Implement nested id support

Now the 'id' specifier can optionally include the data member path
to the id inside the composite value. For example:

#pragma db id(first)
std::pair<int, int> p;

Note that one somewhat counter-intuitive aspect of this new feature
is that the whole member marked with id ('p' in the above example)
and not just the actual id member ('p.first' in the above example)
is treated as readonly.

Such nested id also cannot be automatically assigned (auto specifier).

1 files changed, 24 insertions, 16 deletions

diff --git a/odb/context.cxx b/odb/context.cxx
index 4e354d8..59058ba 100644
--- a/odb/context.cxx
+++ b/odb/context.cxx
@@ -1001,14 +1001,25 @@ context* context::current_;
 semantics::data_member* context::
 id (data_member_path const& mp)
 {
-  for (data_member_path::const_reverse_iterator i (mp.rbegin ());
-       i != mp.rend (); ++i)
-  {
-    if (id (**i))
-      return *i;
-  }
+  semantics::data_member* idf (mp.front ());
 
-  return 0;
+  if (!id (*idf))
+    return 0;
+
+  // This is for special ids, such as polymorphic-ref, which
+  // don't have "id-member" set (and we want to keep it that
+  // way since it is not really a full-fledged id).
+  //
+  if (idf->get<string> ("id").empty ()) // Not a nested id.
+    return idf;
+
+  const data_member_path& id (
+    *id_member (
+      dynamic_cast<semantics::class_&> (idf->scope ())));
+
+  // Now we need to make sure id is a prefix of mp;
+  //
+  return mp.sub (id) ? idf : 0;
 }
 
 semantics::data_member* context::
@@ -1696,8 +1707,9 @@ inc_member (semantics::data_member& m,
   }
 }
 
-data_member_path context::
-resolve_data_members (semantics::class_& c,
+void context::
+resolve_data_members (data_member_path& r,
+                      semantics::class_& c,
                       const string& name,
                       const location& l,
                       cxx_string_lexer& lex)
@@ -1705,8 +1717,6 @@ resolve_data_members (semantics::class_& c,
   using semantics::class_;
   using semantics::data_member;
 
-  data_member_path r;
-
   // The name was already verified to be syntactically correct so
   // we don't need to do any extra error checking in this area.
   //
@@ -1722,7 +1732,7 @@ resolve_data_members (semantics::class_& c,
     r.push_back (&m);
 
     if (container (m))
-      return r;
+      return;
 
     // Resolve nested members if any.
     //
@@ -1749,7 +1759,7 @@ resolve_data_members (semantics::class_& c,
       r.push_back (&nm);
 
       if (container (nm))
-        return r;
+        return;
     }
   }
   catch (semantics::unresolved const& e)
@@ -1775,8 +1785,6 @@ resolve_data_members (semantics::class_& c,
 
     throw operation_failed ();
   }
-
-  return r;
 }
 
 bool context::
@@ -2177,7 +2185,7 @@ column_name (semantics::data_member& m, column_prefix const& cp) const
   string n (column_name (m, d));
   n = compose_name (cp.prefix, n);
 
-  // If any component is derived, the run it through the SQL name regex.
+  // If any component is derived, then run it through the SQL name regex.
   //
   if (d || cp.derived)
     n = transform_name (n, sql_name_column);