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|
----------------------------------------------------------------------
-- |
-- Module : PrSLF
-- Maintainer : BB
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/09/07 14:21:30 $
-- > CVS $Author: bringert $
-- > CVS $Revision: 1.3 $
--
-- This module converts a CFG to an SLF finite-state network
-- for use with the ATK recognizer. The SLF format is described
-- in the HTK manual, and an example for use in ATK is shown
-- in the ATK manual.
--
-- FIXME: remove \/ warn \/ fail if there are int \/ string literal
-- categories in the grammar
-----------------------------------------------------------------------------
module GF.Speech.PrSLF (slfPrinter) where
import GF.Speech.SRG
import GF.Speech.TransformCFG
import GF.Speech.FiniteState
import GF.Infra.Ident
import GF.Formalism.CFG
import GF.Formalism.Utilities (Symbol(..))
import GF.Conversion.Types
import GF.Infra.Print
import GF.Infra.Option
import Data.Char (toUpper,toLower)
import Data.Maybe (fromMaybe)
data SLF = SLF { slfNodes :: [SLFNode], slfEdges :: [SLFEdge] }
data SLFNode = SLFNode { nId :: Int, nWord :: SLFWord }
-- | An SLF word is a word, or the empty string.
type SLFWord = Maybe String
data SLFEdge = SLFEdge { eId :: Int, eStart :: Int, eEnd :: Int }
slfPrinter :: Ident -- ^ Grammar name
-> Options -> CGrammar -> String
slfPrinter name opts cfg = prSLF (regularToSLF start rgr) ""
where start = getStartCat opts
rgr = makeRegular $ removeEmptyCats $ cfgToCFRules cfg
regularToSLF :: String -> CFRules -> SLF
regularToSLF s rs = automatonToSLF $ compileAutomaton s rs
automatonToSLF :: FA () (Maybe String) -> SLF
automatonToSLF fa =
SLF { slfNodes = map mkSLFNode (states fa'),
slfEdges = zipWith mkSLFEdge [0..] (transitions fa') }
where fa' = moveLabelsToNodes fa
mkSLFNode (i,w) = SLFNode { nId = i, nWord = w }
mkSLFEdge i (f,t,()) = SLFEdge { eId = i, eStart = f, eEnd = t }
prSLF :: SLF -> ShowS
prSLF (SLF { slfNodes = ns, slfEdges = es}) = header . unlinesS (map prNode ns) . unlinesS (map prEdge es)
where
header = showString "VERSION=1.0" . nl
. prFields [("N",show (length ns)),("L", show (length es))] . nl
prNode n = prFields [("I",show (nId n)),("W",showWord (nWord n))]
prEdge e = prFields [("J",show (eId e)),("S",show (eStart e)),("E",show (eEnd e))]
showWord :: SLFWord -> String
showWord Nothing = "!NULL"
showWord (Just w) = w -- FIXME: convert words to upper case
-- FIXME: could this be the empty string? if so, print as !NULL
prFields :: [(String,String)] -> ShowS
prFields fs = unwordsS [ showString l . showChar '=' . showString v | (l,v) <- fs ]
|
