{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 -} {-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE BangPatterns #-} {-# LANGUAGE OverloadedStrings #-} -- | -- #name_types# -- GHC uses several kinds of name internally: -- -- * 'OccName.OccName' represents names as strings with just a little more information: -- the \"namespace\" that the name came from, e.g. the namespace of value, type constructors or -- data constructors -- -- * 'RdrName.RdrName': see "RdrName#name_types" -- -- * 'Name.Name': see "Name#name_types" -- -- * 'Id.Id': see "Id#name_types" -- -- * 'Var.Var': see "Var#name_types" module OccName ( -- * The 'NameSpace' type NameSpace, -- Abstract nameSpacesRelated, -- ** Construction -- $real_vs_source_data_constructors tcName, clsName, tcClsName, dataName, varName, tvName, srcDataName, -- ** Pretty Printing pprNameSpace, pprNonVarNameSpace, pprNameSpaceBrief, -- * The 'OccName' type OccName, -- Abstract, instance of Outputable pprOccName, -- ** Construction mkOccName, mkOccNameFS, mkVarOcc, mkVarOccFS, mkDataOcc, mkDataOccFS, mkTyVarOcc, mkTyVarOccFS, mkTcOcc, mkTcOccFS, mkClsOcc, mkClsOccFS, mkDFunOcc, setOccNameSpace, demoteOccName, HasOccName(..), -- ** Derived 'OccName's isDerivedOccName, mkDataConWrapperOcc, mkWorkerOcc, mkMatcherOcc, mkBuilderOcc, mkDefaultMethodOcc, isDefaultMethodOcc, isTypeableBindOcc, mkNewTyCoOcc, mkClassOpAuxOcc, mkCon2TagOcc, mkTag2ConOcc, mkMaxTagOcc, mkClassDataConOcc, mkDictOcc, mkIPOcc, mkSpecOcc, mkForeignExportOcc, mkRepEqOcc, mkGenR, mkGen1R, mkDataTOcc, mkDataCOcc, mkDataConWorkerOcc, mkSuperDictSelOcc, mkSuperDictAuxOcc, mkLocalOcc, mkMethodOcc, mkInstTyTcOcc, mkInstTyCoOcc, mkEqPredCoOcc, mkRecFldSelOcc, mkTyConRepOcc, -- ** Deconstruction occNameFS, occNameString, occNameSpace, isVarOcc, isTvOcc, isTcOcc, isDataOcc, isDataSymOcc, isSymOcc, isValOcc, parenSymOcc, startsWithUnderscore, isTcClsNameSpace, isTvNameSpace, isDataConNameSpace, isVarNameSpace, isValNameSpace, -- * The 'OccEnv' type OccEnv, emptyOccEnv, unitOccEnv, extendOccEnv, mapOccEnv, lookupOccEnv, mkOccEnv, mkOccEnv_C, extendOccEnvList, elemOccEnv, occEnvElts, foldOccEnv, plusOccEnv, plusOccEnv_C, extendOccEnv_C, extendOccEnv_Acc, filterOccEnv, delListFromOccEnv, delFromOccEnv, alterOccEnv, pprOccEnv, -- * The 'OccSet' type OccSet, emptyOccSet, unitOccSet, mkOccSet, extendOccSet, extendOccSetList, unionOccSets, unionManyOccSets, minusOccSet, elemOccSet, isEmptyOccSet, intersectOccSet, intersectsOccSet, filterOccSet, -- * Tidying up TidyOccEnv, emptyTidyOccEnv, initTidyOccEnv, tidyOccName, avoidClashesOccEnv, -- FsEnv FastStringEnv, emptyFsEnv, lookupFsEnv, extendFsEnv, mkFsEnv ) where import GhcPrelude import Util import Unique import DynFlags import UniqFM import UniqSet import FastString import FastStringEnv import Outputable import Lexeme import Binary import Control.DeepSeq import Data.Char import Data.Data {- ************************************************************************ * * \subsection{Name space} * * ************************************************************************ -} data NameSpace = VarName -- Variables, including "real" data constructors | DataName -- "Source" data constructors | TvName -- Type variables | TcClsName -- Type constructors and classes; Haskell has them -- in the same name space for now. deriving( Eq, Ord ) -- Note [Data Constructors] -- see also: Note [Data Constructor Naming] in DataCon.hs -- -- $real_vs_source_data_constructors -- There are two forms of data constructor: -- -- [Source data constructors] The data constructors mentioned in Haskell source code -- -- [Real data constructors] The data constructors of the representation type, which may not be the same as the source type -- -- For example: -- -- > data T = T !