Commit 98a9f073 authored by Björn Peemöller 's avatar Björn Peemöller
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{- |
Module : $Header$
Description : Top-Level Environments
Copyright : 1999 - 2003 Wolfgang Lux
2005 Martin Engelke
2011 - 2012 Björn Peemöller
License : OtherLicense
Maintainer : bjp@informatik.uni-kiel.de
Stability : experimental
Portability : portable
The module \texttt{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 \cite{DiatchkiJonesHallgren02:ModuleSystem}, 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
\texttt{Entity} is used to handle this merge.
The code in this module ensures that the list of entities returned by
the functions \texttt{lookupTopEnv} and \texttt{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, lookupTopEnv, qualLookupTopEnv
, allImports, moduleImports, localBindings, allLocalBindings
) 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 :: Entity a => QualIdent -> a -> TopEnv a -> TopEnv a
predefTopEnv k v (TopEnv env) = case Map.lookup k env of
Just _ -> internalError "TopEnv.predefTopEnv"
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 :: String -> Ident -> a -> TopEnv a -> TopEnv a
bindTopEnv fun x y env = qualBindTopEnv fun (qualify x) y env
qualBindTopEnv :: String -> QualIdent -> a -> TopEnv a -> TopEnv a
qualBindTopEnv fun 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
++ "\" failed in function \"" ++ fun
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"
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"
unbindLocal ((Local, _) : ys) = ys
unbindLocal (imported : ys) = imported : unbindLocal ys
lookupTopEnv :: Ident -> TopEnv a -> [a]
lookupTopEnv = qualLookupTopEnv . qualify
qualLookupTopEnv :: QualIdent -> TopEnv a -> [a]
qualLookupTopEnv x (TopEnv env) = map snd (entities 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 ]
% $Id: TopEnv.lhs,v 1.20 2003/10/04 17:04:32 wlux Exp $
%
% Copyright (c) 1999-2003, Wolfgang Lux
% See LICENSE for the full license.
%
% Modified by Martin Engelke (men@informatik.uni-kiel.de)
%
\nwfilename{TopEnv.lhs}
\subsection{Top-Level Environments}\label{sec:toplevel-env}
The module \texttt{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 \cite{DiatchkiJonesHallgren02:ModuleSystem}, 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
\texttt{Entity} is used to handle this merge.
The code in this module ensures that the list of entities returned by
the functions \texttt{lookupTopEnv} and \texttt{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.
\begin{verbatim}
> module Base.TopEnv
> ( -- * Data types
> TopEnv (..), Entity (..)
> -- * creation and insertion
> , emptyTopEnv, predefTopEnv, importTopEnv, qualImportTopEnv
> , bindTopEnv, qualBindTopEnv, rebindTopEnv
> , qualRebindTopEnv, unbindTopEnv, lookupTopEnv, qualLookupTopEnv
> , allImports, moduleImports, localBindings, allLocalBindings
> ) 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 prefined 'Entity'
> predefTopEnv :: Entity a => QualIdent -> a -> TopEnv a -> TopEnv a
> predefTopEnv k v (TopEnv env) = case Map.lookup k env of
> Just _ -> internalError "TopEnv.predefTopEnv"
> 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 :: String -> Ident -> a -> TopEnv a -> TopEnv a
> bindTopEnv fun x y env = qualBindTopEnv fun (qualify x) y env
> qualBindTopEnv :: String -> QualIdent -> a -> TopEnv a -> TopEnv a
> qualBindTopEnv fun 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
> ++ "\" failed in function \"" ++ fun
> 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"
> 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"
> unbindLocal ((Local, _) : ys) = ys
> unbindLocal (imported : ys) = imported : unbindLocal ys
> lookupTopEnv :: Ident -> TopEnv a -> [a]
> lookupTopEnv = qualLookupTopEnv . qualify
> qualLookupTopEnv :: QualIdent -> TopEnv a -> [a]
> qualLookupTopEnv x (TopEnv env) = map snd (entities 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 ]
\end{verbatim}
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