66 lines
1.7 KiB
Haskell
66 lines
1.7 KiB
Haskell
module Parser where
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import Monpar
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import Control.Applicative ((<|>), Alternative, many, some)
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import Data.Char (isDigit, digitToInt)
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import Control.Monad (MonadPlus(mzero), void)
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type ZorthAST = [ZorthExpr]
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data ZorthExpr = ZorthASTInteger Int
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| ZorthASTWord String
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| ZorthASTWordDecl (String,ZorthAST)
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deriving Show
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word1 :: Parser String
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word1 = do
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x <- sat (\x -> x /= '\n' && x /= ' ')
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xs <- word
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return $ x:xs
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nonsenseSymbol :: Parser Char
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nonsenseSymbol = char ' ' <|> char '\n'
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skipNonsenseSymbols :: Parser [Char]
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skipNonsenseSymbols = many nonsenseSymbol
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digit :: Parser Int
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digit = digitToInt <$> sat isDigit
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pZorthUnsignedInteger :: Parser ZorthExpr
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pZorthUnsignedInteger = ZorthASTInteger . foldr (\n t -> n + t*10) 0 . reverse <$> some digit
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pZorthSignedInteger :: Parser ZorthExpr
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pZorthSignedInteger = do
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char '-'
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(ZorthASTInteger i) <- pZorthUnsignedInteger
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return $ ZorthASTInteger $ negate i
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pZorthInteger :: Parser ZorthExpr
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pZorthInteger = do
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skipNonsenseSymbols
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i <- pZorthSignedInteger <|> pZorthUnsignedInteger
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eof <|> void nonsenseSymbol
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return i
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pZorthWord :: Parser ZorthExpr
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pZorthWord = do
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skipNonsenseSymbols
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ZorthASTWord <$> word1
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pZorthWordDecl :: Parser ZorthExpr
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pZorthWordDecl = do
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ZorthASTWord ":" <- pZorthWord
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ZorthASTWord name <- pZorthWord
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xs <- manyTill pZorthExpr (do { ZorthASTWord ";" <- pZorthWord; return () })
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return $ ZorthASTWordDecl (name,xs)
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pZorthExpr :: Parser ZorthExpr
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pZorthExpr = pZorthWordDecl <++ pZorthInteger <++ pZorthWord
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pZorth :: Parser ZorthAST
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pZorth = some pZorthExpr
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parseZorth :: String -> ZorthAST
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parseZorth = fst . head . runParser pZorth
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