diff options
| author | bringert <bringert@cs.chalmers.se> | 2006-12-17 13:29:12 +0000 |
|---|---|---|
| committer | bringert <bringert@cs.chalmers.se> | 2006-12-17 13:29:12 +0000 |
| commit | f252bb60901ce909719f2aad11e77fba7793ac60 (patch) | |
| tree | c84f33614c57ccad84a10894184d0a8de5364301 /src/GF | |
| parent | 0bf909b0fd50a29f9d52a82f50c12af0c6abbc9e (diff) | |
Some clean-up in GF/Speech/TransformCFG.hs
Diffstat (limited to 'src/GF')
| -rw-r--r-- | src/GF/Speech/TransformCFG.hs | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/src/GF/Speech/TransformCFG.hs b/src/GF/Speech/TransformCFG.hs index 27435ed89..38fb82b68 100644 --- a/src/GF/Speech/TransformCFG.hs +++ b/src/GF/Speech/TransformCFG.hs @@ -56,14 +56,6 @@ cfgToCFRules cfg = groupProds [CFRule (catToString c) (map symb r) n | CFRule c -- symb (Tok t) = Tok t catToString = prt --- | Group productions by their lhs categories -groupProds :: [CFRule_] -> CFRules -groupProds = Map.toList . Map.fromListWith (++) . map (\r -> (lhsCat r,[r])) - -ungroupProds :: CFRules -> [CFRule_] -ungroupProds = concat . map snd - - -- | Remove productions which use categories which have no productions removeEmptyCats :: CFRules -> CFRules removeEmptyCats = fix removeEmptyCats' @@ -84,6 +76,8 @@ removeIdenticalRules g = [(c,sortNubBy cmpRules rs) | (c,rs) <- g] cmpRules (CFRule c1 ss1 _) (CFRule c2 ss2 _) = mconcat [c1 `compare` c2, ss1 `compare` ss2] +-- * Removing left recursion + -- Paull's algorithm, see -- http://research.microsoft.com/users/bobmoore/naacl2k-proc-rev.pdf removeLeftRecursion :: CFRules -> CFRules @@ -125,6 +119,8 @@ isDirectLeftRecursive :: CFRule_ -> Bool isDirectLeftRecursive (CFRule c (Cat c':_) _) = c == c' isDirectLeftRecursive _ = False +-- * Removing cycles + removeCycles :: CFRules -> CFRules removeCycles = groupProds . removeCycles_ . ungroupProds where removeCycles_ rs = [r | r@(CFRule c rhs n) <- rs, rhs /= [Cat c]] @@ -133,6 +129,13 @@ removeCycles = groupProds . removeCycles_ . ungroupProds -- * CFG rule utilities -- +-- | Group productions by their lhs categories +groupProds :: [CFRule_] -> CFRules +groupProds = buildMultiMap . map (\r -> (lhsCat r,r)) + +ungroupProds :: CFRules -> [CFRule_] +ungroupProds = concat . map snd + allCats :: CFRules -> [Cat_] allCats = map fst |