ghc-mod/Language/Haskell/GhcMod/SrcUtils.hs

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-- TODO: remove CPP once Gap(ed)
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{-# LANGUAGE CPP, TupleSections, FlexibleInstances, Rank2Types #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Language.Haskell.GhcMod.SrcUtils where
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import Control.Applicative
import CoreUtils (exprType)
import Data.Generics
import Data.Maybe
import Data.Ord as O
import GHC (LHsExpr, LPat, Id, DynFlags, SrcSpan, Type, Located, ParsedSource, RenamedSource, TypecheckedSource, GenLocated(L))
import Var (Var)
import qualified GHC as G
import qualified Var as G
import qualified Type as G
import GHC.SYB.Utils
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import GhcMonad
import qualified Language.Haskell.Exts as HE
import Language.Haskell.GhcMod.Doc
import Language.Haskell.GhcMod.Gap
import qualified Language.Haskell.GhcMod.Gap as Gap
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import OccName (OccName)
import Outputable (PprStyle)
import TcHsSyn (hsPatType)
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import Prelude
import Control.Monad
import Data.List (nub)
import Control.Arrow
import qualified Data.Map as M
----------------------------------------------------------------
instance HasType (LHsExpr Id) where
getType tcm e = do
hs_env <- G.getSession
mbe <- liftIO $ Gap.deSugar tcm e hs_env
return $ (G.getLoc e, ) <$> CoreUtils.exprType <$> mbe
instance HasType (LPat Id) where
getType _ (G.L spn pat) = return $ Just (spn, hsPatType pat)
----------------------------------------------------------------
-- | Stores mapping from monomorphic to polymorphic types
type CstGenQS = M.Map Var Type
-- | Generic type to simplify SYB definition
type CstGenQT a = forall m. GhcMonad m => a Id -> CstGenQS -> (m [(SrcSpan, Type)], CstGenQS)
collectSpansTypes :: (GhcMonad m) => Bool -> G.TypecheckedModule -> (Int, Int) -> m [(SrcSpan, Type)]
collectSpansTypes withConstraints tcs lc =
-- This walks AST top-down, left-to-right, while carrying CstGenQS down the tree
-- (but not left-to-right)
everythingStagedWithContext TypeChecker M.empty (liftM2 (++))
(return [])
((return [],)
`mkQ` (hsBind :: CstGenQT G.LHsBind) -- matches on binds
`extQ` (genericCT :: CstGenQT G.LHsExpr) -- matches on expressions
`extQ` (genericCT :: CstGenQT G.LPat) -- matches on patterns
)
(G.tm_typechecked_source tcs)
where
-- Helper function to insert mapping into CstGenQS
insExp x = M.insert (G.abe_mono x) (G.varType $ G.abe_poly x)
-- If there is AbsBinds here, insert mapping into CstGenQS if needed
hsBind (L _ G.AbsBinds{abs_exports = es'}) s
| withConstraints = (return [], foldr insExp s es')
| otherwise = (return [], s)
#if __GLASGOW_HASKELL__ >= 800
-- TODO: move to Gap
-- Note: this deals with bindings with explicit type signature, e.g.
-- double :: Num a => a -> a
-- double x = 2*x
hsBind (L _ G.AbsBindsSig{abs_sig_export = poly, abs_sig_bind = bind}) s
| withConstraints =
let new_s =
case bind of
G.L _ G.FunBind{fun_id = i} -> M.insert (G.unLoc i) (G.varType poly) s
_ -> s
in (return [], new_s)
| otherwise = (return [], s)
#endif
-- Otherwise, it's the same as other cases
hsBind x s = genericCT x s
-- Generic SYB function to get type
genericCT x s
| withConstraints
= (maybe [] (uncurry $ constrainedType (collectBinders x) s) <$> getType' x, s)
| otherwise = (maybeToList <$> getType' x, s)
-- Collects everything with Id from LHsBind, LHsExpr, or LPat
collectBinders :: Data a => a -> [Id]
collectBinders = listifyStaged TypeChecker (const True)
-- Gets monomorphic type with location
getType' x@(L spn _)
| G.isGoodSrcSpan spn && spn `G.spans` lc
= getType tcs x
| otherwise = return Nothing
-- Gets constrained type
constrainedType :: [Var] -- ^ Binders in expression, i.e. anything with Id
-> CstGenQS -- ^ Map from Id to polymorphic type
-> SrcSpan -- ^ extent of expression, copied to result
-> Type -- ^ monomorphic type
-> [(SrcSpan, Type)] -- ^ result
constrainedType pids s spn genTyp =
let
-- runs build on every binder.
ctys = mapMaybe build (nub pids)
-- Computes constrained type for x. Returns (constraints, substitutions)
-- Substitutions are needed because type variables don't match
-- between polymorphic and monomorphic types.
