{- |

Module : $Id$

Copyright : (c) DFKI GmbH

License : GPLv2 or higher, see LICENSE.txt

Maintainer : Christian.Maeder@dfki.de

Stability : provisional

Portability : portable

This module coordinates the whole shebang.

Parses input and plucks out data and newtype declarations and

processor commands.

The commands are combined with the parsed data, and if any data is missing,

derive goes hunting for it, looking in

the path variable DERIVEPATH. Derive searches recusively though modules

imported until all the types needed are found, or it runs out of links,

which causes an error.

-}

module ChaseImports where

import RuleUtils (Tag)

import DataP

import CommandP

import ParseLib2

import System.Environment

import Control.Monad

import qualified Control.Exception as Exception

-- GHC version

try :: IO a -> IO (Either IOError a)

try x = Exception.catch (fmap Right x) (return . Left)

-- Parser - extract data and newtypes from code

type ToDo = [([Tag], Data)]

parser :: String -> ToDo

parser = sanitycheck . papply p (0, 0) . \ s -> ((0, 0), s)

where

p = parse . skipUntilOff $ statemnt +++ command

statemnt = do

d <- datadecl +++ newtypedecl

ts <- opt local

return (ts, d)

sanitycheck l = case l of

[(x, _)] -> x

_ -> error "***Error: no or ambiguous DriFT directives"

-- -----Go Hunting for files, recursively ----------------------------------

chaseImports :: String -> ToDo -> IO ToDo

chaseImports txt dats = do

(left, found) <- chaseImports' txt dats

if (not . null) left then error ("can't find type " ++ show left)

else return found

chaseImports' :: String -> ToDo -> IO (ToDo, ToDo)

chaseImports' text indats =

case papply (parse header) (0, -1) ((0, 0), text) of

[] -> return (indats, [])

(modnames : _) -> foldM action (indats, []) (fst modnames)

where

action :: (ToDo, ToDo) -> FilePath -> IO (ToDo, ToDo)

action (dats, done) m = if null dats then return ([], done) else do

mp <- Exception.catch (fmap return $ getEnv "DERIVEPATH")

$ \ e -> return . fail $ show (e :: Exception.IOException)

let paths = maybe [] breakPaths mp

mc <- findModule paths m

return $ case mc of

Nothing -> (dats, done)

Just c -> let (found, rest) = scanModule m dats c in

(rest, done ++ found)

-- only one level of imports is now supported for more speed!

-- break DERIVEPATH into it's components

breakPaths :: String -> [String]

breakPaths x = case break (`elem` ":;") x of

(p, _ : pp) -> p : breakPaths pp

(p, []) -> [p]

-- search through paths, using try

findModule :: [String] -> String -> IO (Maybe String)

findModule paths modname = do

let action p = try $ readFile p

fnames = combine paths hiracle_modname

hiracle_modname = map (\ x -> if x == '.' then '/' else x) modname

isLeft e = case e of

Left _ -> True

Right _ -> False

hh <- mapM action fnames

case dropWhile isLeft hh of

Right h : _ -> return $ Just h

_ -> return Nothing

{- generate filepaths by combining module names with different suffixes.

Note : Dedicated Hugs-only users may wish to remove ".hi" from the list of

file types to search. -}

combine :: [String] -> String -> [FilePath]

combine paths modname = [p ++ '/' : modname ++ ".hs" | p <- "." : paths]

-- pluck out the bits of interest

scanModule :: String -> ToDo -> String -> (ToDo, ToDo)

scanModule modname dats txt = let

newDats = filter isData . myparse $ txt

myparse l = map snd . parser $ l

in resolve modname newDats dats ([], [])

-- update what's still missing

resolve :: String -> [Data] -> ToDo -> (ToDo, ToDo) -> (ToDo, ToDo)

resolve _ _ [] acc = acc

resolve modname parsed (tv : tt) p@(locals, imported) =

case tv of

(tags, TypeName t) ->

case filter ( \ d -> name d == t ||

modname ++ "." ++ name d == t) parsed of

[x] -> resolve modname parsed tt

( (tags, x { name = modname ++ "." ++ name x }) : locals

, imported)

_ -> resolve modname parsed tt (locals, tv : imported)

_ -> resolve modname parsed tt p

isData :: Data -> Bool

isData D {} = True

isData _ = False