(Int, Int) -- -- The source datacon has type @(Int, Int) -> T@ -- The real datacon has type @Int -> Int -> T@ -- -- GHC chooses a representation based on the strictness etc. tcName, clsName, tcClsName :: NameSpace dataName, srcDataName :: NameSpace tvName, varName :: NameSpace -- Though type constructors and classes are in the same name space now, -- the NameSpace type is abstract, so we can easily separate them later tcName = TcClsName -- Type constructors clsName = TcClsName -- Classes tcClsName = TcClsName -- Not sure which! dataName = DataName srcDataName = DataName -- Haskell-source data constructors should be -- in the Data name space tvName = TvName varName = VarName isDataConNameSpace :: NameSpace -> Bool isDataConNameSpace DataName = True isDataConNameSpace _ = False isTcClsNameSpace :: NameSpace -> Bool isTcClsNameSpace TcClsName = True isTcClsNameSpace _ = False isTvNameSpace :: NameSpace -> Bool isTvNameSpace TvName = True isTvNameSpace _ = False isVarNameSpace :: NameSpace -> Bool -- Variables or type variables, but not constructors isVarNameSpace TvName = True isVarNameSpace VarName = True isVarNameSpace _ = False isValNameSpace :: NameSpace -> Bool isValNameSpace DataName = True isValNameSpace VarName = True isValNameSpace _ = False pprNameSpace :: NameSpace -> SDoc pprNameSpace DataName = text "data constructor" pprNameSpace VarName = text "variable" pprNameSpace TvName = text "type variable" pprNameSpace TcClsName = text "type constructor or class" pprNonVarNameSpace :: NameSpace -> SDoc pprNonVarNameSpace VarName = empty pprNonVarNameSpace ns = pprNameSpace ns pprNameSpaceBrief :: NameSpace -> SDoc pprNameSpaceBrief DataName = char 'd' pprNameSpaceBrief VarName = char 'v' pprNameSpaceBrief TvName = text "tv" pprNameSpaceBrief TcClsName = text "tc" -- demoteNameSpace lowers the NameSpace if possible. We can not know -- in advance, since a TvName can appear in an HsTyVar. -- See Note [Demotion] in RnEnv demoteNameSpace :: NameSpace -> Maybe NameSpace demoteNameSpace VarName = Nothing demoteNameSpace DataName = Nothing demoteNameSpace TvName = Nothing demoteNameSpace TcClsName = Just DataName {- ************************************************************************ * * \subsection[Name-pieces-datatypes]{The @OccName@ datatypes} * * ************************************************************************ -} -- | Occurrence Name -- -- In this context that means: -- "classified (i.e. as a type name, value name, etc) but not qualified -- and not yet resolved" data OccName = OccName { occNameSpace :: !NameSpace , occNameFS :: !FastString } instance Eq OccName where (OccName sp1 s1) == (OccName sp2 s2) = s1 == s2 && sp1 == sp2 instance Ord OccName where -- Compares lexicographically, *not* by Unique of the string compare (OccName sp1 s1) (OccName sp2 s2) = (s1 `compare` s2) `thenCmp` (sp1 `compare` sp2) instance Data OccName where -- don't traverse? toConstr _ = abstractConstr "OccName" gunfold _ _ = error "gunfold" dataTypeOf _ = mkNoRepType "OccName" instance HasOccName OccName where occName = id instance NFData OccName where rnf x = x `seq` () {- ************************************************************************ * * \subsection{Printing} * * ************************************************************************ -} instance Outputable OccName where ppr = pprOccName instance OutputableBndr OccName where pprBndr _ = ppr pprInfixOcc n = pprInfixVar (isSymOcc n) (ppr