Generate alter column migration statements

6 files changed, 292 insertions, 22 deletions

diff --git a/odb/relational/mssql/schema.cxx b/odb/relational/mssql/schema.cxx
index 03406ce..2db0c12 100644
--- a/odb/relational/mssql/schema.cxx
+++ b/odb/relational/mssql/schema.cxx
@@ -336,6 +336,35 @@ namespace relational
       };
       entry<drop_index> drop_index_;
 
+      struct alter_column: relational::alter_column, context
+      {
+        alter_column (base const& x): base (x) {}
+
+        virtual void
+        traverse (sema_rel::alter_column& ac)
+        {
+          assert (ac.null_altered ());
+
+          // Relax (NULL) in pre and tighten (NOT NULL) in post.
+          //
+          if (pre_ != ac.null ())
+            return;
+
+          using sema_rel::alter_table;
+          alter_table& at (static_cast<alter_table&> (ac.scope ()));
+
+          pre_statement ();
+
+          os << "ALTER TABLE " << quote_id (at.name ()) << endl
+             << "  ALTER COLUMN ";
+          alter (ac);
+          os << endl;
+
+          post_statement ();
+        }
+      };
+      entry<alter_column> alter_column_;
+
       struct alter_table_pre: relational::alter_table_pre, context
       {
         alter_table_pre (base const& x): base (x) {}
@@ -352,13 +381,21 @@ namespace relational
             os << "  ADD ";
 
             instance<create_column> c (emitter (), stream (), format_);
-            trav_rel::unames n;
-            n >> c;
+            trav_rel::unames n (*c);
             names (at, n);
             os << endl;
 
             post_statement ();
           }
+
+          // For ALTER COLUMN, SQL Server can only have one per ALTER TABLE.
+          //
+          {
+            bool tl (true); // (Im)perfect forwarding.
+            instance<alter_column> ac (emitter (), stream (), format_, tl);
+            trav_rel::unames n (*ac);
+            names (at, n);
+          }
         }
       };
       entry<alter_table_pre> alter_table_pre_;
@@ -379,13 +416,21 @@ namespace relational
             os << "  DROP COLUMN ";
 
             instance<drop_column> c (emitter (), stream (), format_);
-            trav_rel::unames n;
-            n >> c;
+            trav_rel::unames n (*c);
             names (at, n);
             os << endl;
 
             post_statement ();
           }
+
+          // For ALTER COLUMN, SQL Server can only have one per ALTER TABLE.
+          //
+          {
+            bool fl (false); // (Im)perfect forwarding.
+            instance<alter_column> ac (emitter (), stream (), format_, fl);
+            trav_rel::unames n (*ac);
+            names (at, n);
+          }
         }
       };
       entry<alter_table_post> alter_table_post_;
diff --git a/odb/relational/mysql/schema.cxx b/odb/relational/mysql/schema.cxx
index c3f7571..6ce619b 100644
--- a/odb/relational/mysql/schema.cxx
+++ b/odb/relational/mysql/schema.cxx
@@ -367,6 +367,18 @@ namespace relational
         }
       };
       entry<drop_index> drop_index_;
+
+      struct alter_column: relational::alter_column, context
+      {
+        alter_column (base const& x): base (x) {}
+
+        virtual void
+        alter_header ()
+        {
+          os << "MODIFY COLUMN ";
+        }
+      };
+      entry<alter_column> alter_column_;
     }
   }
 }
diff --git a/odb/relational/oracle/schema.cxx b/odb/relational/oracle/schema.cxx
index 34ede1c..024701c 100644
--- a/odb/relational/oracle/schema.cxx
+++ b/odb/relational/oracle/schema.cxx
@@ -344,6 +344,31 @@ namespace relational
       };
       entry<drop_index> drop_index_;
 
+      struct alter_column: relational::alter_column, context
+      {
+        alter_column (base const& x): base (x) {}
+
+        virtual void
+        traverse (sema_rel::alter_column& ac)
+        {
+          assert (ac.null_altered ());
+
+          // Relax (NULL) in pre and tighten (NOT NULL) in post.
+          //
+          if (pre_ != ac.null ())
+            return;
+
+          if (first_)
+            first_ = false;
+          else
+            os << "," << endl
+               << "          ";
+
+          os << quote_id (ac.name ()) << (ac.null () ? " NULL" : " NOT NULL");
+        }
+      };
+      entry<alter_column> alter_column_;
+
       struct alter_table_pre: relational::alter_table_pre, context
       {
         alter_table_pre (base const& x): base (x) {}
@@ -360,9 +385,23 @@ namespace relational
             alter_header (at.name ());
             os << "  ADD (";
 
