Sweep mode for Arrangement_2

Arrangement_on_surface_2/include/CGAL/Arr_dcel_base.h

@@ -482,11 +482,10 @@ public:
     const Inner_ccb* out = reinterpret_cast<const Inner_ccb*>(_clean_pointer(this->p_comp));
     if (out->is_valid())
       return out;
-    // else
-    while (!out->is_valid())
-      out = out->next();
-    const_cast<Halfedge*>(this)->set_inner_ccb(out);
 
+    // else
+    out = const_cast<Inner_ccb*>(out)->reduce_path();
+    const_cast<Halfedge*>(this)->set_inner_ccb(out);
     return out;
   }
 
@@ -500,14 +499,19 @@ public:
     Inner_ccb* out = reinterpret_cast<Inner_ccb*>(_clean_pointer(this->p_comp));
     if (out->is_valid())
       return out;
-    // else
-    while (!out->is_valid())
-      out = out->next();
-    set_inner_ccb(out);
 
+    // else
+    out = out->reduce_path();
+    set_inner_ccb(out);
     return out;
   }
 
+  Inner_ccb* inner_ccb_no_redirect()
+  {
+    CGAL_precondition(is_on_inner_ccb());
+    return reinterpret_cast<Inner_ccb*>(_clean_pointer(this->p_comp));
+  }
+
   /*! Set the incident inner CCB. */
   void set_inner_ccb(const Inner_ccb *ic)
   {
@@ -809,13 +813,25 @@ public:
   { if (other.status == ITER_IS_NOT_SINGULAR) iter = other.iter; }
 
   /*! Get a halfedge along the component (const version). */
-  const Halfedge* halfedge() const { return (*iter); }
+  const Halfedge* halfedge() const
+  {
+    CGAL_assertion (is_valid());
+    return (*iter);
+  }
 
   /*! Get a halfedge along the component (non-const version). */
-  Halfedge* halfedge() { return (*iter); }
+  Halfedge* halfedge()
+  {
+    CGAL_assertion (is_valid());
+    return (*iter);
+  }
 
   /*! Set a representative halfedge for the component. */
-  void set_halfedge(Halfedge *he) { *iter = he; }
+  void set_halfedge(Halfedge *he)
+  {
+    CGAL_assertion (is_valid());
+    *iter = he;
+  }
 
   /*! Get the incident face (const version). */
   const Face* face() const
@@ -855,7 +871,7 @@ public:
   /*! Set the inner CCB iterator. */
   void set_iterator(Inner_ccb_iterator it)
   {
-    CGAL_assertion (status != INVALID);
+    CGAL_assertion (is_valid());
     iter = it;
     status = ITER_IS_NOT_SINGULAR;
   }
@@ -876,6 +892,15 @@ public:
     status = INVALID;
     f_or_icc.icc = next;
   }
+
+  Arr_inner_ccb* reduce_path()
+  {
+    if (is_valid())
+      return this;
+    // else
+    f_or_icc.icc = f_or_icc.icc->reduce_path();
+    return f_or_icc.icc;
+  }
 };
 
 /*! \class
@@ -999,6 +1024,7 @@ public:
   typedef typename Face_list::iterator                Face_iterator;
   typedef CGAL::N_step_adaptor_derived<Halfedge_iterator, 2>
                                                       Edge_iterator;
+  typedef typename Inner_ccb_list::iterator           Inner_ccb_iterator;
 
   // Definitions of const iterators.
   typedef typename Vertex_list::const_iterator        Vertex_const_iterator;
@@ -1075,6 +1101,9 @@ public:
   {
     return make_prevent_deref_range(edges_begin(), edges_end());
   }
+
+  Inner_ccb_iterator inner_ccbs_begin() { return in_ccbs.begin(); }
+  Inner_ccb_iterator inner_ccbs_end()   { return in_ccbs.end(); }
   //@}
 
   /// \name Obtaining constant iterators.

Arrangement_on_surface_2/include/CGAL/Arrangement_2/Arrangement_on_surface_2_impl.h

@@ -2739,14 +2739,22 @@ _insert_at_vertices(DHalfedge* he_to,
       he1->set_inner_ccb(ic1);
       he2->set_inner_ccb(ic1);
 
-      // Make all halfedges along ic2 to point to ic1.
-      DHalfedge* curr;
+      if (m_sweep_mode)
+      {
+        CGAL_assertion(ic1->is_valid());
+        CGAL_assertion(ic2->is_valid());
+        ic2->set_next(ic1);
+      }
+      else
+      {
+        // Make all halfedges along ic2 to point to ic1.
+        DHalfedge* curr;
+        for (curr = he2->next(); curr != he1; curr = curr->next())
+          curr->set_inner_ccb(ic1);
 
