added collision filter

CMakeLists.txt

@@ -320,6 +320,7 @@ list(APPEND libopenmc_SOURCES
   src/tallies/filter_distribcell.cpp
   src/tallies/filter_energyfunc.cpp
   src/tallies/filter_energy.cpp
+  src/tallies/filter_collision.cpp
   src/tallies/filter_legendre.cpp
   src/tallies/filter_material.cpp
   src/tallies/filter_mesh.cpp

include/openmc/tallies/filter_collision.h

@@ -0,0 +1,54 @@
+#ifndef OPENMC_TALLIES_FILTER_COLLISIONS_H
+#define OPENMC_TALLIES_FILTER_COLLISIONS_H
+
+#include <vector>
+
+#include <gsl/gsl>
+
+#include "openmc/tallies/filter.h"
+
+namespace openmc {
+
+//==============================================================================
+//! Bins the incident neutron energy.
+//==============================================================================
+
+class CollisionFilter : public Filter
+{
+public:
+  //----------------------------------------------------------------------------
+  // Constructors, destructors
+
+  ~CollisionFilter() = default;
+
+  //----------------------------------------------------------------------------
+  // Methods
+
+  std::string type() const override {return "numCollisions";}
+
+  void from_xml(pugi::xml_node node) override;
+
+  void get_all_bins(const Particle& p, TallyEstimator estimator, FilterMatch& match)
+  const override;
+
+  void to_statepoint(hid_t filter_group) const override;
+
+  std::string text_label(int bin) const override;
+
+  //----------------------------------------------------------------------------
+  // Accessors
+
+  const std::vector<int>& bins() const { return bins_; }
+  void set_bins(gsl::span<const int> bins);
+
+protected:
+  //----------------------------------------------------------------------------
+  // Data members
+
+  std::vector<int> bins_;
+
+};
+
+
+} // namespace openmc
+#endif // OPENMC_TALLIES_FILTER_COLLISIONS_H

src/tallies/filter.cpp

@@ -19,6 +19,7 @@
 #include "openmc/tallies/filter_distribcell.h"
 #include "openmc/tallies/filter_energyfunc.h"
 #include "openmc/tallies/filter_energy.h"
+#include "openmc/tallies/filter_collision.h"
 #include "openmc/tallies/filter_legendre.h"
 #include "openmc/tallies/filter_material.h"
 #include "openmc/tallies/filter_mesh.h"
@@ -125,6 +126,8 @@ Filter* Filter::create(const std::string& type, int32_t id)
     return Filter::create<EnergyFunctionFilter>(id);
   } else if (type == "energy") {
     return Filter::create<EnergyFilter>(id);
+  } else if (type == "collision") {
+    return Filter::create<CollisionFilter>(id);
   } else if (type == "energyout") {
     return Filter::create<EnergyoutFilter>(id);
   } else if (type == "legendre") {

src/tallies/filter_collision.cpp

@@ -0,0 +1,124 @@
+#include "openmc/tallies/filter_collision.h"
+
+#include <fmt/core.h>
+
+#include "openmc/capi.h"
+#include "openmc/constants.h"  // For F90_NONE
+#include "openmc/mgxs_interface.h"
+#include "openmc/search.h"
+#include "openmc/settings.h"
+#include "openmc/xml_interface.h"
+
+namespace openmc {
+
+//==============================================================================
+// CollisionFilter implementation
+//==============================================================================
+
+void
+CollisionFilter::from_xml(pugi::xml_node node)
+{
+  auto bins = get_node_array<int>(node, "bins");
+  this->set_bins(bins);
+}
+
+void
+CollisionFilter::set_bins(gsl::span<const int> bins)
+{
+  // Clear existing bins
+  bins_.clear();
+  bins_.reserve(bins.size());
+
+  // Copy bins, ensuring they are valid
+  for (gsl::index i = 0; i < bins.size(); ++i) {
+    if (i > 0 && bins[i] <= bins[i-1]) {
+      throw std::runtime_error{"Number of Collisions bins must be monotonically increasing."};
+    }
+    bins_.push_back(bins[i]);
+  }
+
+  n_bins_ = bins_.size();
+
+}
+
+void
+CollisionFilter::get_all_bins(const Particle& p, TallyEstimator estimator, FilterMatch& match)
+const
+{
+    // Get the number of collisions for the particle
+    auto n = p.n_collision_;
+
+    // Bin the collision number. Must fit exactly the desired collision number .
+    if (n >= bins_.front() && n <= bins_.back()) {
+      auto it = find(bins_.begin(), bins_.end(), n);
+      if (it != bins_.end()){
+        size_t bin = it - bins_.begin();
+        if (int(bins_[bin]) == n){ 
+          match.bins_.push_back(bin);
+          match.weights_.push_back(1.0);
+        }
+      }
+    }
+}
+
+void
+CollisionFilter::to_statepoint(hid_t filter_group) const
+{
+  Filter::to_statepoint(filter_group);
+  write_dataset(filter_group, "bins", bins_);
+}
+
+std::string
+CollisionFilter::text_label(int bin) const
+{
+  return fmt::format("Collision Number {}", int(bins_[bin]));
+}
+
+//==============================================================================
+// C-API functions
+//==============================================================================
+
+extern"C" int
+openmc_collision_filter_get_bins(int32_t index, const int** energies, size_t* n)
+{
+  // Make sure this is a valid index to an allocated filter.
+  if (int err = verify_filter(index)) return err;
+
+  // Get a pointer to the filter and downcast.
+  const auto& filt_base = model::tally_filters[index].get();
+  auto* filt = dynamic_cast<CollisionFilter*>(filt_base);
+
+  // Check the filter type.
+  if (!filt) {
+    set_errmsg("Tried to get collision bins on a non-collision filter.");
+    return OPENMC_E_INVALID_TYPE;
+  }
+
+  // Output the bins.
+  *energies = filt->bins().data();
+  *n = filt->bins().size();
+  return 0;
+}
+
+extern "C" int
+openmc_collision_filter_set_bins(int32_t index, size_t n, const int* energies)
+{
+  // Make sure this is a valid index to an allocated filter.
+  if (int err = verify_filter(index)) return err;
+
+  // Get a pointer to the filter and downcast.
+  const auto& filt_base = model::tally_filters[index].get();
+  auto* filt = dynamic_cast<CollisionFilter*>(filt_base);
+
+  // Check the filter type.
+  if (!filt) {
+    set_errmsg("Tried to set collision bins on a non-collision filter.");
+    return OPENMC_E_INVALID_TYPE;
+  }
+
+  // Update the filter.
+  filt->set_bins({energies, n});
+  return 0;
+}
+
+}// namespace openmc

src/tallies/tally.cpp

@@ -20,6 +20,7 @@
 #include "openmc/tallies/filter_cellfrom.h"
 #include "openmc/tallies/filter_delayedgroup.h"
 #include "openmc/tallies/filter_energy.h"
+#include "openmc/tallies/filter_collision.h"
 #include "openmc/tallies/filter_legendre.h"
 #include "openmc/tallies/filter_mesh.h"
 #include "openmc/tallies/filter_meshsurface.h"