-- C->Haskell Compiler: traversals of C structure tree -- -- Author : Manuel M. T. Chakravarty -- Created: 16 October 99 -- -- Version $Revision: 1.1 $ from $Date: 2004/11/21 21:05:27 $ -- -- Copyright (c) [1999..2001] Manuel M. T. Chakravarty -- -- This file is free software; you can redistribute it and/or modify -- it under the terms of the GNU General Public License as published by -- the Free Software Foundation; either version 2 of the License, or -- (at your option) any later version. -- -- This file is distributed in the hope that it will be useful, -- but WITHOUT ANY WARRANTY; without even the implied warranty of -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -- GNU General Public License for more details. -- --- DESCRIPTION --------------------------------------------------------------- -- -- This modules provides for traversals of C structure trees. The C -- traversal monad supports traversals that need convenient access to the -- attributes of an attributed C structure tree. The monads state can still -- be extended. -- --- DOCU ---------------------------------------------------------------------- -- -- language: Haskell 98 -- -- Handling of redefined tag values -- -------------------------------- -- -- Structures allow both -- -- struct s {...} ...; -- struct s ...; -- -- and -- -- struct s ...; /* this is called a forward reference */ -- struct s {...} ...; -- -- In contrast enumerations only allow (in ANSI C) -- -- enum e {...} ...; -- enum e ...; -- -- The function `defTag' handles both types and establishes an object -- association from the tag identifier in the empty declaration (ie, the one -- without `{...}') to the actually definition of the structure of -- enumeration. This implies that when looking for the details of a -- structure or enumeration, possibly a chain of references on tag -- identifiers has to be chased. Note that the object association attribute -- is _not_defined_ when the `{...}' part is present in a declaration. -- --- TODO ---------------------------------------------------------------------- -- -- * `extractStruct' doesn't account for forward declarations that have no -- full declaration yet; if `extractStruct' is called on such a declaration, -- we have a user error, but currently an internal error is raised -- module CTrav (CT, readCT, transCT, getCHeaderCT, runCT, throwCTExc, ifCTExc, raiseErrorCTExc, enter, enterObjs, leave, leaveObjs, defObj, findObj, findObjShadow, defTag, findTag, findTagShadow, applyPrefixToNameSpaces, getDefOf, refersToDef, refersToNewDef, getDeclOf, findTypeObjMaybe, findTypeObj, findValueObj, findFunObj, -- -- C structure tree query functions -- isTypedef, simplifyDecl, declrFromDecl, declrNamed, declaredDeclr, declaredName, structMembers, expandDecl, structName, enumName, tagName, isArrDeclr, isPtrDeclr, dropPtrDeclr, isPtrDecl, isFunDeclr, structFromDecl, funResultAndArgs, chaseDecl, findAndChaseDecl, checkForAlias, checkForOneAliasName, lookupEnum, lookupStructUnion, lookupDeclOrTag) where import Data.List (find) import Data.Maybe (fromMaybe) import Control.Monad (liftM) import Control.Exception (assert) import Position (Position, Pos(..), nopos) import Errors (interr) import Idents (Ident, dumpIdent, identToLexeme) import Attributes (Attr(..), newAttrsOnlyPos) import C2HSState (CST, nop, readCST, transCST, runCST, raiseError, catchExc, throwExc, Traces(..), putTraceStr) import CAST import CAttrs (AttrC, getCHeader, enterNewRangeC, enterNewObjRangeC, leaveRangeC, leaveObjRangeC, addDefObjC, lookupDefObjC, lookupDefObjCShadow, addDefTagC, lookupDefTagC, lookupDefTagCShadow, applyPrefix, getDefOfIdentC, setDefOfIdentC, updDefOfIdentC, CObj(..), CTag(..), CDef(..)) -- the