Generate add/drop table migration statements

3 files changed, 62 insertions, 3 deletions

diff --git a/odb/semantics/relational/changelog.hxx b/odb/semantics/relational/changelog.hxx
index 93b327d..d9e220c 100644
--- a/odb/semantics/relational/changelog.hxx
+++ b/odb/semantics/relational/changelog.hxx
@@ -88,6 +88,12 @@ namespace semantics
         return *contains_changeset_.back ();
       }
 
+      contains_changeset const&
+      contains_changeset_at (contains_changeset_list::size_type i) const
+      {
+        return *contains_changeset_[i];
+      }
+
       contains_changeset_iterator
       contains_changeset_begin () const
       {
diff --git a/odb/semantics/relational/changeset.cxx b/odb/semantics/relational/changeset.cxx
index fd5a17f..669394f 100644
--- a/odb/semantics/relational/changeset.cxx
+++ b/odb/semantics/relational/changeset.cxx
@@ -13,14 +13,16 @@ namespace semantics
     changeset::
     changeset (changeset const& c, qscope& b, graph& g)
         : qscope (c, &b, g),
-          version_ (c.version_)
+          version_ (c.version_),
+          alters_model_ (0)
     {
     }
 
     changeset::
     changeset (xml::parser& p, qscope& b, graph& g)
         : qscope (p, &b, g),
-          version_ (p.attribute<version_type> ("version"))
+          version_ (p.attribute<version_type> ("version")),
+          alters_model_ (0)
     {
     }
 
diff --git a/odb/semantics/relational/changeset.hxx b/odb/semantics/relational/changeset.hxx
index 76fd683..27c80fe 100644
--- a/odb/semantics/relational/changeset.hxx
+++ b/odb/semantics/relational/changeset.hxx
@@ -11,6 +11,43 @@ namespace semantics
 {
   namespace relational
   {
+    class model;
+    class changeset;
+
+    class alters_model: public edge
+    {
+    public:
+      typedef relational::model model_type;
+      typedef relational::changeset changeset_type;
+
+      model_type&
+      model () const {return *model_;}
+
+      changeset_type&
+      changeset () const {return *changeset_;}
+
+    public:
+      alters_model () : model_ (0), changeset_ (0) {}
+
+      void
+      set_left_node (changeset_type& c)
+      {
+        assert (changeset_ == 0);
+        changeset_ = &c;
+      }
+
+      void
+      set_right_node (model_type& m)
+      {
+        assert (model_ == 0);
+        model_ = &m;
+      }
+
+    protected:
+      model_type* model_;
+      changeset_type* changeset_;
+    };
+
     class changeset: public qscope
     {
     public:
@@ -19,8 +56,14 @@ namespace semantics
       version_type
       version () const {return version_;}
 
+      // Returns model to which this changeset applies (as opposed to the
+      // ultimate base model). Note that it may not be set.
+      //
+      model&
+      base_model () const {return alters_model_->model ();}
+
     public:
-      changeset (version_type v): version_ (v) {}
+      changeset (version_type v): version_ (v), alters_model_ (0) {}
       changeset (changeset const&, qscope& base, graph&);
       changeset (xml::parser&, qscope& base, graph&);
 
@@ -31,11 +74,19 @@ namespace semantics
       serialize (xml::serializer&) const;
 
     public:
+      virtual void
+      add_edge_left (alters_model& am)
+      {
+        assert (alters_model_ == 0);
+        alters_model_ = &am;
+      }
+
       using qscope::add_edge_left;
       using qscope::add_edge_right;
 
     private:
       version_type version_;
+      alters_model* alters_model_;
     };
   }
 }