n) pprPrefixOcc n = pprPrefixVar (isSymOcc n) (ppr n) pprOccName :: OccName -> SDoc pprOccName (OccName sp occ) = getPprStyle $ \ sty -> if codeStyle sty then ztext (zEncodeFS occ) else pp_occ <> pp_debug sty where pp_debug sty | debugStyle sty = braces (pprNameSpaceBrief sp) | otherwise = empty pp_occ = sdocWithDynFlags $ \dflags -> if gopt Opt_SuppressUniques dflags then text (strip_th_unique (unpackFS occ)) else ftext occ -- See Note [Suppressing uniques in OccNames] strip_th_unique ('[' : c : _) | isAlphaNum c = [] strip_th_unique (c : cs) = c : strip_th_unique cs strip_th_unique [] = [] {- Note [Suppressing uniques in OccNames] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This is a hack to de-wobblify the OccNames that contain uniques from Template Haskell that have been turned into a string in the OccName. See Note [Unique OccNames from Template Haskell] in Convert.hs ************************************************************************ * * \subsection{Construction} * * ************************************************************************ -} mkOccName :: NameSpace -> String -> OccName mkOccName occ_sp str = OccName occ_sp (mkFastString str) mkOccNameFS :: NameSpace -> FastString -> OccName mkOccNameFS occ_sp fs = OccName occ_sp fs mkVarOcc :: String -> OccName mkVarOcc s = mkOccName varName s mkVarOccFS :: FastString -> OccName mkVarOccFS fs = mkOccNameFS varName fs mkDataOcc :: String -> OccName mkDataOcc = mkOccName dataName mkDataOccFS :: FastString -> OccName mkDataOccFS = mkOccNameFS dataName mkTyVarOcc :: String -> OccName mkTyVarOcc = mkOccName tvName mkTyVarOccFS :: FastString -> OccName mkTyVarOccFS fs = mkOccNameFS tvName fs mkTcOcc :: String -> OccName mkTcOcc = mkOccName tcName mkTcOccFS :: FastString -> OccName mkTcOccFS = mkOccNameFS tcName mkClsOcc :: String -> OccName mkClsOcc = mkOccName clsName mkClsOccFS :: FastString -> OccName mkClsOccFS = mkOccNameFS clsName -- demoteOccName lowers the Namespace of OccName. -- see Note [Demotion] demoteOccName :: OccName -> Maybe OccName demoteOccName (OccName space name) = do space' <- demoteNameSpace space return $ OccName space' name -- Name spaces are related if there is a chance to mean the one when one writes -- the other, i.e. variables <-> data constructors and type variables <-> type constructors nameSpacesRelated :: NameSpace -> NameSpace -> Bool nameSpacesRelated ns1 ns2 = ns1 == ns2 || otherNameSpace ns1 == ns2 otherNameSpace :: NameSpace -> NameSpace otherNameSpace VarName = DataName otherNameSpace DataName = VarName otherNameSpace TvName = TcClsName otherNameSpace TcClsName = TvName {- | Other names in the compiler add additional information to an OccName. This class provides a consistent way to access the underlying OccName. -} class HasOccName name where occName :: name -> OccName {- ************************************************************************ * * Environments * * ************************************************************************ OccEnvs are used mainly for the envts in ModIfaces. Note [The Unique of an OccName] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ They are efficient, because FastStrings have unique Int# keys. We assume this key is less than 2^24, and indeed FastStrings are allocated keys sequentially starting at 0. So we can make a Unique using mkUnique ns key :: Unique where 'ns' is a Char representing the name space. This in turn makes it easy to build an OccEnv. -} instance Uniquable OccName where -- See Note [The Unique of an OccName] getUnique (OccName VarName fs) = mkVarOccUnique fs getUnique (OccName DataName