tock-mirror/pregen/GenOrdAST.hs
2009-04-08 16:34:04 +00:00

90 lines
3.5 KiB
Haskell

{-
Tock: a compiler for parallel languages
Copyright (C) 2007 University of Kent
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 2 of the License, or (at your
option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program. If not, see <http://www.gnu.org/licenses/>.
-}
-- | Generates the OrdAST module. Template Haskell was a bit too heavyweight
-- for this. Uses Data.Generics to pick out all the constructors for the
-- given types, skip Meta tags and write out the OrdAST module
-- (to stdout).
module GenOrdAST where
import Control.Monad.State
import Control.Monad.Writer
import Data.Generics
import Data.List
import Metadata
import PregenUtils
import Utils
genHeader :: [String]
genHeader = [
-- Turn on lots of warnings and make them errors to help ensure our generated code is right:
"{-# OPTIONS_GHC -Werror -fwarn-overlapping-patterns -fwarn-unused-matches -fwarn-unused-binds -fwarn-incomplete-patterns #-}"
,"-- | Contains Ord instances for AST elements."
,"-- NOTE: This file is auto-generated by the GenOrdAST program, and should not be edited directly."
,"module OrdAST where"
,""
,"import qualified AST"
,"import Utils"
,""
]
-- | Here's the idea for easily building a compare function. Go through in ascending order.
-- Match A vs A in detail. For A vs _ give LT, and for _ vs A give GT. Then repeat for B, C, etc
-- But for the last item, do not give the LT and GT matches!
ordFor' :: forall a. (Data a, Typeable a) => String -> a -> [String]
ordFor' typeName x = process $ map processConstr $ dataTypeConstrs $ dataTypeOf x
where
process :: [(String, String, String, [String])] -> [String]
process [] = []
process items =
["instance Ord (" ++ typeName ++ ") where"]
++ concat [ [ " compare (" ++ name ++ headL ++ ") (" ++ name ++ headR ++ ") = " ++
--Shortcut:
if null comparisons then "EQ" else
"combineCompare [" ++ joinWith "," comparisons ++ "]"
] ++ if isLast then [] else
[ " compare (" ++ name ++ " {}) _ = LT"
, " compare _ (" ++ name ++ " {}) = GT"]
| (isLast, (name, headL, headR, comparisons)) <- zip (repeat False) (init items) ++ [(True,last items)] ]
nextVar :: State Int String
nextVar = do n <- get
put (n + 1)
return $ "x" ++ show n
doNormal :: forall a. a -> WriterT (String, String, [String]) (State Int) a
doNormal x = do v <- lift nextVar
tell (" " ++ v ++ " ", " " ++ v ++ "' ", ["compare " ++ v ++ " " ++ v ++ "'"])
return x
doMeta :: Meta -> WriterT (String, String, [String]) (State Int) Meta
doMeta m = tell (" _ ", " _ ", []) >> return m
processConstr :: Constr -> (String, String, String, [String])
processConstr c = let (x,y,z) = flip evalState 0 $ execWriterT $ gmapM (doNormal `extM` doMeta) $ (fromConstr c :: a) in
("AST." ++ showConstr c, x, y, z)
items :: [String]
items = concat [ordFor w | DataBox w <- astTypes]
where
ordFor x = ordFor' (show $ typeOf x) x
main :: IO ()
main = putStr $ unlines $ genHeader ++ items