C traversal monad -- --------------------- -- C traversal monad (EXPORTED ABSTRACTLY) -- type CState s = (AttrC, s) type CT s a = CST (CState s) a -- read attributed struture tree -- readAttrCCT :: (AttrC -> a) -> CT s a readAttrCCT reader = readCST $ \(ac, _) -> reader ac -- transform attributed structure tree -- transAttrCCT :: (AttrC -> (AttrC, a)) -> CT s a transAttrCCT trans = transCST $ \(ac, s) -> let (ac', r) = trans ac in ((ac', s), r) -- access to the user-defined state -- -- read user-defined state (EXPORTED) -- readCT :: (s -> a) -> CT s a readCT reader = readCST $ \(_, s) -> reader s -- transform user-defined state (EXPORTED) -- transCT :: (s -> (s, a)) -> CT s a transCT trans = transCST $ \(ac, s) -> let (s', r) = trans s in ((ac, s'), r) -- usage of a traversal monad -- -- get the raw C header from the monad (EXPORTED) -- getCHeaderCT :: CT s CHeader getCHeaderCT = readAttrCCT getCHeader -- execute a traversal monad (EXPORTED) -- -- * given a traversal monad, an attribute structure tree, and a user -- state, the transformed structure tree and monads result are returned -- runCT :: CT s a -> AttrC -> s -> CST t (AttrC, a) runCT m ac s = runCST m' (ac, s) where m' = do r <- m (ac, _) <- readCST id return (ac, r) -- exception handling -- ------------------ -- exception identifier -- ctExc :: String ctExc = "ctExc" -- throw an exception (EXPORTED) -- throwCTExc :: CT s a throwCTExc = throwExc ctExc "Error during traversal of a C structure tree" -- catch a `ctExc' (EXPORTED) -- ifCTExc :: CT s a -> CT s a -> CT s a ifCTExc m handler = m `catchExc` (ctExc, const handler) -- raise an error followed by throwing a CT exception (EXPORTED) -- raiseErrorCTExc :: Position -> [String] -> CT s a raiseErrorCTExc pos errs = raiseError pos errs >> throwCTExc -- attribute manipulation -- ---------------------- -- name spaces -- -- enter a new local range (EXPORTED) -- enter :: CT s () enter = transAttrCCT $ \ac -> (enterNewRangeC ac, ()) -- enter a new local range, only for objects (EXPORTED) -- enterObjs :: CT s () enterObjs = transAttrCCT $ \ac -> (enterNewObjRangeC ac, ()) -- leave the current local range (EXPORTED) -- leave :: CT s () leave = transAttrCCT $ \ac -> (leaveRangeC ac, ()) -- leave the current local range, only for objects (EXPORTED) -- leaveObjs :: CT s () leaveObjs = transAttrCCT $ \ac -> (leaveObjRangeC ac, ()) -- enter an object definition into the object name space (EXPORTED) -- -- * if a definition of the same name was already present, it is returned -- defObj :: Ident -> CObj -> CT s (Maybe CObj) defObj ide obj = transAttrCCT $ \ac -> addDefObjC ac ide obj -- find a definition in the object name space (EXPORTED) -- findObj :: Ident -> CT s (Maybe CObj) findObj ide = readAttrCCT $ \ac -> lookupDefObjC ac ide -- find a definition in the object name space; if nothing found, try -- whether there is a shadow identifier that matches (EXPORTED) -- findObjShadow :: Ident -> CT s (Maybe (CObj, Ident)) findObjShadow ide = readAttrCCT $ \ac -> lookupDefObjCShadow ac ide -- enter a tag definition into the tag name space (EXPORTED) -- -- * empty definitions of structures get overwritten with complete ones and a -- forward reference is added to their tag identifier; furthermore, both -- structures and enums may be referenced using an empty definition when -- there was a full definition earlier and in this case there is also an -- object association added; otherwise, if a definition of the same name was -- already