{- |
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]