diff options
| -rw-r--r-- | src/equation.hs | 14 | ||||
| -rw-r--r-- | src/main.hs | 21 | ||||
| -rw-r--r-- | src/parser.hs | 33 |
3 files changed, 50 insertions, 18 deletions
diff --git a/src/equation.hs b/src/equation.hs index 9053fa0..040812f 100644 --- a/src/equation.hs +++ b/src/equation.hs @@ -5,6 +5,7 @@ module Equation , degree , reduce , solve +, filterNull ) where import Data.List @@ -26,19 +27,26 @@ instance Show Term where show (Term c e) = show (round c) ++ " * X^" ++ show e instance Show Equation where - show (Equation l r) = showPolynomial l ++ " = " ++ showPolynomial r + show (Equation l r) = showPolynomial (filterNull l) + ++ " = " + ++ showPolynomial (filterNull r) where showPolynomial [] = "0" showPolynomial p = dropWhile (`elem` " +") $ foldl f "" (map show p) - where f s (c:cs) + where f s "" = s + f s (c:cs) | c == '-' = s ++ " - " ++ cs | otherwise = s ++ " + " ++ (c:cs) +filterNull :: Polynomial -> Polynomial +filterNull = filter (\t -> coefficient t /= 0) + equationMap :: (Polynomial -> Polynomial) -> Equation -> Equation equationMap f (Equation l r) = Equation (f l) (f r) degree :: Polynomial -> Int -degree p = Equation.exponent (maximum p) +degree [] = 0 +degree p = Equation.exponent (maximum p) reduce :: Equation -> Equation reduce equ = Equation (merge (left stdForm) (right stdForm)) [] diff --git a/src/main.hs b/src/main.hs index 20815f4..a11f7fc 100644 --- a/src/main.hs +++ b/src/main.hs @@ -1,20 +1,31 @@ import System.Environment +import System.IO +import System.IO.Error +import Control.Exception import Data.List import Parser import Equation - main :: IO () -main = do +main = catchIOError tryMain handler + where handler e + | isUserError e = putStrLn $ trimUserError (show e) + | otherwise = putStrLn "Error" + where trimUserError s = init $ tail $ dropWhile (/='(') s + +tryMain :: IO () +tryMain = do args <- getArgs checkArgs args equ <- checkParsing (head args) let reduced = reduce equ + l = filterNull $ left reduced putStrLn $ "Reduced From: " ++ show reduced - putStrLn $ "Polynomial degree: " ++ (show $ degree $ left reduced) - putSolutions (left reduced) - + putStrLn $ "Polynomial degree: " ++ (show $ degree l) + case l of [] -> putStrLn "Infinite solutions" + [_] -> putStrLn "No solution" + _ -> putSolutions l checkArgs :: [String] -> IO () checkArgs args diff --git a/src/parser.hs b/src/parser.hs index 6c2b8af..09b0421 100644 --- a/src/parser.hs +++ b/src/parser.hs @@ -59,32 +59,45 @@ spacesP :: Parser String spacesP = many (satisfy isSpace) sepBy :: Parser a -> Parser b -> Parser [a] -sepBy x sep = (:) <$> x <*> many (sep *> x) +sepBy x sep = many (sep *> x) - -intP :: Parser Int -intP = read <$> numStr +prefixedIntP :: Parser Int +prefixedIntP = read <$> numStr where numStr = ((:) <$> charP '-' <*> (spacesP *> digitsP)) <|> (charP '+' *> spacesP *> digitsP) - <|> digitsP + +intP :: Parser Int +intP = prefixedIntP <|> (read <$> digitsP) naturalP :: Parser Int naturalP = read <$> digitsP +signP :: Parser Char +signP = charP '-' <|> charP '+' + -- Equation parsers -termP :: Parser Term -termP = notConstantP <|> constantP - where constantP = (\c -> Term (fromIntegral c) 0) <$> intP + +unsignedTermP :: Parser Term +unsignedTermP = notConstantP <|> constantP + where constantP = (\c -> Term (fromIntegral c) 0) <$> naturalP notConstantP = (\coef exp -> Term (fromIntegral coef) exp) - <$> intP <*> (between *> naturalP) + <$> naturalP <*> (between *> naturalP) where between = spacesP *> charP '*' *> spacesP *> charP 'X' *> spacesP *> charP '^' *> spacesP +signedTermP :: Parser Term +signedTermP = signF <$> signP <*> (spacesP *> unsignedTermP) + where signF '-' (Term c e) = Term (-c) e + signF _ t = t + +firstTermP :: Parser Term +firstTermP = signedTermP <|> unsignedTermP + polynomialP :: Parser Polynomial -polynomialP = sepBy termP spacesP +polynomialP = ((:) <$> firstTermP <*> (spacesP *> (sepBy signedTermP spacesP))) equationP :: Parser Equation equationP = (\l r -> Equation l r) |