present, it is returned (see DOCU section) -- -- * it is checked that the first occurence of an enumeration tag is -- accompanied by a full definition of the enumeration -- defTag :: Ident -> CTag -> CT s (Maybe CTag) defTag ide tag = do otag <- transAttrCCT $ \ac -> addDefTagC ac ide tag case otag of Nothing -> do assertIfEnumThenFull tag return Nothing -- no collision Just prevTag -> case isRefinedOrUse prevTag tag of Nothing -> return otag Just (fullTag, foreIde) -> do transAttrCCT $ \ac -> addDefTagC ac ide fullTag foreIde `refersToDef` TagCD fullTag return Nothing -- transparent for env where -- compute whether we have the case of a non-conflicting redefined tag -- definition, and if so, return the full definition and the foreward -- definition's tag identifier -- -- * the first argument contains the _previous_ definition -- -- * in the case of a structure, a foreward definition after a full -- definition is allowed, so we have to handle this case; enumerations -- don't allow foreward definitions -- -- * there may also be multiple foreward definition; if we have two of -- them here, one is arbitrarily selected to take the role of the full -- definition -- isRefinedOrUse (StructUnionCT (CStruct _ (Just ide) [] _)) tag@(StructUnionCT (CStruct _ (Just _ ) _ _)) = Just (tag, ide) isRefinedOrUse tag@(StructUnionCT (CStruct _ (Just _ ) _ _)) (StructUnionCT (CStruct _ (Just ide) [] _)) = Just (tag, ide) isRefinedOrUse tag@(EnumCT (CEnum (Just _ ) _ _)) (EnumCT (CEnum (Just ide) [] _)) = Just (tag, ide) isRefinedOrUse _ _ = Nothing -- find an definition in the tag name space (EXPORTED) -- findTag :: Ident -> CT s (Maybe CTag) findTag ide = readAttrCCT $ \ac -> lookupDefTagC ac ide -- find an definition in the tag name space; if nothing found, try -- whether there is a shadow identifier that matches (EXPORTED) -- findTagShadow :: Ident -> CT s (Maybe (CTag, Ident)) findTagShadow ide = readAttrCCT $ \ac -> lookupDefTagCShadow ac ide -- enrich the object and tag name space with identifiers obtained by dropping -- the given prefix from the identifiers already in the name space (EXPORTED) -- -- * if a new identifier would collides with an existing one, the new one is -- discarded, ie, all associations that existed before the transformation -- started are still in effect after the transformation -- applyPrefixToNameSpaces :: String -> CT s () applyPrefixToNameSpaces prefix = transAttrCCT $ \ac -> (applyPrefix ac prefix, ()) -- definition attribute -- -- get the definition of an identifier (EXPORTED) -- -- * the attribute must be defined, ie, a definition must be associated with -- the given identifier -- getDefOf :: Ident -> CT s CDef getDefOf ide = do def <- readAttrCCT $ \ac -> getDefOfIdentC ac ide assert (not . isUndef $ def) $ return def -- set the definition of an identifier (EXPORTED) -- refersToDef :: Ident -> CDef -> CT s () refersToDef ide def = transAttrCCT $ \akl -> (setDefOfIdentC akl ide def, ()) -- update the definition of an identifier (EXPORTED) -- refersToNewDef :: Ident -> CDef -> CT s () refersToNewDef ide def = transAttrCCT $ \akl -> (updDefOfIdentC akl ide def, ()) -- get the declarator of an identifier (EXPORTED) -- getDeclOf :: Ident -> CT s CDecl getDeclOf ide = do traceEnter def <- getDefOf ide case def of UndefCD -> interr "CTrav.getDeclOf: Undefined!" DontCareCD -> interr "CTrav.getDeclOf: Don't care!" TagCD _ -> interr "CTrav.getDeclOf: Illegal tag!" ObjCD obj -> case obj of TypeCO decl -> traceTypeCO >> return decl ObjCO decl -> traceObjCO >> return decl EnumCO _ _ -> illegalEnum BuiltinCO -> illegalBuiltin where illegalEnum = interr "CTrav.getDeclOf: Illegal enum!" illegalBuiltin = interr "CTrav.getDeclOf: Attempted to get declarator of \ \builtin entity!" -- if the latter ever becomes necessary, we have to -- change the representation of builtins and give them -- some dummy declarator traceEnter = traceCTrav $ "Entering `getDeclOf' for `" ++ identToLexeme ide ++ "'...