Translate volume calculations to C++

include/openmc/hdf5_interface.h

@@ -391,6 +391,14 @@ write_attribute(hid_t obj_id, const char* name, const std::vector<T>& buffer)
   write_attr(obj_id, 1, dims, name, H5TypeMap<T>::type_id, buffer.data());
 }
 
+inline void
+write_attribute(hid_t obj_id, const char* name, Position r)
+{
+  std::array<double, 3> buffer {r.x, r.y, r.z};
+  write_attribute(obj_id, name, buffer);
+}
+
+
 
 //==============================================================================
 // Templates/overloads for write_dataset

include/openmc/volume_calc.h

@@ -0,0 +1,61 @@
+#ifndef VOLUME_CALC_H
+#define VOLUME_CALC_H
+
+#include "openmc/position.h"
+
+#include "pugixml.hpp"
+#include "xtensor/xtensor.hpp"
+
+#include <string>
+#include <vector>
+
+namespace openmc {
+
+//==============================================================================
+// Volume calculation class
+//==============================================================================
+
+class VolumeCalculation {
+public:
+  // Aliases, types
+  using int_2dvec = std::vector<std::vector<int>>;
+
+  struct Result {
+    std::array<double, 2> volume; //!< Mean/standard deviation of volume
+    std::vector<int> nuclides; //!< Index of nuclides
+    std::vector<double> atoms; //!< Number of atoms for each nuclide
+    std::vector<double> uncertainty; //!< Uncertainty on number of atoms
+  }; // Results for a single domain
+
+  // Constructors
+  VolumeCalculation() = default;
+  VolumeCalculation(pugi::xml_node node);
+
+  // Methods
+  std::vector<Result> execute() const;
+  void write_volume(const std::string& filename, const std::vector<Result>& results) const;
+
+  // Data members
+  int domain_type_; //!< Type of domain (cell, material, etc.)
+  int n_samples_; //!< Number of samples to use
+  Position lower_left_; //!< Lower-left position of bounding box
+  Position upper_right_; //!< Upper-right position of bounding box
+  std::vector<int> domain_ids_; //!< IDs of domains to find volumes of
+
+private:
+  void check_hit(int i_domain, int i_material, int_2dvec& indices,
+    int_2dvec& hits) const;
+
+};
+
+//==============================================================================
+// Global variables
+//==============================================================================
+
+namespace model {
+extern std::vector<VolumeCalculation> volume_calcs;
+}
+
+} // namespace openmc
+
+#endif // VOLUME_CALC_H