{- | Module : $Header$ Description : Top-Level Environments Copyright : 1999 - 2003 Wolfgang Lux 2005 Martin Engelke 2011 - 2012 Björn Peemöller 2016 Finn Teegen License : BSD-3-clause Maintainer : bjp@informatik.uni-kiel.de Stability : experimental Portability : portable The module 'TopEnv' implements environments for qualified and possibly ambiguous identifiers. An identifier is ambiguous if two different entities are imported under the same name or if a local definition uses the same name as an imported entity. Following an idea presented in a paper by Diatchki, Jones and Hallgren (2002), an identifier is associated with a list of entities in order to handle ambiguous names properly. In general, two entities are considered equal if the names of their original definitions match. However, in the case of algebraic data types it is possible to hide some or all of their data constructors on import and export, respectively. In this case we have to merge both imports such that all data constructors which are visible through any import path are visible in the current module. The class Entity is used to handle this merge. The code in this module ensures that the list of entities returned by the functions 'lookupTopEnv' and 'qualLookupTopEnv' contains exactly one element for each imported entity regardless of how many times and from which module(s) it was imported. Thus, the result of these function is a list with exactly one element if and only if the identifier is unambiguous. The module names associated with an imported entity identify the modules from which the entity was imported. -} module Base.TopEnv ( -- * Data types TopEnv (..), Entity (..) -- * creation and insertion , emptyTopEnv, predefTopEnv, importTopEnv, qualImportTopEnv , bindTopEnv, qualBindTopEnv, rebindTopEnv , qualRebindTopEnv, unbindTopEnv, qualUnbindTopEnv , lookupTopEnv, qualLookupTopEnv, qualElemTopEnv , allImports, moduleImports, localBindings, allLocalBindings, allBindings , allEntities ) where import Control.Arrow (second) import qualified Data.Map as Map (Map, empty, insert, findWithDefault, lookup, toList) import Curry.Base.Ident import Base.Messages (internalError) class Entity a where origName :: a -> QualIdent merge :: a -> a -> Maybe a merge x y | origName x == origName y = Just x | otherwise = Nothing data Source = Local | Import [ModuleIdent] deriving (Eq, Show) -- |Top level environment newtype TopEnv a = TopEnv { topEnvMap :: Map.Map QualIdent [(Source, a)] } deriving Show instance Functor TopEnv where fmap f (TopEnv env) = TopEnv (fmap (map (second f)) env) -- local helper entities :: QualIdent -> Map.Map QualIdent [(Source, a)] -> [(Source, a)] entities = Map.findWithDefault [] -- |Empty 'TopEnv' emptyTopEnv :: TopEnv a emptyTopEnv = TopEnv Map.empty -- |Insert an 'Entity' into a 'TopEnv' as a predefined 'Entity' predefTopEnv :: QualIdent -> a -> TopEnv a -> TopEnv a predefTopEnv k v (TopEnv env) = case Map.lookup k env of Just _ -> internalError $ "TopEnv.predefTopEnv " ++ show k Nothing -> TopEnv $ Map.insert k [(Import [], v)] env -- |Insert an 'Entity' as unqualified into a 'TopEnv' importTopEnv :: Entity a => ModuleIdent -> Ident -> a -> TopEnv a -> TopEnv a importTopEnv m x y env = addImport m (qualify x) y env -- |Insert