--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rhodecode/lib/dbmigrate/migrate/changeset/databases/firebird.py	Sat Dec 11 01:54:12 2010 +0100
@@ -0,0 +1,80 @@
+"""
+   Firebird database specific implementations of changeset classes.
+"""
+from sqlalchemy.databases import firebird as sa_base
+
+from migrate import exceptions
+from migrate.changeset import ansisql, SQLA_06
+
+
+if SQLA_06:
+    FBSchemaGenerator = sa_base.FBDDLCompiler
+else:
+    FBSchemaGenerator = sa_base.FBSchemaGenerator
+
+class FBColumnGenerator(FBSchemaGenerator, ansisql.ANSIColumnGenerator):
+    """Firebird column generator implementation."""
+
+
+class FBColumnDropper(ansisql.ANSIColumnDropper):
+    """Firebird column dropper implementation."""
+
+    def visit_column(self, column):
+        """Firebird supports 'DROP col' instead of 'DROP COLUMN col' syntax
+
+        Drop primary key and unique constraints if dropped column is referencing it."""
+        if column.primary_key:
+            if column.table.primary_key.columns.contains_column(column):
+                column.table.primary_key.drop()
+                # TODO: recreate primary key if it references more than this column
+        if column.unique or getattr(column, 'unique_name', None):
+            for cons in column.table.constraints:
+                if cons.contains_column(column):
+                    cons.drop()
+                    # TODO: recreate unique constraint if it refenrences more than this column
+
+        table = self.start_alter_table(column)
+        self.append('DROP %s' % self.preparer.format_column(column))
+        self.execute()
+
+
+class FBSchemaChanger(ansisql.ANSISchemaChanger):
+    """Firebird schema changer implementation."""
+
+    def visit_table(self, table):
+        """Rename table not supported"""
+        raise exceptions.NotSupportedError(
+            "Firebird does not support renaming tables.")
+
+    def _visit_column_name(self, table, column, delta):
+        self.start_alter_table(table)
+        col_name = self.preparer.quote(delta.current_name, table.quote)
+        new_name = self.preparer.format_column(delta.result_column)
+        self.append('ALTER COLUMN %s TO %s' % (col_name, new_name))
+
+    def _visit_column_nullable(self, table, column, delta):
+        """Changing NULL is not supported"""
+        # TODO: http://www.firebirdfaq.org/faq103/
+        raise exceptions.NotSupportedError(
+            "Firebird does not support altering NULL bevahior.")
+
+
+class FBConstraintGenerator(ansisql.ANSIConstraintGenerator):
+    """Firebird constraint generator implementation."""
+
+
+class FBConstraintDropper(ansisql.ANSIConstraintDropper):
+    """Firebird constaint dropper implementation."""
+
+    def cascade_constraint(self, constraint):
+        """Cascading constraints is not supported"""
+        raise exceptions.NotSupportedError(
+            "Firebird does not support cascading constraints")
+
+
+class FBDialect(ansisql.ANSIDialect):
+    columngenerator = FBColumnGenerator
+    columndropper = FBColumnDropper
+    schemachanger = FBSchemaChanger
+    constraintgenerator = FBConstraintGenerator
+    constraintdropper = FBConstraintDropper