Add session, database operations on pointers and const objects

Currently, session is just an object cache. The persist, update, and
erase database operations are overloaded to also work on object
pointers. All the database operations and the query facility now
support const objects.

New session-related exceptions: not_in_session, already_in_session,
const_object.

1 files changed, 65 insertions, 0 deletions

diff --git a/odb/session.ixx b/odb/session.ixx
new file mode 100644
index 0000000..0be6bfa
--- /dev/null
+++ b/odb/session.ixx
@@ -0,0 +1,65 @@
+// file      : odb/session.ixx
+// author    : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : Copyright (c) 2009-2010 Code Synthesis Tools CC
+// license   : GNU GPL v2; see accompanying LICENSE file
+
+#include <odb/exceptions.hxx>
+
+namespace odb
+{
+  template <typename T>
+  inline void session::
+  erase (const object_position<T>& p)
+  {
+    // @@ Empty maps are not cleaned up by this version of erase.
+    //
+    p.map_->erase (p.pos_);
+  }
+
+  //
+  // object_pointers
+  //
+  template <typename T>
+  inline session::object_pointers<T>::
+  object_pointers () : p_ (), cp_ () {}
+
+  template <typename T>
+  inline void session::object_pointers<T>::
+  set (const pointer_type& p)
+  {
+    p_ = p;
+    cp_ = const_pointer_type ();
+  }
+
+  template <typename T>
+  inline void session::object_pointers<T>::
+  set (const const_pointer_type& cp)
+  {
+    p_ = pointer_type ();
+    cp_ = cp;
+  }
+
+  template <typename T>
+  inline void session::object_pointers<T>::
+  get (pointer_type& p) const
+  {
+    if (!pointer_traits<pointer_type>::null_ptr (p_))
+      p = p_;
+    else if (!pointer_traits<const_pointer_type>::null_ptr (cp_))
+      throw const_object ();
+    else
+      p = pointer_type ();
+  }
+
+  template <typename T>
+  inline void session::object_pointers<T>::
+  get (const_pointer_type& cp) const
+  {
+    if (!pointer_traits<pointer_type>::null_ptr (p_))
+      cp = const_pointer_type (p_);
+    else if (!pointer_traits<const_pointer_type>::null_ptr (cp_))
+      cp = cp_;
+    else
+      cp = const_pointer_type ();
+  }
+}