = m_cfg.seedFinder->makeState(state.magContext);
 
   std::vector<std::unique_ptr<Vertex>> allVertices;
@@ -140,8 +140,7 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::find(
   return getVertexOutputList(allVerticesPtr, fitterState);
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::doSeeding(
+inline auto Acts::AdaptiveMultiVertexFinder::doSeeding(
     const std::vector<InputTrack>& trackVector, Vertex& currentConstraint,
     const VertexingOptions& vertexingOptions,
     IVertexFinder::State& seedFinderState,
@@ -167,8 +166,7 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::doSeeding(
   return seedVertex;
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::setConstraintAfterSeeding(
+inline auto Acts::AdaptiveMultiVertexFinder::setConstraintAfterSeeding(
     Vertex& currentConstraint, bool useVertexConstraintInFit,
     Vertex& seedVertex) const -> void {
   if (useVertexConstraintInFit) {
@@ -187,8 +185,7 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::setConstraintAfterSeeding(
   }
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::getIPSignificance(
+inline auto Acts::AdaptiveMultiVertexFinder::getIPSignificance(
     const InputTrack& track, const Vertex& vtx,
     const VertexingOptions& vertexingOptions) const -> Result<double> {
   // TODO: In original implementation the covariance of the given vertex is set
@@ -227,11 +224,10 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::getIPSignificance(
   return significance;
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::addCompatibleTracksToVertex(
+inline auto Acts::AdaptiveMultiVertexFinder::addCompatibleTracksToVertex(
     const std::vector<InputTrack>& tracks, Vertex& vtx,
-    FitterState_t& fitterState, const VertexingOptions& vertexingOptions) const
-    -> Result<void> {
+    VertexFitterState& fitterState,
+    const VertexingOptions& vertexingOptions) const -> Result<void> {
   for (const auto& trk : tracks) {
     auto params = m_cfg.extractParameters(trk);
     auto pos = params.position(vertexingOptions.geoContext);
@@ -257,13 +253,11 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::addCompatibleTracksToVertex(
   return {};
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::
-    canRecoverFromNoCompatibleTracks(
-        const std::vector<InputTrack>& allTracks,
-        const std::vector<InputTrack>& seedTracks, Vertex& vtx,
-        const Vertex& currentConstraint, FitterState_t& fitterState,
-        const VertexingOptions& vertexingOptions) const -> Result<bool> {
+inline auto Acts::AdaptiveMultiVertexFinder::canRecoverFromNoCompatibleTracks(
+    const std::vector<InputTrack>& allTracks,
+    const std::vector<InputTrack>& seedTracks, Vertex& vtx,
+    const Vertex& currentConstraint, VertexFitterState& fitterState,
+    const VertexingOptions& vertexingOptions) const -> Result<bool> {
   // Recover from cases where no compatible tracks to vertex
   // candidate were found
   // TODO: This is for now how it's done in athena... this look a bit
@@ -313,11 +307,10 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::
   return Result<bool>::success(true);
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::canPrepareVertexForFit(
+inline auto Acts::AdaptiveMultiVertexFinder::canPrepareVertexForFit(
     const std::vector<InputTrack>& allTracks,
     const std::vector<InputTrack>& seedTracks, Vertex& vtx,
-    const Vertex& currentConstraint, FitterState_t& fitterState,
+    const Vertex& currentConstraint, VertexFitterState& fitterState,
     const VertexingOptions& vertexingOptions) const -> Result<bool> {
   // Add vertex info to fitter state
   fitterState.vtxInfoMap[&vtx] =
@@ -341,10 +334,9 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::canPrepareVertexForFit(
   return Result<bool>::success(*resRec);
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::checkVertexAndCompatibleTracks(
+inline auto Acts::AdaptiveMultiVertexFinder::checkVertexAndCompatibleTracks(
     Vertex& vtx, const std::vector<InputTrack>& seedTracks,
-    FitterState_t& fitterState, bool useVertexConstraintInFit) const
+    VertexFitterState& fitterState, bool useVertexConstraintInFit) const
     -> std::pair<int, bool> {
   bool isGoodVertex = false;
   int nCompatibleTracks = 0;
@@ -380,12 +372,11 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::checkVertexAndCompatibleTracks(
   return {nCompatibleTracks, isGoodVertex};
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::
-    removeCompatibleTracksFromSeedTracks(
-        Vertex& vtx, std::vector<InputTrack>& seedTracks,
-        FitterState_t& fitterState,
-        std::vector<InputTrack>& removedSeedTracks) const -> void {
+inline auto
+Acts::AdaptiveMultiVertexFinder::removeCompatibleTracksFromSeedTracks(
+    Vertex& vtx, std::vector<InputTrack>& seedTracks,
+    VertexFitterState& fitterState,
+    std::vector<InputTrack>& removedSeedTracks) const -> void {
   for (const auto& trk : fitterState.vtxInfoMap[&vtx].trackLinks) {
     const auto& trkAtVtx =
         fitterState.tracksAtVerticesMap.at(std::make_pair(trk, &vtx));
@@ -406,10 +397,9 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::
   }
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::removeTrackIfIncompatible(
+inline auto Acts::AdaptiveMultiVertexFinder::removeTrackIfIncompatible(
     Vertex& vtx, std::vector<InputTrack>& seedTracks,
-    FitterState_t& fitterState, std::vector<InputTrack>& removedSeedTracks,
+    VertexFitterState& fitterState, std::vector<InputTrack>& removedSeedTracks,
     const GeometryContext& geoCtx) const -> bool {
   // Try to find the track with highest compatibility
   double maxCompatibility = 0;
@@ -462,10 +452,9 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::removeTrackIfIncompatible(
   return true;
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::keepNewVertex(
+inline auto Acts::AdaptiveMultiVertexFinder::keepNewVertex(
     Vertex& vtx, const std::vector<Vertex*>& allVertices,
-    FitterState_t& fitterState) const -> bool {
+    VertexFitterState& fitterState) const -> bool {
   double contamination = 0.;
   double contaminationNum = 0;
   double contaminationDeNom = 0;
@@ -490,8 +479,7 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::keepNewVertex(
   return true;
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::isMergedVertex(
+inline auto Acts::AdaptiveMultiVertexFinder::isMergedVertex(
     const Vertex& vtx, const std::vector<Vertex*>& allVertices) const -> bool {
   const Vector4& candidatePos = vtx.fullPosition();
   const SquareMatrix4& candidateCov = vtx.fullCovariance();
@@ -544,10 +532,9 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::isMergedVertex(
   return false;
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::deleteLastVertex(
+inline auto Acts::AdaptiveMultiVertexFinder::deleteLastVertex(
     Vertex& vtx, std::vector<std::unique_ptr<Vertex>>& allVertices,
-    std::vector<Vertex*>& allVerticesPtr, FitterState_t& fitterState,
+    std::vector<Vertex*>& allVerticesPtr, VertexFitterState& fitterState,
     const VertexingOptions& vertexingOptions) const -> Result<void> {
   allVertices.pop_back();
   allVerticesPtr.pop_back();
@@ -584,10 +571,9 @@ auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::deleteLastVertex(
   return {};
 }
 