\n" traceTypeCO = traceCTrav $ "...found a type object.\n" traceObjCO = traceCTrav $ "...found a vanilla object.\n" -- convenience functions -- -- find a type object in the object name space; returns `nothing' if the -- identifier is not defined (EXPORTED) -- -- * if the second argument is `True', use `findObjShadow' -- findTypeObjMaybe :: Ident -> Bool -> CT s (Maybe (CObj, Ident)) findTypeObjMaybe ide useShadows = do oobj <- if useShadows then findObjShadow ide else liftM (fmap (\obj -> (obj, ide))) $ findObj ide case oobj of Just obj@(TypeCO _ , _) -> return $ Just obj Just obj@(BuiltinCO, _) -> return $ Just obj Just _ -> typedefExpectedErr ide Nothing -> return $ Nothing -- find a type object in the object name space; raises an error and exception -- if the identifier is not defined (EXPORTED) -- -- * if the second argument is `True', use `findObjShadow' -- findTypeObj :: Ident -> Bool -> CT s (CObj, Ident) findTypeObj ide useShadows = do oobj <- findTypeObjMaybe ide useShadows case oobj of Nothing -> unknownObjErr ide Just obj -> return obj -- find an object, function, or enumerator in the object name space; raises an -- error and exception if the identifier is not defined (EXPORTED) -- -- * if the second argument is `True', use `findObjShadow' -- findValueObj :: Ident -> Bool -> CT s (CObj, Ident) findValueObj ide useShadows = do oobj <- if useShadows then findObjShadow ide else liftM (fmap (\obj -> (obj, ide))) $ findObj ide case oobj of Just obj@(ObjCO _ , _) -> return obj Just obj@(EnumCO _ _, _) -> return obj Just _ -> unexpectedTypedefErr (posOf ide) Nothing -> unknownObjErr ide -- find a function in the object name space; raises an error and exception if -- the identifier is not defined (EXPORTED) -- -- * if the second argument is `True', use `findObjShadow' -- findFunObj :: Ident -> Bool -> CT s (CObj, Ident) findFunObj ide useShadows = do (obj, ide') <- findValueObj ide useShadows case obj of EnumCO _ _ -> funExpectedErr (posOf ide) ObjCO decl -> do let declr = ide' `declrFromDecl` decl assertFunDeclr (posOf ide) declr return (obj, ide') -- C structure tree query routines -- ------------------------------- -- test if this is a type definition specification (EXPORTED) -- isTypedef :: CDecl -> Bool isTypedef (CDecl specs _ _) = not . null $ [() | CStorageSpec (CTypedef _) <- specs] -- discard all declarators but the one declaring the given identifier -- (EXPORTED) -- -- * the declaration must contain the identifier -- simplifyDecl :: Ident -> CDecl -> CDecl ide `simplifyDecl` (CDecl specs declrs at) = case find (`declrPlusNamed` ide) declrs of Nothing -> err Just declr -> CDecl specs [declr] at where (Just declr, _, _) `declrPlusNamed` ide = declr `declrNamed` ide _ `declrPlusNamed` _ = False -- err = interr $ "CTrav.simplifyDecl: Wrong C object!\n\ \ Looking for `" ++ identToLexeme ide ++ "' in decl \ \at " ++ show (posOf at) -- extract the declarator that declares the given identifier (EXPORTED) -- -- * the declaration must contain the identifier -- declrFromDecl :: Ident -> CDecl -> CDeclr ide `declrFromDecl` decl = let CDecl _ [(Just declr, _, _)] _ = ide `simplifyDecl` decl in declr -- tests whether the given declarator has the given name (EXPORTED) -- declrNamed :: CDeclr -> Ident -> Bool declr `declrNamed` ide = declrName declr == Just ide -- get the declarator of a declaration that has at most one declarator -- (EXPORTED) -- declaredDeclr :: CDecl -> Maybe CDeclr declaredDeclr (CDecl _ [] _) = Nothing declaredDeclr (CDecl _ [(odeclr, _, _)] _) = odeclr declaredDeclr decl = interr $ "CTrav.declaredDeclr: Too many declarators!