Full merge from trunk at revision 41356 of entire boost-root tree.

[SVN r41370]

example/doc_stateful_value_traits.cpp

@@ -0,0 +1,87 @@
+/////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Ion Gaztanaga  2007
+//
+// Distributed under the Boost Software License, Version 1.0.
+//    (See accompanying file LICENSE_1_0.txt or copy at
+//          http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/intrusive for documentation.
+//
+/////////////////////////////////////////////////////////////////////////////
+//[doc_stateful_value_traits
+#include <boost/intrusive/list.hpp>
+
+using namespace boost::intrusive;
+
+//This type is not modifiable so we can't store hooks or custom nodes
+typedef int identifier_t;
+
+//This value traits will associate elements from an array of identifiers with
+//elements of an array of nodes. The element i of the value array will use the
+//node i of the node array:
+struct stateful_value_traits
+{
+   typedef list_node_traits<void*>           node_traits;
+   typedef node_traits::node                 node;
+   typedef node *                            node_ptr;
+   typedef const node *                      const_node_ptr;
+   typedef identifier_t                      value_type;
+   typedef identifier_t *                    pointer; 
+   typedef const identifier_t *              const_pointer; 
+   static const link_mode_type link_mode =   normal_link;
+
+   stateful_value_traits(pointer ids, node_ptr node_array)
+      :  ids_(ids),  nodes_(node_array)
+   {}
+
+   ///Note: non static functions!
+   node_ptr to_node_ptr (value_type &value)
+      {  return this->nodes_ + (&value - this->ids_); }
+   const_node_ptr to_node_ptr (const value_type &value) const
+      {  return this->nodes_ + (&value - this->ids_); }
+   pointer to_value_ptr(node_ptr n)
+      {  return this->ids_ + (n - this->nodes_); }
+   const_pointer to_value_ptr(const_node_ptr n) const
+      {  return this->ids_ + (n - this->nodes_); }
+
+   private:
+   pointer  ids_;
+   node_ptr nodes_;
+};
+
+int main()
+{
+   const int NumElements = 100;
+
+   //This is an array of ids that we want to "store"
+   identifier_t                  ids   [NumElements];
+
+   //This is an array of nodes that is necessary to form the linked list
+   list_node_traits<void*>::node nodes [NumElements];
+
+   //Initialize id objects, each one with a different number
+   for(int i = 0; i != NumElements; ++i)   ids[i] = i;
+
+   //Define a list that will "link" identifiers using external nodes
+   typedef list<identifier_t, value_traits<stateful_value_traits> > List;
+
+   //This list will store ids without modifying identifier_t instances
+   //Stateful value traits must be explicitly passed in the constructor.
+   List  my_list (stateful_value_traits (ids, nodes));
+
+   //Insert ids in reverse order in the list
+   for(identifier_t * it(&ids[0]), *itend(&ids[NumElements]); it != itend; ++it)
+      my_list.push_front(*it);
+
+   //Now test lists
+   List::const_iterator   list_it (my_list.cbegin());
+   identifier_t *it_val(&ids[NumElements-1]), *it_rbeg_val(&ids[0]-1);
+
+   //Test the objects inserted in the base hook list
+   for(; it_val != it_rbeg_val; --it_val, ++list_it)
+      if(&*list_it  != &*it_val)   return 1;
+
+   return 0;
+}
+//]