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| author | hallgren <hallgren@chalmers.se> | 2013-02-28 17:46:13 +0000 |
|---|---|---|
| committer | hallgren <hallgren@chalmers.se> | 2013-02-28 17:46:13 +0000 |
| commit | 8200145513b56b914c9c1896a8293ad4d5b58af9 (patch) | |
| tree | 60fd3a763ee1aaee4c17ddf2468ab1dd7f2ecb73 /src/compiler/GF/Data | |
| parent | 95d77e3c37fa97f770d845dd0d05890455f8119e (diff) | |
Fix a bug that could cause "Prelude.head: empty list"
In Data.Operations, the function topoTest2 assumed too much about the form of
the input, compared to the older function topoTest.
Diffstat (limited to 'src/compiler/GF/Data')
| -rw-r--r-- | src/compiler/GF/Data/Operations.hs | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/src/compiler/GF/Data/Operations.hs b/src/compiler/GF/Data/Operations.hs index 366f5a669..b70df6a90 100644 --- a/src/compiler/GF/Data/Operations.hs +++ b/src/compiler/GF/Data/Operations.hs @@ -266,8 +266,10 @@ topoTest = topologicalSort . mkRel' -- | topological sorting with test of cyclicity, new version /TH 2012-06-26 topoTest2 :: Ord a => [(a,[a])] -> Either [[a]] [[a]] -topoTest2 g = maybe (Right cycles) Left (tsort g) +topoTest2 g0 = maybe (Right cycles) Left (tsort g) where + g = g0++[(n,[])|n<-nub (concatMap snd g0)\\map fst g0] + cycles = findCycles (mkRel' g) tsort nes = |