\n\ \ Declaration at " ++ show (posOf decl) -- get the name declared by a declaration that has exactly one declarator -- (EXPORTED) -- declaredName :: CDecl -> Maybe Ident declaredName decl = declaredDeclr decl >>= declrName -- obtains the member definitions and the tag of a struct (EXPORTED) -- -- * member definitions are expanded -- structMembers :: CStructUnion -> ([CDecl], CStructTag) structMembers (CStruct tag _ members _) = (concat . map expandDecl $ members, tag) -- expand declarators declaring more than one identifier into multiple -- declarators, eg, `int x, y;' becomes `int x; int y;' (EXPORTED) -- expandDecl :: CDecl -> [CDecl] expandDecl (CDecl specs decls at) = map (\decl -> CDecl specs [decl] at) decls -- get a struct's name (EXPORTED) -- structName :: CStructUnion -> Maybe Ident structName (CStruct _ oide _ _) = oide -- get an enum's name (EXPORTED) -- enumName :: CEnum -> Maybe Ident enumName (CEnum oide _ _) = oide -- get a tag's name (EXPORTED) -- -- * fail if the tag is anonymous -- tagName :: CTag -> Ident tagName tag = case tag of StructUnionCT struct -> maybe err id $ structName struct EnumCT enum -> maybe err id $ enumName enum where err = interr "CTrav.tagName: Anonymous tag definition" -- checks whether the given declarator defines an object that is a pointer to -- some other type (EXPORTED) -- -- * as far as parameter passing is concerned, arrays are also pointer -- isPtrDeclr :: CDeclr -> Bool isPtrDeclr (CPtrDeclr _ (CVarDeclr _ _) _) = True isPtrDeclr (CPtrDeclr _ declr _) = isPtrDeclr declr isPtrDeclr (CArrDeclr (CVarDeclr _ _) _ _ _) = True isPtrDeclr (CArrDeclr declr _ _ _) = isPtrDeclr declr isPtrDeclr (CFunDeclr declr _ _ _) = isPtrDeclr declr isPtrDeclr _ = False -- checks whether the given declarator defines an object that is an array of -- some other type (EXPORTED) -- -- * difference between arrays and pure pointers is important for size -- calculations -- isArrDeclr :: CDeclr -> Bool isArrDeclr (CArrDeclr declr _ _ _) = True isArrDeclr _ = False -- drops the first pointer level from the given declarator (EXPORTED) -- -- * the declarator must declare a pointer object -- -- FIXME: this implementation isn't nice, because we retain the `CVarDeclr' -- unchanged; as the declarator is changed, we should maybe make this -- into an anonymous declarator and also change its attributes -- dropPtrDeclr :: CDeclr -> CDeclr dropPtrDeclr (CPtrDeclr qs declr@(CVarDeclr _ _) ats) = declr dropPtrDeclr (CPtrDeclr qs declr ats) = let declr' = dropPtrDeclr declr in CPtrDeclr qs declr' ats dropPtrDeclr (CArrDeclr declr@(CVarDeclr _ _) _ _ _) = declr dropPtrDeclr (CArrDeclr declr tq e ats) = let declr' = dropPtrDeclr declr in CArrDeclr declr' tq e ats dropPtrDeclr (CFunDeclr declr args vari ats) = let declr' = dropPtrDeclr declr in CFunDeclr declr' args vari ats dropPtrDeclr _ = interr "CTrav.dropPtrDeclr: No pointer!" -- checks whether the given declaration defines a pointer object (EXPORTED) -- -- * there may only be a single declarator in the declaration -- isPtrDecl :: CDecl -> Bool isPtrDecl (CDecl _ [] _) = False isPtrDecl (CDecl _ [(Just declr, _, _)] _) = isPtrDeclr declr isPtrDecl _ = interr "CTrav.isPtrDecl: There was more than