fs) = mkDataOccUnique fs getUnique (OccName TvName fs) = mkTvOccUnique fs getUnique (OccName TcClsName fs) = mkTcOccUnique fs newtype OccEnv a = A (UniqFM a) deriving Data emptyOccEnv :: OccEnv a unitOccEnv :: OccName -> a -> OccEnv a extendOccEnv :: OccEnv a -> OccName -> a -> OccEnv a extendOccEnvList :: OccEnv a -> [(OccName, a)] -> OccEnv a lookupOccEnv :: OccEnv a -> OccName -> Maybe a mkOccEnv :: [(OccName,a)] -> OccEnv a mkOccEnv_C :: (a -> a -> a) -> [(OccName,a)] -> OccEnv a elemOccEnv :: OccName -> OccEnv a -> Bool foldOccEnv :: (a -> b -> b) -> b -> OccEnv a -> b occEnvElts :: OccEnv a -> [a] extendOccEnv_C :: (a->a->a) -> OccEnv a -> OccName -> a -> OccEnv a extendOccEnv_Acc :: (a->b->b) -> (a->b) -> OccEnv b -> OccName -> a -> OccEnv b plusOccEnv :: OccEnv a -> OccEnv a -> OccEnv a plusOccEnv_C :: (a->a->a) -> OccEnv a -> OccEnv a -> OccEnv a mapOccEnv :: (a->b) -> OccEnv a -> OccEnv b delFromOccEnv :: OccEnv a -> OccName -> OccEnv a delListFromOccEnv :: OccEnv a -> [OccName] -> OccEnv a filterOccEnv :: (elt -> Bool) -> OccEnv elt -> OccEnv elt alterOccEnv :: (Maybe elt -> Maybe elt) -> OccEnv elt -> OccName -> OccEnv elt emptyOccEnv = A emptyUFM unitOccEnv x y = A $ unitUFM x y extendOccEnv (A x) y z = A $ addToUFM x y z extendOccEnvList (A x) l = A $ addListToUFM x l lookupOccEnv (A x) y = lookupUFM x y mkOccEnv l = A $ listToUFM l elemOccEnv x (A y) = elemUFM x y foldOccEnv a b (A c) = foldUFM a b c occEnvElts (A x) = eltsUFM x plusOccEnv (A x) (A y) = A $ plusUFM x y plusOccEnv_C f (A x) (A y) = A $ plusUFM_C f x y extendOccEnv_C f (A x) y z = A $ addToUFM_C f x y z extendOccEnv_Acc f g (A x) y z = A $ addToUFM_Acc f g x y z mapOccEnv f (A x) = A $ mapUFM f x mkOccEnv_C comb l = A $ addListToUFM_C comb emptyUFM l delFromOccEnv (A x) y = A $ delFromUFM x y delListFromOccEnv (A x) y = A $ delListFromUFM x y filterOccEnv x (A y) = A $ filterUFM x y alterOccEnv fn (A y) k = A $ alterUFM fn y k instance Outputable a => Outputable (OccEnv a) where ppr x = pprOccEnv ppr x pprOccEnv :: (a -> SDoc) -> OccEnv a -> SDoc pprOccEnv ppr_elt (A env) = pprUniqFM ppr_elt env type OccSet = UniqSet OccName emptyOccSet :: OccSet unitOccSet :: OccName -> OccSet mkOccSet :: [OccName] -> OccSet extendOccSet :: OccSet -> OccName -> OccSet extendOccSetList :: OccSet -> [OccName] -> OccSet unionOccSets :: OccSet -> OccSet -> OccSet unionManyOccSets :: [OccSet] -> OccSet minusOccSet :: OccSet -> OccSet -> OccSet elemOccSet :: OccName -> OccSet -> Bool isEmptyOccSet :: OccSet -> Bool intersectOccSet :: OccSet -> OccSet -> OccSet intersectsOccSet :: OccSet -> OccSet -> Bool filterOccSet :: (OccName -> Bool) -> OccSet -> OccSet emptyOccSet = emptyUniqSet unitOccSet = unitUniqSet mkOccSet = mkUniqSet extendOccSet = addOneToUniqSet extendOccSetList = addListToUniqSet unionOccSets = unionUniqSets unionManyOccSets = unionManyUniqSets minusOccSet = minusUniqSet elemOccSet = elementOfUniqSet isEmptyOccSet = isEmptyUniqSet intersectOccSet = intersectUniqSets intersectsOccSet s1 s2 = not (isEmptyOccSet (s1 `intersectOccSet` s2)) filterOccSet = filterUniqSet {- ************************************************************************ * * \subsection{Predicates and taking them apart} * * ************************************************************************ -} occNameString :: OccName -> String occNameString (OccName _ s) = unpackFS s setOccNameSpace :: NameSpace -> OccName -> OccName setOccNameSpace sp (OccName _ occ) = OccName sp occ isVarOcc, isTvOcc, isTcOcc, isDataOcc :: OccName -> Bool isVarOcc (OccName VarName _) = True isVarOcc _ = False isTvOcc (OccName TvName _) = True isTvOcc _ = False isTcOcc (OccName TcClsName _) = True isTcOcc _ = False -- | /Value/ 'OccNames's are those that are either in -- the variable or data constructor namespaces isValOcc :: OccName -> Bool isValOcc (OccName VarName _) = True isValOcc (OccName DataName _) = True isValOcc _ = False isDataOcc (OccName DataName _) = True isDataOcc _ = False -- | Test if the 'OccName' is a data constructor that starts with -- a symbol (e.g. @:@, or @[]@) isDataSymOcc :: OccName -> Bool isDataSymOcc (OccName DataName s) = isLexConSym s isDataSymOcc _ = False -- Pretty inefficient! -- | Test if the 'OccName' is that for any operator (whether -- it is a data constructor or variable or whatever) isSymOcc :: OccName -> Bool isSymOcc (OccName DataName s) = isLexConSym s isSymOcc (OccName TcClsName s) = isLexSym s isSymOcc (OccName VarName s) = isLexSym s isSymOcc (OccName TvName s) = isLexSym s -- Pretty inefficient! parenSymOcc :: OccName -> SDoc -> SDoc -- ^ Wrap parens around an operator parenSymOcc occ doc | isSymOcc occ = parens doc | otherwise = doc startsWithUnderscore :: OccName -> Bool -- ^ Haskell 98 encourages compilers to suppress warnings about unsed -- names in a pattern if they start with @_@: this implements that test startsWithUnderscore occ = headFS (occNameFS occ) == '_' {- ************************************************************************ * * \subsection{Making system names} * * ************************************************************************ Here's our convention for splitting up the interface file name space: d... dictionary identifiers (local variables, so no name-clash worries) All of these other OccNames contain a mixture of alphabetic and symbolic characters, and hence cannot possibly clash with a user-written type or function name $f... Dict-fun identifiers (from inst decls) $dmop Default method for 'op' $pnC n'th superclass selector for class C $wf Worker for function 'f' $sf.. Specialised version of f D:C Data constructor for dictionary for class C NTCo:T Coercion connecting newtype T with its representation type TFCo:R Coercion connecting a data family to its representation type R In encoded form these appear as Zdfxxx etc :... keywords (export:, letrec: etc.) --- I THINK THIS IS WRONG! This knowledge is encoded in the following functions. @mk_deriv@ generates an @OccName@ from the prefix and a string. NB: The string must already be encoded! -} -- | Build an 'OccName' derived from another 'OccName'. -- -- Note that the pieces of the name are passed in as a @[FastString]@ so that -- the whole name can be constructed with a single 'concatFS', minimizing -- unnecessary intermediate allocations. mk_deriv :: NameSpace -> FastString -- ^ A prefix which distinguishes one sort of -- derived name from another -> [FastString] -- ^ The name we are deriving from in pieces which -- will be concatenated. -> OccName mk_deriv occ_sp sys_prefix str = mkOccNameFS occ_sp (concatFS $ sys_prefix : str) isDerivedOccName :: OccName -> Bool -- ^ Test for definitions internally generated by GHC. This predicte -- is used to suppress printing of internal definitions in some debug prints isDerivedOccName occ = case occNameString occ of '$':c:_ | isAlphaNum c -> True -- E.g. $wfoo c:':':_ | isAlphaNum c -> True -- E.g. N:blah newtype coercions _other -> False isDefaultMethodOcc :: OccName -> Bool isDefaultMethodOcc occ = case occNameString occ of '$':'d':'m':_ -> True _ -> False -- | Is an 'OccName' one of a Typeable @TyCon@ or @Module@ binding? -- This is needed as these bindings are renamed differently. -- See Note [Grand plan