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|
----------------------------------------------------------------------
-- |
-- Maintainer : Peter Ljunglöf
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/04/21 16:22:01 $
-- > CVS $Author: bringert $
-- > CVS $Revision: 1.3 $
--
-- Simple implementation of deductive chart parsing
-----------------------------------------------------------------------------
module GF.Data.GeneralDeduction
(-- * Type definition
ParseChart,
-- * Main functions
chartLookup,
buildChart, buildChartM,
-- * Probably not needed
emptyChart,
chartMember,
chartInsert, chartInsertM,
chartList, chartKeys,
addToChart, addToChartM
) where
-- import Trace
import GF.Data.RedBlackSet
import Control.Monad (foldM)
----------------------------------------------------------------------
-- main functions
chartLookup :: (Ord item, Ord key) => ParseChart item key -> key -> [item]
chartList :: (Ord item, Ord key) => ParseChart item key -> [item]
chartKeys :: (Ord item, Ord key) => ParseChart item key -> [key]
buildChart :: (Ord item, Ord key) =>
(item -> key) -- ^ key lookup function
-> [ParseChart item key -> item -> [item]] -- ^ list of inference rules as functions
-- from triggering items to lists of items
-> [item] -- ^ initial chart
-> ParseChart item key -- ^ final chart
buildChartM :: (Ord item, Ord key) =>
(item -> [key]) -- ^ many-valued key lookup function
-> [ParseChart item key -> item -> [item]] -- ^ list of inference rules as functions
-- from triggering items to lists of items
-> [item] -- ^ initial chart
-> ParseChart item key -- ^ final chart
buildChart keyof rules axioms = addItems axioms emptyChart
where addItems [] = id
addItems (item:items) = addItems items . addItem item
-- addItem item | trace ("+ "++show item++"\n") False = undefined
addItem item = addToChart item (keyof item)
(\chart -> foldr (consequence item) chart rules)
consequence item rule chart = addItems (rule chart item) chart
buildChartM keysof rules axioms = addItems axioms emptyChart
where addItems [] = id
addItems (item:items) = addItems items . addItem item
-- addItem item | trace ("+ "++show item++"\n") False = undefined
addItem item = addToChartM item (keysof item)
(\chart -> foldr (consequence item) chart rules)
consequence item rule chart = addItems (rule chart item) chart
-- probably not needed
emptyChart :: (Ord item, Ord key) => ParseChart item key
chartMember :: (Ord item, Ord key) => ParseChart item key
-> item -> key -> Bool
chartInsert :: (Ord item, Ord key) => ParseChart item key
-> item -> key -> Maybe (ParseChart item key)
chartInsertM :: (Ord item, Ord key) => ParseChart item key
-> item -> [key] -> Maybe (ParseChart item key)
addToChart :: (Ord item, Ord key) => item -> key
-> (ParseChart item key -> ParseChart item key)
-> ParseChart item key -> ParseChart item key
addToChart item keys after chart = maybe chart after (chartInsert chart item keys)
addToChartM :: (Ord item, Ord key) => item -> [key]
-> (ParseChart item key -> ParseChart item key)
-> ParseChart item key -> ParseChart item key
addToChartM item keys after chart = maybe chart after (chartInsertM chart item keys)
--------------------------------------------------------------------------------
-- key charts as red/black trees
newtype ParseChart item key = KC (RedBlackMap key item)
deriving Show
emptyChart = KC rbmEmpty
chartMember (KC tree) item key = rbmElem key item tree
chartLookup (KC tree) key = rbmLookup key tree
chartList (KC tree) = concatMap snd (rbmList tree)
chartKeys (KC tree) = map fst (rbmList tree)
chartInsert (KC tree) item key = fmap KC (rbmInsert key item tree)
chartInsertM (KC tree) item keys = fmap KC (foldM insertItem tree keys)
where insertItem tree key = rbmInsert key item tree
--------------------------------------------------------------------------------}
{--------------------------------------------------------------------------------
-- key charts as unsorted association lists -- OBSOLETE!
newtype Chart item key = SC [(key, item)]
emptyChart = SC []
chartMember (SC chart) item key = (key,item) `elem` chart
chartInsert (SC chart) item key = if (key,item) `elem` chart then Nothing else Just (SC ((key,item):chart))
chartLookup (SC chart) key = [ item | (key',item) <- chart, key == key' ]
chartList (SC chart) = map snd chart
--------------------------------------------------------------------------------}
|
