{- | Module : $Header$

- Description : Implementation of logic formula parser

- Copyright : (c) Georgel Calin & Lutz Schroeder, DFKI Lab Bremen

- License : Similar to LGPL, see HetCATS/LICENSE.txt or LIZENZ.txt

- Maintainer : g.calin@jacobs-university.de

- Stability : provisional

- Portability : portable

-

- Provides the implementation of the generic parser for the L formula datatype

-}

module GMP.Parser where

import GMP.Generic

import Text.ParserCombinators.Parsec

data ModalOperator = Sqr | Ang | None

deriving Eq

-- | Main parser

par5er :: ModalOperator -> GenParser Char st a -> GenParser Char st (L a)

par5er flag pa = implFormula flag pa

-- | Parser which translates all implications in disjunctions & conjunctions

implFormula :: ModalOperator -> GenParser Char st a -> GenParser Char st (L a)

implFormula flag pa = do

f <- orFormula flag pa

option f (do string "->"

spaces

i <- implFormula flag pa

return $ Or (Neg f) i

<|> do try(string "<->")

spaces

i <- implFormula flag pa

return $ And (Or (Neg f) i) (Or f (Neg i))

<|> do string "<-"

spaces

i <- implFormula flag pa

return $ Or f (Neg i)

<|> do return f

<?> "GMPParser.implFormula")

-- | Parser for disjunction - used for handling binding order

orFormula :: ModalOperator -> GenParser Char st a -> GenParser Char st (L a)

orFormula flag pa = do

f <- andFormula flag pa

option f $ do

string "\\/"

spaces

g <- orFormula flag pa

return $ Or f g

<?> "GMPParser.orFormula"

-- | Parser for conjunction - used for handling the binding order

andFormula :: ModalOperator -> GenParser Char st a -> GenParser Char st (L a)

andFormula flag pa = do

f <- primFormula flag pa

option f $ do

string "/\\"

spaces

g <- andFormula flag pa

return $ And f g

<?> "GMPParser.andFormula"

{- | Parse a primitive formula: T, F, ~f, <i>f, [i]f, p*,

- where i stands for an index, f for a formula and

- * for a series of digits i.e. and integer -}

primFormula :: ModalOperator -> GenParser Char st a -> GenParser Char st (L a)

primFormula flag pa =

do string "T"

spaces

return T

<|> do string "F"

spaces

return F

<|> do f <- parenFormula flag pa

return f

<|> do string "~"

spaces

f <- primFormula flag pa

return $ nneg f

<|> do char '<'

spaces

i <- pa

spaces

char '>'

spaces

f <- primFormula flag pa

-- restrict to the default modal operator

case flag of

Ang -> return $ M i f

Sqr -> return $ Neg (M i (nneg f))

_ -> return $ M i f

<|> do char '['

spaces

i <- pa

spaces

char ']'

spaces

f <- primFormula flag pa

-- restrict to the default modal operator

case flag of

Sqr -> return $ M i f

Ang -> return $ Neg (M i (nneg f))

_ -> return $ M i f

<|> do char 'p'

i <- atomIndex

return $ Atom (fromInteger i)

<?> "GMPParser.primFormula"

-- | Parser for un-parenthesizing a formula

parenFormula :: ModalOperator -> GenParser Char st a -> GenParser Char st (L a)

parenFormula flag pa =

do char '('

spaces

f <- par5er flag pa

spaces

char ')'

spaces

return f

<?> "GMPParser.parenFormula"

-- | Parse integer number

natural :: GenParser Char st Integer

natural = fmap read $ many1 digit

-- | Parse the possible integer index of a variable

atomIndex :: GenParser Char st Integer

atomIndex = do i <- try natural

spaces

return $ i

<?> "GMPParser.atomIndex"

-- | Parsers for the different modal logic indexes

parseCindex :: Parser C

parseCindex = do -- checks whether there are more numbers to be parsed

let stopParser = do char ','

return False

<|> do char '}'

return True

<?> "Parser.parseCindex.stop"

-- checks whether the index is of the for x1,..,x&

let normalParser l = do x <- natural

let n = fromInteger x

spaces

q <- stopParser

spaces

case q of

False -> normalParser (n:l)

_ -> return (n:l)

<?> "Parser.parseCindex.normal"

char '{'

res <- try(normalParser [])

return $ C res

<|> do -- checks whether the index is of the form "n..m"

let shortParser = do x <- natural

let n = fromInteger x

spaces

string ".."

spaces

y <- natural

let m = fromInteger y

return $ [n..m]

<?> "Parser.parseCindex.short"

res <- try(shortParser)

return $ C res

<?> "Parser.parseCindex"

parseGindex :: Parser G

parseGindex = do n <- natural

return $ G (fromInteger n)

parseHMindex :: Parser HM

parseHMindex = do c <- letter

return $ HM c

<?> "Parser.parseHMindex"

parseKindex :: Parser K

parseKindex = return K

parseKDindex ::Parser KD

parseKDindex = return KD

parsePindex :: Parser P

parsePindex =

do x <- natural

let auxP n = do char '/'

m<-natural

return $ toRational (fromInteger n/fromInteger m)

<|> do char '.'

m<-natural

let noDig n

| n<10 = 1

| n>=10 = 1 + noDig (div n 10)

let rat n = toRational(fromInteger n /

fromInteger (10^(noDig n)))

let res = toRational n + rat m

return res

<|> do return $ toRational n

<?> "Parser.parsePindex.auxP"

aux <- auxP x

return $ P aux

parseMindex :: Parser Mon

parseMindex = return Mon