-      for (curr = he2->next(); curr != he1; curr = curr->next())
-        curr->set_inner_ccb(ic1);
-
-      // Delete the redundant inner CCB.
-      _dcel().delete_inner_ccb(ic2);
+        // Delete the redundant inner CCB.
+        _dcel().delete_inner_ccb(ic2);
+      }
 
       // Notify the observers that we have merged the two inner CCBs.
       _notify_after_merge_inner_ccb(fh, (Halfedge_handle(he1))->ccb());

Arrangement_on_surface_2/include/CGAL/Arrangement_on_surface_2.h

@@ -909,6 +909,14 @@ protected:
   bool                    m_own_traits;    // inidicates whether the geometry
                                            // traits should be freed up.
 
+  bool                    m_sweep_mode = false;
+                                           // sweep mode efficiently
+                                           // merges inner CCB but
+                                           // keeps invalid inner CCB
+                                           // and memory overhead that
+                                           // should be cleaned
+                                           // afterwards
+
 public:
   /// \name Constructors.
   //@{
@@ -939,6 +947,9 @@ public:
   /*! Destructor. */
   virtual ~Arrangement_on_surface_2();
 
+  /*! Change mode. */
+  void set_sweep_mode (bool mode) { m_sweep_mode = mode; }
+
   /*! Clear the arrangement. */
   virtual void clear();
   //@}
@@ -1516,6 +1527,37 @@ public:
 
   //@}
 
+  /*!
+   * Cleans the inner CCB if sweep mode was used, by removing all
+   * non-valid inner CCBs
+   */
+  void clean_inner_ccbs()
+  {
+    for (DHalfedge_iter he = _dcel().halfedges_begin();
+         he != _dcel().halfedges_end(); ++ he)
+    {
+      if (!he->is_on_inner_ccb())
+        continue;
+
+      DInner_ccb* ic1 = he->inner_ccb_no_redirect();
+      if (ic1->is_valid())
+        continue;
+
+      DInner_ccb* ic2 = he->inner_ccb();
+      if (!ic2->halfedge()->is_on_inner_ccb()
+          || ic2->halfedge()->inner_ccb_no_redirect() != ic2)
+        ic2->set_halfedge(&(*he));
+    }
+
+    typename Dcel::Inner_ccb_iterator it = _dcel().inner_ccbs_begin();
+    while (it != _dcel().inner_ccbs_end())
+    {
+      typename Dcel::Inner_ccb_iterator current = it ++;
+      if (!current->is_valid())
+        _dcel().delete_inner_ccb(&*current);
+    }
+  }
+
 protected:
   /// \name Determining the boundary-side conditions.
   //@{

Arrangement_on_surface_2/include/CGAL/Surface_sweep_2/Arr_construction_ss_visitor.h

@@ -142,6 +142,9 @@ public:
   /* A notification issued before the sweep process starts. */
   inline void before_sweep();
 
+  /* A notification issued after the sweep process stops. */
+  inline void after_sweep();
+
   /*!
    * A notification invoked before the sweep-line starts handling the given
    * event.
@@ -267,7 +270,21 @@ private:
 // Notifies the helper that the sweep process now starts.
 template <typename Hlpr, typename Vis>
 void Arr_construction_ss_visitor<Hlpr, Vis>::before_sweep()
-{ m_helper.before_sweep(); }
+{
+  m_helper.before_sweep();
+  m_arr->set_sweep_mode(true);
+}
+
+
+//-----------------------------------------------------------------------------
+// A notification issued after the sweep process stops.
+template <typename Hlpr, typename Vis>
+void Arr_construction_ss_visitor<Hlpr, Vis>::after_sweep()
+{
+  m_arr->clean_inner_ccbs();
+  m_arr->set_sweep_mode(false);
+}
+
 
 //-----------------------------------------------------------------------------
 // A notification invoked before the sweep-line starts handling the given

Arrangement_on_surface_2/include/CGAL/Surface_sweep_2/Arr_overlay_ss_visitor.h

@@ -552,6 +552,8 @@ Arr_overlay_ss_visitor<OvlHlpr, OvlTr, Vis>::update_event(Event* e,
 template <typename OvlHlpr, typename OvlTr, typename Vis>
 void Arr_overlay_ss_visitor<OvlHlpr, OvlTr, Vis>::after_sweep()
 {
+  Base::after_sweep();
+
   // Notify boundary vertices:
   typename Vertex_map::iterator it;
   for (it = m_vertices_map.begin(); it != m_vertices_map.end(); ++it) {