module GF.Parsing.MCFG.Incremental (parse, parseR) where

import Data.List
import Control.Monad (guard) 

import GF.Data.Utilities (select)
import GF.Data.GeneralDeduction

import GF.Formalism.GCFG
import GF.Formalism.MCFG
import GF.Formalism.Utilities

import GF.Parsing.MCFG.Range
import GF.Parsing.MCFG.PInfo

import GF.System.Tracing
import GF.Infra.Print

----------------------------------------------------------------------
-- parsing

parse :: (Ord n, Ord c, Ord l, Ord t) => MCFParser c n l t
parse pinfo starts toks =
    [ Abs (cat, found) (zip rhs rrecs) fun |
      Final (Abs cat rhs fun) found rrecs <- chartLookup chart Fin ]
    where chart = process pinfo toks ntoks
	  ntoks = snd (inputBounds toks)

-- parseR :: (Ord n, Ord c, Ord l, Ord t) => MCFParser c n l t
parseR pinfo starts ntoks =
    [ Abs (cat, found) (zip rhs rrecs) fun |
      Final (Abs cat rhs fun) found rrecs <- chartLookup chart Fin ]
    where chart = processR pinfo ntoks 

process :: (Ord n, Ord c, Ord l, Ord t) => MCFPInfo c n l t -> Input t -> Int -> IChart c n l
process pinfo toks ntoks
    = tracePrt "MCFG.Incremental - chart size" prtSizes $
      buildChart keyof [complete ntoks, scan, combine, convert] (predict pinfo toks ntoks)

processR :: (Ord n, Ord c, Ord l) => MCFPInfo c n l Range -> Int -> IChart c n l
processR pinfo ntoks
    = tracePrt "MCFG.Incremental Range - chart size" prtSizes $
      buildChart keyof [complete ntoks, scan, combine, convert] (predictR pinfo ntoks)

complete ::  (Ord n, Ord c, Ord l) => Int -> IChart c n l -> Item c n l -> [Item c n l]
complete ntoks _ (Active rule found rng (Lin l []) lins recs) = 
    do (lin, lins') <- select lins
       k <- [minRange rng .. ntoks]
       return $ Active rule (found ++ [(l, rng)]) (Range (k,k)) lin lins' recs 
complete _ _ _ = []


predict :: (Ord n, Ord c, Ord l, Ord t) => MCFPInfo c n l t -> Input t -> Int -> [Item c n l]
predict pinfo toks n = 
    tracePrt "MCFG.Incremental - predicted rules" (prt . length) $
    do Rule abs@(Abs _ rhs _) (Cnc _ _ lins) <- rulesMatchingInput pinfo toks
       let daughters = replicate (length rhs) []
       lins' <- rangeRestRec toks lins
       (lin', lins'') <- select lins'
       k <- [0..n] 
       return $ Active abs [] (Range (k,k)) lin' lins'' daughters 


predictR :: (Ord n, Ord c, Ord l) => MCFPInfo c n l Range -> Int -> [Item c n l]
predictR pinfo n = 
    tracePrt "MCFG.Incremental Range - predicted rules" (prt . length) $
    do Rule abs@(Abs _ rhs _) (Cnc _ _ lins) <- allRules pinfo 
       let daughters = replicate (length rhs) []
       (lin, lins') <- select lins
       k <- [0..n] 
       return $ Active abs [] (Range (k,k)) lin lins' daughters 


scan :: (Ord n, Ord c, Ord l) => IChart c n l -> Item c n l -> [Item c n l]
scan _ (Active abs found rng (Lin l (Tok rng':syms)) lins recs) = 
    do rng'' <- concatRange rng rng' 
       return $ Active abs found rng'' (Lin l syms) lins recs 
scan _ _ = []


