From b23f61eefd7e87cec1e1c4b4d90a6e18f6329437 Mon Sep 17 00:00:00 2001
From: Sylvain Pion <Sylvain.Pion@sophia.inria.fr>
Date: Sun, 30 Dec 2007 16:51:02 +0000
Subject: [PATCH] Make Tree_base_node type safe using CRTP. (removes
 frightening aliasing breakage warnings)

---
 SearchStructures/include/CGAL/Range_tree_d.h  | 21 ++++++++++---------
 .../include/CGAL/Segment_tree_d.h             | 21 +++++++++++--------
 SearchStructures/include/CGAL/Tree_base.h     | 19 +++++++----------
 3 files changed, 30 insertions(+), 31 deletions(-)

diff --git a/SearchStructures/include/CGAL/Range_tree_d.h b/SearchStructures/include/CGAL/Range_tree_d.h
index da9acb99a08..545b66237b4 100644
--- a/SearchStructures/include/CGAL/Range_tree_d.h
+++ b/SearchStructures/include/CGAL/Range_tree_d.h
@@ -44,7 +44,7 @@ template <class C_Data, class C_Window, class C_Interface>
 class Range_tree_d;
 
 template <class C_Data, class C_Window, class C_Interface>
-struct Range_tree_node: public Tree_node_base
+struct Range_tree_node: public Tree_node_base<Range_tree_node<C_Data, C_Window, C_Interface> >
 {
   private:
   typedef  C_Data Data;
@@ -56,23 +56,24 @@ struct Range_tree_node: public Tree_node_base
   //typedef Range_tree_d< C_Data,  C_Window,  C_Interface> rT_d;
 public:
   friend class Range_tree_d< C_Data,  C_Window,  C_Interface>;
-  
+
+  typedef Tree_node_base<Range_tree_node<C_Data, C_Window, C_Interface> >  Base;
+
   Range_tree_node()
     : sublayer(0)
   {} 
-  
-  
+
   Range_tree_node( Range_tree_node    * p_left,
 		   Range_tree_node    * p_right,
 		   const  Data & v_obj,
 		   const  Key  & v_key )
-    : Tree_node_base(p_left, p_right), object( v_obj ), key( v_key ), sublayer(0)
+    : Base(p_left, p_right), object( v_obj ), key( v_key ), sublayer(0)
   {}
   
   Range_tree_node( Range_tree_node    * p_left,
 		   Range_tree_node    * p_right,
 		   const  Key  & v_key )
-    : Tree_node_base(p_left, p_right), key( v_key ), sublayer(0)
+    : Base(p_left, p_right), key( v_key ), sublayer(0)
   {}
 
   virtual ~Range_tree_node()
@@ -112,14 +113,14 @@ protected:
   typedef Range_tree_node<C_Data,C_Window,C_Interface> *link_type;
 
   static link_type& left(link_type x) { 
-    return CGAL__static_cast(link_type&, (*x).left_link);
+    return x->left_link;
   }
   static link_type& right(link_type x) {
-    return CGAL__static_cast(link_type&, (*x).right_link);   
+    return x->right_link;   
   }
 
   static link_type& parent(link_type x) {
-    return CGAL__static_cast(link_type&, (*x).parent_link);
+    return x->parent_link;
   }
 
   link_type header;
@@ -128,7 +129,7 @@ protected:
   link_type leftmost(){return left(header);}
   link_type root() const {
     if(header!=0)
-      return CGAL__static_cast(link_type&, header->parent_link);
+      return header->parent_link;
     // return parent(header);
     else 
       return 0;
diff --git a/SearchStructures/include/CGAL/Segment_tree_d.h b/SearchStructures/include/CGAL/Segment_tree_d.h
index 984623a5cd9..04a99d5d0f5 100644
--- a/SearchStructures/include/CGAL/Segment_tree_d.h
+++ b/SearchStructures/include/CGAL/Segment_tree_d.h
@@ -41,7 +41,8 @@ template <class C_Data, class C_Window, class C_Interface>
 class Segment_tree_d;
 
 template <class C_Data, class C_Window, class C_Interface>
-struct Segment_tree_node: public Tree_node_base
+struct Segment_tree_node
+  : public Tree_node_base<Segment_tree_node<C_Data, C_Window, C_Interface> >
 {
   typedef  C_Data Data;
   typedef  C_Window Window;
@@ -54,21 +55,23 @@ struct Segment_tree_node: public Tree_node_base
   Tree_base<C_Data, C_Window> *sublayer;
 public:
   friend class Segment_tree_d< C_Data,  C_Window,  C_Interface>;
-  
+
+  typedef Tree_node_base<Segment_tree_node<C_Data, C_Window, C_Interface> >  Base;
+
   Segment_tree_node()
-    : Tree_node_base(), sublayer(0)
+    : sublayer(0)
   {}
 
   Segment_tree_node(const Key& p_left_key,
 		    const Key& p_right_key)
-    : Tree_node_base(), left_key(p_left_key), right_key(p_right_key), sublayer(0)
+    : left_key(p_left_key), right_key(p_right_key), sublayer(0)
   {}
 
   Segment_tree_node(Segment_tree_node * p_left,
 		    Segment_tree_node * p_right,
 		    const Key& p_left_key,
 		    const Key& p_right_key)
-    : Tree_node_base(p_left,p_right), left_key(p_left_key), right_key(p_right_key), sublayer(0)
+    : Base(p_left,p_right), left_key(p_left_key), right_key(p_right_key), sublayer(0)
   {}
   
   ~Segment_tree_node(){
@@ -111,13 +114,13 @@ protected:
   }   
   
   static link_type left(link_type x) { 
-    return static_cast<link_type>(x->left_link);
+    return x->left_link;
   }
   static link_type right(link_type x) {
-    return static_cast<link_type>(x->right_link); 
+    return x->right_link; 
    }
   static link_type parent(link_type x) {
-    return static_cast<link_type>( x->parent_link);
+    return x->parent_link;
   }
 
   link_type header;
@@ -126,7 +129,7 @@ protected:
   link_type leftmost(){return left(header);}
   link_type root() const{
     if(header!=0)
-      return static_cast<link_type>(header->parent_link); 
+      return header->parent_link; 
     return 0;
   }
   
diff --git a/SearchStructures/include/CGAL/Tree_base.h b/SearchStructures/include/CGAL/Tree_base.h
index 0d7910923c9..48e8bd11f95 100644
--- a/SearchStructures/include/CGAL/Tree_base.h
+++ b/SearchStructures/include/CGAL/Tree_base.h
@@ -32,26 +32,21 @@
 #define TREE_BASE_NULL 0
 #endif
 
-#ifndef CGAL__static_cast
-#define CGAL__static_cast(TYPE,EXPR) (TYPE)(EXPR)
-#endif
-
 #define stlvector
 
 CGAL_BEGIN_NAMESPACE
 
-
-
 //link type definition of an ordinary vertex of the tree
+template < typename Node >
 struct Tree_node_base {
-  void *parent_link;
-  void *left_link;
-  void *right_link;
+  Node *parent_link;
+  Node *left_link;
+  Node *right_link;
   Tree_node_base()
-    :parent_link(0), left_link(0), right_link(0)
+    : parent_link(0), left_link(0), right_link(0)
   {}
-  Tree_node_base(void* ll, void* rl)
-    :parent_link(0), left_link(ll), right_link(rl)
+  Tree_node_base(Node* ll, Node* rl)
+    : parent_link(0), left_link(ll), right_link(rl)
   {}
 };