-            instance<create_column> c (emitter (), stream (), format_);
-            trav_rel::unames n;
-            n >> c;
+            instance<create_column> cc (emitter (), stream (), format_);
+            trav_rel::unames n (*cc);
+            names (at, n);
+            os << ")" << endl;
+
+            post_statement ();
+          }
+
+          if (check_alter_null (at, true))
+          {
+            pre_statement ();
+            alter_header (at.name ());
+            os << "  MODIFY (";
+
+            bool tl (true); // (Im)perfect forwarding.
+            instance<alter_column> ac (emitter (), stream (), format_, tl);
+            trav_rel::unames n (*ac);
             names (at, n);
             os << ")" << endl;
 
@@ -388,9 +427,23 @@ namespace relational
             alter_header (at.name ());
             os << "  DROP (";
 
-            instance<drop_column> c (emitter (), stream (), format_);
-            trav_rel::unames n;
-            n >> c;
+            instance<drop_column> dc (emitter (), stream (), format_);
+            trav_rel::unames n (*dc);
+            names (at, n);
+            os << ")" << endl;
+
+            post_statement ();
+          }
+
+          if (check_alter_null (at, false))
+          {
+            pre_statement ();
+            alter_header (at.name ());
+            os << "  MODIFY (";
+
+            bool fl (false); // (Im)perfect forwarding.
+            instance<alter_column> ac (emitter (), stream (), format_, fl);
+            trav_rel::unames n (*ac);
             names (at, n);
             os << ")" << endl;
 
diff --git a/odb/relational/pgsql/schema.cxx b/odb/relational/pgsql/schema.cxx
index efe9b40..7e0b7a5 100644
--- a/odb/relational/pgsql/schema.cxx
+++ b/odb/relational/pgsql/schema.cxx
@@ -209,6 +209,19 @@ namespace relational
         }
       };
       entry<create_index> create_index_;
+
+      struct alter_column: relational::alter_column, context
+      {
+        alter_column (base const& x): base (x) {}
+
+        virtual void
+        alter (sema_rel::alter_column& ac)
+        {
+          os << quote_id (ac.name ()) << " " <<
+            (ac.null () ? "DROP" : "SET") << " NOT NULL";
+        }
+      };
+      entry<alter_column> alter_column_;
     }
   }
 }
diff --git a/odb/relational/schema.hxx b/odb/relational/schema.hxx
index b0d70df..69e8089 100644
--- a/odb/relational/schema.hxx
+++ b/odb/relational/schema.hxx
@@ -64,8 +64,24 @@ namespace relational
     {
       typedef drop_column base;
 
-      drop_column (emitter_type& e, ostream& os, schema_format f)
-          : common (e, os), format_ (f), first_ (true)
+      drop_column (emitter_type& e,
+                   ostream& os,
+                   schema_format f,
+                   bool* first = 0)
+          : common (e, os),
+            format_ (f),
+            first_ (first != 0 ? *first : first_data_),
+            first_data_ (true)
+      {
+      }
+
+      drop_column (drop_column const& c)
+          : root_context (), // @@ -Wextra
+            context (),
+            common (c),
+            format_ (c.format_),
+            first_ (&c.first_ != &c.first_data_ ? c.first_ : first_data_),
+            first_data_ (c.first_data_)
       {
       }
 
@@ -92,7 +108,8 @@ namespace relational
 
     protected:
       schema_format format_;
-      bool first_;
+      bool& first_;
+      bool first_data_;
     };
 
     // Currently only used in migration.
@@ -292,8 +309,24 @@ namespace relational
     {
       typedef create_column base;
 
-      create_column (emitter_type& e, ostream& os, schema_format f)
-          : common (e, os), format_ (f), first_ (true)
+      create_column (emitter_type& e,
+                     ostream& os,
+                     schema_format f,
+                     bool* first = 0)
+          : common (e, os),
+            format_ (f),
+            first_ (first != 0 ? *first : first_data_),
+            first_data_ (true)
+      {
+      }
+
+      create_column (create_column const& c)
+          : root_context (), // @@ -Wextra
+            context (),
+            common (c),
+            format_ (c.format_),
+            first_ (&c.first_ != &c.first_data_ ? c.first_ : first_data_),
+            first_data_ (c.first_data_)
       {
       }
 
@@ -394,7 +427,8 @@ namespace relational
 
     protected:
       schema_format format_;
-      bool first_;
+      bool& first_;
+      bool first_data_;
     };
 
     struct create_primary_key: trav_rel::primary_key, virtual context
@@ -775,6 +809,78 @@ namespace relational
     // Migration.
     //
 
