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Fix handling of external categories in SRG generation.

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This commit is contained in:
bjorn
2008-06-16 15:49:17 +00:00
parent 361c6cb096
commit 395dd70f58
5 changed files with 27 additions and 13 deletions
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5
src-3.0/GF/Speech/CFG.hs
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@@ -80,12 +80,13 @@ bottomUpFilter gr = fix grow (gr { cfgRules = Map.empty })
where grow g = g `unionCFG` filterCFG (all (okSym g) . ruleRhs) gr
okSym g = symbol (`elem` allCats g) (const True)
-- | Removes categories which are not reachable from the start category.
-- | Removes categories which are not reachable from any external category.
topDownFilter :: CFG -> CFG
topDownFilter cfg = filterCFGCats (isRelatedTo uses (cfgStartCat cfg)) cfg
topDownFilter cfg = filterCFGCats (`Set.member` keep) cfg
where
rhsCats = [ (lhsCat r, c') | r <- allRules cfg, c' <- filterCats (ruleRhs r) ]
uses = reflexiveClosure_ (allCats cfg) $ transitiveClosure $ mkRel rhsCats
keep = Set.unions $ map (allRelated uses) $ Set.toList $ cfgExternalCats cfg
-- | Merges categories with identical right-hand-sides.
-- FIXME: handle probabilities