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module CC.Parser(runPass, parseProgram) where
import Control.Monad
import Text.Parsec hiding (SourcePos, getPosition, token)
import qualified Text.Parsec
import CC.AST.Source
import CC.Context
import CC.Pretty
type Parser a = Parsec String () a
runPass :: Context -> RawString -> Either (PrettyShow ParseError) Program
runPass (Context path _) (RawString src) = fmapLeft PrettyShow (parseProgram path src)
where fmapLeft f (Left x) = Left (f x)
fmapLeft _ (Right x) = Right x
parseProgram :: FilePath -> String -> Either ParseError Program
parseProgram fname src = parse pProgram fname src
pProgram :: Parser Program
pProgram = do
prog <- Program <$> many pDecl
emptyLines
eof
return prog
pDecl :: Parser Decl
pDecl = Def <$> pDef
pDef :: Parser Def
pDef = do
func <- try $ do
emptyLines
name <- pName0 <?> "declaration head name"
return name
mtyp <- optionMaybe $ do
symbol "::"
typ <- pType
whitespace >> void newline
emptyLines
func' <- fst <$> pName0
guard (fst func == func')
return typ
args <- many pName
symbol "="
expr <- pExpr
return (Function mtyp func args expr)
pType :: Parser Type
pType = chainr1 pTypeAtom (symbol "->" >> return TFun)
pTypeAtom :: Parser Type
pTypeAtom = (wordToken "Int" >> return TInt) <|> pParenType
pParenType :: Parser Type
pParenType = do
token "("
tys <- pType `sepBy` token ","
token ")"
case tys of
[ty] -> return ty
_ -> return (TTup tys)
pExpr :: Parser Expr
pExpr = label (pLam <|> pLet <|> pCall) "expression"
where
pCall = do
atoms <- many1 pExprAtom
annot <- optionMaybe (do symbol "::"
p1 <- getPosition
ty <- pType
p2 <- getPosition
return (ty, SourceRange p1 p2))
let call = foldl1 (\a b -> Call (mergeRange (range a) (range b)) a b) atoms
case annot of
Just (ty, sr) -> return (Annot (mergeRange (range call) sr) call ty)
Nothing -> return call
pLam = do
p1 <- try $ do
whitespace
p <- getPosition
void (char '\\')
return p
names <- many1 pName
symbol "->"
body <- pExpr
p2 <- getPosition
return (Lam (SourceRange p1 p2) names body)
pLet = do
p1 <- try $ do
whitespace
p <- getPosition
void (string "let")
return p
afterKeyword p1
where
afterKeyword p1 = do
whitespace1
lhs <- pName0
symbol "="
rhs <- pExpr
let fullRange rest = mergeRange (SourceRange p1 p1) (range rest)
choice [ do p1' <- try $ do
whitespace
p1' <- getPosition
void (string "let")
return p1'
rest <- afterKeyword p1'
return (Let (fullRange rest) lhs rhs rest)
, do symbol "in"
body <- pExpr
return (Let (fullRange body) lhs rhs body) ]
pExprAtom :: Parser Expr
pExprAtom =
choice [ uncurry (flip Int) <$> pInt
, uncurry (flip Var) <$> pName
, pParenExpr ]
pParenExpr :: Parser Expr
pParenExpr = do
p1 <- getPosition
token "("
exprs <- pExpr `sepBy` token ","
token ")"
p2 <- getPosition
case exprs of
[expr] -> return expr
_ -> return (Tup (SourceRange p1 p2) exprs)
pInt :: Parser (Int, SourceRange)
pInt = try (whitespace >> pInt0)
where
pInt0 = do
p1 <- getPosition
num <- read <$> many1 digit
p2 <- getPosition
return (num, SourceRange p1 p2)
pName0 :: Parser (Name, SourceRange)
pName0 = do
p1 <- getPosition
s <- try $ do
c <- pWordFirstChar
cs <- many pWordMidChar
let s = c : cs
guard (s `notElem` ["let", "in"])
return s
p2 <- getPosition
notFollowedBy pWordMidChar
return (s, SourceRange p1 p2)
pWordFirstChar :: Parser Char
pWordFirstChar = letter <|> oneOf "_$#!"
pWordMidChar :: Parser Char
pWordMidChar = alphaNum <|> oneOf "_$#!"
pName :: Parser (Name, SourceRange)
pName = try (whitespace >> pName0)
symbol :: String -> Parser ()
symbol s = token s >> (eof <|> void space <|> void (oneOf "(){}[]"))
wordToken :: String -> Parser ()
wordToken s = token s >> notFollowedBy pWordMidChar
token :: String -> Parser ()
token s = try (whitespace >> void (string s))
emptyLines :: Parser ()
emptyLines = (try (whitespace >> newline) >> emptyLines) <|> try (whitespace >> eof) <|> return ()
whitespace, whitespace1 :: Parser ()
whitespace = void (many (void (char ' ') <|> void (try (string "\n "))))
whitespace1 = void (many1 (void (char ' ') <|> void (try (string "\n "))))
getPosition :: Parser SourcePos
getPosition = do
pos <- Text.Parsec.getPosition
return (SourcePos (sourceLine pos - 1) (sourceColumn pos - 1))
|
