{- |

Module : $Header$

Copyright : (c) Florian Mossakowski, Uni Bremen 2006

License : GPLv2 or higher

Maintainer : till@informatik.uni-bremen.de

Stability : provisional

Portability : portable

parse terms and formulae

-}

module ConstraintCASL.Formula where

import Common.AnnoState

import Common.Id

import Common.Lexer

import Common.Token

import ConstraintCASL.AS_ConstraintCASL

import Text.ParserCombinators.Parsec

import CASL.AS_Basic_CASL

-- ------------------------------------------------------------------------

-- formula

-- ------------------------------------------------------------------------

cformula :: [String] -> AParser st ConstraintFORMULA

cformula k =

try(

do c1 <- conjunction k

impliesT

c2 <- conjunction k

return (Implication_ConstraintFormula c1 c2))

<|>

try(

do c1 <- conjunction k

equivalentT

c2 <- conjunction k

return (Equivalence_ConstraintFormula c1 c2))

<|>

do impliesT

c <- conjunction k

return (Axiom_ConstraintFormula c)

conjunction :: [String] -> AParser st ATOMCONJUNCTION

conjunction k =

do (atoms,_) <- atom k `separatedBy` anComma

return (Atom_Conjunction atoms)

atom :: [String] -> AParser st ATOM

atom k =

try (do r <- relation k

oParenT

(terms,_) <- constraintterm k `separatedBy` anComma

cParenT `notFollowedWith` (relation k)

return (Prefix_Atom r terms))

<|>

do t1 <- constraintterm k

r <- relation k

t2 <- constraintterm k

return (Infix_Atom t1 r t2)

simplerelation :: [String] -> AParser st RELATION

simplerelation k =

do emptyRelationT

return Empty_Relation

<|>

do equalityRelationT

return Equal_Relation

<|>

do oParenT

r <- relation k

cParenT

return r

<|>

do ide <- parseId k

return (Id_Relation ide)

<|>

do inverseT

r <- relation k

return (Inverse_Relation r)

relation :: [String] -> AParser st RELATION

relation k =

try ( do (rels,_) <- simplerelation k `separatedBy` anComma

return (Relation_Disjunction rels))

<|>

do r <- simplerelation k

return r

constraintterm :: [String] -> AParser st ConstraintTERM

constraintterm k =

try(do ide <- parseId k

return (Atomar_Term ide))

<|>

do ide <- parseId k

oParenT

(terms,_) <- constraintterm k `separatedBy` anComma

cParenT

return (Composite_Term ide terms)

formula :: [String] -> AParser st ConstraintCASLFORMULA

formula k = do x <- cformula k

return (ExtFORMULA x)

emptyRelation :: String

emptyRelation = "{}"

emptyRelationT :: GenParser Char st Token

emptyRelationT = pToken $ toKey emptyRelation

equalityRelation :: String

equalityRelation = "="

equalityRelationT :: GenParser Char st Token

equalityRelationT = pToken $ toKey equalityRelation

inverse :: String

inverse = "~"

inverseT :: GenParser Char st Token

inverseT = pToken $ toKey inverse

implies :: String

implies = "|-"

impliesT :: GenParser Char st Token

impliesT = pToken $ toKey implies

equivalent :: String

equivalent = "-||-"

equivalentT :: GenParser Char st Token

equivalentT = pToken $ toKey equivalent

constraintKeywords :: [String]

constraintKeywords = (equivalent:implies:[])

instance AParsable ConstraintFORMULA where

aparser = cformula []