From e6466e9867cdb5dbd810d6e48ffd1c73fa5042d5 Mon Sep 17 00:00:00 2001
From: Sterling Harper <smharper@mit.edu>
Date: Tue, 18 Dec 2018 15:06:22 -0500
Subject: [PATCH] Remove surface-based neighbor lists

---
 include/openmc/geometry_aux.h |  6 ------
 include/openmc/surface.h      |  3 ---
 src/geometry.F90              |  5 +----
 src/geometry_aux.cpp          | 27 ---------------------------
 src/input_xml.F90             | 10 +---------
 5 files changed, 2 insertions(+), 49 deletions(-)

diff --git a/include/openmc/geometry_aux.h b/include/openmc/geometry_aux.h
index da55c3d9b..e456f700c 100644
--- a/include/openmc/geometry_aux.h
+++ b/include/openmc/geometry_aux.h
@@ -32,12 +32,6 @@ extern "C" void assign_temperatures();
 
 extern "C" int32_t find_root_universe();
 
-//!=============================================================================
-//! Build a list of neighboring cells to each surface to speed up tracking.
-//!=============================================================================
-
-extern "C" void neighbor_lists();
-
 //==============================================================================
 //! Populate all data structures needed for distribcells.
 //==============================================================================
diff --git a/include/openmc/surface.h b/include/openmc/surface.h
index d0ada79ea..3df791ba3 100644
--- a/include/openmc/surface.h
+++ b/include/openmc/surface.h
@@ -66,9 +66,6 @@ public:
   int bc_;                    //!< Boundary condition
   std::string name_;          //!< User-defined name
 
-  std::vector<int> neighbor_pos_; //!< List of cells on positive side
-  std::vector<int> neighbor_neg_; //!< List of cells on negative side
-
   explicit Surface(pugi::xml_node surf_node);
   Surface();
 
diff --git a/src/geometry.F90 b/src/geometry.F90
index 91ed6bbdc..83bf2325f 100644
--- a/src/geometry.F90
+++ b/src/geometry.F90
@@ -53,9 +53,6 @@ module geometry
       integer(C_INT), intent(out)   :: next_level
     end subroutine distance_to_boundary
 
-    subroutine neighbor_lists() bind(C)
-    end subroutine neighbor_lists
-
 #ifdef DAGMC
 
     function next_cell_c(current_cell, surface_crossed) &
@@ -97,7 +94,7 @@ contains
     if (present(use_neighbor_lists)) then
       found = find_cell_c(p, logical(use_neighbor_lists, kind=C_BOOL))
     else
-      found = find_cell_c(p, logical(.false., kind=C_BOOL))
+      found = find_cell_c(p, .false._C_BOOL)
     end if
 
   end subroutine find_cell
diff --git a/src/geometry_aux.cpp b/src/geometry_aux.cpp
index c326744eb..eca9b6c13 100644
--- a/src/geometry_aux.cpp
+++ b/src/geometry_aux.cpp
@@ -155,33 +155,6 @@ find_root_universe()
 
 //==============================================================================
 
-void
-neighbor_lists()
-{
-  write_message("Building neighboring cells lists for each surface...", 6);
-
-  for (int i = 0; i < model::cells.size(); i++) {
-    for (auto token : model::cells[i]->region_) {
-      // Skip operator tokens.
-      if (std::abs(token) >= OP_UNION) continue;
-
-      // This token is a surface index.  Add the cell to the surface's list.
-      if (token > 0) {
-        model::surfaces[std::abs(token)-1]->neighbor_pos_.push_back(i);
-      } else {
-        model::surfaces[std::abs(token)-1]->neighbor_neg_.push_back(i);
-      }
-    }
-  }
-
-  for (Surface* surf : model::surfaces) {
-    surf->neighbor_pos_.shrink_to_fit();
-    surf->neighbor_neg_.shrink_to_fit();
-  }
-}
-
-//==============================================================================
-
 void
 prepare_distribcell()
 {
diff --git a/src/input_xml.F90 b/src/input_xml.F90
index 1da1bf9df..7bba72d15 100644
--- a/src/input_xml.F90
+++ b/src/input_xml.F90
@@ -9,7 +9,6 @@ module input_xml
   use dict_header,      only: DictIntInt, DictCharInt, DictEntryCI
   use endf,             only: reaction_name
   use error,            only: fatal_error, warning, write_message, openmc_err_msg
-  use geometry,         only: neighbor_lists
   use geometry_header
 #ifdef DAGMC
   use dagmc_header
@@ -132,7 +131,7 @@ contains
     call read_materials_xml()
     call read_geometry_xml()
 
-    ! Set up neighbor lists, convert user IDs -> indices, assign temperatures
+    ! Convert user IDs -> indices, assign temperatures
     call finalize_geometry(nuc_temps, sab_temps)
 
     if (run_mode /= MODE_PLOTTING) then
@@ -182,12 +181,6 @@ contains
     call adjust_indices()
     call count_cell_instances(root_universe)
 
-    ! After reading input and basic geometry setup is complete, build lists of
-    ! neighboring cells for efficient tracking
-    if (.not. dagmc) then
-      call neighbor_lists()
-    end if
-
     ! Assign temperatures to cells that don't have temperatures already assigned
     call assign_temperatures()
 
@@ -2297,7 +2290,6 @@ contains
     logical :: file_exists                 ! Does multipole library exist?
     character(7) :: readable               ! Is multipole library readable?
     character(MAX_FILE_LEN) :: filename    ! Path to multipole xs library
-    character(kind=C_CHAR), pointer :: string(:)
     integer(HID_T) :: file_id
     integer(HID_T) :: group_id