Add odb::connection class

This abstract class represents a connection to the database. One can
use it to start a transaction or to execute a native statement out
of a transaction.

Before we had concrete connection classes in the database runtime
libraries (e.g., odb::mysql::connection). Now these classes derive
from odb::connection.

1 files changed, 16 insertions, 2 deletions

diff --git a/odb/transaction.hxx b/odb/transaction.hxx
index 17487b2..c2b1f77 100644
--- a/odb/transaction.hxx
+++ b/odb/transaction.hxx
@@ -20,6 +20,7 @@ namespace odb
   {
   public:
     typedef odb::database database_type;
+    typedef odb::connection connection_type;
 
     explicit
     transaction (transaction_impl*);
@@ -40,6 +41,11 @@ namespace odb
     database_type&
     database ();
 
+    // Return the connection this transaction is on.
+    //
+    connection_type&
+    connection ();
+
     // Return current transaction or throw if there is no transaction
     // in effect.
     //
@@ -72,9 +78,10 @@ namespace odb
     friend class transaction;
 
     typedef odb::database database_type;
+    typedef odb::connection connection_type;
 
-    transaction_impl (database_type& db)
-        : database_ (db)
+    transaction_impl (database_type& db, connection_type& c)
+      : database_ (db), connection_ (c)
     {
     }
 
@@ -93,8 +100,15 @@ namespace odb
       return database_;
     }
 
+    connection_type&
+    connection ()
+    {
+      return connection_;
+    }
+
   protected:
     database_type& database_;
+    connection_type& connection_;
   };
 }