{-
Tock: a compiler for parallel languages
Copyright (C) 2007, 2008, 2009  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/>.
-}

-- | Simplify types in the AST.
module SimplifyTypes (
    simplifyTypes
  , resolveNamedTypes
  ) where

import Control.Monad.State

import qualified AST as A
import Metadata
import Pass
import qualified Properties as Prop
import Traversal
import Types

simplifyTypes :: [Pass A.AST]
simplifyTypes
  = [ resolveNamedTypes
    ]

-- | Turn named data types into their underlying types.
resolveNamedTypes :: PassOn A.Type
resolveNamedTypes
    = pass "Resolve user-defined types"
           (Prop.agg_namesDone
            ++ [Prop.expressionTypesChecked, Prop.processTypesChecked])
           [Prop.typesResolvedInAST, Prop.typesResolvedInState]
           (\t -> do get >>= resolve >>= flatten >>= put
                     resolve t >>= flatten)
  where
    resolve :: PassTypeOn A.Type
    resolve = applyTopDownM (resolveUserType emptyMeta)

    flatten :: PassTypeOn A.Type
    flatten = applyBottomUpM doType
      where
        doType :: Transform A.Type
        doType (A.Array dsA (A.Array dsB t)) = return $ A.Array (dsA++dsB) t
        doType t = return t