{-# LANGUAGE ApplicativeDo #-} {-# LANGUAGE DeriveFunctor #-} {-# LANGUAGE DerivingVia #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE NamedFieldPuns #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilies #-} {- | This module implements 'addHaddockToModule', which inserts Haddock comments accumulated during parsing into the AST (#17544). We process Haddock comments in two phases: 1. Parse the program (via the Happy parser in `Parser.y`), generating an AST, and (quite separately) a list of all the Haddock comments found in the file. More precisely, the Haddock comments are accumulated in the `hdk_comments` field of the `PState`, the parser state (see Lexer.x): data PState = PState { ... , hdk_comments :: [PsLocated HdkComment] } Each of these Haddock comments has a `PsSpan`, which gives the `BufPos` of the beginning and end of the Haddock comment. 2. Walk over the AST, attaching the Haddock comments to the correct parts of the tree. This step is called `addHaddockToModule`, and is implemented in this module. See Note [Adding Haddock comments to the syntax tree]. This approach codifies an important principle: The presence or absence of a Haddock comment should never change the parsing of a program. Alternative approaches that did not work properly: 1. Using 'RealSrcLoc' instead of 'BufPos'. This led to failures in presence of {-# LANGUAGE CPP #-} and other sources of line pragmas. See documentation on 'BufPos' (in GHC.Types.SrcLoc) for the details. 2. In earlier versions of GHC, the Haddock comments were incorporated into the Parser.y grammar. The parser constructed the AST and attached comments to it in a single pass. See Note [Old solution: Haddock in the grammar] for the details. -} module GHC.Parser.PostProcess.Haddock (addHaddockToModule) where import GHC.Prelude hiding (head, init, last, mod, tail) import GHC.Hs import GHC.Types.SrcLoc import GHC.Data.Bag import Data.Semigroup import Data.Foldable import Data.Traversable import qualified Data.List.NonEmpty as NE import Control.Applicative import Control.Monad import Control.Monad.Trans.State.Strict import Control.Monad.Trans.Reader import Data.Functor.Identity import {-# SOURCE #-} GHC.Parser (parseIdentifier) import GHC.Parser.Lexer import GHC.Parser.HaddockLex import GHC.Parser.Errors.Types import GHC.Utils.Misc (mergeListsBy, filterOut, (<&&>)) import qualified GHC.Data.Strict as Strict {- Note [Adding Haddock comments to the syntax tree] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'addHaddock' traverses the AST in concrete syntax order, building a computation (represented by HdkA) that reconstructs the AST but with Haddock comments inserted in appropriate positions: addHaddock :: HasHaddock a => a -> HdkA a Consider this code example: f :: Int -- ^ comment on argument -> Bool -- ^ comment on result In the AST, the "Int" part of this snippet is represented like this (pseudo-code): L (BufSpan 6 8) (HsTyVar "Int") :: LHsType GhcPs And the comments are represented like this (pseudo-code): L (BufSpan 11 35) (HdkCommentPrev "comment on argument") L (BufSpan 46 69) (HdkCommentPrev "comment on result") So when we are traversing the AST and 'addHaddock' is applied to HsTyVar "Int", how does it know to associate it with "comment on argument" but not with "comment on result"? The trick is to look in the space between syntactic elements. In the example above, the location range in which we search for HdkCommentPrev is as follows: f :: Int████████████████████████ ████Bool -- ^ comment on result We search for comments after HsTyVar "Int" and until the next syntactic element, in this case HsTyVar "Bool". Ignoring the "->" allows us to accommodate alternative coding styles: f :: Int -> -- ^ comment on argument Bool -- ^ comment on result Sometimes we also need to take indentation information into account. Compare the following examples: class C a where f :: a -> Int -- ^ comment on f class C a where f :: a -> Int -- ^ comment on C Notice how "comment on f" and "comment on C" differ only by indentation level. Therefore, in order to know the location range in which the comments are applicable to a syntactic elements, we need three nuggets of information: 1. lower bound on the BufPos of a comment 2. upper bound on the BufPos of a comment 3. minimum indentation level of a comment This information is represented by the 'LocRange' type. In order to propagate this information, we have the 'HdkA' applicative. 'HdkA' is defined as follows: data HdkA a = HdkA (Maybe BufSpan) (HdkM a) The first field contains a 'BufSpan', which represents the location span taken by a syntactic element: addHaddock (L bufSpan ...) = HdkA (Just bufSpan) ... The second field, 'HdkM', is a stateful computation that looks up Haddock comments in the specified location range: HdkM a ≈ LocRange -- The allowed location range -> [PsLocated HdkComment] -- Unallocated comments -> (a, -- AST with comments inserted into it [PsLocated HdkComment]) -- Leftover comments The 'Applicative' instance for 'HdkA' is defined in such a way that the location range of every computation is defined by its neighbours: addHaddock aaa <*> addHaddock bbb <*> addHaddock ccc Here, the 'LocRange' passed to the 'HdkM' computation of addHaddock bbb is determined by the BufSpan recorded in addHaddock aaa and addHaddock ccc. This is why it's important to traverse the AST in the order of the concrete syntax. In the example above we assume that aaa, bbb, ccc are ordered by location: * getBufSpan (getLoc aaa) < getBufSpan (getLoc bbb) * getBufSpan (getLoc bbb) < getBufSpan (getLoc ccc) Violation of this assumption would lead to bugs, and care must be taken to traverse the AST correctly. For example, when dealing with class declarations, we have to use 'flattenBindsAndSigs' to traverse it in the correct order. -} -- | Add Haddock documentation accumulated in the parser state -- to a parsed HsModule. -- -- Reports badly positioned comments when -Winvalid-haddock is enabled. addHaddockToModule :: Located (HsModule GhcPs) -> P (Located (HsModule GhcPs)) addHaddockToModule lmod = do pState <- getPState let all_comments = toList (hdk_comments pState) initial_hdk_st = HdkSt all_comments [] (lmod', final_hdk_st) = runHdkA (addHaddock lmod) initial_hdk_st hdk_warnings = collectHdkWarnings final_hdk_st -- lmod': module with Haddock comments inserted into the AST -- hdk_warnings: warnings accumulated during AST/comment processing mapM_ reportHdkWarning hdk_warnings return lmod' reportHdkWarning :: HdkWarn -> P () reportHdkWarning (HdkWarnInvalidComment (L l _)) = addPsMessage (mkSrcSpanPs l) PsWarnHaddockInvalidPos reportHdkWarning (HdkWarnExtraComment (L l _)) = addPsMessage l PsWarnHaddockIgnoreMulti collectHdkWarnings :: HdkSt -> [HdkWarn] collectHdkWarnings HdkSt{ hdk_st_pending, hdk_st_warnings } = map HdkWarnInvalidComment hdk_st_pending -- leftover Haddock comments not inserted into the AST ++ hdk_st_warnings {- ********************************************************************* * * * addHaddock: a family of functions that processes the AST * * in concrete syntax order, adding documentation comments to it * * * ********************************************************************* -} -- HasHaddock is a convenience class for overloading the addHaddock operation. -- Alternatively, we could define a family of monomorphic functions: -- -- addHaddockSomeTypeX :: SomeTypeX -> HdkA SomeTypeX -- addHaddockAnotherTypeY :: AnotherTypeY -> HdkA AnotherTypeY -- addHaddockOneMoreTypeZ :: OneMoreTypeZ -> HdkA OneMoreTypeZ -- -- But having a single name for all of them is just easier to read, and makes it clear -- that they all are of the form t -> HdkA t for some t. -- -- If you need to handle a more complicated scenario that doesn't fit this -- pattern, it's always possible to define separate functions outside of this -- class, as is done in case of e.g. addHaddockConDeclField. -- -- See Note [Adding Haddock comments to the syntax tree]. class HasHaddock a where addHaddock :: a -> HdkA a instance HasHaddock a => HasHaddock [a] where addHaddock = traverse addHaddock -- -- | Module header comment -- module M ( -- -- * Export list comment -- Item1, -- Item2, -- -- * Export list comment -- item3, -- item4 -- ) where -- instance HasHaddock (Located (HsModule GhcPs)) where addHaddock (L l_mod mod) = do -- Step 1, get the module header documentation comment: -- -- -- | Module header comment -- module M where -- -- Only do this when the module header exists. headerDocs <- for @Maybe (hsmodName mod) $ \(L l_name _) -> extendHdkA (locA l_name) $ liftHdkA $ do -- todo: register keyword location of 'module', see Note [Register keyword location] docs <- inLocRange (locRangeTo (getBufPos (srcSpanStart (locA l_name)))) $ takeHdkComments mkDocNext dc <- selectDocString docs pure $ lexLHsDocString <$> dc -- Step 2, process documentation comments in the export list: -- -- module M ( -- -- * Export list comment -- Item1, -- Item2, -- -- * Export list comment -- item3, -- item4 -- ) where -- -- Only do this when the export list exists. hsmodExports' <- traverse @Maybe addHaddock (hsmodExports mod) -- Step 3, register the import section to reject invalid comments: -- -- import Data.Maybe -- -- | rejected comment (cannot appear here) -- import Data.Bool -- traverse_ registerHdkA (hsmodImports mod) -- Step 4, process declarations: -- -- module M where -- -- | Comment on D -- data D = MkD -- ^ Comment on MkD -- data C = MkC -- ^ Comment on MkC -- -- ^ Comment on C -- let layout = hsmodLayout (hsmodExt mod) hsmodDecls' <- addHaddockInterleaveItems layout (mkDocHsDecl layout) (hsmodDecls mod) pure $ L l_mod $ mod { hsmodExports = hsmodExports' , hsmodDecls = hsmodDecls' , hsmodExt = (hsmodExt mod) { hsmodHaddockModHeader = join @Maybe headerDocs } } lexHsDocString :: HsDocString -> HsDoc GhcPs lexHsDocString = lexHsDoc parseIdentifier lexLHsDocString :: Located HsDocString -> LHsDoc GhcPs lexLHsDocString = fmap lexHsDocString -- | Only for module exports, not module imports. -- -- module M (a, b, c) where -- use on this [LIE GhcPs] -- import I (a, b, c) -- do not use here! -- -- Imports cannot have documentation comments anyway. instance HasHaddock (LocatedL [LocatedA (IE GhcPs)]) where addHaddock (L l_exports exports) = extendHdkA (locA l_exports) $ do exports' <- addHaddockInterleaveItems EpNoLayout mkDocIE exports registerLocHdkA (srcLocSpan (srcSpanEnd (locA l_exports))) -- Do not consume comments after the closing parenthesis pure $ L l_exports exports' -- Needed to use 'addHaddockInterleaveItems' in 'instance HasHaddock (Located [LIE GhcPs])'. instance HasHaddock (LocatedA (IE GhcPs)) where addHaddock (L l_export ie ) = extendHdkA (locA l_export) $ liftHdkA $ do docs <- inLocRange (locRangeFrom (getBufPos (srcSpanEnd (locA l_export)))) $ takeHdkComments mkDocPrev mb_doc <- selectDocString docs let mb_ldoc = lexLHsDocString <$> mb_doc let ie' = case ie of IEVar ext nm _ -> IEVar ext nm mb_ldoc IEThingAbs ext nm _ -> IEThingAbs ext nm mb_ldoc IEThingAll ext nm _ -> IEThingAll ext nm mb_ldoc IEThingWith ext nm wild subs _ -> IEThingWith ext nm wild subs mb_ldoc x -> x pure $ L l_export ie' {- Add Haddock items to a list of non-Haddock items. Used to process export lists (with mkDocIE) and declarations (with mkDocHsDecl). For example: module M where -- | Comment on D data D = MkD -- ^ Comment on MkD data C = MkC -- ^ Comment on MkC -- ^ Comment on C In this case, we should produce four HsDecl items (pseudo-code): 1. DocD (DocCommentNext "Comment on D") 2. TyClD (DataDecl "D" ... [ConDeclH98 "MkD" ... (Just "Comment on MkD")]) 3. TyClD (DataDecl "C" ... [ConDeclH98 "MkC" ... (Just "Comment on MkC")]) 4. DocD (DocCommentPrev "Comment on C") The inputs to addHaddockInterleaveItems are: * layout :: EpLayout In the example above, note that the indentation level inside the module is 2 spaces. It would be represented as layout = EpVirtualBraces 2. It is used to delimit the search space for comments when processing declarations. Here, we restrict indentation levels to >=(2+1), so that when we look up comment on MkC, we get "Comment on MkC" but not "Comment on C". * get_doc_item :: PsLocated HdkComment -> Maybe a This is the function used to look up documentation comments. In the above example, get_doc_item = mkDocHsDecl layout, and it will produce the following parts of the output: DocD (DocCommentNext "Comment on D") DocD (DocCommentPrev "Comment on C") * The list of items. These are the declarations that will be annotated with documentation comments. Before processing: TyClD (DataDecl "D" ... [ConDeclH98 "MkD" ... Nothing]) TyClD (DataDecl "C" ... [ConDeclH98 "MkC" ... Nothing]) After processing: TyClD (DataDecl "D" ... [ConDeclH98 "MkD" ... (Just "Comment on MkD")]) TyClD (DataDecl "C" ... [ConDeclH98 "MkC" ... (Just "Comment on MkC")]) -} addHaddockInterleaveItems :: forall a. HasHaddock a => EpLayout -> (PsLocated HdkComment -> Maybe a) -- Get a documentation item -> [a] -- Unprocessed (non-documentation) items -> HdkA [a] -- Documentation items & processed non-documentation items addHaddockInterleaveItems layout get_doc_item = go where go :: [a] -> HdkA [a] go [] = liftHdkA (takeHdkComments get_doc_item) go (item : items) = do docItems <- liftHdkA (takeHdkComments get_doc_item) item' <- with_layout (addHaddock item) other_items <- go items pure $ docItems ++ item':other_items with_layout :: HdkA a -> HdkA a with_layout = case layout of EpNoLayout -> id EpExplicitBraces{} -> id EpVirtualBraces n -> let loc_range = mempty { loc_range_col = ColumnFrom (n+1) } in hoistHdkA (inLocRange loc_range) instance HasHaddock (LocatedA (HsDecl GhcPs)) where addHaddock ldecl = extendHdkA (getLocA ldecl) $ traverse @LocatedA addHaddock ldecl -- Process documentation comments *inside* a declaration, for example: -- -- data T = MkT -- ^ Comment on MkT (inside DataDecl) -- f, g -- :: Int -- ^ Comment on Int (inside TypeSig) -- -> Bool -- ^ Comment on Bool (inside TypeSig) -- -- Comments that relate to the entire declaration are processed elsewhere: -- -- -- | Comment on T (not processed in this instance) -- data T = MkT -- -- -- | Comment on f, g (not processed in this instance) -- f, g :: Int -> Bool -- f = ... -- g = ... -- -- Such comments are inserted into the syntax tree as DocD declarations -- by addHaddockInterleaveItems, and then associated with other declarations -- in GHC.HsToCore.Docs (see DeclDocMap). -- -- In this instance, we only process comments that relate to parts of the -- declaration, not to the declaration itself. instance HasHaddock (HsDecl GhcPs) where -- Type signatures: -- -- f, g -- :: Int -- ^ Comment on Int -- -> Bool -- ^ Comment on Bool -- addHaddock (SigD _ (TypeSig x names t)) = do traverse_ registerHdkA names t' <- addHaddock t pure (SigD noExtField (TypeSig x names t')) -- Pattern synonym type signatures: -- -- pattern MyPat -- :: Bool -- ^ Comment on Bool -- -> Maybe Bool -- ^ Comment on Maybe Bool -- addHaddock (SigD _ (PatSynSig x names t)) = do traverse_ registerHdkA names t' <- addHaddock t pure (SigD noExtField (PatSynSig x names t')) -- Class method signatures and default signatures: -- -- class C x where -- method_of_c -- :: Maybe x -- ^ Comment on Maybe x -- -> IO () -- ^ Comment on IO () -- default method_of_c -- :: Eq x -- => Maybe x -- ^ Comment on Maybe x -- -> IO () -- ^ Comment on IO () -- addHaddock (SigD _ (ClassOpSig x is_dflt names t)) = do traverse_ registerHdkA names t' <- addHaddock t pure (SigD noExtField (ClassOpSig x is_dflt names t')) -- Data/newtype declarations: -- -- data T = MkT -- ^ Comment on MkT -- A -- ^ Comment on A -- B -- ^ Comment on B -- -- data G where -- -- | Comment on MkG -- MkG :: A -- ^ Comment on A -- -> B -- ^ Comment on B -- -> G -- -- newtype N = MkN { getN :: Natural } -- ^ Comment on N -- deriving newtype (Eq {- ^ Comment on Eq N -}) -- deriving newtype (Ord {- ^ Comment on Ord N -}) -- addHaddock (TyClD x decl) | DataDecl { tcdDExt, tcdLName, tcdTyVars, tcdFixity, tcdDataDefn = defn } <- decl = do registerHdkA tcdLName defn' <- addHaddock defn pure $ TyClD x (DataDecl { tcdDExt, tcdLName, tcdTyVars, tcdFixity, tcdDataDefn = defn' }) -- Class declarations: -- -- class C a where -- -- | Comment on the first method -- first_method :: a -> Bool -- second_method :: a -> String -- -- ^ Comment on the second method -- addHaddock (TyClD _ decl) | ClassDecl { tcdCExt = (x, layout, NoAnnSortKey), tcdCtxt, tcdLName, tcdTyVars, tcdFixity, tcdFDs, tcdSigs, tcdMeths, tcdATs, tcdATDefs } <- decl = do registerHdkA tcdLName -- todo: register keyword location of 'where', see Note [Register keyword location] where_cls' <- addHaddockInterleaveItems layout (mkDocHsDecl layout) $ flattenBindsAndSigs (tcdMeths, tcdSigs, tcdATs, tcdATDefs, [], []) pure $ let (tcdMeths', tcdSigs', tcdATs', tcdATDefs', _, tcdDocs) = partitionBindsAndSigs where_cls' decl' = ClassDecl { tcdCExt = (x, layout, NoAnnSortKey) , tcdCtxt, tcdLName, tcdTyVars, tcdFixity, tcdFDs , tcdSigs = tcdSigs' , tcdMeths = tcdMeths' , tcdATs = tcdATs' , tcdATDefs = tcdATDefs' , tcdDocs } in TyClD noExtField decl' -- Data family instances: -- -- data instance D Bool where ... (same as data/newtype declarations) -- data instance D Bool = ... (same as data/newtype declarations) -- addHaddock (InstD _ decl) | DataFamInstD { dfid_ext, dfid_inst } <- decl , DataFamInstDecl { dfid_eqn } <- dfid_inst = do dfid_eqn' <- case dfid_eqn of FamEqn { feqn_ext, feqn_tycon, feqn_bndrs, feqn_pats, feqn_fixity, feqn_rhs } -> do registerHdkA feqn_tycon feqn_rhs' <- addHaddock feqn_rhs pure $ FamEqn { feqn_ext, feqn_tycon, feqn_bndrs, feqn_pats, feqn_fixity, feqn_rhs = feqn_rhs' } pure $ InstD noExtField (DataFamInstD { dfid_ext, dfid_inst = DataFamInstDecl { dfid_eqn = dfid_eqn' } }) -- Type synonyms: -- -- type T = Int -- ^ Comment on Int -- addHaddock (TyClD _ decl) | SynDecl { tcdSExt, tcdLName, tcdTyVars, tcdFixity, tcdRhs } <- decl = do registerHdkA tcdLName -- todo: register keyword location of '=', see Note [Register keyword location] tcdRhs' <- addHaddock tcdRhs pure $ TyClD noExtField (SynDecl { tcdSExt, tcdLName, tcdTyVars, tcdFixity, tcdRhs = tcdRhs' }) -- Foreign imports: -- -- foreign import ccall unsafe -- o :: Float -- ^ The input float -- -> IO Float -- ^ The output float -- addHaddock (ForD _ decl) = do registerHdkA (fd_name decl) fd_sig_ty' <- addHaddock (fd_sig_ty decl) pure $ ForD noExtField (decl{ fd_sig_ty = fd_sig_ty' }) -- Other declarations addHaddock d = pure d -- The right-hand side of a data/newtype declaration or data family instance. instance HasHaddock (HsDataDefn GhcPs) where addHaddock defn@HsDataDefn{} = do -- Register the kind signature: -- data D :: Type -> Type where ... -- data instance D Bool :: Type where ... traverse_ @Maybe registerHdkA (dd_kindSig defn) -- todo: register keyword location of '=' or 'where', see Note [Register keyword location] -- Process the data constructors: -- -- data T -- = MkT1 Int Bool -- ^ Comment on MkT1 -- | MkT2 Char Int -- ^ Comment on MkT2 -- dd_cons' <- traverse addHaddock (dd_cons defn) -- Process the deriving clauses: -- -- newtype N = MkN Natural -- deriving (Eq {- ^ Comment on Eq N -}) -- deriving (Ord {- ^ Comment on Ord N -}) -- dd_derivs' <- addHaddock (dd_derivs defn) pure $ defn { dd_cons = dd_cons', dd_derivs = dd_derivs' } -- Process the deriving clauses of a data/newtype declaration. -- Not used for standalone deriving. instance HasHaddock (Located [LocatedAn NoEpAnns (HsDerivingClause GhcPs)]) where addHaddock lderivs = extendHdkA (getLoc lderivs) $ traverse @Located addHaddock lderivs -- Process a single deriving clause of a data/newtype declaration: -- -- newtype N = MkN Natural -- deriving newtype (Eq {- ^ Comment on Eq N -}) -- deriving (Ord {- ^ Comment on Ord N -}) via Down N -- -- Not used for standalone deriving. instance HasHaddock (LocatedAn NoEpAnns (HsDerivingClause GhcPs)) where addHaddock lderiv = extendHdkA (getLocA lderiv) $ for @(LocatedAn NoEpAnns) lderiv $ \deriv -> case deriv of HsDerivingClause { deriv_clause_ext, deriv_clause_strategy, deriv_clause_tys } -> do let -- 'stock', 'anyclass', and 'newtype' strategies come -- before the clause types. -- -- 'via' comes after. -- -- See tests/.../T11768.hs (register_strategy_before, register_strategy_after) = case deriv_clause_strategy of Nothing -> (pure (), pure ()) Just (L l (ViaStrategy _)) -> (pure (), registerLocHdkA (locA l)) Just (L l _) -> (registerLocHdkA (locA l), pure ()) register_strategy_before deriv_clause_tys' <- addHaddock deriv_clause_tys register_strategy_after pure HsDerivingClause { deriv_clause_ext, deriv_clause_strategy, deriv_clause_tys = deriv_clause_tys' } -- Process the types in a single deriving clause, which may come in one of the -- following forms: -- -- 1. A singular type constructor: -- deriving Eq -- ^ Comment on Eq -- -- 2. A list of comma-separated types surrounded by enclosing parentheses: -- deriving ( Eq -- ^ Comment on Eq -- , C a -- ^ Comment on C a -- ) instance HasHaddock (LocatedC (DerivClauseTys GhcPs)) where addHaddock (L l_dct dct) = extendHdkA (locA l_dct) $ case dct of DctSingle x ty -> do ty' <- addHaddock ty pure $ L l_dct $ DctSingle x ty' DctMulti x tys -> do tys' <- addHaddock tys pure $ L l_dct $ DctMulti x tys' -- Process a single data constructor declaration, which may come in one of the -- following forms: -- -- 1. H98-syntax PrefixCon: -- data T = -- MkT -- ^ Comment on MkT -- Int -- ^ Comment on Int -- Bool -- ^ Comment on Bool -- -- 2. H98-syntax InfixCon: -- data T = -- Int -- ^ Comment on Int -- :+ -- ^ Comment on (:+) -- Bool -- ^ Comment on Bool -- -- 3. H98-syntax RecCon: -- data T = -- MkT { int_field :: Int, -- ^ Comment on int_field -- bool_field :: Bool } -- ^ Comment on bool_field -- -- 4. GADT-syntax PrefixCon: -- data T where -- -- | Comment on MkT -- MkT :: Int -- ^ Comment on Int -- -> Bool -- ^ Comment on Bool -- -> T -- -- 5. GADT-syntax RecCon: -- data T where -- -- | Comment on MkT -- MkT :: { int_field :: Int, -- ^ Comment on int_field -- bool_field :: Bool } -- ^ Comment on bool_field -- -> T -- instance HasHaddock (LocatedA (ConDecl GhcPs)) where addHaddock (L l_con_decl con_decl) = extendHdkA (locA l_con_decl) $ case con_decl of ConDeclGADT { con_g_ext, con_names, con_bndrs, con_mb_cxt, con_g_args, con_res_ty } -> do con_doc' <- getConDoc (getLocA (NE.head con_names)) con_g_args' <- case con_g_args of PrefixConGADT x ts -> PrefixConGADT x <$> addHaddock ts RecConGADT arr (L l_rec flds) -> do flds' <- traverse addHaddockConDeclField flds pure $ RecConGADT arr (L l_rec flds') con_res_ty' <- addHaddock con_res_ty pure $ L l_con_decl $ ConDeclGADT { con_g_ext, con_names, con_bndrs, con_mb_cxt, con_doc = lexLHsDocString <$> con_doc', con_g_args = con_g_args', con_res_ty = con_res_ty' } ConDeclH98 { con_ext, con_name, con_forall, con_ex_tvs, con_mb_cxt, con_args } -> let -- See Note [Leading and trailing comments on H98 constructors] getTrailingLeading :: HdkM (LocatedA (ConDecl GhcPs)) getTrailingLeading = do con_doc' <- getPrevNextDoc (locA l_con_decl) return $ L l_con_decl $ ConDeclH98 { con_ext, con_name, con_forall, con_ex_tvs, con_mb_cxt, con_args , con_doc = lexLHsDocString <$> con_doc' } -- See Note [Leading and trailing comments on H98 constructors] getMixed :: HdkA (LocatedA (ConDecl GhcPs)) getMixed = case con_args of PrefixCon _ ts -> do con_doc' <- getConDoc (getLocA con_name) ts' <- traverse addHaddockConDeclFieldTy ts pure $ L l_con_decl $ ConDeclH98 { con_ext, con_name, con_forall, con_ex_tvs, con_mb_cxt, con_doc = lexLHsDocString <$> con_doc', con_args = PrefixCon noTypeArgs ts' } InfixCon t1 t2 -> do t1' <- addHaddockConDeclFieldTy t1 con_doc' <- getConDoc (getLocA con_name) t2' <- addHaddockConDeclFieldTy t2 pure $ L l_con_decl $ ConDeclH98 { con_ext, con_name, con_forall, con_ex_tvs, con_mb_cxt, con_doc = lexLHsDocString <$> con_doc', con_args = InfixCon t1' t2' } RecCon (L l_rec flds) -> do con_doc' <- getConDoc (getLocA con_name) flds' <- traverse addHaddockConDeclField flds pure $ L l_con_decl $ ConDeclH98 { con_ext, con_name, con_forall, con_ex_tvs, con_mb_cxt, con_doc = lexLHsDocString <$> con_doc', con_args = RecCon (L l_rec flds') } in hoistHdkA (\m -> do { a <- onlyTrailingOrLeading (locA l_con_decl) ; if a then getTrailingLeading else m }) getMixed -- See Note [Leading and trailing comments on H98 constructors] onlyTrailingOrLeading :: SrcSpan -> HdkM Bool onlyTrailingOrLeading l = peekHdkM $ do leading <- inLocRange (locRangeTo (getBufPos (srcSpanStart l))) $ takeHdkComments mkDocNext inner <- inLocRange (locRangeIn (getBufSpan l)) $ takeHdkComments (\x -> mkDocNext x <|> mkDocPrev x) trailing <- inLocRange (locRangeFrom (getBufPos (srcSpanEnd l))) $ takeHdkComments mkDocPrev return $ case (leading, inner, trailing) of (_:_, [], []) -> True -- leading comment only ([], [], _:_) -> True -- trailing comment only _ -> False -- Get the documentation comment associated with the data constructor in a -- data/newtype declaration. getConDoc :: SrcSpan -- Location of the data constructor -> HdkA (Maybe (Located HsDocString)) getConDoc l = extendHdkA l $ liftHdkA $ getPrevNextDoc l -- Add documentation comment to a data constructor field. -- Used for PrefixCon and