+    struct alter_column: trav_rel::alter_column, common
+    {
+      typedef alter_column base;
+
+      alter_column (emitter_type& e,
+                    ostream& os,
+                    schema_format f,
+                    bool pre,
+                    bool* first = 0)
+          : common (e, os),
+            format_ (f),
+            pre_ (pre),
+            first_ (first != 0 ? *first : first_data_),
+            first_data_ (true),
+            def_ (e, os, f)
+      {
+      }
+
+      alter_column (alter_column const& c)
+          : root_context (), // @@ -Wextra
+            context (),
+            common (c),
+            format_ (c.format_),
+            pre_ (c.pre_),
+            first_ (&c.first_ != &c.first_data_ ? c.first_ : first_data_),
+            first_data_ (c.first_data_),
+            def_ (common::e_, common::os_, c.format_)
+      {
+      }
+
+      virtual void
+      alter_header ()
+      {
+        os << "ALTER COLUMN ";
+      }
+
+      virtual void
+      alter (sema_rel::alter_column& ac)
+      {
+        // By default use the whole definition.
+        //
+        def_->create (ac);
+      }
+
+      virtual void
+      traverse (sema_rel::alter_column& ac)
+      {
+        assert (ac.null_altered ());
+
+        // Relax (NULL) in pre and tighten (NOT NULL) in post.
+        //
+        if (pre_ != ac.null ())
+          return;
+
+        if (first_)
+          first_ = false;
+        else
+          os << "," << endl;
+
+        os << "  ";
+        alter_header ();
+        alter (ac);
+      }
+
+    protected:
+      schema_format format_;
+      bool pre_;
+      bool& first_;
+      bool first_data_;
+      instance<create_column> def_;
+    };
+
     struct alter_table_common: trav_rel::alter_table, common
     {
       alter_table_common (emitter_type& e, ostream& os, schema_format f)
@@ -796,6 +902,24 @@ namespace relational
         return 0;
       }
 
+      sema_rel::alter_column*
+      check_alter_null (sema_rel::alter_table& at, bool v)
+      {
+        using sema_rel::alter_column;
+
+        for (sema_rel::alter_table::names_iterator i (at.names_begin ());
+             i != at.names_end (); ++i)
+        {
+          if (alter_column* ac = dynamic_cast<alter_column*> (&i->nameable ()))
+          {
+            if (ac->null_altered () && ac->null () == v)
+              return ac;
+          }
+        }
+
+        return 0;
+      }
+
       virtual void
       alter_header (sema_rel::qname const& table)
       {
@@ -829,7 +953,8 @@ namespace relational
       virtual bool
       check (sema_rel::alter_table& at)
       {
-        return check<sema_rel::add_column> (at);
+        return check<sema_rel::add_column> (at) ||
+          check_alter_null (at, true);
       }
 
       virtual void
@@ -841,9 +966,14 @@ namespace relational
         pre_statement ();
         alter_header (at.name ());
 
-        instance<create_column> c (emitter (), stream (), format_);
+        bool f (true);  // Shared first flag.
+        bool* pf (&f);  // (Im)perfect forwarding.
+        bool tl (true); // (Im)perfect forwarding.
+        instance<create_column> cc (emitter (), stream (), format_, pf);
+        instance<alter_column> ac (emitter (), stream (), format_, tl, pf);
         trav_rel::unames n;
-        n >> c;
+        n >> cc;
+        n >> ac;
         names (at, n);
         os << endl;
 
@@ -933,7 +1063,8 @@ namespace relational
       virtual bool
       check (sema_rel::alter_table& at)
       {
-        return check<sema_rel::drop_column> (at);
+        return check<sema_rel::drop_column> (at) ||
+          check_alter_null (at, false);
       }
 
       virtual void
@@ -945,9 +1076,14 @@ namespace relational
         pre_statement ();
         alter_header (at.name ());
 
-        instance<drop_column> c (emitter (), stream (), format_);
+        bool f (true); // Shared first flag.
+        bool* pf (&f); // (Im)perfect forwarding.
+        bool fl (false); // (Im)perfect forwarding.
+        instance<drop_column> dc (emitter (), stream (), format_, pf);
+        instance<alter_column> ac (emitter (), stream (), format_, fl, pf);
         trav_rel::unames n;
-        n >> c;
+        n >> dc;
+        n >> ac;
         names (at, n);
         os << endl;
 
diff --git a/odb/relational/sqlite/schema.cxx b/odb/relational/sqlite/schema.cxx
index ac19328..6d3cba4 100644
--- a/odb/relational/sqlite/schema.cxx
+++ b/odb/relational/sqlite/schema.cxx
@@ -122,6 +122,17 @@ namespace relational
           trav_rel::unames n;
           n >> c;
           names (at, n);
+
+          // SQLite does not support altering columns.
+          //
+          if (sema_rel::alter_column* ac = check<sema_rel::alter_column> (at))
+          {
+            cerr << "error: SQLite does not support altering of columns"
+                 << endl;
+            cerr << "info: first altered column is '" << ac->name () <<
+              "' in table '" << at.name () << "'" << endl;
+            throw operation_failed ();
+          }
         }
       };
       entry<alter_table_pre> alter_table_pre_;