Seems ok for bracket flatering and spurs removal.

Combinatorial_map/include/CGAL/Path_on_surface.h

@@ -63,10 +63,10 @@ public:
   { m_path.clear(); }
   
   std::size_t next_index(std::size_t i) const
-  { return (i==m_path.size()-1?0:i+1); }
+  { return (is_closed() && i==m_path.size()-1?0:i+1); }
 
   std::size_t prev_index(std::size_t i) const
-  { return (i==0?m_path.size()-1:i-1); }
+  { return (is_closed() && i==0?m_path.size()-1:i-1); }
 
   Dart_const_handle get_ith_dart(std::size_t i) const
   {
@@ -284,24 +284,32 @@ public:
     { transform_negative_bracket(begin, end, new_path); }
   }
 
+  // copy all darts starting from begin and going to the dart before end
+  // from this path to new_path.
+  void copy_rest_of_path(std::size_t begin, std::size_t end,
+                         std::vector<Dart_const_handle>& new_path)
+  {
+    assert(end<=length());
+    assert(begin<=end);
+    while(begin!=end)
+    {
+      new_path.push_back(get_ith_dart(begin));
+      ++begin;
+    }
+  }
+
   bool bracket_flattening_one_step()
   {
     if (is_empty()) return false;
 
-    bool res=false;
     std::vector<Dart_const_handle> new_path;
     std::size_t i;
     bool positive=false;
 
-    for (i=0; i<m_path.size()-1; )
+    for (i=0; i<m_path.size()-1; ++i)
     {
       positive=(next_turn(i)==1);
-      if (!positive && next_negative_turn(i)!=1)
-      {
-        new_path.push_back(m_path[i]); // We copy this dart
-        ++i;
-      }
-      else
+      if (positive || next_negative_turn(i)==1)
       {
         // i is maybe the beginning of a bracket
         std::size_t begin=i;
@@ -310,27 +318,32 @@ public:
         {
           /* std::cout<<"Bracket: ["<<begin<<"; "<<end<<"] "
                    <<(positive?"+":"-")<<std::endl; */
-          if (end<begin)
-          { i=m_path.size(); }
-          else if (next_index(begin)==end) // Special case of (1 2^r)
-          { i=m_path.size(); }
+          if (next_index(begin)==end) // Special case of (1 2^r)
+          {
+            new_path.clear(); // TODO BETTER; MOREOVER THERE IS A POSSIBLE BUG IF END<BEGIN; in this case I already copied some darts which must be not copied
+            i=m_path.size(); }
           else // Normal case
           { i=end+1; }
+          if (end<begin)
+          { // Necessarily a closed path !
+            assert(is_closed());
+            copy_rest_of_path(end+1, begin, new_path);
+          }
+          else if (next_index(begin)!=end) // Special case of (1 2^r)
+          { copy_rest_of_path(0, begin, new_path); }
+
           transform_bracket(begin, end, new_path, positive);
-          res=true;
-        }
-        else
-        {
-          new_path.push_back(m_path[i]); // We copy this dart
-          ++i;
+
+          if (begin<end && next_index(begin)!=end && end<length()-1)
+          { copy_rest_of_path(end+1, length(), new_path); }
+
+          new_path.swap(m_path);
+          return true;
         }
       }
     }
-    if (i==m_path.size()-1)
-    { new_path.push_back(m_path[m_path.size()-1]); }
-    
-    new_path.swap(m_path);
-    return res;
+
+    return false;
   }
 
   bool bracket_flattening()

Linear_cell_complex/examples/Linear_cell_complex/compute_example.cpp

@@ -23,7 +23,7 @@ void simplify_path(CGAL::Path_on_surface<LCC_3_cmap>& path,
   if (draw)
   {
     v.push_back(&path);
-    display(path.get_map(), v);
+    // display(path.get_map(), v);
   }
 
   CGAL::Path_on_surface<LCC_3_cmap>* prevp=&path;
@@ -31,33 +31,42 @@ void simplify_path(CGAL::Path_on_surface<LCC_3_cmap>& path,
   do
   {
     curp=new CGAL::Path_on_surface<LCC_3_cmap>(*prevp);
+    /* std::cout<<"+ "; curp->display_negative_turns();
+    std::cout<<"- "; curp->display_positive_turns();
+    std::cout<<" -> "<<std::flush; */
+
     if (curp->bracket_flattening_one_step())
     {
       if (draw) { v.push_back(curp); }
       prevp=curp;
+
+      /* std::cout<<"+ "; curp->display_negative_turns();
+      std::cout<<"- "; curp->display_positive_turns();
+      std::cout<<std::endl; */
     }
     else
     {
-      delete curp;
-      curp=NULL;
+      if (curp->remove_spurs())
+      {
+        if (draw) { v.push_back(curp); }
+        prevp=curp;
+
+       /* std::cout<<"+ "; curp->display_negative_turns();
+        std::cout<<"- "; curp->display_positive_turns();
+        std::cout<<std::endl; */
+      }
+      else
+      {
+        delete curp;
+        curp=NULL;
+        // std::cout<<"unchanged."<<std::endl;
+      }
     }
-     if (draw /* && nbtest==1*/)
-      display(path.get_map(), v);
+     // if (draw /* && nbtest==1*/)
+     // display(path.get_map(), v);
   }
   while(curp!=NULL);
 
-  curp=new CGAL::Path_on_surface<LCC_3_cmap>(*prevp);
-  if (curp->remove_spurs())
-  {
-    if (draw) { v.push_back(curp); }
-    prevp=curp;
-  }
-  else
-  {
-    delete curp;
-    curp=NULL;
-  }
-
   if (draw)
   { display(path.get_map(), v); }
 
@@ -245,7 +254,7 @@ void test_all_cases_spurs_and_bracket()
   generate_negative_bracket_special2(path);
   std::cout<<"Negative special case 1 (-1 -2^10): "<<std::flush;
   path.display_negative_turns();
-  simplify_path(path, true);
+  simplify_path(path, false);
   std::cout<<" -> +"; path.display_positive_turns();
   std::cout<<" -"; path.display_negative_turns(); std::cout<<std::endl;
 
@@ -255,7 +264,7 @@ int main(int argc, char** argv)
 {
   // test_file(argc, argv);
   // test_some_random_paths_on_cube();
-   test_all_cases_spurs_and_bracket();
+  test_all_cases_spurs_and_bracket();
 
   return EXIT_SUCCESS;
 }

Linear_cell_complex/include/CGAL/Linear_cell_complex_constructors.h

@@ -21,9 +21,9 @@
 #ifndef CGAL_LINEAR_CELL_COMPLEX_CONSTRUCTORS_H
 #define CGAL_LINEAR_CELL_COMPLEX_CONSTRUCTORS_H 1
 
-#include <CGAL/IO/Polyhedron_iostream.h>
 #include <CGAL/IO/File_header_OFF.h>
 #include <CGAL/IO/File_scanner_OFF.h>
+#include <CGAL/IO/File_writer_OFF.h>
 #include <CGAL/Linear_cell_complex_incremental_builder.h>
 
 #include <iostream>