one declarator!" -- checks whether the given declarator defines a function object (EXPORTED) -- isFunDeclr :: CDeclr -> Bool isFunDeclr (CPtrDeclr _ declr _) = isFunDeclr declr isFunDeclr (CArrDeclr declr _ _ _) = isFunDeclr declr isFunDeclr (CFunDeclr (CVarDeclr _ _) _ _ _) = True isFunDeclr (CFunDeclr declr _ _ _) = isFunDeclr declr isFunDeclr _ = False -- extract the structure from the type specifiers of a declaration (EXPORTED) -- structFromDecl :: Position -> CDecl -> CT s CStructUnion structFromDecl pos (CDecl specs _ _) = case head [ts | CTypeSpec ts <- specs] of CSUType su _ -> extractStruct pos (StructUnionCT su) _ -> structExpectedErr pos -- extracts the arguments from a function declaration (must be a unique -- declarator) and constructs a declaration for the result of the function -- (EXPORTED) -- -- * the boolean result indicates whether the function is variadic -- funResultAndArgs :: CDecl -> ([CDecl], CDecl, Bool) funResultAndArgs (CDecl specs [(Just declr, _, _)] _) = let (args, declr', variadic) = funArgs declr result = CDecl specs [(Just declr', Nothing, Nothing)] (newAttrsOnlyPos nopos) in (args, result, variadic) where funArgs (CFunDeclr var@(CVarDeclr _ _) args variadic _) = (args, var, variadic) funArgs (CPtrDeclr qs declr at) = let (args, declr', variadic) = funArgs declr in (args, CPtrDeclr qs declr' at, variadic) funArgs (CArrDeclr declr tqs oe at) = let (args, declr', variadic) = funArgs declr in (args, CArrDeclr declr' tqs oe at, variadic) funArgs (CFunDeclr declr args var at) = let (args, declr', variadic) = funArgs declr in (args, CFunDeclr declr' args var at, variadic) funArgs _ = interr "CTrav.funResultAndArgs: Illegal declarator!" -- name chasing -- -- find the declarator identified by the given identifier; if the declarator -- is itself only a `typedef'ed name, the operation recursively searches for -- the declarator associated with that name (this is called ``typedef -- chasing'') (EXPORTED) -- -- * if `ind = True', we have to hop over one indirection -- -- * remove all declarators except the one we just looked up -- chaseDecl :: Ident -> Bool -> CT s CDecl -- -- * cycles are no issue, as they cannot occur in a correct C header (we would -- have spotted the problem during name analysis) -- chaseDecl ide ind = do traceEnter cdecl <- getDeclOf ide let sdecl = ide `simplifyDecl` cdecl case extractAlias sdecl ind of Just (ide', ind') -> chaseDecl ide' ind' Nothing -> return sdecl where traceEnter = traceCTrav $ "Entering `chaseDecl' for `" ++ identToLexeme ide ++ "' " ++ (if ind then "" else "not ") ++ "following indirections...\n" -- find type object in object name space and then chase it (EXPORTED) -- -- * see also `chaseDecl' -- -- * also create an object association from the given identifier to the object -- that it _directly_ represents -- -- * if the third argument is `True', use `findObjShadow' -- findAndChaseDecl :: Ident -> Bool -> Bool -> CT s CDecl findAndChaseDecl ide ind useShadows = do (obj, ide') <- findTypeObj ide useShadows -- is there an object def? ide `refersToNewDef` ObjCD obj ide' `refersToNewDef` ObjCD obj -- assoc needed for chasing chaseDecl ide' ind -- given a declaration (which must have exactly one declarator), if the -- declarator is an alias, chase it to the actual declaration (EXPORTED) -- checkForAlias :: CDecl -> CT s (Maybe CDecl) checkForAlias decl = case extractAlias decl False of Nothing -> return Nothing Just (ide', _) -> liftM Just $ chaseDecl ide' False -- given a declaration (which must have exactly one declarator), if the -- declarator is an alias, yield the