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Rain: added the parsing of else (skip) guards in alts

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Neil Brown 2007-09-26 19:56:22 +00:00
parent 420839ef1e
commit 68c468fbea
1 changed files with 8 additions and 1 deletions
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9
frontends/ParseRain.hs
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@ -328,13 +328,20 @@ comm isAlt
possSemiColon = if isAlt then return () else sSemiColon >> return () possSemiColon = if isAlt then return () else sSemiColon >> return ()
alt :: RainParser A.Process alt :: RainParser A.Process
alt = do {m <- sPri ; sAlt ; m' <- sLeftC ; cases <- manyTill altCase sRightC ; return $ A.Alt m True $ A.Several m' cases} alt = do {m <- sPri ; sAlt ; m' <- sLeftC ; cases <- many altCase ; optElseCase <- option [] (singleton elseCase) ; sRightC ; return $ A.Alt m True $ A.Several m' (cases ++ optElseCase)}
where where
singleton :: RainParser a -> RainParser [a]
singleton p = do {a <- p ; return [a]}
altCase :: RainParser A.Structured altCase :: RainParser A.Structured
altCase = do input <- comm True altCase = do input <- comm True
case input of case input of
A.Input m lv im -> do { body <- block ; return $ A.OnlyA m $ A.Alternative m lv im body } A.Input m lv im -> do { body <- block ; return $ A.OnlyA m $ A.Alternative m lv im body }
_ -> dieP (findMeta input) $ "communication type not supported in an alt: \"" ++ show input ++ "\"" _ -> dieP (findMeta input) $ "communication type not supported in an alt: \"" ++ show input ++ "\""
elseCase :: RainParser A.Structured
elseCase = do m <- sElse
body <- block
return $ A.OnlyA m $ A.AlternativeSkip m (A.True m) body
tuple :: RainParser [A.Expression] tuple :: RainParser [A.Expression]
tuple = do { sLeftR ; items <- expression `sepBy` sComma ; sRightR ; return items } tuple = do { sLeftR ; items <- expression `sepBy` sComma ; sRightR ; return items }