-- E.g. poly type might be `Monad m => m ()`, while monomorphic might be `f ()`
build x | Just cti <- x `M.lookup` s
= let
(preds', ctt) = getPreds cti
-- list of type variables in monomorphic type
vts = listifyStaged TypeChecker G.isTyVar $ G.varType x
-- list of type variables in polymorphic type
tvm = listifyStaged TypeChecker G.isTyVarTy ctt
in Just (preds', zip vts tvm)
| otherwise = Nothing
-- list of constraints
preds = concatMap fst ctys
-- Type variable substitutions
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#if __GLASGOW_HASKELL__ >= 800
-- TODO: move to Gap
subs = G.mkTvSubstPrs $ concatMap snd ctys
#else
subs = G.mkTopTvSubst $ concatMap snd ctys
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#endif
-- Constrained type
ty = G.substTy subs $ G.mkFunTys preds genTyp
in [(spn, ty)]
-- Splits a given type into list of constraints and simple type. Drops foralls.
getPreds :: Type -> ([Type], Type)
getPreds x | G.isForAllTy x = getPreds $ G.dropForAlls x
| Just (c, t) <- G.splitFunTy_maybe x
, G.isPredTy c = first (c:) $ getPreds t
| otherwise = ([], x)
listifySpans :: Typeable a => TypecheckedSource -> (Int, Int) -> [Located a]
listifySpans tcs lc = listifyStaged TypeChecker p tcs
where
p (L spn _) = G.isGoodSrcSpan spn && spn `G.spans` lc
listifyParsedSpans :: Typeable a => ParsedSource -> (Int, Int) -> [Located a]
listifyParsedSpans pcs lc = listifyStaged Parser p pcs
where
p (L spn _) = G.isGoodSrcSpan spn && spn `G.spans` lc
listifyRenamedSpans :: Typeable a => RenamedSource -> (Int, Int) -> [Located a]
listifyRenamedSpans pcs lc = listifyStaged Renamer p pcs
where
p (L spn _) = G.isGoodSrcSpan spn && spn `G.spans` lc
listifyStaged :: Typeable r => Stage -> (r -> Bool) -> GenericQ [r]
listifyStaged s p = everythingStaged s (++) [] ([] `mkQ` (\x -> [x | p x]))
cmp :: SrcSpan -> SrcSpan -> Ordering
cmp a b
| a `G.isSubspanOf` b = O.LT
| b `G.isSubspanOf` a = O.GT
| otherwise = O.EQ
toTup :: DynFlags -> PprStyle -> (SrcSpan, Type) -> ((Int,Int,Int,Int),String)
toTup dflag style (spn, typ) = (fourInts spn, pretty dflag style typ)
fourInts :: SrcSpan -> (Int,Int,Int,Int)
fourInts = fromMaybe (0,0,0,0) . Gap.getSrcSpan
fourIntsHE :: HE.SrcSpan -> (Int,Int,Int,Int)
fourIntsHE loc = ( HE.srcSpanStartLine loc, HE.srcSpanStartColumn loc
, HE.srcSpanEndLine loc, HE.srcSpanEndColumn loc)
-- Check whether (line,col) is inside a given SrcSpanInfo
typeSigInRangeHE :: Int -> Int -> HE.Decl HE.SrcSpanInfo -> Bool
typeSigInRangeHE lineNo colNo (HE.TypeSig (HE.SrcSpanInfo s _) _ _) =
HE.srcSpanStart s <= (lineNo, colNo) && HE.srcSpanEnd s >= (lineNo, colNo)
typeSigInRangeHE lineNo colNo (HE.TypeFamDecl (HE.SrcSpanInfo s _) _ _ _) =
HE.srcSpanStart s <= (lineNo, colNo) && HE.srcSpanEnd s >= (lineNo, colNo)
typeSigInRangeHE lineNo colNo (HE.DataFamDecl (HE.SrcSpanInfo s _) _ _ _) =
HE.srcSpanStart s <= (lineNo, colNo) && HE.srcSpanEnd s >= (lineNo, colNo)
typeSigInRangeHE _ _ _= False
pretty :: DynFlags -> PprStyle -> Type -> String
pretty dflag style = showOneLine dflag style . Gap.typeForUser
showName :: DynFlags -> PprStyle -> G.Name -> String
showName dflag style name = showOneLine dflag style $ Gap.nameForUser name
showOccName :: DynFlags -> PprStyle -> OccName -> String
showOccName dflag style name = showOneLine dflag style $ Gap.occNameForUser name