alias name; *no* chasing (EXPORTED) -- checkForOneAliasName :: CDecl -> Maybe Ident checkForOneAliasName decl = fmap fst $ extractAlias decl False -- smart lookup -- -- for the given identifier, either find an enumeration in the tag name space -- or a type definition referring to an enumeration in the object name space; -- raises an error and exception if the identifier is not defined (EXPORTED) -- -- * if the second argument is `True', use `findTagShadow' -- lookupEnum :: Ident -> Bool -> CT s CEnum lookupEnum ide useShadows = do otag <- if useShadows then liftM (fmap fst) $ findTagShadow ide else findTag ide case otag of Just (StructUnionCT _ ) -> enumExpectedErr ide -- wrong tag definition Just (EnumCT enum) -> return enum -- enum tag definition Nothing -> do -- no tag definition (CDecl specs _ _) <- findAndChaseDecl ide False useShadows case head [ts | CTypeSpec ts <- specs] of CEnumType enum _ -> return enum _ -> enumExpectedErr ide -- for the given identifier, either find a struct/union in the tag name space -- or a type definition referring to a struct/union in the object name space; -- raises an error and exception if the identifier is not defined (EXPORTED) -- -- * if `ind = True', the identifier names a reference type to the searched -- for struct/union -- -- * typedef chasing is used only if there is no tag of the same name or an -- indirection (ie, `ind = True') is explicitly required -- -- * if the third argument is `True', use `findTagShadow' -- -- * when finding a forward definition of a tag, follow it to the real -- definition -- lookupStructUnion :: Ident -> Bool -> Bool -> CT s CStructUnion lookupStructUnion ide ind useShadows | ind = chase | otherwise = do otag <- if useShadows then liftM (fmap fst) $ findTagShadow ide else findTag ide maybe chase (extractStruct (posOf ide)) otag -- `chase' if `Nothing' where chase = do decl <- findAndChaseDecl ide ind useShadows structFromDecl (posOf ide) decl -- for the given identifier, check for the existance of both a type definition -- or a struct, union, or enum definition (EXPORTED) -- -- * if a typedef and a tag exists, the typedef takes precedence -- -- * typedefs are chased -- -- * if the second argument is `True', look for shadows, too -- lookupDeclOrTag :: Ident -> Bool -> CT s (Either CDecl CTag) lookupDeclOrTag ide useShadows = do oobj <- findTypeObjMaybe ide useShadows case oobj of Just (_, ide) -> liftM Left $ findAndChaseDecl ide False False -- already did check shadows Nothing -> do otag <- if useShadows then liftM (fmap fst) $ findTagShadow ide else findTag ide case otag of Nothing -> unknownObjErr ide Just tag -> return $ Right tag -- auxiliary routines (internal) -- -- if the given declaration (which may have at most one declarator) is a -- `typedef' alias, yield the referenced name -- -- * a `typedef' alias has one of the following forms -- -- at x, ...; -- at *x, ...; -- -- where `at' is the alias type, which has been defined by a `typedef', and -- are arbitrary specifiers and qualifiers. Note that `x' may be a -- variable, a type name (if `typedef' is in ), or be entirely -- omitted. -- -- * if `ind = True', the alias may be via an indirection -- -- * if `ind = True' and the alias is _not_ over an indirection, yield `True'; -- otherwise `False' (ie, the ability to hop over an indirection is consumed) -- -- * this may be an anonymous declaration, ie, the name in `CVarDeclr' may be -- omitted or there may be no declarator at all -- extractAlias :: CDecl -> Bool -> Maybe (Ident, Bool) extractAlias decl@(CDecl specs _ _) ind = case [ts | CTypeSpec ts <- specs] of [CTypeDef ide' _] -> -- type spec is aliased ident case declaredDeclr decl of Nothing -> Just (ide', ind) Just (CVarDeclr _ _ ) -> Just (ide', ind) Just (CPtrDeclr [_] (CVarDeclr _ _) _) | ind -> Just (ide', False) | otherwise -> Nothing _ -> Nothing _ -> Nothing -- if the given tag is a forward declaration of a structure, follow the -- reference to the full declaration -- -- * the recursive call is not dangerous as there can't be any cycles -- extractStruct :: Position -> CTag -> CT s CStructUnion extractStruct pos (EnumCT _ ) = structExpectedErr pos extractStruct pos (StructUnionCT su) = case su of CStruct _ (Just ide') [] _ -> do -- found forward definition def <- getDefOf ide' case def of TagCD tag -> extractStruct pos tag _ -> err _ -> return su where err = interr "CTrav.extractStruct: Illegal reference!" -- yield the name declared by a declarator if any -- declrName :: CDeclr -> Maybe Ident declrName (CVarDeclr oide _) = oide declrName (CPtrDeclr _ declr _) = declrName declr declrName (CArrDeclr declr _ _ _) = declrName declr declrName (CFunDeclr declr _ _ _) = declrName declr -- raise an error if the given declarator does not declare a C function or if -- the function is supposed to return an array (the latter is illegal in C) -- assertFunDeclr :: Position -> CDeclr -> CT s () assertFunDeclr pos (CArrDeclr (CFunDeclr (CVarDeclr _ _) _ _ _) _ _ _) = illegalFunResultErr pos assertFunDeclr pos (CFunDeclr (CVarDeclr _ _) _ _ _) = nop -- everything is ok assertFunDeclr pos (CFunDeclr declr _ _ _) = assertFunDeclr pos declr assertFunDeclr pos (CPtrDeclr _ declr _) = assertFunDeclr pos declr assertFunDeclr pos (CArrDeclr declr _ _ _) = assertFunDeclr pos declr assertFunDeclr pos _ = funExpectedErr pos -- raise an error if the given tag defines an enumeration, but does not fully -- define it -- assertIfEnumThenFull :: CTag -> CT s () assertIfEnumThenFull (EnumCT (CEnum _ [] at)) = enumForwardErr (posOf at) assertIfEnumThenFull _ = nop -- trace for this module -- traceCTrav :: String -> CT s () traceCTrav = putTraceStr traceCTravSW -- error messages -- -------------- unknownObjErr :: Ident -> CT s a unknownObjErr ide = raiseErrorCTExc (posOf ide) ["Unknown identifier!", "Cannot find a definition for `" ++ identToLexeme ide ++ "' in the \ \header file."] typedefExpectedErr :: Ident -> CT s a typedefExpectedErr ide = raiseErrorCTExc (posOf ide) ["Expected type definition!", "The identifier `" ++ identToLexeme ide ++ "' needs to be a C type name."] unexpectedTypedefErr :: Position -> CT s a unexpectedTypedefErr pos = raiseErrorCTExc pos ["Unexpected type name!", "An object, function, or enum constant is required here."] illegalFunResultErr :: Position -> CT s a illegalFunResultErr pos = raiseErrorCTExc pos ["Function cannot return an array!", "ANSI C does not allow functions to return an array."] funExpectedErr :: Position -> CT s a funExpectedErr pos = raiseErrorCTExc pos ["Function expected!", "A function is needed here, but this declarator does not declare", "a function."] enumExpectedErr :: Ident -> CT s a enumExpectedErr ide = raiseErrorCTExc (posOf ide) ["Expected enum!", "Expected `" ++ identToLexeme ide ++ "' to denote an enum; instead found", "a struct, union, or object."] structExpectedErr :: Position -> CT s a structExpectedErr pos = raiseErrorCTExc pos ["Expected a struct!", "Expected a structure or union; instead found an enum or basic type."] enumForwardErr :: Position -> CT s a enumForwardErr pos = raiseErrorCTExc pos ["Forward definition of enumeration!", "ANSI C does not permit foreward definitions of enumerations!"]