add generation clause support to create table

Language/SQL/SimpleSQL/Parser.lhs

@@ -1472,6 +1472,9 @@ TODO: change style
 >     defaultClause = choice [
 >         keyword_ "default" >>
 >         DefaultClause <$> valueExpr
+>         -- todo: left factor
+>        ,try (keywords_ ["generated","always","as"] >>
+>              GenerationClause <$> parens valueExpr)
 >        ,keyword_ "generated" >>
 >         IdentityColumnSpec
 >         <$> option GeneratedDefault

Language/SQL/SimpleSQL/Pretty.lhs

@@ -463,6 +463,8 @@ which have been changed to try to improve the layout of the output.
 >              Nothing -> empty
 >              Just (DefaultClause def) ->
 >                  text "default" <+> valueExpr d def
+>              Just (GenerationClause e) ->
+>                  texts ["generated","always","as"] <+> parens (valueExpr d e)
 >              Just (IdentityColumnSpec w o) ->
 >                  text "generated"
 >                  <+> (case w of

Language/SQL/SimpleSQL/Syntax.lhs

@@ -504,7 +504,7 @@ I'm not sure if this is valid syntax or not.
 > data DefaultClause =
 >      DefaultClause ValueExpr
 >    | IdentityColumnSpec IdentityWhen [SequenceGeneratorOption]
->    --  | GenerationClause
+>    | GenerationClause ValueExpr
 >     deriving (Eq,Show,Read,Data,Typeable)
 
 > data IdentityWhen =

tools/Language/SQL/SimpleSQL/SQL2011Schema.lhs

@@ -356,6 +356,16 @@ generated always (valueexpr)
 <generation expression> ::=
   <left paren> <value expression> <right paren>
 
+>     ,(TestStatement SQL2011
+>       "create table t (a int, \
+>       \                a2 int generated always as (a * 2));"
+>      $ CreateTable [Name "t"]
+>        [ColumnDef (Name "a") (TypeName [Name "int"]) Nothing
+>        ,ColumnDef (Name "a2") (TypeName [Name "int"])
+>         (Just $ GenerationClause
+>          (BinOp (Iden [Name "a"]) [Name "*"] (NumLit "2")))])
+
+
 
 11.5 <default clause>