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, 72 insertions, 0 deletions

diff --git a/odb/session.cxx b/odb/session.cxx
new file mode 100644
index 0000000..b34c1d7
--- /dev/null
+++ b/odb/session.cxx
@@ -0,0 +1,72 @@
+// file      : odb/session.cxx
+// 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>
+#include <odb/session.hxx>
+
+#include <odb/details/tls.hxx>
+
+namespace odb
+{
+  using namespace details;
+
+  static ODB_TLS_POINTER (session) current_session;
+
+  session::
+  session ()
+  {
+    if (has_current ())
+      throw already_in_session ();
+
+    current (*this);
+  }
+
+  session::
+  ~session ()
+  {
+    // If we are the current thread's session, reset it.
+    //
+    if (has_current () && &current () == this)
+      reset_current ();
+  }
+
+  bool session::
+  has_current ()
+  {
+    return tls_get (current_session) != 0;
+  }
+
+  session& session::
+  current ()
+  {
+    session* cur (tls_get (current_session));
+
+    if (cur == 0)
+      throw not_in_session ();
+
+    return *cur;
+  }
+
+  void session::
+  current (session& s)
+  {
+    tls_set (current_session, &s);
+  }
+
+  void session::
+  reset_current ()
+  {
+    session* s (0);
+    tls_set (current_session, s);
+  }
+
+  //
+  // object_map_base
+  //
+  session::object_map_base::
+  ~object_map_base ()
+  {
+  }
+}