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|
----------------------------------------------------------------------
-- |
-- Maintainer : PL
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/04/12 10:49:44 $
-- > CVS $Author: peb $
-- > CVS $Revision: 1.2 $
--
-- Adding coercion functions to a MCFG if necessary.
-----------------------------------------------------------------------------
module GF.Conversion.SimpleToMCFG.Coercions
(addCoercions) where
import GF.System.Tracing
import GF.Infra.Print
import GF.Formalism.Utilities
import GF.Formalism.GCFG
import GF.Formalism.MCFG
import GF.Conversion.Types
import GF.Data.SortedList
import List (groupBy)
----------------------------------------------------------------------
addCoercions :: MGrammar -> MGrammar
addCoercions rules = coercions ++ rules
where (allHeads, allArgs) = unzip [ ((head, lbls), nubsort args) |
Rule (Abs head args _) (Cnc lbls _ _) <- rules ]
allHeadSet = nubsort allHeads
allArgSet = union allArgs <\\> map fst allHeadSet
coercions = tracePrt "#MCFG coercions" (prt . length) $
concat $
tracePrt "#MCFG coercions per category" (prtList . map length) $
combineCoercions
(groupBy sameCatFst allHeadSet)
(groupBy sameCat allArgSet)
sameCatFst a b = sameCat (fst a) (fst b)
combineCoercions [] _ = []
combineCoercions _ [] = []
combineCoercions allHeads'@(heads:allHeads) allArgs'@(args:allArgs)
= case compare (mcat2scat $ fst $ head heads) (mcat2scat $ head args) of
LT -> combineCoercions allHeads allArgs'
GT -> combineCoercions allHeads' allArgs
EQ -> makeCoercion heads args : combineCoercions allHeads allArgs
makeCoercion heads args
= [ Rule (Abs arg [head] coercionName) (Cnc lbls [lbls] lins) |
(head@(MCat _ headCns), lbls) <- heads,
let lins = [ Lin lbl [Cat (head, lbl, 0)] | lbl <- lbls ],
arg@(MCat _ argCns) <- args,
argCns `subset` headCns ]
|
