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Added regexps grammar printer. This is a first step towards recursion-free SRGS.

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bringert
2007-06-20 16:08:23 +00:00
parent 91dcc27668
commit 6968004f19
4 changed files with 21 additions and 7 deletions
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8
src/GF/Speech/RegExp.hs
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@@ -19,14 +19,14 @@ data RE a =
deriving (Eq,Ord,Show)
dfa2re :: (Show a,Ord a) => DFA a -> RE a
dfa2re :: (Ord a) => DFA a -> RE a
dfa2re = finalRE . elimStates . modifyTransitions merge . addLoops
. oneFinalState () epsilonRE . mapTransitions RESymbol
where addLoops fa = newTransitions [(s,s,nullRE) | (s,_) <- states fa] fa
merge es = [(f,t,unionRE ls)
| ((f,t),ls) <- buildMultiMap [((f,t),l) | (f,t,l) <- es]]
elimStates :: (Show a, Ord a) => DFA (RE a) -> DFA (RE a)
elimStates :: (Ord a) => DFA (RE a) -> DFA (RE a)
elimStates fa =
case [s | (s,_) <- states fa, isInternal fa s] of
[] -> fa
@@ -120,10 +120,10 @@ joinRE (RESymbol ss) = ss
-- Debugging
prRE :: Show a => RE a -> String
prRE :: RE String -> String
prRE (REUnion []) = "<NULL>"
prRE (REUnion xs) = "(" ++ concat (intersperse " | " (map prRE xs)) ++ ")"
prRE (REConcat xs) = "(" ++ unwords (map prRE xs) ++ ")"
prRE (RERepeat x) = "(" ++ prRE x ++ ")*"
prRE (RESymbol s) = show s
prRE (RESymbol s) = s