From 36fb89dead8d79b5b144d3035ea940ae6de9a719 Mon Sep 17 00:00:00 2001
From: Patrick Shriwise <pshriwise@gmail.com>
Date: Fri, 13 Sep 2019 07:58:27 -0500
Subject: [PATCH] Making analagous function for finding the right parenthesis.

---
 include/openmc/cell.h |  4 ++++
 src/cell.cpp          | 43 +++++++++++++++++++++++++++++++++++++------
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/include/openmc/cell.h b/include/openmc/cell.h
index 2cd98ada1a..f6524c6ee3 100644
--- a/include/openmc/cell.h
+++ b/include/openmc/cell.h
@@ -218,6 +218,10 @@ protected:
   static std::vector<int32_t>::iterator
   find_left_parenthesis(std::vector<int32_t>::iterator start,
                         const std::vector<int32_t>& rpn);
+  static std::vector<int32_t>::iterator
+  find_right_parenthesis(std::vector<int32_t>::iterator start,
+                        const std::vector<int32_t>& rpn);
+
 };
 
 //==============================================================================
diff --git a/src/cell.cpp b/src/cell.cpp
index 7ad48bd326..bc0acbe73d 100644
--- a/src/cell.cpp
+++ b/src/cell.cpp
@@ -642,6 +642,40 @@ CSGCell::find_left_parenthesis(std::vector<int32_t>::iterator start,
   return it;
 }
 
+std::vector<int32_t>::iterator
+CSGCell::find_right_parenthesis(std::vector<int32_t>::iterator start,
+                                const std::vector<int32_t>& rpn) {
+  // start search at zero
+  int level = 0;
+  auto it = start;
+  while (it != rpn.end()) {
+    // look at two tokens at a time
+    int32_t one = *it;
+    int32_t two = *(it + 1);
+
+    // decrement parenthesis level if there are two adjacent surfaces
+    if (one < OP_UNION && two < OP_UNION) {
+      level++;
+    // increment if there are two adjacent operators
+    } else if (one >= OP_UNION && two >= OP_UNION) {
+      level--;
+    }
+
+    // if the level gets to zero, return the position
+    if (level == 0) {
+      // move the iterator back one before leaving the loop
+      // so that all tokens in the parenthesis are included
+      it++;
+      break;
+    }
+
+    // continue loop, one token at a time
+    it++;
+  }
+  return it;
+}
+
+
 void CSGCell::remove_complement_ops(std::vector<int32_t>& rpn) {
   auto it = std::find(rpn.begin(), rpn.end(), OP_COMPLEMENT);
   while (it != rpn.end()) {
@@ -687,20 +721,17 @@ BoundingBox CSGCell::bounding_box_complex(std::vector<int32_t> rpn) {
       // add until last two tokens in the sub-rpn are operators
       // (indicates a right parenthesis)
       auto subrpn_start = it - 2; // include current tokens
-      auto subrpn_end = it;
-      while (!((*subrpn_end >= OP_UNION) && (*(subrpn_end + 1) >= OP_UNION))) {
-        subrpn_end++;
-      }
+      auto subrpn_end = find_right_parenthesis(subrpn_start, rpn);
 
       // create the subrpn, including the first of our current tokens
-      std::vector<int32_t> subrpn(subrpn_start, ++subrpn_end);
+      std::vector<int32_t> subrpn(subrpn_start, subrpn_end);
 
       // save the last operator, tells us how to combine this region
       // with our current bounding box
       int32_t op = *subrpn_end++;
       it = subrpn_end;
 
-      // get bounding box for the subrpn
+      // get bounding box for the sub-rpn
       BoundingBox sub_box = bounding_box_complex(subrpn);
       // combine the sub-rpn bounding box with our current cell box
       if (op == OP_UNION) {