Added speech recognition grammar generation code. There is no way yet to invoke the SRG printer, and only SRGS is included.

src-3.0/GF/Speech/SRG.hs

@@ -0,0 +1,175 @@
+----------------------------------------------------------------------
+-- |
+-- Module      : SRG
+--
+-- Representation of, conversion to, and utilities for 
+-- printing of a general Speech Recognition Grammar. 
+--
+-- FIXME: remove \/ warn \/ fail if there are int \/ string literal
+-- categories in the grammar
+----------------------------------------------------------------------
+module GF.Speech.SRG (SRG(..), SRGRule(..), SRGAlt(..), SRGItem
+                     , SRGNT, CFTerm
+                     , makeSRG
+                     , makeSimpleSRG
+                     , makeNonRecursiveSRG
+                     , lookupFM_, prtS
+                     ) where
+
+import GF.Data.Operations
+import GF.Data.Utilities
+import GF.Infra.Ident
+import GF.Infra.PrintClass
+import GF.Speech.CFG
+import GF.Speech.PGFToCFG
+import GF.Speech.Relation
+import GF.Speech.FiniteState
+import GF.Speech.RegExp
+import GF.Speech.CFGToFA
+import GF.Infra.Option
+import PGF.CId
+import PGF.Data
+import PGF.Macros
+
+import Data.List
+import Data.Maybe (fromMaybe, maybeToList)
+import Data.Map (Map)
+import qualified Data.Map as Map
+import Data.Set (Set)
+import qualified Data.Set as Set
+
+import Debug.Trace
+
+data SRG = SRG { srgName :: String    -- ^ grammar name
+		 , srgStartCat :: Cat     -- ^ start category name
+                 , srgExternalCats :: Set Cat
+                 , srgLanguage :: Maybe String -- ^ The language for which the grammar 
+                                                   --   is intended, e.g. en-UK
+	         , srgRules :: [SRGRule] 
+	       }
+	 deriving (Eq,Show)
+
+data SRGRule = SRGRule Cat [SRGAlt] -- ^ SRG category name, original category name
+	                                      --   and productions
+	     deriving (Eq,Show)
+
+-- | maybe a probability, a rule name and an EBNF right-hand side
+data SRGAlt = SRGAlt (Maybe Double) CFTerm SRGItem
+	      deriving (Eq,Show)
+
+type SRGItem = RE SRGSymbol
+
+type SRGSymbol = Symbol SRGNT Token
+
+-- | An SRG non-terminal. Category name and its number in the profile.
+type SRGNT = (Cat, Int)
+
+
+-- | Create a non-left-recursive SRG. 
+--   FIXME: the probabilities in the returned 
+--   grammar may be meaningless.
+makeSimpleSRG :: PGF
+              -> CId -- ^ Concrete syntax name.
+	      -> SRG
+makeSimpleSRG = makeSRG preprocess 
+    where
+      preprocess = traceStats "After mergeIdentical"
+                   . mergeIdentical
+                   . traceStats "After removeLeftRecursion"
+                   . removeLeftRecursion 
+                   . traceStats "After topDownFilter" 
+                   . topDownFilter
+                   . traceStats "After bottomUpFilter"
+                   . bottomUpFilter
+                   . traceStats "After removeCycles"
+                   . removeCycles 
+                   . traceStats "Inital CFG"
+
+traceStats s g = trace ("---- " ++ s ++ ": " ++ stats g {- ++ "\n" ++ prCFRules g ++ "----" -}) g
+
+stats g = "Categories: " ++ show (countCats g)
+          ++ " Rules: " ++ show (countRules g)
+
+makeNonRecursiveSRG :: PGF
+                    -> CId -- ^ Concrete syntax name.
