Add support for forward-declaring shared_base-based types

The forward declaration must specialize the counter_type template
to explicitly specify shared_base as the counter type.

6 files changed, 58 insertions, 9 deletions

diff --git a/odb/details/shared-ptr-fwd.hxx b/odb/details/shared-ptr-fwd.hxx
new file mode 100644
index 0000000..4483b90
--- /dev/null
+++ b/odb/details/shared-ptr-fwd.hxx
@@ -0,0 +1,26 @@
+// file      : odb/details/shared-ptr-fwd.hxx
+// author    : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : Copyright (c) 2009-2011 Code Synthesis Tools CC
+// license   : GNU GPL v2; see accompanying LICENSE file
+
+#ifndef ODB_DETAILS_SHARED_PTR_FWD_HXX
+#define ODB_DETAILS_SHARED_PTR_FWD_HXX
+
+#include <odb/pre.hxx>
+
+#include <odb/details/shared-ptr/counter-type.hxx>
+
+namespace odb
+{
+  namespace details
+  {
+    template <typename X>
+    class shared_ptr;
+
+    class shared_base;
+  }
+}
+
+#include <odb/post.hxx>
+
+#endif // ODB_DETAILS_SHARED_PTR_FWD_HXX
diff --git a/odb/details/shared-ptr.hxx b/odb/details/shared-ptr.hxx
index bfe48cf..c795318 100644
--- a/odb/details/shared-ptr.hxx
+++ b/odb/details/shared-ptr.hxx
@@ -8,6 +8,7 @@
 
 #include <odb/pre.hxx>
 
+#include <odb/details/shared-ptr-fwd.hxx>
 #include <odb/details/shared-ptr/base.hxx>
 
 namespace odb
diff --git a/odb/details/shared-ptr/base.hxx b/odb/details/shared-ptr/base.hxx
index 7cf44da..3bc2df1 100644
--- a/odb/details/shared-ptr/base.hxx
+++ b/odb/details/shared-ptr/base.hxx
@@ -12,8 +12,8 @@
 #include <cstddef>   // std::size_t
 
 #include <odb/exception.hxx>
-
 #include <odb/details/export.hxx>
+#include <odb/details/shared-ptr/counter-type.hxx>
 
 namespace odb
 {
@@ -52,8 +52,9 @@ namespace odb
       what () const throw ();
     };
 
-    struct LIBODB_EXPORT shared_base
+    class LIBODB_EXPORT shared_base
     {
+    public:
       shared_base ();
       shared_base (const shared_base&);
       shared_base&
diff --git a/odb/details/shared-ptr/base.txx b/odb/details/shared-ptr/base.txx
index a836974..a57ce91 100644
--- a/odb/details/shared-ptr/base.txx
+++ b/odb/details/shared-ptr/base.txx
@@ -68,7 +68,7 @@ namespace odb
       template <typename X>
       struct counter_type<X, sizeof (meta::no)>
       {
-        typedef X r;
+        typedef typename details::counter_type<X>::counter r;
       };
 
       template <typename X>
diff --git a/odb/details/shared-ptr/counter-type.hxx b/odb/details/shared-ptr/counter-type.hxx
new file mode 100644
index 0000000..f208a4f
--- /dev/null
+++ b/odb/details/shared-ptr/counter-type.hxx
@@ -0,0 +1,25 @@
+// file      : odb/details/shared-ptr/counter-type.hxx
+// author    : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : Copyright (c) 2009-2011 Code Synthesis Tools CC
+// license   : GNU GPL v2; see accompanying LICENSE file
+
+#ifndef ODB_DETAILS_SHARED_PTR_COUNTER_TYPE_HXX
+#define ODB_DETAILS_SHARED_PTR_COUNTER_TYPE_HXX
+
+#include <odb/pre.hxx>
+
+namespace odb
+{
+  namespace details
+  {
+    template <typename X>
+    struct counter_type
+    {
+      typedef X counter;
+    };
+  }
+}
+
+#include <odb/post.hxx>
+
+#endif // ODB_DETAILS_SHARED_PTR_COUNTER_TYPE_HXX
diff --git a/odb/forward.hxx b/odb/forward.hxx
index ec502d2..c387fb4 100644
--- a/odb/forward.hxx
+++ b/odb/forward.hxx
@@ -8,6 +8,8 @@
 
 #include <odb/pre.hxx>
 
+#include <odb/details/shared-ptr-fwd.hxx>
+
 namespace odb
 {
   class database;
@@ -45,12 +47,6 @@ namespace odb
 
   template <typename T>
   struct object_traits;
-
-  namespace details
-  {
-    template <typename X>
-    class shared_ptr;
-  }
 }
 
 #include <odb/post.hxx>