InfixCon. addHaddockConDeclFieldTy :: HsScaled GhcPs (LHsType GhcPs) -> HdkA (HsScaled GhcPs (LHsType GhcPs)) addHaddockConDeclFieldTy (HsScaled mult (L l t)) = extendHdkA (locA l) $ liftHdkA $ do mDoc <- getPrevNextDoc (locA l) return (HsScaled mult (mkLHsDocTy (L l t) mDoc)) -- Add documentation comment to a data constructor field. -- Used for RecCon. addHaddockConDeclField :: LConDeclField GhcPs -> HdkA (LConDeclField GhcPs) addHaddockConDeclField (L l_fld fld) = extendHdkA (locA l_fld) $ liftHdkA $ do cd_fld_doc <- fmap lexLHsDocString <$> getPrevNextDoc (locA l_fld) return (L l_fld (fld { cd_fld_doc })) {- Note [Leading and trailing comments on H98 constructors] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The trailing comment after a constructor declaration is associated with the constructor itself when it is the only comment: data T = MkT A B -- ^ Comment on MkT data T = MkT { x :: A } -- ^ Comment on MkT data T = A `MkT` B -- ^ Comment on MkT When there are other comments, the trailing comment applies to the last field: data T = MkT -- ^ Comment on MkT A -- ^ Comment on A B -- ^ Comment on B data T = MkT { a :: A -- ^ Comment on a , b :: B -- ^ Comment on b , c :: C } -- ^ Comment on c data T = A -- ^ Comment on A `MkT` -- ^ Comment on MkT B -- ^ Comment on B When it comes to the leading comment, there is no such ambiguity in /prefix/ constructor declarations (plain or record syntax): data T = -- | Comment on MkT MkT A B data T = -- | Comment on MkT MkT -- | Comment on A A -- | Comment on B B data T = -- | Comment on MkT MkT { x :: A } data T = -- | Comment on MkT MkT { -- | Comment on a a :: A, -- | Comment on b b :: B, -- | Comment on c c :: C } However, in /infix/ constructor declarations the leading comment is associated with the constructor itself if it is the only comment, and with the first field if there are other comments: data T = -- | Comment on MkT A `MkT` B data T = -- | Comment on A A -- | Comment on MkT `MkT` -- | Comment on B B This makes the leading and trailing comments context-sensitive. Example: data T = -- | comment 1 MkT Int Bool -- ^ comment 2 Here, "comment 2" applies to the Bool field. But if we removed "comment 1", then "comment 2" would be apply to the data constructor rather than its field. All of this applies to H98-style data declarations only. GADTSyntax data constructors don't have any special treatment for the trailing comment. We implement this in two steps: 1. Gather information about available comments using `onlyTrailingOrLeading`. It inspects available comments but does not consume them, and returns a boolean that tells us what algorithm we should use True <=> expect a single leading/trailing comment False <=> expect inner comments or more than one comment 2. Collect the comments using the algorithm determined in the previous step a) `getTrailingLeading`: a single leading/trailing comment is applied to the entire constructor declaration as a whole; see the `con_doc` field b) `getMixed`: comments apply to individual parts of a constructor declaration, including its field types -} instance HasHaddock a => HasHaddock (HsScaled GhcPs a) where addHaddock (HsScaled mult a) = HsScaled mult <$> addHaddock a instance HasHaddock a => HasHaddock (HsWildCardBndrs GhcPs a) where addHaddock (HsWC _ t) = HsWC noExtField <$> addHaddock t instance HasHaddock (LocatedA (HsSigType GhcPs)) where addHaddock (L l (HsSig{sig_bndrs = outer_bndrs, sig_body = body})) = extendHdkA (locA l) $ do case outer_bndrs of HsOuterImplicit{} -> pure () HsOuterExplicit{hso_bndrs = bndrs} -> registerLocHdkA (getLHsTyVarBndrsLoc bndrs) body' <- addHaddock body pure $ L l $ HsSig noExtField outer_bndrs body' -- Process a type, adding documentation comments to function arguments -- and the result. Many formatting styles are supported. -- -- my_function :: -- forall a. -- Eq a => -- Maybe a -> -- ^ Comment on Maybe a (function argument) -- Bool -> -- ^ Comment on Bool (function argument) -- String -- ^ Comment on String (the result) -- -- my_function -- :: forall a. Eq a -- => Maybe a -- ^ Comment on Maybe a (function argument) -- -> Bool -- ^ Comment on Bool (function argument) -- -> String -- ^ Comment on String (the result) -- -- my_function :: -- forall a. Eq a => -- -- | Comment on Maybe a (function argument) -- Maybe a -> -- -- | Comment on Bool (function argument) -- Bool -> -- -- | Comment on String (the result) -- String -- -- This is achieved by simply ignoring (not registering the location of) the -- function arrow (->). instance HasHaddock (LocatedA (HsType GhcPs)) where addHaddock (L l t) = extendHdkA (locA l) $ case t of -- forall a b c. t HsForAllTy x tele body -> do registerLocHdkA (getForAllTeleLoc tele) body' <- addHaddock body pure $ L l (HsForAllTy x tele body') -- (Eq a, Num a) => t HsQualTy x lhs rhs -> do registerHdkA lhs rhs' <- addHaddock rhs pure $ L l (HsQualTy x lhs rhs') -- arg -> res HsFunTy u mult lhs rhs -> do lhs' <- addHaddock lhs rhs' <- addHaddock rhs pure $ L l (HsFunTy u mult lhs' rhs') -- other types _ -> liftHdkA $ do mDoc <- getPrevNextDoc (locA l) return (mkLHsDocTy (L l t) mDoc) {- ********************************************************************* * * * HdkA: a layer over HdkM that propagates location information * * * ********************************************************************* -} -- See Note [Adding Haddock comments to the syntax tree]. -- -- 'HdkA' provides a way to propagate location information from surrounding -- computations: -- -- left_neighbour <*> HdkA inner_span inner_m <*> right_neighbour -- -- Here, the following holds: -- -- * the 'left_neighbour' will only see Haddock comments until 'bufSpanStart' of 'inner_span' -- * the 'right_neighbour' will only see Haddock comments after 'bufSpanEnd' of 'inner_span' -- * the 'inner_m' will only see Haddock comments between its 'left_neighbour' and its 'right_neighbour' -- -- In other words, every computation: -- -- * delimits the surrounding computations -- * is delimited by the surrounding computations -- -- Therefore, a 'HdkA' computation must be always considered in the context in -- which it is used. data HdkA a = HdkA !(Strict.Maybe BufSpan) -- Just b <=> BufSpan occupied by the processed AST element. -- The surrounding computations will not look inside. -- -- Nothing <=> No BufSpan (e.g. when the HdkA is constructed by 'pure' or 'liftHdkA'). -- The surrounding computations are not delimited. !