Add support for value wrappers

Wrapper is a class that wraps another type. Examples of wrappers are
various smart pointers, holders, etc. A wrapper can be transparent or
it can handle the NULL semantics.

The new odb::nullable class template is a NULL wrapper that helps
to add the NULL semantics to a value type.

New test: common/wrapper.

1 files changed, 73 insertions, 0 deletions

diff --git a/common/wrapper/driver.cxx b/common/wrapper/driver.cxx
new file mode 100644
index 0000000..ed4d83f
--- /dev/null
+++ b/common/wrapper/driver.cxx
@@ -0,0 +1,73 @@
+// file      : common/wrapper/driver.cxx
+// author    : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : Copyright (c) 2009-2011 Code Synthesis Tools CC
+// license   : GNU GPL v2; see accompanying LICENSE file
+
+// Test wrapper machinery.
+//
+
+#include <memory>   // std::auto_ptr
+#include <cassert>
+#include <iostream>
+
+#include <odb/database.hxx>
+#include <odb/transaction.hxx>
+
+#include <common/common.hxx>
+
+#include "test.hxx"
+#include "test-odb.hxx"
+
+using namespace std;
+using namespace odb::core;
+
+int
+main (int argc, char* argv[])
+{
+  try
+  {
+    auto_ptr<database> db (create_database (argc, argv));
+
+    //
+    //
+    unsigned long id;
+    {
+      object o;
+      o.num.reset (new unsigned long (123));
+      o.nstrs.push_back (nullable_string ());
+      o.nstrs.push_back (nullable_string ("123"));
+#ifdef HAVE_TR1_MEMORY
+      o.tr1_strs.push_back (tr1_nullable_string ());
+      o.tr1_strs.push_back (tr1_nullable_string (new string ("123")));
+#endif
+
+      transaction t (db->begin ());
+      id = db->persist (o);
+      t.commit ();
+    }
+
+    //
+    //
+    {
+      transaction t (db->begin ());
+      auto_ptr<object> o (db->load<object> (id));
+      t.commit ();
+
+      assert (*o->num == 123);
+      assert (o->str.get () == 0);
+      assert (o->nstr.null ());
+      assert (o->nstrs[0].null ());
+      assert (o->nstrs[1].get () == "123");
+#ifdef HAVE_TR1_MEMORY
+      assert (!o->tr1_str);
+      assert (!o->tr1_strs[0]);
+      assert (*o->tr1_strs[1] == "123");
+#endif
+    }
+  }
+  catch (const odb::exception& e)
+  {
+    cerr << e.what () << endl;
+    return 1;
+  }
+}