diff options
| -rw-r--r-- | haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs | 54 |
1 files changed, 28 insertions, 26 deletions
diff --git a/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs b/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs index 139a4c44..1ae4fd62 100644 --- a/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs +++ b/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs @@ -3,6 +3,8 @@ module Haddock.Backends.Hyperlinker.Parser (parse) where import Control.Applicative ( Alternative(..) ) +import Control.Monad.Trans.Maybe ( MaybeT(..) ) +import Control.Monad.Trans.Class ( MonadTrans(lift) ) import Data.List ( isPrefixOf, isSuffixOf ) import qualified Data.ByteString as BS @@ -56,7 +58,10 @@ parse dflags fpath bs = case unP (go False []) initState of (b, _) <- getInput if not (atEnd b) then do - (newToks, inPrag') <- parseCppLine <|> parsePlainTok inPrag <|> unknownLine + mtok <- runMaybeT (parseCppLine <|> parsePlainTok inPrag) + (newToks, inPrag') <- case mtok of + Nothing -> unknownLine + Just a -> pure a go inPrag' (newToks ++ toks) else pure toks @@ -72,23 +77,23 @@ parse dflags fpath bs = case unP (go False []) initState of andThen _ = wrappedLexer -- | Try to parse a CPP line (can fail) - parseCppLine :: P ([T.Token], Bool) - parseCppLine = do + parseCppLine :: MaybeT P ([T.Token], Bool) + parseCppLine = MaybeT $ do (b, l) <- getInput case tryCppLine l b of Just (cppBStr, l', b') -> let cppTok = T.Token { tkType = TkCpp , tkValue = cppBStr , tkSpan = mkRealSrcSpan l l' } - in setInput (b', l') *> pure ([cppTok], False) - _ -> empty + in setInput (b', l') *> pure (Just ([cppTok], False)) + _ -> return Nothing -- | Try to parse a regular old token (can fail) - parsePlainTok :: Bool -> P ([T.Token], Bool) -- return list is only ever 0-2 elements + parsePlainTok :: Bool -> MaybeT P ([T.Token], Bool) -- return list is only ever 0-2 elements parsePlainTok inPrag = do - (bInit, lInit) <- getInput - L sp tok <- Lexer.lexer False return - (bEnd, _) <- getInput + (bInit, lInit) <- lift getInput + L sp tok <- tryP (Lexer.lexer False return) + (bEnd, _) <- lift getInput case sp of UnhelpfulSpan _ -> pure ([], False) -- pretend the token never existed RealSrcSpan rsp -> do @@ -101,24 +106,24 @@ parse dflags fpath bs = case unP (go False []) initState of -- Update internal line + file position if this is a LINE pragma ITline_prag _ -> tryOrElse (bEnd, inPragDef) $ do - L _ (ITinteger (IL { il_value = line })) <- wrappedLexer - L _ (ITstring _ file) <- wrappedLexer - L spF ITclose_prag <- wrappedLexer + L _ (ITinteger (IL { il_value = line })) <- tryP wrappedLexer + L _ (ITstring _ file) <- tryP wrappedLexer + L spF ITclose_prag <- tryP wrappedLexer let newLoc = mkRealSrcLoc file (fromIntegral line - 1) (srcSpanEndCol spF) - (bEnd'', _) <- getInput - setInput (bEnd'', newLoc) + (bEnd'', _) <- lift getInput + lift $ setInput (bEnd'', newLoc) pure (bEnd'', False) -- Update internal column position if this is a COLUMN pragma ITcolumn_prag _ -> tryOrElse (bEnd, inPragDef) $ do - L _ (ITinteger (IL { il_value = col })) <- wrappedLexer - L spF ITclose_prag <- wrappedLexer + L _ (ITinteger (IL { il_value = col })) <- tryP wrappedLexer + L spF ITclose_prag <- tryP wrappedLexer let newLoc = mkRealSrcLoc (srcSpanFile spF) (srcSpanEndLine spF) (fromIntegral col) - (bEnd'', _) <- getInput - setInput (bEnd'', newLoc) + (bEnd'', _) <- lift getInput + lift $ setInput (bEnd'', newLoc) pure (bEnd'', False) @@ -154,15 +159,12 @@ getInput = P $ \p@PState { buffer = buf, loc = srcLoc } -> POk p (buf, srcLoc) setInput :: (StringBuffer, RealSrcLoc) -> P () setInput (buf, srcLoc) = P $ \p -> POk (p { buffer = buf, loc = srcLoc }) () +tryP :: P a -> MaybeT P a +tryP (P f) = MaybeT $ P $ \s -> case f s of + POk s' a -> POk s' (Just a) + PFailed _ -> POk s Nothing --- | Orphan instance that adds backtracking to 'P' -instance Alternative P where - empty = addFatalError noSrcSpan (text "Alterative.empty") - P x <|> P y = P $ \s -> case x s of { p@POk{} -> p - ; _ -> y s } - --- | Try a parser. If it fails, backtrack and return the pure value. -tryOrElse :: a -> P a -> P a +tryOrElse :: Alternative f => a -> f a -> f a tryOrElse x p = p <|> pure x -- | Classify given tokens as appropriate Haskell token type. |