combine :: (Ord n, Ord c, Ord l) => IChart c n l -> Item c n l -> [Item c n l]
combine chart active@(Active _ _ rng (Lin _ (Cat (c,l,_):_)) _ _) = 
    do passive <- chartLookup chart (Pass c l (maxRange rng))
       combine2 active passive
combine chart passive@(Active (Abs c _ _) _ rng (Lin l []) _ _) = 
    do active <- chartLookup chart (Act c l (minRange rng))
       combine2 active passive
combine _ _ = [] 

combine2 (Active abs found rng (Lin l (Cat (c,l',d):syms)) lins recs) 
	     (Active _ found' rng' _ _ _)
    = do rng'' <- concatRange rng rng' 
	 recs' <- unifyRec recs d found''
	 return $ Active abs found rng'' (Lin l syms) lins recs'
    where found'' = found' ++ [(l',rng')]


convert _ (Active rule found rng (Lin lbl []) [] recs) = 
    return $ Final rule (found ++ [(lbl,rng)]) recs
convert _ _ = []

----------------------------------------------------------------------
-- type definitions

type IChart c n l = ParseChart (Item c n l) (IKey c l) 

data Item   c n l = Active (Abstract c n) 
                           (RangeRec l) 
			   Range 
			   (Lin c l Range) 
			   (LinRec c l Range) 
			   [RangeRec l]
		  | Final (Abstract c n) (RangeRec l) [RangeRec l]
--		  | Passive c (RangeRec l) 
		    deriving (Eq, Ord, Show)

data IKey     c l = Act c l Int
                  | Pass c l Int
		  | Useless
		  | Fin
		    deriving (Eq, Ord, Show)

keyof :: Item c n l -> IKey c l
keyof (Active _ _ rng (Lin _ (Cat (next,lbl,_):_)) _ _) 
    = Act next lbl (maxRange rng)
keyof (Active (Abs cat _ _) found rng (Lin lbl []) _ _) 
    = Pass cat lbl (minRange rng)
keyof (Final _ _ _) = Fin
keyof _                                                       
    = Useless


----------------------------------------------------------------------
-- for tracing purposes
prtSizes chart = "final=" ++ show (length (chartLookup chart Fin)) ++
		 ", passive=" ++ show (sum [length (chartLookup chart k) | 
					    k@(Pass _ _ _) <- chartKeys chart ]) ++
		 ", active=" ++ show (sum [length (chartLookup chart k) | 
					   k@(Act _ _ _) <- chartKeys chart ]) ++
		 ", useless=" ++ show (length (chartLookup chart Useless)) 

prtChart chart = concat [ "\n*** KEY: " ++ prt k ++ 
			  prtBefore "\n  " (chartLookup chart k) | 
			  k <- chartKeys chart ] 

instance (Print c, Print n, Print l) => Print (Item c n l) where
    prt (Active abs found rng lin tofind children) = 
	"? " ++ prt abs ++ ";\n\t" ++ 
	"{" ++ prtSep " " found ++ "} " ++ prt rng ++ " . " ++ 
	prt lin ++ "{" ++ prtSep " " tofind ++ "}" ++
        ( if null children then ";" else ";\n\t" ++
	  "{" ++ prtSep "} {" (map (prtSep " ") children) ++ "}" )
--    prt (Passive c rrec) = "- " ++ prt c ++ "; {" ++ prtSep " " rrec ++ "}"
    prt (Final abs rr rrs) = ": " ++ prt abs ++ ";\n\t{" ++ prtSep " " rr ++ "}" ++ 
			     ( if null rrs then ";" else ";\n\t" ++ 
			       "{" ++ prtSep "} {" (map (prtSep " ") rrs) ++ "}" )

instance (Print c, Print l) => Print (IKey c l) where
    prt (Act c l i) = "Active " ++ prt c ++ " " ++ prt l ++ " @ " ++ prt i
    prt (Pass c l i) = "Passive " ++ prt c ++ " " ++ prt l ++ " @ " ++ prt i
    prt (Fin) = "Final"
    prt (Useless) = "Useless"