Initial implementation

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+// file      : odb/traits.hxx
+// author    : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : Copyright (c) 2009-2010 Code Synthesis Tools CC
+// license   : GNU GPL v2; see accompanying LICENSE file
+
+#ifndef ODB_TRAITS_HXX
+#define ODB_TRAITS_HXX
+
+#include <memory>  // std::auto_ptr
+
+#include <odb/forward.hxx>
+#include <odb/shared-ptr.hxx>
+#include <odb/shared-ptr-traits.hxx>
+
+namespace odb
+{
+  enum id_source
+  {
+    ids_assigned /* Assigned by the application. */
+  };
+
+  // Specializations should defined the following members:
+  //
+  // id_type               - object id (primary key) type
+  // id_source             - object id (primary key) source
+  // id_type id (const T&) - get object id
+  //
+  // void insert (database&, const T&)
+  // void update (database&, const T&)
+  // void erase (database&, const id_type&)
+  // memory_traits<T>::shared_ptr find (database&, const id_type&)
+  //
+  // And inherit from object_memory and object_factory.
+  //
+  // template <typename T>
+  // class access::object_traits;
+
+  template <typename T>
+  class access::object_memory
+  {
+  public:
+    typedef odb::shared_ptr<T> shared_ptr;
+    typedef std::auto_ptr<T> unique_ptr;
+  };
+
+  template <typename T>
+  class access::object_factory
+  {
+  public:
+    static typename object_memory<T>::shared_ptr
+    create ()
+    {
+      // By default use shared_ptr-specific construction.
+      //
+      return shared_factory<typename object_memory<T>::shared_ptr>::create ();
+    }
+  };
+
+  template <typename P>
+  class access::shared_factory
+  {
+  public:
+    typedef typename shared_ptr_traits<P>::type object_type;
+
+    static P
+    create ()
+    {
+      void* v (shared_ptr_traits<P>::allocate (sizeof (object_type)));
+      guard g (v);
+      P p (new (v) object_type);
+      g.release ();
+      return p;
+    }
+  private:
+    struct guard
+    {
+      guard (void* p): p_ (p) {}
+      ~guard () {if (p_) shared_ptr_traits<P>::free (p_);}
+      void release () {p_ = 0;}
+      void* p_;
+    };
+  };
+
+  template <typename T>
+  struct object_traits: access::object_traits<T>
+  {
+    typedef
+    shared_ptr_traits<typename access::object_traits<T>::shared_ptr>
+    shared_ops;
+  };
+}
+
+#endif // ODB_TRAITS_HXX