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|
----------------------------------------------------------------------
-- |
-- Maintainer : Krasimir Angelov
-- Stability : (stable)
-- Portability : (portable)
--
-- FCFG parsing
-----------------------------------------------------------------------------
module GF.Parsing.FCFG
(parseFCF,buildFCFPInfo,FCFPInfo(..),makeFinalEdge) where
import GF.Data.SortedList
import GF.Data.Assoc
import GF.Infra.PrintClass
import GF.Formalism.Utilities
import qualified GF.Parsing.FCFG.Active as Active
import GF.Parsing.FCFG.PInfo
import GF.GFCC.DataGFCC
import GF.GFCC.CId
import GF.GFCC.Macros
import GF.Data.ErrM
import qualified Data.Map as Map
----------------------------------------------------------------------
-- parsing
-- main parsing function
parseFCF ::
String -> -- ^ parsing strategy
FCFPInfo -> -- ^ 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 <- Map.lookup startCat (startupCats pinfo)
fcfParser <- {- trace lctree $ -} 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
trees = nubsort $ filteredForests >>= forest2trees
return $ map tree2term trees
where
parseFCF :: String -> Err (FCFParser)
parseFCF "bottomup" = Ok $ Active.parse "b"
parseFCF "topdown" = Ok $ Active.parse "t"
parseFCF strat = Bad $ "FCFG parsing strategy not defined: " ++ strat
----------------------------------------------------------------------
-- parse trees to GFCC terms
tree2term :: SyntaxTree CId -> Exp
tree2term (TNode f ts) = tree (AC f) (map tree2term ts)
tree2term (TString s) = tree (AS s) []
tree2term (TInt n) = tree (AI n) []
tree2term (TFloat f) = tree (AF f) []
tree2term (TMeta) = exp0
----------------------------------------------------------------------
-- conversion and unification of forests
-- simplest implementation
applyProfileToForest :: SyntaxForest (CId,[Profile]) -> [SyntaxForest CId]
applyProfileToForest (FNode (fun,profiles) children)
| fun == wildCId = concat chForests
| otherwise = [ FNode fun chForests | not (null chForests) ]
where chForests = concat [ mapM (unifyManyForests . map (forests !!)) profiles |
forests0 <- children,
forests <- mapM applyProfileToForest forests0 ]
applyProfileToForest (FString s) = [FString s]
applyProfileToForest (FInt n) = [FInt n]
applyProfileToForest (FFloat f) = [FFloat f]
applyProfileToForest (FMeta) = [FMeta]
|