for Typeable] in TcTypeable. isTypeableBindOcc :: OccName -> Bool isTypeableBindOcc occ = case occNameString occ of '$':'t':'c':_ -> True -- mkTyConRepOcc '$':'t':'r':_ -> True -- Module binding _ -> False mkDataConWrapperOcc, mkWorkerOcc, mkMatcherOcc, mkBuilderOcc, mkDefaultMethodOcc, mkClassDataConOcc, mkDictOcc, mkIPOcc, mkSpecOcc, mkForeignExportOcc, mkRepEqOcc, mkGenR, mkGen1R, mkDataConWorkerOcc, mkNewTyCoOcc, mkInstTyCoOcc, mkEqPredCoOcc, mkClassOpAuxOcc, mkCon2TagOcc, mkTag2ConOcc, mkMaxTagOcc, mkTyConRepOcc :: OccName -> OccName -- These derived variables have a prefix that no Haskell value could have mkDataConWrapperOcc = mk_simple_deriv varName "$W" mkWorkerOcc = mk_simple_deriv varName "$w" mkMatcherOcc = mk_simple_deriv varName "$m" mkBuilderOcc = mk_simple_deriv varName "$b" mkDefaultMethodOcc = mk_simple_deriv varName "$dm" mkClassOpAuxOcc = mk_simple_deriv varName "$c" mkDictOcc = mk_simple_deriv varName "$d" mkIPOcc = mk_simple_deriv varName "$i" mkSpecOcc = mk_simple_deriv varName "$s" mkForeignExportOcc = mk_simple_deriv varName "$f" mkRepEqOcc = mk_simple_deriv tvName "$r" -- In RULES involving Coercible mkClassDataConOcc = mk_simple_deriv dataName "C:" -- Data con for a class mkNewTyCoOcc = mk_simple_deriv tcName "N:" -- Coercion for newtypes mkInstTyCoOcc = mk_simple_deriv tcName "D:" -- Coercion for type functions mkEqPredCoOcc = mk_simple_deriv tcName "$co" -- Used in derived instances mkCon2TagOcc = mk_simple_deriv varName "$con2tag_" mkTag2ConOcc = mk_simple_deriv varName "$tag2con_" mkMaxTagOcc = mk_simple_deriv varName "$maxtag_" -- TyConRepName stuff; see Note [Grand plan for Typeable] in TcTypeable mkTyConRepOcc occ = mk_simple_deriv varName prefix occ where prefix | isDataOcc occ = "$tc'" | otherwise = "$tc" -- Generic deriving mechanism mkGenR = mk_simple_deriv tcName "Rep_" mkGen1R = mk_simple_deriv tcName "Rep1_" -- Overloaded record field selectors mkRecFldSelOcc :: String -> OccName mkRecFldSelOcc s = mk_deriv varName "$sel" [fsLit s] mk_simple_deriv :: NameSpace -> FastString -> OccName -> OccName mk_simple_deriv sp px occ = mk_deriv sp px [occNameFS occ] -- Data constructor workers are made by setting the name space -- of the data constructor OccName (which should be a DataName) -- to VarName mkDataConWorkerOcc datacon_occ = setOccNameSpace varName datacon_occ mkSuperDictAuxOcc :: Int -> OccName -> OccName mkSuperDictAuxOcc index cls_tc_occ = mk_deriv varName "$cp" [fsLit $ show index, occNameFS cls_tc_occ] mkSuperDictSelOcc :: Int -- ^ Index of superclass, e.g. 3 -> OccName -- ^ Class, e.g. @Ord@ -> OccName -- ^ Derived 'Occname', e.g. @$p3Ord@ mkSuperDictSelOcc index cls_tc_occ = mk_deriv varName "$p" [fsLit $ show index, occNameFS cls_tc_occ] mkLocalOcc :: Unique -- ^ Unique to combine with the 'OccName' -> OccName -- ^ Local name, e.g. @sat@ -> OccName -- ^ Nice unique version, e.g. @$L23sat@ mkLocalOcc uniq occ = mk_deriv varName "$L" [fsLit $ show uniq, occNameFS occ] -- The Unique might print with characters -- that need encoding (e.g. 'z'!) -- | Derive a name for the representation type constructor of a -- @data@\/@newtype@ instance. mkInstTyTcOcc :: String -- ^ Family name, e.g. @Map@ -> OccSet -- ^ avoid these Occs -> OccName -- ^ @R:Map@ mkInstTyTcOcc str = chooseUniqueOcc tcName ('R' : ':' : str) mkDFunOcc :: String -- ^ Typically the class and type glommed together e.g. @OrdMaybe@. -- Only used in debug mode, for extra clarity -> Bool -- ^ Is this a hs-boot instance DFun? -> OccSet -- ^ avoid these Occs -> OccName -- ^ E.g. @$f3OrdMaybe@ -- In hs-boot files we make dict funs like $fx7ClsTy, which get bound to the real -- thing when we compile the mother module. Reason: we don't know exactly -- what the mother module will call it. mkDFunOcc info_str is_boot set = chooseUniqueOcc VarName (prefix ++ info_str) set where prefix | is_boot = "$fx" | otherwise = "$f" mkDataTOcc, mkDataCOcc :: OccName -- ^ TyCon or data con string -> OccSet -- ^ avoid these Occs -> OccName -- ^ E.g. @$f3OrdMaybe@ -- data T = MkT ... deriving( Data ) needs definitions for -- $tT :: Data.Generics.Basics.DataType -- $cMkT :: Data.Generics.Basics.Constr mkDataTOcc occ = chooseUniqueOcc VarName ("$t" ++ occNameString occ) mkDataCOcc occ = chooseUniqueOcc VarName ("$c" ++ occNameString occ) {- Sometimes we need to pick an OccName that has not already been used, given a set of in-use OccNames. -} chooseUniqueOcc :: NameSpace -> String -> OccSet -> OccName chooseUniqueOcc ns str set = loop (mkOccName ns str) (0::Int) where loop occ n | occ `elemOccSet` set = loop (mkOccName ns (str ++ show n)) (n+1) | otherwise = occ {- We used to add a '$m' to indicate a method, but that gives rise to bad error messages from the type checker when we print the function name or pattern of an instance-decl binding. Why? Because the binding is zapped to use the method name in place of the selector name. (See TcClassDcl.tcMethodBind) The way it is now, -ddump-xx output may look confusing, but you can always say -dppr-debug to get the uniques. However, we *do* have to zap the first character to be lower case, because overloaded constructors (blarg) generate methods too. And convert to VarName space e.g. a call to constructor MkFoo where data (Ord a) => Foo a = MkFoo a If this is necessary, we do it by prefixing '$m'. These guys never show up in error messages. What a hack. -} mkMethodOcc :: OccName -> OccName mkMethodOcc occ@(OccName VarName _) = occ mkMethodOcc occ = mk_simple_deriv varName "$m" occ {- ************************************************************************ * * \subsection{Tidying them up} * * ************************************************************************ Before we print chunks of code we like to rename it so that we don't have to print lots of silly uniques in it. But we mustn't accidentally introduce name clashes! So the idea is that we leave the OccName alone unless it accidentally clashes with one that is already in scope; if so, we tack on '1' at the end and try again, then '2', and so on till we find a unique one. There's a wrinkle for operators. Consider '>>='. We can't use '>>=1' because that isn't a single lexeme. So we encode it to 'lle' and *then* tack on the '1', if necessary. Note [TidyOccEnv] ~~~~~~~~~~~~~~~~~ type TidyOccEnv = UniqFM Int * Domain = The OccName's FastString. These FastStrings are "taken"; make sure that we don't re-use * Int, n = A plausible starting point for new guesses There is no guarantee that "FSn" is available; you must look that up in the TidyOccEnv. But it's a good place to start looking. * When looking for a renaming for "foo2" we strip off the "2" and start with "foo". Otherwise if we tidy twice we get silly names like foo23. However, if it started with digits at the end, we always make a name with digits at the end, rather than shortening "foo2" to just "foo", even if "foo" is unused. Reasons: - Plain "foo" might be used later - We use trailing digits to subtly indicate a unification variable in typechecker error message; see TypeRep.tidyTyVarBndr We have to take care though! Consider a machine-generated module (Trac #10370) module Foo where a1 = e1 a2 = e2 ... a2000 = e2000 Then "a1", "a2" etc are all marked