From 3f8448f280a4e19b0f9d31cdd97f8559d158dca2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Loriot?= <sebastien.loriot@cgal.org>
Date: Tue, 8 Aug 2017 12:12:29 +0200
Subject: [PATCH] avoid infinite loop in 3D and dD

---
 .../include/CGAL/Hilbert_sort_middle_3.h      | 24 ++++++++++++-------
 .../include/CGAL/Hilbert_sort_middle_d.h      | 12 ++++++----
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/Spatial_sorting/include/CGAL/Hilbert_sort_middle_3.h b/Spatial_sorting/include/CGAL/Hilbert_sort_middle_3.h
index 01a5747b7f7..1d61a6890d1 100644
--- a/Spatial_sorting/include/CGAL/Hilbert_sort_middle_3.h
+++ b/Spatial_sorting/include/CGAL/Hilbert_sort_middle_3.h
@@ -141,14 +141,22 @@ public:
 	  internal::fixed_hilbert_split (m6, m8, Cmp< z, !upz> (zmed,_k));
 
 
-        sort<z, upz, upx, upy> (m0, m1, zmin, xmin, ymin, zmed, xmed, ymed);
-        sort<y, upy, upz, upx> (m1, m2, ymin, zmed, xmin, ymed, zmax, xmed);
-        sort<y, upy, upz, upx> (m2, m3, ymed, zmed, xmin, ymax, zmax, xmed);
-        sort<x, upx,!upy,!upz> (m3, m4, xmin, ymax, zmed, xmed, ymed, zmin);
-        sort<x, upx,!upy,!upz> (m4, m5, xmed, ymax, zmed, xmax, ymed, zmin);
-        sort<y,!upy, upz,!upx> (m5, m6, ymax, zmed, xmax, ymed, zmax, xmed);
-        sort<y,!upy, upz,!upx> (m6, m7, ymed, zmed, xmax, ymin, zmax, xmed);
-        sort<z,!upz,!upx, upy> (m7, m8, zmed, xmax, ymin, zmin, xmed, ymed);
+        if (m1!=m8)
+          sort<z, upz, upx, upy> (m0, m1, zmin, xmin, ymin, zmed, xmed, ymed);
+        if (m1!=m0 || m2!=m8)
+          sort<y, upy, upz, upx> (m1, m2, ymin, zmed, xmin, ymed, zmax, xmed);
+        if (m2!=m0 || m3!=m8)
+          sort<y, upy, upz, upx> (m2, m3, ymed, zmed, xmin, ymax, zmax, xmed);
+        if (m3!=m0 || m4!=m8)
+          sort<x, upx,!upy,!upz> (m3, m4, xmin, ymax, zmed, xmed, ymed, zmin);
+        if (m4!=m0 || m5!=m8)
+          sort<x, upx,!upy,!upz> (m4, m5, xmed, ymax, zmed, xmax, ymed, zmin);
+        if (m5!=m0 || m6!=m8)
+          sort<y,!upy, upz,!upx> (m5, m6, ymax, zmed, xmax, ymed, zmax, xmed);
+        if (m6!=m0 || m7!=m8)
+          sort<y,!upy, upz,!upx> (m6, m7, ymed, zmed, xmax, ymin, zmax, xmed);
+        if (m7!=m0)
+          sort<z,!upz,!upx, upy> (m7, m8, zmed, xmax, ymin, zmin, xmed, ymed);
     }
 
     template <class RandomAccessIterator>
diff --git a/Spatial_sorting/include/CGAL/Hilbert_sort_middle_d.h b/Spatial_sorting/include/CGAL/Hilbert_sort_middle_d.h
index 4cd7b61e074..9f6dce7efe1 100644
--- a/Spatial_sorting/include/CGAL/Hilbert_sort_middle_d.h
+++ b/Spatial_sorting/include/CGAL/Hilbert_sort_middle_d.h
@@ -117,19 +117,22 @@ public:
      /////////////start recursive calls
      last_dir = (direction + _dimension -1) % _dimension;
      // first step is special
-     sort( places[0], places[1], start, last_dir,cmin,cmax);
+     if (places[1]!=end)
+       sort( places[0], places[1], start, last_dir,cmin,cmax);
      cmin[last_dir] = med[last_dir];
      cmax[last_dir] = maxi[last_dir];
      
 
      for(int i=1; i<two_to_dim-1; i +=2){
        //std::cout<<i<<";"<<start[0]<<start[1]<<start[2]<<start[3]<<"/"<<dir[i+1]<<std::endl;
-       sort( places[i  ], places[i+1], start, dir[i+1],cmin,cmax);
+       if (places[i]!=begin || places[i+1]!=end)
+         sort( places[i  ], places[i+1], start, dir[i+1],cmin,cmax);
        cmax[ dir[i+1] ] =  (cmin[ dir[i+1]]==mini[ dir[i+1]])
 	                    ? maxi[ dir[i+1] ] : mini[ dir[i+1] ];
        cmin[ dir[i+1] ] =  med[ dir[i+1] ];
 
-       sort( places[i+1], places[i+2], start, dir[i+1],cmin,cmax);
+       if (places[i+1]!=begin || places[i+2]!=end)
+         sort( places[i+1], places[i+2], start, dir[i+1],cmin,cmax);
        cmin[ dir[i+1] ] =  cmax[ dir[i+1] ];
        cmax[ dir[i+1] ] =  med[ dir[i+1] ];
        cmax[ last_dir ] = (cmax[last_dir]==maxi[last_dir])
@@ -139,7 +142,8 @@ public:
      }
 
      //last step is special
-     sort( places[two_to_dim-1], places[two_to_dim], start, last_dir,cmin,cmax);
+     if (places[two_to_dim-1]!=begin)
+       sort( places[two_to_dim-1], places[two_to_dim], start, last_dir,cmin,cmax);
     }