43 lines
1 KiB
Haskell
43 lines
1 KiB
Haskell
{- |
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Module : Civilisation
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Description :
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Copyright : (c) Dimitri Lozeve
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License : BSD3
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Maintainer : Dimitri Lozeve <dimitri.lozeve@gmail.com>
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Stability : unstable
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Portability : portable
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-}
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import Data.Maybe
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import Sat
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-- Main entry point of the program
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main :: IO ()
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main = do
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text <- readFile "test.cnf"
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let f = parseDIMACS text in
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case solveDPLL (f, []) of
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UNSAT -> putStrLn "UNSAT"
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SAT a -> putStrLn $ "SAT " ++ show a
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-- Parses a formula in the DIMACS CNF format.
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parseDIMACS :: String -> CNF
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parseDIMACS = mapMaybe parseClause . lines
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-- Parses a clause (a single line in the DIMACS file).
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parseClause :: String -> Maybe Clause
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parseClause "" = Nothing
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parseClause ('c':_) = Nothing
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parseClause ('p':_) = Nothing
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parseClause ('%':_) = Nothing
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parseClause ('0':_) = Nothing
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parseClause s = (Just . map (litFromInt . read) . init . words) s
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-- Interprets an Int, such as (-5), as a Lit, such as (Neg 5).
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litFromInt :: Int -> Lit
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litFromInt n | n < 0 = Neg (-n)
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| otherwise = Pos n
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