-template <typename vfitter_t>
-auto Acts::AdaptiveMultiVertexFinder<vfitter_t>::getVertexOutputList(
+inline auto Acts::AdaptiveMultiVertexFinder::getVertexOutputList(
     const std::vector<Vertex*>& allVerticesPtr,
-    FitterState_t& fitterState) const -> Acts::Result<std::vector<Vertex>> {
+    VertexFitterState& fitterState) const -> Acts::Result<std::vector<Vertex>> {
   std::vector<Vertex> outputVec;
   for (auto vtx : allVerticesPtr) {
     auto& outVtx = *vtx;

Core/include/Acts/Vertexing/GaussianTrackDensity.hpp

@@ -22,7 +22,6 @@ namespace Acts {
 /// their d0 and z0 perigee parameters (mean value) and covariance
 /// matrices (determining the width of the function)
 class GaussianTrackDensity {
-  // @TODO: Remove template
  public:
   /// @brief Struct to store information for a single track
   struct TrackEntry {

Core/include/Acts/Vertexing/IterativeVertexFinder.hpp

@@ -56,12 +56,9 @@ namespace Acts {
 ///   from tracksAtVertex if not compatible.
 /// 5. Add vertex to vertexCollection
 /// 6. Repeat until no seedTracks are left or max. number of vertices found
-///
-////////////////////////////////////////////////////////////
-///
-/// @tparam vfitter_t Vertex fitter type
-template <typename vfitter_t>
 class IterativeVertexFinder final : public IVertexFinder {
+  using VertexFitter = FullBilloirVertexFitter;
+
  public:
   /// Configuration struct
   struct Config {
@@ -71,14 +68,14 @@ class IterativeVertexFinder final : public IVertexFinder {
     /// @param lin Track linearizer
     /// @param sfinder The seed finder
     /// @param est ImpactPointEstimator
-    Config(vfitter_t fitter, std::shared_ptr<IVertexFinder> sfinder,
+    Config(VertexFitter fitter, std::shared_ptr<IVertexFinder> sfinder,
            ImpactPointEstimator est)
         : vertexFitter(std::move(fitter)),
           seedFinder(std::move(sfinder)),
           ipEst(std::move(est)) {}
 
     /// Vertex fitter
-    vfitter_t vertexFitter;
+    VertexFitter vertexFitter;
 
     /// Track linearizer
     TrackLinearizer trackLinearizer;