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|
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE ViewPatterns #-}
module Common
( PluginDefs(..)
, mkPlugin
, don'tSolve, don'tRewrite
)
where
-- ghc
import GHC.Core.Class
( Class )
import GHC.Core.DataCon
( promoteDataCon )
import GHC.Core.TyCon
( TyCon )
import GHC.Core.Type
( Type
, mkTyConApp
)
import GHC.Plugins
( Plugin(..)
, defaultPlugin, purePlugin
)
import GHC.Tc.Plugin
( TcPluginM
, findImportedModule, lookupOrig
, tcLookupClass, tcLookupDataCon, tcLookupTyCon
)
import GHC.Tc.Types
( TcPlugin(..), TcPluginSolveResult(..), TcPluginRewriteResult(..)
, TcPluginRewriter
)
import GHC.Tc.Types.Constraint
( Ct )
import GHC.Tc.Types.Evidence
( EvBindsVar )
import GHC.Types.Name.Occurrence
( mkClsOcc, mkDataOcc, mkTcOcc )
import GHC.Types.Unique.FM
( UniqFM, emptyUFM )
import GHC.Types.PkgQual
import GHC.Unit.Finder
( FindResult(..) )
import GHC.Unit.Module
( Module
, mkModuleName
)
--------------------------------------------------------------------------------
-- This module defines some common operations so that each individual plugin
-- doesn't have to do the same work over again:
--
-- - lookup the names of things the plugins will use
-- (the definitions are shared between most type-checking plugin tests)
-- - create a type-checking plugin from a solver, taking care of passing
-- the relevant data to the solver stage.
data PluginDefs =
PluginDefs
{ nullary :: !Class
, myClass :: !Class
, myTyFam :: !TyCon
, nat :: !Type
, zero :: !TyCon
, succ :: !TyCon
, add :: !TyCon
}
definitionsModule :: TcPluginM Module
definitionsModule = do
findResult <- findImportedModule ( mkModuleName "Definitions" ) NoPkgQual
case findResult of
Found _ res -> pure res
FoundMultiple _ -> error $ "TcPlugin test: found multiple modules named 'Definitions'."
_ -> error $ "TcPlugin test: could not find any module named 'Defintiions'."
lookupDefs :: TcPluginM PluginDefs
lookupDefs = do
defs <- definitionsModule
nullary <- tcLookupClass =<< lookupOrig defs ( mkClsOcc "Nullary" )
myClass <- tcLookupClass =<< lookupOrig defs ( mkClsOcc "MyClass" )
myTyFam <- tcLookupTyCon =<< lookupOrig defs ( mkTcOcc "MyTyFam" )
( (`mkTyConApp` []) -> nat ) <- tcLookupTyCon =<< lookupOrig defs ( mkTcOcc "Nat" )
( promoteDataCon -> zero ) <- tcLookupDataCon =<< lookupOrig defs ( mkDataOcc "Zero" )
( promoteDataCon -> succ ) <- tcLookupDataCon =<< lookupOrig defs ( mkDataOcc "Succ" )
add <- tcLookupTyCon =<< lookupOrig defs ( mkTcOcc "Add" )
pure ( PluginDefs { .. } )
mkPlugin :: ( [String] -> PluginDefs -> EvBindsVar -> [Ct] -> [Ct] -> TcPluginM TcPluginSolveResult )
-> ( [String] -> PluginDefs -> UniqFM TyCon TcPluginRewriter )
-> Plugin
mkPlugin solve rewrite =
defaultPlugin
{ tcPlugin = \ args -> Just $ mkTcPlugin ( solve args ) ( rewrite args )
, pluginRecompile = purePlugin
}
mkTcPlugin :: ( PluginDefs -> EvBindsVar -> [Ct] -> [Ct] -> TcPluginM TcPluginSolveResult )
-> ( PluginDefs -> UniqFM TyCon TcPluginRewriter )
-> TcPlugin
mkTcPlugin solve rewrite =
TcPlugin
{ tcPluginInit = lookupDefs
, tcPluginSolve = solve
, tcPluginRewrite = rewrite
, tcPluginStop = \ _ -> pure ()
}
don'tSolve :: [String] -> s -> EvBindsVar -> [Ct] -> [Ct] -> TcPluginM TcPluginSolveResult
don'tSolve _ _ _ _ _ = pure $ TcPluginOk [] []
don'tRewrite :: [String] -> s -> UniqFM TyCon TcPluginRewriter
don'tRewrite _ _ = emptyUFM
|
