blob: 0e5dafb38b8ab1ae9adcc472191a540ec39a0405 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
|
----------------------------------------------------------------------
-- |
-- Maintainer : PL
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/05/30 08:11:32 $
-- > CVS $Author: peb $
-- > CVS $Revision: 1.3 $
--
-- Removing epsilon linearizations from MCF grammars
-----------------------------------------------------------------------------
module GF.Conversion.RemoveEpsilon where
-- (convertGrammar) where
import GF.System.Tracing
import GF.Infra.Print
import Control.Monad
import Data.List (mapAccumL)
import Data.Maybe (mapMaybe)
import GF.Formalism.Utilities
import GF.Formalism.GCFG
import GF.Formalism.MCFG
import GF.Conversion.Types
import GF.Data.Assoc
import GF.Data.SortedList
import GF.Data.GeneralDeduction
convertGrammar :: EGrammar -> EGrammar
convertGrammar grammar = trace2 "RemoveEpsilon: initialEmpties" (prt initialEmpties) $
trace2 "RemoveEpsilon: emptyCats" (prt emptyCats) $
grammar
where initialEmpties = nubsort [ (cat, lbl) |
Rule (Abs cat _ _) (Cnc _ _ lins) <- grammar,
Lin lbl [] <- lins ]
emptyCats = limitEmpties initialEmpties
limitEmpties es = if es==es' then es else limitEmpties es'
where es' = nubsort [ (cat, lbl) | Rule (Abs cat _ _) (Cnc _ _ lins) <- grammar,
Lin lbl rhs <- lins,
all (symbol (\(c,l,n) -> (c,l) `elem` es) (const False)) rhs ]
|
