From 9127ff4f5ecacd46692784f1a75e490490d1b3f2 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Thu, 8 Sep 2022 11:24:08 -0500
Subject: [PATCH] [WIP] started region refactor

---
 include/openmc/cell.h | 40 ++++++++++++++++++++++++++++++++++++++--
 src/cell.cpp          |  7 +++++--
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/include/openmc/cell.h b/include/openmc/cell.h
index 8171967273..fcce520fed 100644
--- a/include/openmc/cell.h
+++ b/include/openmc/cell.h
@@ -52,8 +52,41 @@ extern vector<unique_ptr<Cell>> cells;
 } // namespace model
 
 //==============================================================================
+
+// TODO: Maybe not, just move this inline to Region::bounding_box() for complex
+// case
+class RegionPostfix {
+public:
+  BoundingBox bounding_box() const;
+};
+
+class Region {
+public:
+  Region() {}
+  explicit Region(std::string region_expression);
+
+  void add_precedence();
+  std::string str() const;
+  BoundingBox bounding_box() const;
+  bool contains(Position r, Direction u, int32_t on_surface) const;
+
+  RegionPostfix to_postfix() const;
+
+private:
+  void add_parentheses();
+  void apply_demorgan(
+    vector<int32_t>::iterator start, vector<int32_t>::iterator stop);
+
+  //! Definition of spatial region as Boolean expression of half-spaces
+  // TODO: Should this be a vector of some other type
+  vector<int32_t> tokens_;
+  bool simple_; //!< Does the region contain only intersections?
+};
+
 //==============================================================================
 
+// TODO: Think about what data members really need to live in this class versus
+// putting them in the Region class
 class Cell {
 public:
   //----------------------------------------------------------------------------
@@ -198,9 +231,9 @@ public:
   //! T. The units are sqrt(eV).
   vector<double> sqrtkT_;
 
+  // TODO: Probably move this guy to CSGCell
   //! Definition of spatial region as Boolean expression of half-spaces
-  vector<int32_t> region_;
-  bool simple_; //!< Does the region contain only intersections?
+  Region region_;
 
   //! \brief Neighboring cells in the same universe.
   NeighborList neighbors_;
@@ -263,6 +296,9 @@ protected:
   //! \param rpn The rpn being searched
   static vector<int32_t>::iterator find_left_parenthesis(
     vector<int32_t>::iterator start, const vector<int32_t>& rpn);
+
+private:
+  Region region_;
 };
 
 //==============================================================================
diff --git a/src/cell.cpp b/src/cell.cpp
index 4ff35498c6..4eb0fa0b95 100644
--- a/src/cell.cpp
+++ b/src/cell.cpp
@@ -43,6 +43,7 @@ vector<unique_ptr<Cell>> cells;
 //! operators.
 //==============================================================================
 
+// TODO: Move this to be Region::Region(...)
 vector<int32_t> tokenize(const std::string region_spec)
 {
   // Check for an empty region_spec first.
@@ -183,7 +184,8 @@ void add_precedence(std::vector<int32_t>& infix)
         // Set the current operator if is hasn't been set
         current_op = token;
       } else if (token != current_op) {
-        // If the current operator doesn't match the token, add parenthesis to assert precedence
+        // If the current operator doesn't match the token, add parenthesis to
+        // assert precedence
         it = add_parentheses(it, infix);
         current_op = 0;
       }
@@ -586,7 +588,7 @@ CSGCell::CSGCell(pugi::xml_node cell_node)
 
   // Get a tokenized representation of the region specification and apply De
   // Morgans law
-  region_ = tokenize(region_spec);
+  region_ = Region(region_spec);
   remove_complement_ops(region_);
 
   // Convert user IDs to surface indices.
@@ -696,6 +698,7 @@ void CSGCell::to_hdf5_inner(hid_t group_id) const
 
   write_string(group_id, "geom_type", "csg", false);
 
+  // TODO: Move to Region::str()
   // Write the region specification.
   if (!region_.empty()) {
     std::stringstream region_spec {};