(HdkM a) -- The stateful computation that looks up Haddock comments and -- adds them to the resulting AST node. deriving (Functor) instance Applicative HdkA where HdkA l1 m1 <*> HdkA l2 m2 = HdkA (l1 <> l2) -- The combined BufSpan that covers both subcomputations. -- -- The Semigroup instance for Maybe quite conveniently does the right thing: -- Nothing <> b = b -- a <> Nothing = a -- Just a <> Just b = Just (a <> b) (delim1 m1 <*> delim2 m2) -- Stateful computations are run in left-to-right order, -- without any smart reordering strategy. So users of this -- operation must take care to traverse the AST -- in concrete syntax order. -- See Note [Smart reordering in HdkA (or lack thereof)] -- -- Each computation is delimited ("sandboxed") -- in a way that it doesn't see any Haddock -- comments past the neighbouring AST node. -- These delim1/delim2 are key to how HdkA operates. where -- Delimit the LHS by the location information from the RHS delim1 = inLocRange (locRangeTo (fmap @Strict.Maybe bufSpanStart l2)) -- Delimit the RHS by the location information from the LHS delim2 = inLocRange (locRangeFrom (fmap @Strict.Maybe bufSpanEnd l1)) pure a = -- Return a value without performing any stateful computation, and without -- any delimiting effect on the surrounding computations. liftHdkA (pure a) {- Note [Smart reordering in HdkA (or lack thereof)] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When traversing the AST, the user must take care to traverse it in concrete syntax order. For example, when processing HsFunTy, it's important to get it right and write it like so: HsFunTy _ mult lhs rhs -> do lhs' <- addHaddock lhs rhs' <- addHaddock rhs pure $ L l (HsFunTy noExtField mult lhs' rhs') Rather than like so: HsFunTy _ mult lhs rhs -> do rhs' <- addHaddock rhs -- bad! wrong order lhs' <- addHaddock lhs -- bad! wrong order pure $ L l (HsFunTy noExtField mult lhs' rhs') This is somewhat bug-prone, so we could try to fix this with some Applicative magic. When we define (<*>) for HdkA, why not reorder the computations as necessary? In pseudo-code: a1 <*> a2 | a1 `before` a2 = ... normal processing ... | otherwise = a1 <**> a2 While this trick could work for any two *adjacent* AST elements out of order (as in HsFunTy example above), it would fail in more elaborate scenarios (e.g. processing a list of declarations out of order). If it's not obvious why this trick doesn't work, ponder this: it's a bit like trying to get a sorted list by defining a 'smart' concatenation operator in the following manner: a ?++ b | a <= b = a ++ b | otherwise = b ++ a At first glance it seems to work: ghci> [1] ?++ [2] ?++ [3] [1,2,3] ghci> [2] ?++ [1] ?++ [3] [1,2,3] -- wow, sorted! But it actually doesn't: ghci> [3] ?++ [1] ?++ [2] [1,3,2] -- not sorted... -} -- Run a HdkA computation in an unrestricted LocRange. This is only used at the -- top level to run the final computation for the entire module. runHdkA :: HdkA a -> HdkSt -> (a, HdkSt) runHdkA (HdkA _ m) = unHdkM m mempty -- Let the neighbours know about an item at this location. -- -- Consider this example: -- -- class -- | peculiarly placed comment -- MyClass a where -- my_method :: a -> a -- -- How do we know to reject the "peculiarly placed comment" instead of -- associating it with my_method? Its indentation level matches. -- -- But clearly, there's "MyClass a where" separating the comment and my_method. -- To take it into account, we must register its location using registerLocHdkA -- or registerHdkA. -- -- See Note [Register keyword location]. -- See Note [Adding Haddock comments to the syntax tree]. registerLocHdkA :: SrcSpan -> HdkA () registerLocHdkA l = HdkA (getBufSpan l) (pure ()) -- Let the neighbours know about an item at this location. -- A small wrapper over registerLocHdkA. -- -- See Note [Adding Haddock comments to the syntax tree]. registerHdkA :: GenLocated (EpAnn a) e -> HdkA () registerHdkA a = registerLocHdkA (getLocA a) -- Modify the action of a HdkA computation. hoistHdkA :: (HdkM a -> HdkM b) -> HdkA a -> HdkA b hoistHdkA f (HdkA l m) = HdkA l (f m) -- Lift a HdkM computation to HdkA. liftHdkA :: HdkM a -> HdkA a liftHdkA = HdkA mempty -- Extend the declared location span of a 'HdkA' computation: -- -- left_neighbour <*> extendHdkA l x <*> right_neighbour -- -- The declared location of 'x' now includes 'l', so that the surrounding -- computations 'left_neighbour' and 'right_neighbour' will not look for -- Haddock comments inside the 'l' location span. extendHdkA :: SrcSpan -> HdkA a -> HdkA a extendHdkA l' (HdkA l m) = HdkA (getBufSpan l' <> l) m {- ********************************************************************* * * * HdkM: a stateful computation to associate * * accumulated documentation comments with AST nodes * * * ********************************************************************* -} -- The state of 'HdkM' contains a list of pending Haddock comments. We go -- over the AST, looking up these comments using 'takeHdkComments' and removing -- them from the state. The remaining, un-removed ones are ignored with a -- warning (-Winvalid-haddock). Also, using a state means we never use the same -- Haddock twice. -- -- See Note [Adding Haddock comments to the syntax tree]. newtype HdkM a = HdkM { unHdkM :: LocRange -> HdkSt -> (a, HdkSt) } deriving (Functor, Applicative, Monad) via (ReaderT LocRange (State HdkSt)) -- | The state of HdkM. data HdkSt = HdkSt { hdk_st_pending :: [PsLocated HdkComment] -- a list of pending (unassociated with an AST node) -- Haddock comments, sorted by location: in ascending order of the starting 'BufPos' , hdk_st_warnings :: [HdkWarn] -- accumulated warnings (order doesn't matter) } -- | Warnings accumulated in HdkM. data HdkWarn = HdkWarnInvalidComment (PsLocated HdkComment) | HdkWarnExtraComment (Located HsDocString) -- Restrict the range in which a HdkM computation will look up comments: -- -- inLocRange r1 $ -- inLocRange r2 $ -- takeHdkComments ... -- Only takes comments in the (r1 <> r2) location range. -- -- Note that it does not blindly override the range but tightens it using (<>). -- At many use sites, you will see something along the lines of: -- -- inLocRange (locRangeTo end_pos) $ ... -- -- And 'locRangeTo' defines a location range from the start of the file to -- 'end_pos'. This does not mean that we now search for every comment from the -- start of the file, as this restriction will be combined with other -- restrictions. Somewhere up the callstack we might have: -- -- inLocRange (locRangeFrom start_pos) $ ... -- -- The net result is that the location range is delimited by 'start_pos' on -- one side and by 'end_pos' on the other side. -- -- In 'HdkA', every (<*>) may restrict the location range of its -- subcomputations. inLocRange :: LocRange -> HdkM a -> HdkM a inLocRange r (HdkM m) = HdkM (\r' -> m (r <> r')) -- Take the Haddock comments that satisfy the matching function, -- leaving the rest pending. takeHdkComments :: forall a. (PsLocated HdkComment -> Maybe a) -> HdkM [a] takeHdkComments f = HdkM $ \(LocRange hdk_from hdk_to hdk_col) -> \hdk_st -> let comments = hdk_st_pending hdk_st (comments_before_range, comments') = break (is_after hdk_from) comments (comments_in_range, comments_after_range) = span (is_before hdk_to <&&> is_indented hdk_col) comments' (items, other_comments) = foldr add_comment ([], []) comments_in_range remaining_comments = comments_before_range ++ other_comments ++ comments_after_range hdk_st' = hdk_st{ hdk_st_pending = remaining_comments } in (items, hdk_st') where is_after StartOfFile _ = True is_after (StartLoc l) (L l_comment _) = bufSpanStart (psBufSpan l_comment) >= l is_before EndOfFile _ = True is_before (EndLoc l) (L l_comment _) = bufSpanStart (psBufSpan l_comment) <= l is_indented (ColumnFrom n) (L l_comment _) = srcSpanStartCol (psRealSpan l_comment) >= n add_comment :: PsLocated HdkComment -> ([a], [PsLocated HdkComment]) -> ([a], [PsLocated HdkComment]) add_comment hdk_comment (items, other_hdk_comments) = case f hdk_comment of Just item -> (item : items, other_hdk_comments) Nothing -> (items, hdk_comment : other_hdk_comments) -- Run a HdkM action and restore the original state. peekHdkM :: HdkM a -> HdkM a peekHdkM m = HdkM $ \r s -> case unHdkM m r s of (a, _) -> (a, s) -- Get the docnext or docprev comment for an AST node at the given source span. getPrevNextDoc :: SrcSpan -> HdkM (Maybe (Located HsDocString)) getPrevNextDoc l = do let (l_start, l_end) = (srcSpanStart l, srcSpanEnd l) before_t = locRangeTo (getBufPos l_start) after_t = locRangeFrom (getBufPos l_end) nextDocs <- inLocRange before_t $ takeHdkComments mkDocNext prevDocs <- inLocRange after_t $ takeHdkComments mkDocPrev selectDocString (nextDocs ++ prevDocs) appendHdkWarning :: HdkWarn -> HdkM () appendHdkWarning e = HdkM $ \_ hdk_st -> let hdk_st' = hdk_st { hdk_st_warnings = e : hdk_st_warnings hdk_st } in ((), hdk_st') selectDocString :: [Located HsDocString] -> HdkM (Maybe (Located HsDocString)) selectDocString = select . filterOut (isEmptyDocString . unLoc) where select [] = return Nothing select [doc] = return (Just doc) select (doc : extra_docs) = do reportExtraDocs extra_docs return (Just doc) reportExtraDocs :: [Located HsDocString] -> HdkM () reportExtraDocs = traverse_ (\extra_doc -> appendHdkWarning (HdkWarnExtraComment extra_doc)) {- ********************************************************************* * * * Matching functions for extracting documentation comments * * * ********************************************************************* -} mkDocHsDecl :: EpLayout -> PsLocated HdkComment -> Maybe (LHsDecl GhcPs) mkDocHsDecl layout a = fmap (DocD noExtField) <$> mkDocDecl layout a mkDocDecl :: EpLayout -> PsLocated HdkComment -> Maybe (LDocDecl GhcPs) mkDocDecl layout (L l_comment hdk_comment) | indent_mismatch = Nothing | otherwise = Just $ L (noAnnSrcSpan span) $ case hdk_comment of HdkCommentNext doc -> DocCommentNext (L span $ lexHsDocString doc) HdkCommentPrev doc -> DocCommentPrev (L span $ lexHsDocString doc) HdkCommentNamed s doc -> DocCommentNamed s (L span $ lexHsDocString doc) HdkCommentSection n doc -> DocGroup n (L span $ lexHsDocString doc) where span = mkSrcSpanPs l_comment -- 'indent_mismatch' checks if the documentation comment has the exact -- indentation level expected by the parent node. -- -- For example, when extracting documentation comments between class -- method declarations, there are three cases to consider: -- -- 1. Indent matches (indent_mismatch=False): -- class C a where -- f :: a -> a -- -- ^ doc on f -- -- 2. Indented too much (indent_mismatch=True): -- class C a where -- f :: a -> a -- -- ^ indent mismatch -- -- 3. Indented too little (indent_mismatch=True): -- class C a where -- f :: a -> a -- -- ^ indent mismatch indent_mismatch = case layout of EpNoLayout -> False EpExplicitBraces{} -> False EpVirtualBraces n -> n /= srcSpanStartCol (psRealSpan l_comment) mkDocIE :: PsLocated HdkComment -> Maybe (LIE GhcPs) mkDocIE (L l_comment hdk_comment) = case hdk_comment of HdkCommentSection n doc -> Just $ L l (IEGroup noExtField n $ L span $ lexHsDocString doc) HdkCommentNamed s _doc -> Just $ L l (IEDocNamed noExtField s) HdkCommentNext doc -> Just $ L l (IEDoc noExtField $ L span $ lexHsDocString doc) HdkCommentPrev doc -> Just $ L l (IEDoc noExtField $ L span $ lexHsDocString doc) where l = noAnnSrcSpan span span = mkSrcSpanPs l_comment mkDocNext :: PsLocated HdkComment -> Maybe (Located HsDocString) mkDocNext (L l (HdkCommentNext doc)) = Just (L (mkSrcSpanPs l) doc) mkDocNext _ = Nothing mkDocPrev :: PsLocated HdkComment -> Maybe (Located HsDocString) mkDocPrev (L l (HdkCommentPrev doc)) = Just (L (mkSrcSpanPs l) doc) mkDocPrev _ = Nothing {- ********************************************************************* * * * LocRange: a location range * * * ********************************************************************* -} -- A location range for extracting documentation comments. data LocRange = LocRange { loc_range_from :: !LowerLocBound, loc_range_to :: !UpperLocBound, loc_range_col :: !ColumnBound } instance Semigroup LocRange where LocRange from1 to1 col1 <> LocRange from2 to2 col2 = LocRange (from1 <> from2) (to1 <> to2) (col1 <> col2) instance Monoid LocRange where mempty = LocRange mempty mempty mempty -- The location range from the specified position to the end of the file. locRangeFrom :: Strict.Maybe BufPos -> LocRange locRangeFrom (Strict.Just l) = mempty { loc_range_from = StartLoc l } locRangeFrom