67 lines
1.4 KiB
Haskell
67 lines
1.4 KiB
Haskell
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module CommonParsing where
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import Data.Char
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import Data.Functor
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import Text.Parsec
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import Text.Parsec.Char
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import Text.Parsec.Combinator
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type Parser a b = Parsec String a b
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kw :: String -> Parser a ()
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kw s = string s $> ()
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kwIf :: Parser a ()
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kwIf = kw "if"
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kwThen :: Parser a ()
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kwThen = kw "then"
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kwElse :: Parser a ()
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kwElse = kw "else"
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kwState :: Parser a ()
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kwState = kw "state"
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kwEffect :: Parser a ()
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kwEffect = kw "effect"
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kwCombine :: Parser a ()
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kwCombine = kw "combine"
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kwRand :: Parser a ()
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kwRand = kw "rand"
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op :: String -> op -> Parser a op
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op s o = string s $> o
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int :: Parser a Int
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int = read <$> (many1 digit <* spaces)
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var :: [String] -> Parser a String
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var reserved =
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do
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c <- satisfy $ \c -> isLetter c || c == '_'
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cs <- many (satisfy isLetter <|> digit) <* spaces
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let name = c:cs
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if name `elem` reserved
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then fail "Can't use reserved keyword as identifier"
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else return name
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surround :: Char -> Char -> Parser a b -> Parser a b
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surround c1 c2 pe =
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do
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char c1 >> spaces
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e <- pe
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spaces >> char c2 >> spaces
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return e
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level :: (o -> e -> e -> e) -> Parser a o -> Parser a e -> Parser a e
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level c po pe =
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do
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e <- pe <* spaces
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ops <- many $ try $ (flip . c <$> (po <* spaces) <*> pe) <* spaces
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return $ foldl (flip ($)) e ops
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precedence :: (o -> e -> e -> e) -> Parser a e -> [ Parser a o ] -> Parser a e
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precedence = foldl . flip . level
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