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|
----------------------------------------------------------------------
-- |
-- Maintainer : Krasimir Angelov
-- Stability : (stable)
-- Portability : (portable)
--
-- MCFG parsing, the active algorithm
-----------------------------------------------------------------------------
module GF.Parsing.FCFG.Active (parse) where
import GF.Data.GeneralDeduction
import GF.Data.Assoc
import GF.Data.Utilities
import GF.Formalism.GCFG
import GF.Formalism.FCFG
import GF.Formalism.MCFG(Lin(..))
import GF.Formalism.Utilities
import GF.Infra.Ident
import GF.Parsing.FCFG.Range
import GF.Parsing.FCFG.PInfo
import Control.Monad (guard)
import qualified Data.List as List
import qualified Data.Map as Map
import qualified Data.Set as Set
import Data.Array
----------------------------------------------------------------------
-- * parsing
parse :: (Ord c, Ord n, Ord t) => String -> FCFParser c n t
parse strategy pinfo starts toks =
[ Abs (cat, found) (zip rhs rrecs) fun |
Final ruleid found rrecs <- listXChartFinal chart,
let FRule (Abs cat rhs fun) _ = allRules pinfo ! ruleid ]
where chart = process strategy pinfo toks axioms emptyXChart
axioms | isBU strategy = initialBU pinfo toks
| isTD strategy = initialTD pinfo starts toks
isBU s = s=="b"
isTD s = s=="t"
-- used in prediction
emptyChildren :: Abstract c n -> [RangeRec]
emptyChildren (Abs _ rhs _) = replicate (length rhs) []
updateChildren :: [RangeRec] -> Int -> RangeRec -> [[RangeRec]]
updateChildren recs i rec = updateNthM update i recs
where update rec' = do guard (null rec' || rec' == rec)
return rec
makeMaxRange (Range _ j) = Range j j
makeMaxRange EmptyRange = EmptyRange
process :: (Ord c, Ord n, Ord t) => String -> FCFPInfo c n t -> Input t -> [Item] -> XChart c -> XChart c
process strategy pinfo toks [] chart = chart
process strategy pinfo toks (item:items) chart = process strategy pinfo toks items $! univRule item chart
where
univRule item@(Active ruleid found rng lbl ppos recs) chart
| inRange (bounds lin) ppos =
case lin ! ppos of
FSymCat c r d -> case insertXChart chart item c of
Nothing -> chart
Just chart -> let items = do Final _ found' _ <- lookupXChartFinal chart c
rng' <- concatRange rng (found' !! r)
recs' <- updateChildren recs d found'
return (Active ruleid found rng' lbl (ppos+1) recs')
++
do guard (isTD strategy)
ruleid <- topdownRules pinfo ? c
let FRule abs lins = allRules pinfo ! ruleid
return (Active ruleid [] EmptyRange 0 0 (emptyChildren abs))
in process strategy pinfo toks items chart
FSymTok tok -> let items = do (i,j) <- inputToken toks ? tok
rng' <- concatRange rng (makeRange i j)
return (Active ruleid found rng' lbl (ppos+1) recs)
in process strategy pinfo toks items chart
| otherwise =
if inRange (bounds lins) (lbl+1)
then univRule (Active ruleid (rng:found) EmptyRange (lbl+1) 0 recs) chart
else univRule (Final ruleid (reverse (rng:found)) recs) chart
where
(FRule (Abs cat _ fn) lins) = allRules pinfo ! ruleid
lin = lins ! lbl
univRule item@(Final ruleid found' recs) chart =
case insertXChart chart item cat of
Nothing -> chart
Just chart -> let items = do (Active ruleid found rng l ppos recs) <- lookupXChartAct chart cat
let FRule _ lins = allRules pinfo ! ruleid
FSymCat cat r d = lins ! l ! ppos
rng' <- concatRange rng (found' !! r)
recs' <- updateChildren recs d found'
return (Active ruleid found rng' l (ppos+1) recs')
++
do guard (isBU strategy)
ruleid <- leftcornerCats pinfo ? cat
let FRule abs lins = allRules pinfo ! ruleid
FSymCat cat r d = lins ! 0 ! 0
return (Active ruleid [] (found' !! r) 0 1 (updateNth (const found') d (emptyChildren abs)))
in process strategy pinfo toks items chart
where
(FRule (Abs cat _ fn) _) = allRules pinfo ! ruleid
----------------------------------------------------------------------
-- * XChart
data Item
= Active {-# UNPACK #-} !RuleId
RangeRec
Range
{-# UNPACK #-} !FLabel
{-# UNPACK #-} !FPointPos
[RangeRec]
| Final {-# UNPACK #-} !RuleId RangeRec [RangeRec]
deriving (Eq, Ord)
data XChart c = XChart !(ParseChart Item c) !(ParseChart Item c)
emptyXChart :: Ord c => XChart c
emptyXChart = XChart emptyChart emptyChart
insertXChart (XChart actives finals) item@(Active _ _ _ _ _ _) c =
case chartInsert actives item c of
Nothing -> Nothing
Just actives -> Just (XChart actives finals)
insertXChart (XChart actives finals) item@(Final _ _ _) c =
case chartInsert finals item c of
Nothing -> Nothing
Just finals -> Just (XChart actives finals)
lookupXChartAct (XChart actives finals) c = chartLookup actives c
lookupXChartFinal (XChart actives finals) c = chartLookup finals c
listXChartAct (XChart actives finals) = chartList actives
listXChartFinal (XChart actives finals) = chartList finals
----------------------------------------------------------------------
-- Earley --
-- called with all starting categories
initialTD :: (Ord c, Ord n, Ord t) => FCFPInfo c n t -> [c] -> Input t -> [Item]
initialTD pinfo starts toks =
do cat <- starts
ruleid <- topdownRules pinfo ? cat
let FRule abs lins = allRules pinfo ! ruleid
return $ Active ruleid [] (Range 0 0) 0 0 (emptyChildren abs)
----------------------------------------------------------------------
-- Kilbury --
-- terminal :: (Ord c, Ord n, Ord t) => FCFPInfo c n t -> Input t -> [Item]
-- terminal pinfo toks = $
-- tracePrt "MCFG.Active (Kilbury) - initial terminal rules" (prt . length) $
-- do ruleid <- emptyRules pinfo
-- let FRule abs lins = allRules pinfo ! ruleid
-- rrec <- mapM (rangeRestSyms toks EmptyRange . elems) (elems lins)
-- return $ Final ruleid rrec []
-- where
-- rangeRestSyms toks rng [] = return rng
-- rangeRestSyms toks rng (FSymTok tok:syms) = do (i,j) <- inputToken toks ? tok
-- rng' <- concatRange rng (makeRange i j)
-- rangeRestSyms toks rng' syms
initialBU :: (Ord c, Ord n, Ord t) => FCFPInfo c n t -> Input t -> [Item]
initialBU pinfo toks =
do tok <- aElems (inputToken toks)
ruleid <- leftcornerTokens pinfo ? tok ++
epsilonRules pinfo
let FRule abs lins = allRules pinfo ! ruleid
return $ Active ruleid [] EmptyRange 0 0 (emptyChildren abs)
|
