Files
gf-core/src-3.0/PGF/Parsing/FCFG.hs
2008-05-30 13:07:11 +00:00

53 lines
1.8 KiB
Haskell

----------------------------------------------------------------------
-- |
-- Maintainer : Krasimir Angelov
-- Stability : (stable)
-- Portability : (portable)
--
-- FCFG parsing
-----------------------------------------------------------------------------
module PGF.Parsing.FCFG
(parseFCF,buildParserInfo,ParserInfo(..),makeFinalEdge) where
import GF.Data.ErrM
import GF.Data.Assoc
import GF.Data.SortedList
import PGF.CId
import PGF.Data
import PGF.Macros
import PGF.BuildParser
import PGF.Parsing.FCFG.Utilities
import PGF.Parsing.FCFG.Active
import qualified Data.Map as Map
----------------------------------------------------------------------
-- parsing
-- main parsing function
parseFCF :: String -- ^ parsing strategy
-> ParserInfo -- ^ compiled grammar (fcfg)
-> CId -- ^ starting category
-> [String] -- ^ input tokens
-> Err [Exp] -- ^ resulting GF terms
parseFCF strategy pinfo startCat inString =
do let inTokens = input inString
startCats <- case Map.lookup startCat (startupCats pinfo) of
Just cats -> return cats
Nothing -> fail $ "Unknown startup category: " ++ prCId startCat
fcfParser <- parseFCF strategy
let chart = fcfParser pinfo startCats inTokens
(i,j) = inputBounds inTokens
finalEdges = [makeFinalEdge cat i j | cat <- startCats]
forests = chart2forests chart (const False) finalEdges
filteredForests = forests >>= applyProfileToForest
return $ nubsort $ filteredForests >>= forest2exps
where
parseFCF :: String -> Err (FCFParser)
parseFCF "bottomup" = return $ parse "b"
parseFCF "topdown" = return $ parse "t"
parseFCF strat = fail $ "FCFG parsing strategy not defined: " ++ strat