+                    -> SRG
+makeNonRecursiveSRG pgf cnc = 
+      SRG { srgName = prCId cnc,
+	    srgStartCat = start,
+            srgExternalCats = cfgExternalCats cfg,
+            srgLanguage = getSpeechLanguage pgf cnc,
+	    srgRules = rs }
+  where
+    cfg = pgfToCFG pgf cnc
+    MFA start dfas = cfgToMFA cfg
+    rs = [SRGRule l [SRGAlt Nothing dummyCFTerm (dfaToSRGItem dfa)] | (l,dfa) <- dfas]
+      where dfaToSRGItem = mapRE dummySRGNT . minimizeRE . dfa2re
+            dummyCFTerm = CFMeta (mkCId "dummy")
+            dummySRGNT = mapSymbol (\c -> (c,0)) id
+
+makeSRG :: (CFG -> CFG)
+	-> PGF
+        -> CId -- ^ Concrete syntax name.
+	-> SRG
+makeSRG preprocess pgf cnc = 
+      SRG { srgName = prCId cnc,
+	    srgStartCat = cfgStartCat cfg,
+            srgExternalCats = cfgExternalCats cfg,
+            srgLanguage = getSpeechLanguage pgf cnc,
+	    srgRules = rs }
+    where 
+    cfg = pgfToCFG pgf cnc
+    (_,cfgRules) = unzip $ allRulesGrouped $ preprocess cfg
+    rs = map cfRulesToSRGRule cfgRules
+
+getSpeechLanguage :: PGF -> CId -> Maybe String
+getSpeechLanguage pgf cnc = fmap (replace '_' '-') $ lookConcrFlag pgf cnc (mkCId "language")
+
+cfRulesToSRGRule :: [CFRule] -> SRGRule
+cfRulesToSRGRule rs@(r:_) = SRGRule (lhsCat r) rhs
+    where 
+      alts = [((n,Nothing),mkSRGSymbols 0 ss) | CFRule c ss n <- rs]
+      rhs = [SRGAlt p n (srgItem sss) | ((n,p),sss) <- buildMultiMap alts ]
+
+      mkSRGSymbols _ [] = []
+      mkSRGSymbols i (NonTerminal c:ss) = NonTerminal (c,i) : mkSRGSymbols (i+1) ss
+      mkSRGSymbols i (Terminal t:ss)    = Terminal t : mkSRGSymbols i ss
+
+allSRGCats :: SRG -> [String]
+allSRGCats SRG { srgRules = rs } = [c | SRGRule c _ <- rs]
+
+--
+-- * Size-optimized EBNF SRGs
+--
+
+srgItem :: [[SRGSymbol]] -> SRGItem
+srgItem = unionRE . map mergeItems . sortGroupBy (compareBy filterCats)
+-- non-optimizing version:
+--srgItem = unionRE . map seqRE
+
+-- | Merges a list of right-hand sides which all have the same 
+-- sequence of non-terminals.
+mergeItems :: [[SRGSymbol]] -> SRGItem
+mergeItems = minimizeRE . ungroupTokens . minimizeRE . unionRE . map seqRE . map groupTokens
+
+groupTokens :: [SRGSymbol] -> [Symbol SRGNT [Token]]
+groupTokens [] = []
+groupTokens (Terminal t:ss) = case groupTokens ss of
+                                Terminal ts:ss' -> Terminal (t:ts):ss'
+                                ss'             -> Terminal [t]:ss'
+groupTokens (NonTerminal c:ss) = NonTerminal c : groupTokens ss
+
+ungroupTokens :: RE (Symbol SRGNT [Token]) -> RE SRGSymbol
+ungroupTokens = joinRE . mapRE (symbol (RESymbol . NonTerminal) (REConcat . map (RESymbol . Terminal)))
+
+--
+-- * Utilities for building and printing SRGs
+--
+
+lookupFM_ :: (Ord key, Show key) => Map key elt -> key -> elt
+lookupFM_ fm k = Map.findWithDefault err k fm
+  where err = error $ "Key not found: " ++ show k
+                      ++ "\namong " ++ show (Map.keys fm)
+
+prtS :: Print a => a -> ShowS
+prtS = showString . prt