1 files changed, 63 insertions, 0 deletions
diff --git a/libbrep/wrapper-traits.hxx b/libbrep/wrapper-traits.hxx
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+++ b/libbrep/wrapper-traits.hxx
@@ -0,0 +1,63 @@
+// file      : libbrep/wrapper-traits.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBREP_WRAPPER_TRAITS_HXX
+#define LIBBREP_WRAPPER_TRAITS_HXX
+
+#include <odb/pre.hxx>
+
+#include <butl/optional>
+
+#include <odb/wrapper-traits.hxx>
+
+namespace odb
+{
+  template <typename T>
+  class wrapper_traits<butl::optional<T>>
+  {
+  public:
+    typedef T wrapped_type;
+    typedef butl::optional<T> wrapper_type;
+
+    // T can be const.
+    //
+    typedef
+    typename odb::details::meta::remove_const<T>::result
+    unrestricted_wrapped_type;
+
+    static const bool null_handler = true;
+    static const bool null_default = true;
+
+    static bool
+    get_null (const wrapper_type& o)
+    {
+      return !o;
+    }
+
+    static void
+    set_null (wrapper_type& o)
+    {
+      o = wrapper_type ();
+    }
+
+    static const wrapped_type&
+    get_ref (const wrapper_type& o)
+    {
+      return *o;
+    }
+
+    static unrestricted_wrapped_type&
+    set_ref (wrapper_type& o)
+    {
+      if (!o)
+        o = unrestricted_wrapped_type ();
+
+      return const_cast<unrestricted_wrapped_type&> (*o);
+    }
+  };
+}
+
+#include <odb/post.hxx>
+
+#endif // LIBBREP_WRAPPER_TRAITS_HXX