Strict.Nothing = mempty -- The location range from the start of the file to the specified position. locRangeTo :: Strict.Maybe BufPos -> LocRange locRangeTo (Strict.Just l) = mempty { loc_range_to = EndLoc l } locRangeTo Strict.Nothing = mempty -- The location range within the specified span. locRangeIn :: Strict.Maybe BufSpan -> LocRange locRangeIn (Strict.Just l) = mempty { loc_range_from = StartLoc (bufSpanStart l) , loc_range_to = EndLoc (bufSpanEnd l) } locRangeIn Strict.Nothing = mempty -- Represents a predicate on BufPos: -- -- LowerLocBound | BufPos -> Bool -- --------------+----------------- -- StartOfFile | const True -- StartLoc p | (>= p) -- -- The semigroup instance corresponds to (&&). -- -- We don't use the BufPos -> Bool representation -- as it would lead to redundant checks. -- -- That is, instead of -- -- (pos >= 20) && (pos >= 30) && (pos >= 40) -- -- We'd rather only do the (>=40) check. So we reify the predicate to make -- sure we only check for the most restrictive bound. data LowerLocBound = StartOfFile | StartLoc !BufPos deriving Show instance Semigroup LowerLocBound where StartOfFile <> l = l l <> StartOfFile = l StartLoc l1 <> StartLoc l2 = StartLoc (max l1 l2) instance Monoid LowerLocBound where mempty = StartOfFile -- Represents a predicate on BufPos: -- -- UpperLocBound | BufPos -> Bool -- --------------+----------------- -- EndOfFile | const True -- EndLoc p | (<= p) -- -- The semigroup instance corresponds to (&&). -- -- We don't use the BufPos -> Bool representation -- as it would lead to redundant checks. -- -- That is, instead of -- -- (pos <= 40) && (pos <= 30) && (pos <= 20) -- -- We'd rather only do the (<=20) check. So we reify the predicate to make -- sure we only check for the most restrictive bound. data UpperLocBound = EndOfFile | EndLoc !BufPos deriving Show instance Semigroup UpperLocBound where EndOfFile <> l = l l <> EndOfFile = l EndLoc l1 <> EndLoc l2 = EndLoc (min l1 l2) instance Monoid UpperLocBound where mempty = EndOfFile -- | Represents a predicate on the column number. -- -- ColumnBound | Int -> Bool -- --------------+----------------- -- ColumnFrom n | (>=n) -- -- The semigroup instance corresponds to (&&). -- newtype ColumnBound = ColumnFrom Int -- n >= GHC.Types.SrcLoc.leftmostColumn deriving Show instance Semigroup ColumnBound where ColumnFrom n <> ColumnFrom m = ColumnFrom (max n m) instance Monoid ColumnBound where mempty = ColumnFrom leftmostColumn {- ********************************************************************* * * * AST manipulation utilities * * * ********************************************************************* -} mkLHsDocTy :: LHsType GhcPs -> Maybe (Located HsDocString) -> LHsType GhcPs mkLHsDocTy t Nothing = t mkLHsDocTy t (Just doc) = L (getLoc t) (HsDocTy noAnn t $ lexLHsDocString doc) getForAllTeleLoc :: HsForAllTelescope GhcPs -> SrcSpan getForAllTeleLoc tele = case tele of HsForAllVis{ hsf_vis_bndrs } -> getLHsTyVarBndrsLoc hsf_vis_bndrs HsForAllInvis { hsf_invis_bndrs } -> getLHsTyVarBndrsLoc hsf_invis_bndrs getLHsTyVarBndrsLoc :: [LHsTyVarBndr flag GhcPs] -> SrcSpan getLHsTyVarBndrsLoc bndrs = foldr combineSrcSpans noSrcSpan $ map getLocA bndrs -- | The inverse of 'partitionBindsAndSigs' that merges partitioned items back -- into a flat list. Elements are put back into the order in which they -- appeared in the original program before partitioning, using BufPos to order -- them. -- -- Precondition (unchecked): the input lists are already sorted. flattenBindsAndSigs :: (LHsBinds GhcPs, [LSig GhcPs], [LFamilyDecl GhcPs], [LTyFamInstDecl GhcPs], [LDataFamInstDecl GhcPs], [LDocDecl GhcPs]) -> [LHsDecl GhcPs] flattenBindsAndSigs (all_bs, all_ss, all_ts, all_tfis, all_dfis, all_docs) = -- 'cmpBufSpan' is safe here with the following assumptions: -- -- - 'LHsDecl' produced by 'decl_cls' in Parser.y always have a 'BufSpan' -- - 'partitionBindsAndSigs' does not discard this 'BufSpan' mergeListsBy cmpBufSpanA [ mapLL (\b -> ValD noExtField b) (bagToList all_bs), mapLL (\s -> SigD noExtField s) all_ss, mapLL (\t -> TyClD noExtField (FamDecl noExtField t)) all_ts, mapLL (\tfi -> InstD noExtField (TyFamInstD noExtField tfi)) all_tfis, mapLL (\dfi -> InstD noExtField (DataFamInstD noExtField dfi)) all_dfis, mapLL (\d -> DocD noExtField d) all_docs ] cmpBufSpanA :: GenLocated (EpAnn a1) a2 -> GenLocated (EpAnn a3) a2 -> Ordering cmpBufSpanA (L la a) (L lb b) = cmpBufSpan (L (locA la) a) (L (locA lb) b) {- ********************************************************************* * * * General purpose utilities * * * ********************************************************************* -} -- Map a function over a list of located items. mapLL :: (a -> b) -> [GenLocated l a] -> [GenLocated l b] mapLL f = map (fmap f) {- Note [Old solution: Haddock in the grammar] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In the past, Haddock comments were incorporated into the grammar (Parser.y). This led to excessive complexity and duplication. For example, here's the grammar production for types without documentation: type : btype | btype '->' ctype To support Haddock, we had to also maintain an additional grammar production for types with documentation on function arguments and function result: typedoc : btype | btype docprev | docnext btype | btype '->' ctypedoc | btype docprev '->' ctypedoc | docnext btype '->' ctypedoc Sometimes handling documentation comments during parsing led to bugs (#17561), and sometimes it simply made it hard to modify and extend the grammar. Another issue was that sometimes Haddock would fail to parse code that GHC could parse successfully: class BadIndent where f :: a -> Int -- ^ comment g :: a -> Int This declaration was accepted by ghc but rejected by ghc -haddock. -} {- Note [Register keyword location] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ At the moment, 'addHaddock' erroneously associates some comments with constructs that are separated by a keyword. For example: data Foo -- | Comment for MkFoo where MkFoo :: Foo We could use EPA (exactprint annotations) to fix this, but not without modification. For example, EpaLocation contains RealSrcSpan but not BufSpan. Also, the fix would be more straightforward after #19623. For examples, see tests/haddock/should_compile_flag_haddock/T17544_kw.hs -}