taken. But now if we come across "a7" again, we have to do a linear search to find a free one, "a2001". That might just be acceptable once. But if we now come across "a8" again, we don't want to repeat that search. So we use the TidyOccEnv mapping for "a" (not "a7" or "a8") as our base for starting the search; and we make sure to update the starting point for "a" after we allocate a new one. Node [Tidying multiple names at once] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider > :t (id,id,id) Every id contributes a type variable to the type signature, and all of them are "a". If we tidy them one by one, we get (id,id,id) :: (a2 -> a2, a1 -> a1, a -> a) which is a bit unfortunate, as it unfairly renames only one of them. What we would like to see is (id,id,id) :: (a3 -> a3, a2 -> a2, a1 -> a1) To achieve this, the function avoidClashesOccEnv can be used to prepare the TidyEnv, by “blocking” every name that occurs twice in the map. This way, none of the "a"s will get the privilege of keeping this name, and all of them will get a suitable number by tidyOccName. This prepared TidyEnv can then be used with tidyOccName. See tidyTyCoVarBndrs for an example where this is used. This is #12382. -} type TidyOccEnv = UniqFM Int -- The in-scope OccNames -- See Note [TidyOccEnv] emptyTidyOccEnv :: TidyOccEnv emptyTidyOccEnv = emptyUFM initTidyOccEnv :: [OccName] -> TidyOccEnv -- Initialise with names to avoid! initTidyOccEnv = foldl' add emptyUFM where add env (OccName _ fs) = addToUFM env fs 1 -- see Note [Tidying multiple names at once] avoidClashesOccEnv :: TidyOccEnv -> [OccName] -> TidyOccEnv avoidClashesOccEnv env occs = go env emptyUFM occs where go env _ [] = env go env seenOnce ((OccName _ fs):occs) | fs `elemUFM` env = go env seenOnce occs | fs `elemUFM` seenOnce = go (addToUFM env fs 1) seenOnce occs | otherwise = go env (addToUFM seenOnce fs ()) occs tidyOccName :: TidyOccEnv -> OccName -> (TidyOccEnv, OccName) tidyOccName env occ@(OccName occ_sp fs) | not (fs `elemUFM` env) = -- Desired OccName is free, so use it, -- and record in 'env' that it's no longer available (addToUFM env fs 1, occ) | otherwise = case lookupUFM env base1 of Nothing -> (addToUFM env base1 2, OccName occ_sp base1) Just n -> find 1 n where base :: String -- Drop trailing digits (see Note [TidyOccEnv]) base = dropWhileEndLE isDigit (unpackFS fs) base1 = mkFastString (base ++ "1") find !k !n = case lookupUFM env new_fs of Just {} -> find (k+1 :: Int) (n+k) -- By using n+k, the n argument to find goes -- 1, add 1, add 2, add 3, etc which -- moves at quadratic speed through a dense patch Nothing -> (new_env, OccName occ_sp new_fs) where new_fs = mkFastString (base ++ show n) new_env = addToUFM (addToUFM env new_fs 1) base1 (n+1) -- Update: base1, so that next time we'll start where we left off -- new_fs, so that we know it is taken -- If they are the same (n==1), the former wins -- See Note [TidyOccEnv] {- ************************************************************************ * * Binary instance Here rather than BinIface because OccName is abstract * * ************************************************************************ -} instance Binary NameSpace where put_ bh VarName = do putByte bh 0 put_ bh DataName = do putByte bh 1 put_ bh TvName = do putByte bh 2 put_ bh TcClsName = do putByte bh 3 get bh = do h <- getByte bh case h of 0 -> do return VarName 1 -> do return DataName 2 -> do return TvName _ -> do return TcClsName instance Binary OccName where put_ bh (OccName aa ab) = do put_ bh aa put_ bh ab get bh = do aa <- get bh ab <- get bh return (OccName aa ab)