an 'Entity' as qualified into a 'TopEnv' qualImportTopEnv :: Entity a => ModuleIdent -> Ident -> a -> TopEnv a -> TopEnv a qualImportTopEnv m x y env = addImport m (qualifyWith m x) y env -- local helper addImport :: Entity a => ModuleIdent -> QualIdent -> a -> TopEnv a -> TopEnv a addImport m k v (TopEnv env) = TopEnv $ Map.insert k (mergeImport v (entities k env)) env where mergeImport :: Entity a => a -> [(Source, a)] -> [(Source, a)] mergeImport y [] = [(Import [m], y)] mergeImport y (loc@(Local , _) : xs) = loc : mergeImport y xs mergeImport y (imp@(Import ms, y') : xs) = case merge y y' of Just y'' -> (Import (m : ms), y'') : xs Nothing -> imp : mergeImport y xs bindTopEnv :: Ident -> a -> TopEnv a -> TopEnv a bindTopEnv x y env = qualBindTopEnv (qualify x) y env qualBindTopEnv :: QualIdent -> a -> TopEnv a -> TopEnv a qualBindTopEnv x y (TopEnv env) = TopEnv $ Map.insert x (bindLocal y (entities x env)) env where bindLocal y' ys | null [ y'' | (Local, y'') <- ys ] = (Local, y') : ys | otherwise = internalError $ "qualBindTopEnv " ++ show x rebindTopEnv :: Ident -> a -> TopEnv a -> TopEnv a rebindTopEnv = qualRebindTopEnv . qualify qualRebindTopEnv :: QualIdent -> a -> TopEnv a -> TopEnv a qualRebindTopEnv x y (TopEnv env) = TopEnv $ Map.insert x (rebindLocal (entities x env)) env where rebindLocal [] = internalError $ "TopEnv.qualRebindTopEnv " ++ show x rebindLocal ((Local, _) : ys) = (Local, y) : ys rebindLocal (imported : ys) = imported : rebindLocal ys unbindTopEnv :: Ident -> TopEnv a -> TopEnv a unbindTopEnv x (TopEnv env) = TopEnv $ Map.insert x' (unbindLocal (entities x' env)) env where x' = qualify x unbindLocal [] = internalError $ "TopEnv.unbindTopEnv " ++ show x unbindLocal ((Local, _) : ys) = ys unbindLocal (imported : ys) = imported : unbindLocal ys qualUnbindTopEnv :: QualIdent -> TopEnv a -> TopEnv a qualUnbindTopEnv x (TopEnv env) = TopEnv $ Map.insert x (unbind (entities x env)) env where unbind [] = internalError $ "TopEnv.qualUnbindTopEnv " ++ show x unbind _ = [] lookupTopEnv :: Ident -> TopEnv a -> [a] lookupTopEnv = qualLookupTopEnv . qualify qualLookupTopEnv :: QualIdent -> TopEnv a -> [a] qualLookupTopEnv x (TopEnv env) = map snd (entities x env) qualElemTopEnv :: QualIdent -> TopEnv a -> Bool qualElemTopEnv x env = not (null (qualLookupTopEnv x env)) allImports :: TopEnv a -> [(QualIdent, a)] allImports (TopEnv env) = [ (x, y) | (x, ys) <- Map.toList env, (Import _, y) <- ys ] unqualBindings :: TopEnv a -> [(Ident, (Source, a))] unqualBindings (TopEnv env) = [ (x', y) | (x, ys) <- filter (not . isQualified . fst) (Map.toList env) , let x' = unqualify x, y <- ys] moduleImports :: ModuleIdent -> TopEnv a -> [(Ident, a)] moduleImports m env = [(x, y) | (x, (Import ms, y)) <- unqualBindings env, m `elem` ms] localBindings :: TopEnv a -> [(Ident, a)] localBindings env = [ (x, y) | (x, (Local, y)) <- unqualBindings env ] allLocalBindings :: TopEnv a -> [(QualIdent, a)] allLocalBindings (TopEnv env) = [ (x, y) | (x, ys) <- Map.toList env , (Local, y) <- ys ] allBindings :: TopEnv a -> [(QualIdent, a)] allBindings (TopEnv env) = [(x, y) | (x, ys) <- Map.toList env, (_, y) <- ys] allEntities :: TopEnv a -> [a] allEntities (TopEnv env) = [ y | (_, ys) <- Map.toList env, (_, y) <- ys]