From c237f700adcd8436b5db01a4bb84f3e72f34f9f0 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Mon, 28 Sep 2015 14:02:20 +0700
Subject: [PATCH] Fix bug in tokenize algorithm

The algorithm was failing to add intersections after right parentheses when appropriate.
---
 openmc/region.py | 13 +++++++++----
 src/string.F90   |  8 ++++----
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/openmc/region.py b/openmc/region.py
index 025babba8..a89658c03 100644
--- a/openmc/region.py
+++ b/openmc/region.py
@@ -27,6 +27,9 @@ class Region(object):
 
         """
 
+        # Strip leading and trailing whitespace
+        expression = expression.strip()
+
         # Convert the string expression into a list of tokens, i.e., operators
         # and surface half-spaces, representing the expression in infix
         # notation.
@@ -49,13 +52,15 @@ class Region(object):
                     # to the list of tokens
                     tokens.append(expression[i])
                 else:
-                    # For spaces, we need to check the context further. If it
-                    # doesn't appear before a right parentheses or union, it is
-                    # interpreted to be as an intersection operator
+                    # Find next non-space character
                     while expression[i+1] == ' ':
                         i += 1
 
-                    if i_start >= 0 and expression[i+1] not in ')^':
+                    # If previous token is a halfspace or right parenthesis and next token
+                    # is not a left parenthese or union operator, that implies that the
+                    # whitespace is to be interpreted as an intersection operator
+                    if (i_start >= 0 or tokens[-1] == ')') and \
+                       expression[i+1] not in ')^':
                         tokens.append(' ')
 
                 i_start = -1
diff --git a/src/string.F90 b/src/string.F90
index 213627892..b505aa869 100644
--- a/src/string.F90
+++ b/src/string.F90
@@ -108,10 +108,10 @@ contains
             i = i + 1
           end do
 
-          ! If previous token is not an operator and next token is not a left
-          ! parenthese or union operator, that implies that the whitespace is to
-          ! be interpreted as an intersection operator
-          if (i_start > 0) then
+          ! If previous token is a halfspace or right parenthesis and next token
+          ! is not a left parenthese or union operator, that implies that the
+          ! whitespace is to be interpreted as an intersection operator
+          if (i_start > 0 .or. tokens%data(tokens%size()) == OP_RIGHT_PAREN) then
             if (index(')^', string_(i+1:i+1)) == 0) then
               call tokens%push_back(OP_INTERSECTION)
             end if